A proposed seawater air conditioning plant in Honolulu, Hawaii will draw cold seawater from the deep ocean, and a potential agricultural resource with it: phosphorus.
Credit: Sam Kimbrel

By Alexandra Branscombe

WASHINGTON, DC – Discharged seawater pumped from the ocean and used for a renewable air conditioning system would overload surface waters with minerals that could potentially be captured instead for use in agriculture, according to a noted oceanographer.

Pumps designed to move thousands of tons of water from the sea floor to a proposed Honolulu air-conditioning plant would bring up phosphates located hundreds of feet below the ocean surface, David Karl told an audience of scientists, ocean-policy experts, and students on March 13 at the Smithsonian National Museum of Natural History in Washington, D.C.

When phosphate-rich water is discharged, the sudden availability of the nutrient at the ocean surface is known to cause rapid growth and reproduction of phytoplankton, which can change water transparency and color, and impact marine ecosystems. But instead of being discharged into the ocean, the mineral could be extracted and used as fertilizer by local farmers, Karl said.

“Development of a marine-based, phosphate-capture and reuse process is a major contemporary challenge for science, society, and sustainability,” said Karl, who is a professor of oceanography at the University of Hawaii at Manoa, in Honolulu. He discussed the plant during his 2014 Roger Revelle Commemorative Lecture as an example of solving a sustainability challenge using oceanographic research.

Farmers around the world are facing an impending shortage of terrestrial phosphate, which is mainly used as an agricultural fertilizer, Karl noted. However, the ocean is a rich reservoir of dissolved phosphate. Marine microbes, such as phytoplankton, take in phosphorus and then sink to the depths when they die. As a result, deeper ocean water contains phosphate in higher concentrations than surface water. The only difficulty is finding a method to access the low-lying phosphate and then concentrate it into mineral form, Karl said.

The sea water air conditioning plant will use deep ocean water to cool freshwater that will be cycled through downtown buildings as a sustainable air conditioning technology.
Photo Credit: OTEC

The proposed seawater air conditioning plant could be a test bed for solving the looming phosphate shortage and making seawater-based air-conditioning more environmentally friendly, he added. Unlike conventional air conditioning, the proposed plant could help Honolulu use less fossil fuel and conserve fresh water by recycling it within the system, Karl said.

Cold seawater drawn from more than 1,700 feet below sea level would be used to cool freshwater at the plant. The system would then pump the low-temperature freshwater into city buildings with existing chilled-water air-conditioning systems. Meanwhile, it would return used seawater to the ocean.

Karl said that his early field research has shown that removing phosphate from the seawater used in such a plant before discharging the effluent would prevent phytoplankton blooms.

The chief science adviser of Ocean Thermal Energy Conversion, a company contributing part of the cooling technology for the Honolulu plant, downplayed ecological concerns from discharging the plant’s used seawater. The plant would discard it through a diffuser system offshore and in deep water so as not to greatly affect surface waters or coral communities, said Stephen Oney, in a separate interview.

Karl gave his talk as the latest in a long-standing series of lectures in honor of famed oceanographer Roger Revelle, and created by the Ocean Studies Board of the National Research Council. The series focuses on the connection between ocean sciences and public policy. Revelle served as president for AGU’s Ocean Sciences section from 1956 until 1959.

 – Alexandra Branscombe is a science writing intern in AGU’s Public Information department

By Katy Human

During two days of intensive airborne measurements, oil and gas operations in Colorado’s Front Range leaked nearly three times as much methane, a greenhouse gas, as predicted based on inventory estimates, and seven times as much benzene, a regulated air toxic. Emissions of other chemicals that contribute to summertime ozone pollution were about twice as high as estimates, according to the new paper, accepted for publication in the American Geophysical Union’s Journal of Geophysical Research: Atmospheres.

“These discrepancies are substantial,” said lead author Gabrielle Petron, an atmospheric scientist with NOAA’s Cooperative Institute for Research in Environmental Sciences at the University of Colorado Boulder. “Emission estimates or ‘inventories’ are the primary tool that policy makers and regulators use to evaluate air quality and climate impacts of various sources, including oil and gas sources. If they’re off, it’s important to know.”

The new paper provides independent confirmation of findings from research performed from 2008-2010, also by Petron and her colleagues, on the magnitude of air pollutant emissions from oil and gas activities in northeastern Colorado. In the earlier study, the team used a mobile laboratory—sophisticated chemical detection instruments packed into a car—and an instrumented NOAA tall tower near Erie, Colo. to measure atmospheric concentrations of several chemicals downwind of various sources, including oil and gas equipment, landfills and animal feedlots.

A drilling rig and associated equipment near a neighborhood in Weld County, Colorado, just south of Dacono. During two days of measurements in May 2012, researchers found oil and gas activities in northeastern Colorado released more methane, pollution precursors and benzene than estimated by regulators. The large structure on the left is a water tower.
Credit: David Oonk, CIRES

Back then, the scientists determined that methane emissions from oil and gas activities in the region were likely about twice as high as estimates from state and federal agencies, and benzene emissions were several times higher. In 2008, northeastern Colorado’s Weld County had about 14,000 operating oil and gas wells, all located in a geological formation called the Denver-Julesburg Basin.

In May 2012, when measurements for the new analysis were collected, there were about 24,000 active oil and gas wells in Weld County. The new work relied on a different technique, too, called mass-balance. In 2012, Petron and her colleagues contracted with a small aircraft to measure the concentrations of methane and other chemicals in the air downwind and upwind of the Denver-Julesburg Basin. On the ground, NOAA wind profilers near Platteville and Greeley tracked around-the-clock wind speed and wind direction.

When winds are steady and other key atmospheric conditions are met, the researchers can calculate emissions within a region by placing a virtual “box” over it. The difference between the amount of methane leaving (downwind) and entering (upwind) the box lets the scientists calculate emissions inside.

On two days in May 2012, conditions were ideal for mass-balance work. Petron and her team calculated that 26 metric tons of methane were emitted hourly in a region centered on Weld County. To estimate the fraction from oil and gas activities, the authors subtracted inventory estimates of methane emissions from other sources, including animal feedlots, landfills and wastewater treatment plants. Petron and her team found that during those two days, oil and gas operations in the Denver-Julesburg Basin emitted about 19 metric tons of methane per hour, 75 percent of the total methane emissions. That’s about three times as large as an hourly average estimate for oil and gas operations based on Environmental Protection Agency’s (EPA’s) Greenhouse Gas Reporting Program (itself based on industry-reported emissions).

Petron and her colleagues combined information from the mass-balance technique and detailed chemical analysis of air samples in the laboratory to come up with emissions estimates for volatile organic compounds, a class of chemicals that contribute to ozone pollution; and benzene, an air toxic.

Atmospheric scientist and pilot Stephen Conley (University of California Davis and Scientific Aviation) prepares to take off from Boulder Municipal Airport in a single-engine Mooney TLS aircraft, retrofitted for atmospheric research, in May 2012. During two days of measurements that month, researchers found oil and gas activities in northeastern Colorado released more methane, ozone pollution precursors and benzene than estimated by regulators.
Credit: Will von Dauster, NOAA

Benzene emissions from oil and gas activities reported in the paper are significantly higher than state estimates: about 380 pounds (173 kilograms) per hour, compared with a state estimate of about 50 pounds (25 kilograms) per hour. Car and truck tailpipes are a known source of the toxic chemical; the new results suggest that oil and gas operations may also be a significant source.

Oil-and-gas-related emissions for a subset of volatile organic compounds (VOCs), which can contribute to ground-level ozone pollution, were about 25 metric tons per hour, compared to the state inventory, which amounts to 13.1 tons. Ozone at high levels can harm people’s lungs and damage crops and other plants; the northern Front Range of Colorado has been out of compliance with federal health-based 8-hour ozone standards since 2007, according to the EPA. Another CIRES- and NOAA-led paper published last year showed that oil and natural gas activities were responsible for about half of the contributions of VOCs to ozone formation in northeastern Colorado.

This summer, dozens of atmospheric scientists from NASA, the National Center for Atmospheric Research, NOAA, CIRES and other institutions will gather in the Front Range, to participate in an intensive study of the region’s atmosphere. With research aircraft, balloon-borne measurements, mobile laboratories and other ground-based equipment, the scientists hope to further characterize the emissions of many possible sources, including agriculture, animals, and oil and gas activities.

CIRES is a partnership of NOAA and CU-Boulder. Authors of “A new look at methane and non-methane hydrocarbon emissions from oil and natural gas operations in the Colorado Denver-Julesburg Basin,” include 26 scientists from CIRES; NOAA’s Earth System Research Laboratory; the Institute for Arctic and Alpine Research at CU-Boulder; the University of California, Davis; and the University of Colorado Boulder. Funding for the work, which is published in the Journal of Geophysical Research: Atmospheres, came from the Environmental Defense Fund, NOAA (the Office of Oceanic and Atmospheric Research and the Climate Program Office) and the National Science Foundation.

Guest blogger Katy Human is Communications Director of the Cooperative Institute for Research in Environmental Sciences (CIRES) at the University of Colorado Boulder.

By Alexandra Branscombe

“The Arctic in the Anthropocene: Emerging Research Questions” was released in April as an effort by the National Research Council to help chart the course of future research in the region as it goes through rapid change in the area.
Credit: National Research Council

WASHINGTON, DC – What is hidden within and beneath Arctic ice? Why does winter matter? What is being irretrievably lost as the Arctic changes?

These are just some of the emerging questions that scientists are being challenged to answer about the rapidly changing Arctic in a new report, “The Arctic in the Anthropocene: Emerging Research Questions,” released last month by the National Research Council’s Committee on Emerging Research Questions.

The report focuses on questions sparked by recent discoveries about the Arctic and new tools available to investigate the region, said Henry Huntington, an Arctic scientist with the Pew Charitable Trusts in Eagle River, Alaska, who co-chaired the report. Huntington spoke during an April 29 webinar announcing the report, which was written by an international committee of Arctic experts and scientists.

The report’s authors hope to inspire a wave of scientific research that is better equipped to study the changing Arctic. Interest in the region is rising as it undergoes rapid transformations as a result of global warming, they said.

For example, future research should tackle the “Hidden Arctic” – areas of the Arctic that have not been studied because they couldn’t be reached, but are now accessible because glaciers and other ice are melting. Researchers should also explore what is being irretrievably lost as the Arctic changes, including the threat that melting permafrost and ice pose to archeological sites and rare habitats, the report said.

“Our focus was on emerging research questions, distinguished from existing questions that have been asked for a while,” Huntington said. “Existing questions deserve continued attention … The focus on our task is to ask emerging questions on newly recognized phenomena, build on recent results, or on new technology that allows us to do things we couldn’t before.”

Scientists have a lot to sink their teeth into as the Arctic changes, Huntington said, including vanishing sea ice, retreating glaciers, melting permafrost, and the rippling global ecological effects that come with these scenarios.

“The Arctic is increasingly connected to the rest of the world,” Huntington noted. “Whatever happens in the Arctic does not stay in the Arctic.”

Research questions should also not be limited to one field of study, according to the report. New research needs to draw from various scientific disciplines, like anthropology and geoscience, and also include investment from public sources and private industry, the report’s authors said.

This time series from NASA satellites show Arctic sea ice declining from year to year at a rate of 11.5 percent per decade. A new report published by the National Research Council calls for more international and interdisciplinary research strategies to tackle emerging questions in the Arctic.
Credit: NASA/Goddard Scientific Visualization Studio

Huntington said interdisciplinary or international Arctic research that is happening now is not well coordinated. Instead, there should be better systems in place to connect researchers, investors, and the public.

The report also highlights the role humans play in the Arctic, explained Stephanie Pfirman, a professor of environmental science at Barnard College in New York City, and a co-chair of the report. Using the term “Anthropocene” – a geological time period defined by the impact humans have had on the Earth – in the report’s title encompasses not only the influence humans have had on the Arctic, but also our ability to research this part of the planet, she said.

“We wanted to highlight that as human capacity grows, our ability to do research also grows,” said Pfirman.

– Alexandra Branscombe is a science writing intern in AGU’s Public Information department

By Lauren Noakes

Andrew Finlayson, a scientist at the British Geological Survey, on the Falljökull glacier.
Credit: British Geological Survey

Researchers from the British Geological Survey have taken the very first comprehensive health check of a rapidly melting glacier. Their latest study reveals that their icy patient, the Falljökull glacier in southeast Iceland, has been dramatically declining as it tries to adjust to recent changes in the climate.

The new findings on Falljökull show unhealthy changes in the glacier’s behavior and structure. Normal glacial patterns, growing in the winter and retreating in the summer, have been replaced by all year-round melting and rapid retreat of the margin of this Icelandic glacier, while its upper reaches continue to move forward. In fact, the retreat has increased so dramatically over the last five years that there has been complete detachment of the stagnant lower section, like a lizard losing its tail.

“Over the past two decades due to the increasingly warmer summers and milder winters Iceland’s glaciers have been retreating at a dramatically accelerated rate.” commented Jez Everest, a glacial geologist at the British Geological Survey (BGS) and co-author of the new paper that has been accepted for publication in Journal of Geophysical Research: Earth Surface, a journal of the American Geophysical Union.

The research could help scientists understand how other glaciers around the world, exhibiting similar early warning signs, could behave in the future. Working out how glaciers respond to changing climate is vitally important in a world where millions of people rely on them for drinking water and hydroelectric power.

Emrys Phillips, BGS research scientist and lead-author of the paper said: “We took a fully 3D view deep inside Falljökull and what we saw was rapid changes in the structure, a form of ‘downsizing’, to adjust to the changes in climate. We think that other steep, mountain glaciers around the world may be responding in a similar way, rapidly adjusting their active length in response to recent warming of the climate.”

He also added: “This type of behavior has never been described before.”

Andrew Finlayson, a scientist at the British Geological Survey, on the Falljökull glacier.
Credit: British Geological Survey

Previously retreating glaciers are thought to behave in one of two ways: ‘active retreat’ where its margin oscillates backwards and forwards each year, retreating during the summer due to melting and moving forward in the cold winter months; and ‘passive retreat’ were it no longer moves but simply melts away like a giant ice cube (stagnates). Strangely, Falljökull does not fit neatly into either of these ‘pigeon holes’.

Using cutting-edge technologies, BGS scientists were able to look inside the glacier. The monitoring techniques used by the team include:

• Ground Penetrating Radar to image inside the glacier and map the ice’s internal structure
• Terrestrial Laser scanning (LiDAR) to create a detailed 3D model of the surface of the glacier and surrounding glacial landforms
• four Global Navigation Satellite System (GNSS) stations installed onto the surface of the glacier to record its velocity
• digital mapping and measuring of the glaciers surface structures (fractures, crevasses, faults)

Jez Everest and Andrew Finlayson, scientists at the British Geological Survey, on the Falljökull glacier.
Credit: British Geological Survey

Using these techniques, the new study shows that between 1990 and 2004 the margin of Falljökull was ‘active’ with its seasonal oscillations leaving behind a series of ridge-like mounds of sediment which were pushed-up by the glacier during the winter months. But in 2004-2006 the margin of the glacier stopped moving altogether and began to melt back at an increasing rate.

However, time lapse photography and the GNSS/ GPS stations on the glacier surface clearly show that ice is still descending the icefall, and that the upper part of Falljökull is still flowing forward at between 50 and 70 meters (164 to 230 feet) per year.

The researchers have traced a large thrust fault cutting straight across the glacier just below a marked bulge in the glacier surface. This thrust is allowing the still ‘active’ upper part of the glacier to be pushed (thrust) over the lower reaches, which stopped moving in 2004-2006.

For more information, visit the BGS website.

For more photos, visit the AGU Tumblr site.

— Guest blogger Lauren Noakes is a communications officer at the British Geological Survey in Edinburgh, Scotland. This post first appeared on the BGS blog, GeoBlogy.

By Leslie Willoughby

Scientists deploy an ocean bottom electric field sensor on a wire aboard the RV Meteor in May 2012.
Credit: Wu-Cheng Chi.

A simple compound found in underwater structures could generate warmth below the ocean, inside homes, and in the atmosphere. The location of the compound, methane, determines whether it’s dangerous, welcome, or world-changing.

Now, a team from GEOMAR in Kiel, Germany and the University of Southampton in the United Kingdom has used electromagnetic images to more accurately identify and characterize a source of methane beneath the ocean floor.

Finding more exact methods to locate sub-ocean methane and to identify its qualities could protect oilrig operators, assist methane gas prospectors, and provide valuable information for climate scientists.

Methane, the main ingredient in natural gas, can cause blowouts during oil drilling operations. The same substance can comfortably heat a bedroom on a snowy morning. And in the same way that adding an extra blanket to a bed holds more heat beneath the covers, atmospheric methane can trap a layer of heat around the Earth.

Scientists are currently examining whether methane might vent from the ocean floor and contribute to warming of the planet. For now, combinations of temperature and pressure lock most methane beneath the ocean floor in ice. The ice keeps the methane, a gas, from rising to the surface.

A core sample from a pockmark, collected during the 2014 Arctic Landslide Tsunami project, contains hydrate in the lower left corner. Credit: Millie Watts University of Southampton

“Water forms an ice-like cage around the methane, creating what is called a methane hydrate,” said Eric Attias, a marine geophysicist with the University of Southampton who processed and interpreted the electromagnetic information.

“However, as ocean temperatures warm, the hydrates can break down and we can get venting,” said Karen Weitemeyer, a marine geophysicist at the University of Southampton who collected the electromagnetic information.

Previously, a team of geoscientists used acoustic waves in an area along the west continental slope of Norway to find a dip in the mostly flat seabed. That 300- to 500-foot (100- to 150-meter) diameter pockmark, 2,400 feet (720 meters) beneath the ocean surface, indicated that a chimney might lead up toward the sea floor. And that was a possible sign that hydrates lay below.

Scientists also knew that in the same area, 18,000 years ago, a glacier had rapidly laid down layers of rich organic matter on the ocean floor.

“In places like these, bacteria eat up matter and spit out methane,” said Weitemeyer.

The team wanted to learn what lies beneath the pockmark.

An electromagnetic, or marine resistivity, survey uses a transmitter and electric field receivers. This illustration shows seafloor receivers and a towed receiver.
Credit: modified from Weitemeyer et al., 2006 and Weitemeyer et al., 2010.

Attias and his colleagues set out to describe the chimney contents. To do so, they created electromagnetic images that show how strongly the sediment opposes the flow of electric current, or resistivity. They compared the resistivity of the chimney to that of the surrounding sediments. They assumed that more resistivity indicated the presence of methane hydrates and free methane.

They found that increased resistivity in the chimney indicated the presence of between 33 and 43 percent methane hydrate and free methane in the chimney.

They also found unexpected resistivity in two or three additional areas, an indication that a new pockmark is evolving or that it has been there but had not yet been discovered.

For future research, the team plans to determine the relative concentrations of hydrate and free gas in the chimney. To do so, they plan to examine a combination of acoustic wave information that has already been collected with their new resistivity information.

“With resistivity, we have a better tool to calculate concentration than seismic structure on its own,” said Weitemeyer. “A slow wave in an area that is resistive would suggest free methane gas. A high velocity wave combined with resistivity suggests hydrate.”

Measures of one pockmark may lead to more accurate estimates of methane at a regional scale and among 220 known hydrate deposits worldwide, Attias said.

– Leslie Willoughby is a science communication graduate student at UC Santa Cruz.

By Leana Schelvan

Snow telemetry (SNOTEL) station near Blazed Alder Creek in northwest Oregon, United States.
Credit: Natural Resources Conservation Service of the U.S. Department of Agriculture

In a recent study, University of Montana and Montana Climate Office researcher Jared Oyler found that while the western U.S. has warmed, recently observed warming in the mountains of the western U.S. likely is not as large as previously supposed.

His results, published online Jan. 13 in Geophysical Research Letters, show that sensor changes have significantly biased temperature observations from the Snowpack Telemetry (SNOTEL) station network.

More than 700 SNOTEL sites monitor temperature and snowpack across the mountainous western U.S. SNOTEL provides critical data for water supply forecasts. Researchers often use SNOTEL data to study mountain climate trends and impacts to mountain hydrology and ecology.

Oyler and his co-authors applied statistical techniques to account for biases introduced when equipment was switched at SNOTEL sites in the mid-1990s to mid-2000s. His revised datasets reduced the biases to reveal that high-elevation minimum temperatures were warming only slightly more than minimum temperatures at lower elevations.

“Observations from other station networks clearly show that the western U.S. has experienced regional warming,” Oyler said, “but to assess current and future climate change impacts to snowpack and important mountain ecosystem processes, we need accurate observations from the high elevation areas only covered by the SNOTEL network. The SNOTEL bias has likely compromised our ability to understand the unique drivers and impacts of climate change in western U.S. mountains.”

Co-authors on the paper “Artificial Amplification of Warming Trends Across the Mountains of the Western United States” include UM researchers Solomon Dobrowski, Ashley Ballantyne, Anna Klene and Steve Running.

— Leana Schelvan is the director of communications in the College of Forestry and Conservation at the University of Montana. This post originally appeared as a press release from the University of Montana.

By Jenny Seifert

Shallow groundwater can provide much-needed water during droughts, such as the one that hit Wisconsin in 2012.
Credit: Samuel Zipper

High water tables can be a bane to crop yields, compelling many farmers to drain their fields so their crops don’t drown when it rains.

But a high water table may not always be a bad thing. A new study shows it is actually a boon for some fields and during certain times of the growing season, casting light on opportunities for improving yield efficiency to meet global food demands.

The researchers found high water tables can provide much-needed water during drought and to crops planted in coarse-grained soils, which have a harder time retaining water than their fine-grained counterparts, like silt loam.

“Every soil type has a sweet spot in terms of the optimum water table depth for the highest crop yield,” explains Samuel Zipper, a graduate student in the Freshwater and Marine Sciences Program in the College of Engineering at the University of Wisconsin – Madison, and lead author of the new study published online in Water Resources Research, a journal of the American Geophysical Union. Zipper said the study is the first to look at the interactions between water table depth, soil texture and weather.

Timing, too, is everything.

While rains early in the growing season can waterlog fields, a high water table becomes an advantage later in the season, when the weather is drier and crops need the extra water to pollinate and produce grain.

In fact, Zipper found the benefits of a high water table, also called shallow groundwater, often outweighed the costs for crops in the coarse-grained soils and even many of the fine-grained soils in their study site, rendering higher crop yields, or “groundwater yield subsidies.”

“Surprisingly, even in a wet year, the net benefits of shallow groundwater outweighed the losses,” says Zipper.

A significant roadblock to efficiently feeding the world’s growing population is the “yield gap,” when crop yields don’t meet their full potential. Stress from either too much water or not enough is one of the factors that can lead to shortfalls.

Zipper says a better understanding of how groundwater depth, soil texture and the weather interact to affect crop yields can help farmers determine optimal field-draining depths that will help yields reach their full potential.

By comparing fields’ yield performance in wet and dry years and connecting results to water table depth and soil texture, co-author Steven Loheide, an associate professor of civil and environmental engineering at the University of Wisconsin-Madison, explains they were able to map more precisely where fields are sensitive to drought or waterlogging and why, a technique with implications for precision agriculture.

“Our data showed that small patches of the field, separated by just tens of meters, have strikingly different sensitivities to drought due to variations in groundwater depth and soil texture,” says Loheide.

Such knowledge could help farmers better invest their resources and target areas that should perform well, especially as extreme weather becomes more common.

“In the long term, farmers should be able to look at the general forecast for a season, decide what to plant where and control groundwater levels to meet crop needs,” says Zipper.

— Jenny Seifert is the science writer/outreach coordinator for the Water Sustainability and Climate(WSC) project at the University of Wisconsin-Madison. This post originally appeared as a press release on their website. 

by Amy McDermott

Fishermen harvest clams in a coastal mudflat in Maine. Credit: Bridie McGreavy, University of Maine.

In Maine, leaking sewers and failing septic systems, upstream beaver dams, animal waste, and agricultural runoff can easily contaminate coastal watersheds. When heavy rains wash a deluge of those pollutants down coastal streams and out to sea, the contamination can bring the state’s economy to a standstill: two inches of rain is enough to close beaches and shellfish fisheries, following guidelines set by the Clean Water Act. But not every beach is as easily fouled, researchers say, and it may be better to manage watershed closures individually.

The Gulf of Maine’s coastal watersheds, with insets of Wells Harbor and Cromwell Brook watersheds.
Credit: Abigail Bradford, University of Maine.

Scientists from the University of Maine, University of New Hampshire, and College of the Atlantic have now designed a new way to predict fine-scale watershed contamination along Maine’s coast. Their work will inform watershed management throughout the state and ultimately other coastal areas, said Sean Smith, a watershed geomorphologist at the University of Maine who presented the project at the 2015 American Geophysical Union Fall Meeting.

Maine’s coast is a long, jagged stretch of bays, inlets and fragmented islands. Small fishing towns fringe the Atlantic, nestled against thick temperate forests. Tourists descend on the beaches in summer, while fishermen haul in lobster, crab, and clams year-round. Maine depends on those connections between land and sea: together, coastal recreation and shellfishing contribute about $420 million to its economy every year.

Each watershed along the coast is different, however, and local and state governments need guidance on when beach and shellfish closures should be put in place and how long they should last, Smith said. The way contaminants are delivered (from a web of spidery streams or one surging river), the speed they reach the sea, and the amount of time they linger in the water should all inform management decisions as well, he added.

Fishermen harvest clams in a coastal mudflat in Maine. Credit: Bridie McGreavy, University of Maine.

To make better contamination projections, the team created a new, high-resolution topographic map of the whole coast of Maine. The map delineates the boundaries of watersheds and their drainage networks to predict the amount of fresh water injecting bacteria into estuaries, Smith said.

They also measured water flow, bacterial contamination, and total suspended solids at two sites, Bar Harbor in the north and Wells Harbor in the south, to look for correlations between rainfall and bacteria and to calibrate existing models, Smith said. The researchers categorized coastal watersheds based on similarities in bacterial sources, delivery, and residence time.

They found that watersheds near human populations are more vulnerable to contamination by dangerous bacteria. Development creates more sources of contamination, and man-made storm drains and swales make natural drainage networks more efficient, so bacteria moves more quickly from source to sink, Smith explained. Some estuaries are also flushed out more often than others: their size and shape influence the rate of water exchanged as tides come in and out and the amount of time that bacteria lingers in the area, he said.

Ultimately, the team hopes to build a prediction system customized to individual communities—one that accounts for toxin sources, delivery, and duration in Maine’s watersheds. According to Smith, understanding how hydrology and pollution interact will help managers understand which factors are most influential and mitigate their consequences in the future.

‑ Amy McDermott is a graduate student in the Science Communication program at UC Santa Cruz. Follow her on Twitter at @amygmcdermott.

By Jennifer LaVista

The Colorado River near Moab, Utah. The entire Colorado River Basin currently supports 50 million people, and that amount is expected to increase by 23 million between 2000 and 2030. A new study shows more than half of the streamflow in the Upper Colorado River Basin originates as groundwater.
Credit: USGS

More than half of the streamflow in the Upper Colorado River Basin originates as groundwater, according to a new study published online today in Water Resources Research, a journal of the American Geophysical Union.

The entire Colorado River Basin currently supports 50 million people, and that amount is expected to increase by 23 million between 2000 and 2030. On average, 90 percent of streamflow in the Colorado River Basin originates in the Upper Basin, which is the area above Lees Ferry, Arizona. This water has a multitude of uses that include irrigation, municipal and industrial purposes, electric power generation, mining activities, recreation, and supporting habitat for livestock, fish and wildlife.

Scientists used a new method to more accurately estimate the percentage of groundwater that supports streamflow. Researchers studied long-term records of water chemistry and streamflow data at 146 sites in the Upper Colorado River Basin in Colorado, Utah, New Mexico and Arizona. These data were then analyzed to create a model to predict and map where streamflow originates in the basin. On average, 56 percent of the streamflow in the basin originated from groundwater.

“These findings could help decision makers effectively manage current and future water resources in the Colorado River Basin,” said Matthew Miller, a U.S. Geological Survey scientist and the lead author of the study. “In light of recent droughts, predicted climate changes and human consumption, there is an urgent need for us all to continue to think of groundwater and surface water as a single resource.”

These results provide a modeled snapshot of present-day groundwater and surface water conditions at a regional scale and will serve as a foundation for future studies that predict groundwater response to climate and human induced change.

“This is a step in the right direction to further our ability to address regional to global scale water management challenges in both the Upper Colorado River Basin and other watersheds throughout the world,” said Miller.

Water data were analyzed using the USGS Spatially Referenced Regressions On Watershed attributes (SPARROW) water-quality modeling framework. Information on SPARROW modeling applications, data and documentation can be accessed online.

The study was conducted by the USGS WaterSMART initiative and the USGS National Water Quality Assessment Project of the National Water Quality Program.

— Jennifer LaVista is a public affairs specialist at USGS. This post originally appeared as a press release on the USGS website. 

By Karin Vergoth

An aerial view of a drilling oil well in the Bakken Formation in North Dakota. A new study finds that the Bakken region emits 275,000 tons of methane per year.
Credit: S. Haines/USGS.

The Bakken oil and gas field is leaking a lot of methane, but less than some satellites report, and less than the latest Environmental Protection Agency (EPA) inventory for petroleum systems, according to researchers’ calculations. That’s the finding of the first field study measuring emissions of this potent greenhouse gas from the Bakken, which spans parts of North Dakota and Montana. The new study was published today in the Journal of Geophysical Research: Atmospheres.

Researchers found that 275,000 tons of methane leak from the Bakken each year, similar to the emission rate found for another oil-producing region, Colorado’s Denver-Julesburg Basin.

“This study provides a key snapshot of Bakken methane emissions that will help answer the bigger questions: how much methane is the U.S. emitting, where is it coming from, and how is that changing over time?” said Jeff Peischl, a scientist from the Cooperative Institute for Research in Environmental Sciences (CIRES) at the University of Colorado-Boulder working at NOAA and the study’s lead author.

The 200,000 square-mile Bakken Shale formation is one of the country’s top oil-producing regions. At the time of the study in May 2014, the Bakken accounted for 12.5 percent of all crude oil produced in the United States. Only Texas surpasses North Dakota for oil production among states.

Methane is the primary component of natural gas and the second-most common greenhouse gas emitted by human activity in the U.S. Some methane is produced by natural sources such as wetlands, but livestock feedlots, landfills, coal mines, and oil and gas production also add significant amounts of methane to the atmosphere. Pound for pound, methane is significantly more efficient than carbon dioxide at trapping heat in the atmosphere over a 100-year period. Eventually, atmospheric methane reacts to form to carbon dioxide, the most common greenhouse gas, which persists in the atmosphere for thousands of years.

In this study, researchers flew an instrumented NOAA Twin Otter aircraft upwind and downwind of production facilities in the Bakken, and calculated the region’s total methane emissions using a technique called mass balance. The researchers evaluated the chemical composition of the air samples to determine if the methane captured during the flights came from oil and gas operations or other activities, such as livestock feedlots. The majority came from oil and gas, they found.

A map of NOAA-CIRES published studies on oil and natural gas emissions in the U.S.
Credit: CIRES/NOAA.

This study is one of several that are part of an ongoing effort to understand the atmospheric impact of oil and gas drilling across the United States, an effort that has revealed major differences in emission rates among regions and types of oil and gas basins.

The Bakken’s 2014 methane emission rate of 275,000 tons per year is significantly less than estimates generated by satellites for the region between 2006 and 2011. The researchers also compared the measured emission rate for the Bakken to EPA’s 2013 national inventory, the latest year available when the paper was submitted.  EPA only reports total national greenhouse gas emissions from petroleum systems, so researchers calculated the Bakken’s share of the EPA inventoried emissions based on the Bakken’s oil production level.

The EPA, in its 2014 greenhouse gas inventory released last month, increased its estimate of methane emissions from petroleum systems by 2.5 times. The data reported today shows emissions from the Bakken are slightly lower than EPA inventory, scaled to production. Field studies like this one, the researchers say, are vital for improving the accuracy of inventory estimates and satellite-based remote sensing measurements.

Another recent study showed the Bakken leaks ethane, also a component of natural gas, at a rate of about 250,000 tons per year, enough to be detected by atmospheric monitors in Europe.

“Policymakers need good data to make good decisions,” said Tom Ryerson, a scientist at NOAA co-author of the study. “As we transition from coal to natural gas and other sources of energy, it’s important that we understand the climate impacts of the fuel choices we’re making.”

This study is part of a continuing NOAA effort to understand methane emissions from all the major sources in the U.S. and across the globe. This larger effort involves tracking the natural emissions from tropical wetlands and sources in the Arctic, as well as human-caused emissions from landfills, agriculture and animal husbandry, and energy production and use.

—Karin Vergoth is a science writer at CIRES, which is a partnership of NOAA and CU-Boulder. This post originally appeared as a news release on the CIRES website.

By Paul Gabrielsen

Sundial Peak, in the Wasatch Mountains, with Lake Blanche (elevation 2718 meters (8920 feet)) in the foreground, May 2016.
Credit: David White.

Spring snowpack, relied on by ski resorts and water managers throughout the Western United States, may be more vulnerable to a warming climate in coming decades, according to a new study.

The study, accepted for publication in Geophysical Research Letters, a journal of the American Geophysical Union, models the year-to-year variability in precipitation and temperature in Utah’s Wasatch Mountains and other ranges in the West. Jason Scalzitti, a graduate student in atmospheric sciences at the University of Utah in Salt Lake City, and University of Utah atmospheric science professors Court Strong and Adam Kochanski, found that above a threshold elevation, the amount of spring snowpack is dependent more on the amount of precipitation in a year than the temperature. In other words, whether a year is wet matters more than if it’s warm. But below that threshold, temperature matters more. By the end of the century, according to the study, that threshold will move uphill by around 800 feet in the Wasatch and more in the Sierra Nevada, Cascades and parts of the Rocky Mountains.

“In the past we’ve thought mainly about total precipitation as an indicator of how good the ski season’s going to be,” says Strong. “As we move into the future, especially at elevations below the threshold, temperature increases in importance.”

Zooming in on the Wasatch

Strong and his colleagues based their work on a high-resolution, regional-scale climate model called the Weather Research and Forecasting (WRF) model. Conventional climate models make calculations on grids 100 kilometers (62 miles) on a side. For reference, less than 20 miles separate Salt Lake City, west of the Wasatch, and Park City, Utah, on the east.  “You can’t even see the Wasatch Range at that resolution,” Strong says. Although the coarser grid of global climate models works well in flat topography, such as the Great Plains, the complex terrain of the Intermountain West requires a finer resolution.

The researchers employed a technique called “dynamical downscaling,” telescoping the model grid into smaller and smaller grid cells in order to capture fine-scale atmospheric processes affecting local climate. In the team’s final simulations, the Wasatch Range was modeled at a resolution of about 4 kilometers (2.5 miles) to realistically capture impacts of the range’s slopes, canyons, and peaks on the local precipitation pattern. They further accounted for future temperature changes in the Great Salt Lake and evaporation from urban irrigation, both of which contribute moisture to the air. The team projected regional future climate forward to the year 2100 using a business-as-usual carbon emissions scenario that assumes greenhouse gas emissions will continue to increase at the same rate as today.

Crossing the threshold

Modeled percentage changes in the mean April snow water equivalent (SWE), a measure of snowpack, in the Western United States by the end of the century.
Credit: American Geophysical Union

They found that at high elevations, temperatures remain cold enough throughout the spring to turn precipitation to snow and to keep the snow on the ground from melting. Amount of precipitation is the main factor determining how much snow is on the ground during the critical spring months. Going down toward the valley floors, however, temperatures rise, and even in years with high precipitation, the slopes experience more rain and more melting. Temperature becomes the primary driver of the depth of spring snowpack.

The threshold elevation between precipitation-controlled and temperature-controlled snowpack, currently sits at about 1980 meters (6500 feet) in the Wasatch, near the base elevation of the ski resorts in Park City. In future projections, however, the threshold elevation rises to 2230 meters (7300 feet).

In the simulations, modeled threshold elevations rose in mountain ranges all over the West – by about (250 meters (800 feet) in Colorado’s Rockies, about 300 meters (980 feet) in California’s Sierra Nevada and Washington’s Cascades and more than 432 meters (1400 feet) in the middle Rockies of Idaho and Wyoming.

Impacts in peaks and valleys

Four Wasatch ski resorts, Solitude, Snowbird, Alta, and Brighton, sit well above the end-of-century 7300 foot threshold. But the rest, including venues from the 2002 Winter Olympics, sit at base elevations between 5500 and 7200 feet. The peak elevations of all resorts except one, Nordic Valley, extend up above the 7300 future threshold.

An overall warming trend doesn’t mean that every year will be a bad year for low-elevation resorts. But below the threshold elevation, resorts will more susceptible to warm years. “Let’s say we get the same amount of storms every year,” says study co-author Kochanski. “Above the threshold, the resorts will probably be fine. For the others, even if we have the same precipitation, they may be in trouble because they could get more rain instead of snow, and the snowpack will diminish faster.”

Although impacts to ski resorts could affect Utah’s economy, another implication of diminished snowpack affects nearly all Utahns – shrinking water resources. Melting spring snowpack fills reservoirs, providing water for the residents of the Salt Lake Valley. Spring snowpack amounts are a key indicator for water managers of how much water they’ll have available in reservoirs for the coming year.

“They look at that as how much water is available in the form of snow to melt and capture in the reservoirs,” Strong says. “That will be down in the future. Even if we have the same amount of water coming into the system, it will be melting earlier and faster. If we want to supply that to a growing population, then we need increased storage capacity.”

Strong and Kochanski say they can now use their model as a framework to continue exploring questions about future climate and snowpack variation, both by exploring the impacts of different carbon emissions scenarios and by looking at mountain ranges around the world, such as the Himalayas.

This work was funded by the National Science Foundation.

— Paul Gabrielsen is a science writer at the University of Utah. This post originally appeared as a press release on the University of Utah website. 

By Trent Knoss

A subalpine forest in Colorado’s Rocky Mountains.
Credit: Taylor Winchell / University of Colorado Boulder.

Earlier snowmelt periods associated with a warming climate may hinder subalpine forest regulation of atmospheric carbon dioxide, according to the results of a new study.

The findings, which were recently published in Geophysical Research Letters, a journal of the American Geophysical Union, predict that this shift in the timing of the snowmelt could result in a 45 percent reduction of snowmelt period forest carbon uptake by mid-century.

A separate study, also published in Geophysical Research Letters, found that earlier, slower snowmelt reduces the amount of streamflow, a phenomenon with potentially drastic consequences for agriculture, municipal water supplies and recreational opportunities in Colorado and other areas of the western U.S.

Forests located in seasonally snow-covered areas represent a key terrestrial carbon dioxide sink thanks to the natural photosynthetic processes by which trees uptake carbon. The trees’ carbon uptake is restrained during winter, but increases to peak capacity in spring when snowmelt provides sustained water input.

Working at the Niwot Ridge Ameriflux site in Colorado’s Rocky Mountains, University of Colorado Boulder researchers studied 15 years’ worth of snowmelt and atmospheric carbon dioxide data to study the effects of snowmelt periods. The research found that earlier snowmelt periods triggered by climate change align with colder air temperatures, reducing the forests’ ability to take carbon dioxide out of the atmosphere.

“This study shows us that, counterintuitively, warming generally causes snow to melt during colder periods of the seasonal temperature cycle due to the effects that warming has on reducing the depth of snowpacks, which causes melt to begin earlier in the year,” said Taylor Winchell, a graduate researcher in the Institute for Arctic and Alpine Research (INSTAAR) at CU Boulder, and lead author of the study. “The colder temperatures associated with early melt reduce the trees’ ability to uptake carbon during the snowmelt period, a key period for seasonal carbon uptake.”

“The implications of this research are quite profound as mountains in the western U.S. are an important part of the regional cycling of carbon and water,” said Noah Molotch, the director of the Center for Water Earth Science & Technology (CWEST) at CU Boulder, and a co-author of both new studies. “In this regard, earlier snowmelt will reduce carbon uptake in mountain forests, weakening the ability of forests to offset increases in CO2 associated with human burning of fossil fuels.”

A stream in Colorado’s Rocky Mountains.
Credit: Theodore Barnhart / Universityof Colorado Boulder

Snowmelt also acts as a key hydrological driver for rivers and streams across the state, providing water resources to downstream communities. Previous research has suggested that the timing and rate at which snow melts can impact the amount and quality of water available for vegetation, farming, and fishing.

The researchers used a unique modeling system to study the effects of earlier snowmelt across various regions of western United States including the Cascade range, the Sierra Nevada range, the Wasatch range, and the Rocky Mountains. All of these areas see significant seasonal snow accumulation and generate water resources for downstream communities.

The study results show that earlier, slower snowmelt, triggered by warmer temperatures, reduce streamflow. These slower “trickle” melts reduce percolation in hillslope soil and allow more water to evaporate, resulting in less streamflow overall.

“Of all the regions we studied, streamflow from Colorado’s Rocky Mountains is most sensitive to a change in snowmelt,” says Theodore Barnhart, a graduate researcher at INSTAAR and lead author of the study. “This analysis suggests that all of the regions studied will experience a decrease in streamflow with a decrease in snowmelt rate, with some regions exhibiting more streamflow sensitivity than others.”

“The recent western drought has been accompanied by a snowpack restricted to higher elevations, with a significant effect on the ski industry,” says Tom Torgersen, program director in the National Science Foundation (NSF)’s Division of Earth Sciences, which funded the research. “Climate variability also leads to conditions favoring earlier and slower snowmelt, with a decreased and prolonged peak streamflow. This water flow affects mountain fishing and results in less forest growth. The effects of drought and climate variability reach far beyond farm productivity and urban water restrictions.”

“Given that 60 million people in the western U.S. depend on snowmelt for their water supply, the future decline in snowmelt-derived streamflow may place additional stress on over-allocated water supplies,” said Molotch.

“There is a similar theme in these two studies: ‘colder forests in a warmer world’ and ‘slower snowmelt in a warmer world.’ Both phenomena defy expectations,” Molotch added. “In this regard, these studies are reshaping the way scientists and land and water managers think about climate change in mountainous regions.”

— Trent Knoss is a science writer at CU Boulder. This post originally appeared as a press release on the CU Boulder website. 

By Jennifer LaVista

Water flowing on the Colorado River near Moab, Utah. More than half of the streamflow in the Upper Colorado River Basin originates as groundwater, and a new study shows large precipitation events that occur about every 10 years are a critical source of recharge for replenishing groundwater resources.
Credit: Matthew Miller/USGS.

Large precipitation events that occur about every 10 years are a critical source of recharge for replenishing groundwater resources, according to a new study published in Water Resources Research, a journal of the American Geophysical Union.

Groundwater is a vital source of water in the western United States and will be increasingly important with continued population growth and climate variability. Understanding the role of these large recharge events in replenishing aquifers and sustaining water supplies is crucial for long-term groundwater management.

The new study is one of the first in the region to investigate the effects of climate on groundwater resources. The researchers identified and analyzed large, multi-year, quasi-decadal groundwater recharge events in the northern Utah portion of the Great Basin from 1960 to 2013. Researchers evaluated groundwater levels and climate information and identified five large recharge events with a frequency of about 11 to 13 years. Findings show these events provide a significant amount of groundwater recharge and storage across the northern Great Basin, causing water levels to rise in aquifers.

“Informed decisions for water management now and in the future rely on understanding the surface and groundwater resources within a river basin,” said Subhrendu Gangopadhyay, a civil engineer at the U.S. Bureau of Reclamation in Denver and co-author of the new study. “Understanding historical groundwater recharge provides context to better manage groundwater in the future under a variable climate.”

There has been a considerable amount of research linking climatic variability to hydrologic responses; however, most of these studies focus on surface-water resources. The implications of this work indicate if the magnitude or frequency of these recharge events change there will be significant impacts on groundwater, specifically long-term availability, use and sustainability.

“These large recharge events are vital in replenishing and maintaining groundwater storage, especially after multiple years of below average precipitation across the region,” said Melissa Masbruch, a hydrologist at the U.S. Geological Survey in Salt Lake City and lead author of the study. “Without them, groundwater resources become depleted.”

Large groundwater recharge events are characterized by above-average annual precipitation and below-average seasonal temperatures, especially during the spring (April through June). Existing groundwater flow models were then used to simulate changes in groundwater storage in several basins throughout the study area from these events.

—Jennifer LaVista is a public affairs specialist at USGS. This post originally appeared as a press release on the USGS website.

Pelicans at Barataria Bay, Louisiana. A new study shows dramatic, widespread shoreline loss in Louisiana marshlands most heavily coated with oil during the 2010 BP Deepwater Horizon oil spill in the Gulf of Mexico.
Credit: U.S. Fish and Wildlife Service Southeast Region, CC BY 2.0 Wikimedia Commons.

By Alan Buis and Gabrielle Boudreaux Bodin

Dramatic, widespread shoreline loss is revealed in a new study containing annual maps of Louisiana marshlands most heavily coated with oil during the 2010 BP Deepwater Horizon oil spill in the Gulf of Mexico.

Following the spill, the length of shoreline that receded more than 13 feet (4 meters) a year quadrupled compared to the year before the spill. The land losses occurred mainly in areas where oil had washed ashore during the spill. The study results were published today in Geophysical Research Letters, a journal of the American Geophysical Union.

In the new study, researchers used airborne remote sensing imagery to analyze shoreline loss across nearly the entire upper Barataria Bay on the western side of the Mississippi River Delta beginning a year before the spill and extending for 2.5 years after it. To determine whether the erosion was likely to be caused by the oil, they compared shoreline loss linked to the deposited oil with shoreline erosion caused by high waves from Hurricane Isaac in 2012.

The team found that although erosion occurred at isolated sections of the shoreline before the spill, the pre-spill shoreline (as analyzed from 2009 to 2010) was largely stable. In the first year after the spill (2010 to 2011), the erosion pattern changed dramatically, with widespread erosion occurring throughout the northeastern corner of the bay. Erosion occurred mainly along shorelines with documented heavy to moderate oil coating. In the second year after the spill (2011 to 2012), the higher loss rates extended to areas that had less oil coating. Oil is known to weaken or kill vegetation, leading to loss of the roots that help hold soil together.

Northeastern Barataria Bay, Louisiana, showing shores oiled during May-July 2010. This map of the study area shows the shoreline oiling severity categories from the Shoreline Cleanup Assessment Techniques (SCAT) map, documenting cumulative oiling from the Deepwater Horizon spill. The inset on the left shows the study region and the inset on the right locates the study area on a Landsat image.
Credit: Amina Rangoonwala.

In August 2012, two months after the two-year post-spill period, Hurricane Isaac made a direct hit on Barataria Bay. Erosion rates measured in the four months after the hurricane were higher than those measured after the spill. But this erosion occurred primarily on just a few shorelines that were known before the spill to be susceptible to wave-generated erosion.

“Our study uniquely shows that the patterns of shoreline recession seen in this region can be directly related to distinctly different causes: broadly dispersed erosion due to oiling from the Deepwater Horizon spill, and enhanced, but spatially limited, erosion due to intense storm impacts,” said Amina Rangoonwala, a geophysicist with the U.S. Geological Survey (USGS) Wetland and Aquatic Research Center in Lafayette, Louisiana and lead author of the new study.

The wetland impacts of the spill documented by the team included both the loss of wetlands due to shoreline erosion and island fragmentation, where small islands are broken into even smaller islands, creating more shoreline. Land lost as a result of fragmentation is unlikely to be reestablished, particularly in this part of the Mississippi River delta where levees prevent an influx of new sediments from the river. This will alter natural coastal defenses against flooding.

The images collected in the annual surveys and following Hurricane Isaac were obtained from NASA’s Uninhabited Aerial Vehicle Synthetic Aperture Radar (UAVSAR). UAVSAR’s polarized radar produced detailed representations of the marsh, which USGS scientists then used to develop a process to analyze the shoreline recession by mapping the change in shore location.

“Through this process, USGS and NASA scientists developed a repeatable, quantitative mapping method that will allow us to monitor shoreline erosion after oil spills in the future,” said Cathleen Jones, a researcher at NASA’s Jet Propulsion Laboratory in Pasadena, California and co-author of the new study. “Being able to compare shoreline losses in a year without any major storm to losses both after the Deepwater Horizon oil spill and after the hurricane was essential to correlating the erosion of the marsh to its underlying causes.”

—Alan Buis is a media relations specialist at JPL. Gabrielle Boudreaux Bodin is a media specialist at USGS. This post originally appeared as a press release on the JPL and USGS websites.

New research shows carbon emission standards for the power sector benefit crops such as corn, cotton, soybean and potato, as well as several tree species.
Credit: Rosana Prada, Creative Commons Attribution 2.0.

By Britt Faulstick

When the Environmental Protection Agency finalized the Clean Power Plan in 2015, the agency exercised its authority to regulate carbon dioxide emissions to protect public welfare. The Plan, now the focus of escalating debate, also put the nation on course to meet its goals under the Paris Climate Agreement. Given that other pollutants are emitted from power plants—along with carbon dioxide—research has shown that carbon emission standards for the power sector benefit human health. But new research shows they would also benefit crops and trees.

The new study, recently published in the Journal of Geophysical Research: Atmospheres, is the first to model the ecosystem impact of contrasting policies, one of which was similar to the Clean Power Plan.

According to the study, which included an option similar to the Clean Power Plan, the corresponding reduction in carbon, nitrogen and sulfur emissions from coal power plants would also mean a decrease in ground-level ozone—a known inhibitor of plant growth. And by modeling these reductions in the year 2020, the researchers found that they would provide a significant boost to the productivity of key indicator crops, such as corn, cotton, soybean and potato, as well as several tree species.

“Our findings suggest that crops like corn, soybeans and cotton could benefit from substantial productivity gains under moderate carbon standards for power plants,” said Shannon Capps, an engineering professor at Drexel University in Philadelphia and lead author of the new study. “With policies similar to those in the Clean Power Plan, we’re projecting more than a 15 percent reduction in corn productivity losses due to ozone exposure, compared to business as usual, and about half of that for cotton and soybeans. Depending on market value fluctuations of these crops over the next few years, that could mean gains of tens of millions of dollars for farmers—especially in areas like the Ohio River Valley where power plants currently contribute to ground-level ozone.”

“Our work shows the importance of considering the co-benefits of our nation’s energy policies going forward,” said Charles Driscoll, an engineering professor at Syracuse University and co-author of the study. “These benefits to people and plants are nearly immediate and occur in urban and rural communities across the U.S. We know from this and other studies that the economic value of the added benefits from power plant carbon standards are large and exceed the estimated cost of implementation.”

Crops and ozone

The team used three policy scenarios that encompass a range of emissions targets and reductions measures, and they compared each policy scenario with a “business-as-usual” reference case that represents current clean air policies, as well as energy demand and market projections.

Then, using a computer model widely employed to help guide state-level decision making for compliance with the National Ambient Air Quality Standards, the group generated a detailed projection of what the surface-layer ozone would look like across the country under each policy scenario through 2020.

The team looked at the consequences of lower ozone for five crops whose primary growing season is June through August, the period when ground-level ozone is at its peak. They also evaluated the consequences for 11 tree species, including eastern cottonwood, black cherry, quaking aspen and several species of pine. These crops and trees are used as standard indicators in environmental research. Based on previous research by crop and tree scientists, the team could relate their models’ ozone-exposure findings to the productivity of crop and tree species.

A team of researchers projected the effects of carbon reduction policies on the productivity of key crop and tree species. This infographic shows the degree to which three different U.S. carbon reduction policy scenarios would reduce potential productivity loss in four key crops in the year 2020.
Credit: Drexel University.

“The option most similar to the Clean Power Plan has the greatest estimated productivity gains for the crops and trees that we studied,” Capps said. “The improvement in crop yield and tree growth was strongly tied to the level of carbon dioxide emissions reductions and adoption of cleaner energy achieved by the policy.”

Under the business-as-usual scenario, the productivity of soybean, potatoes, and cotton is reduced about 1.5 percent, with only slight impacts on corn. These levels of production only slightly improve under a policy scenario that includes only “inside the fenceline measures” such as improving the efficiency of coal-fired power plants.

A second scenario, that most closely resembles the Clean Power Plan and includes demand-side energy efficiency, substituting lower-emitting natural gas plants and zero-emitting solar and wind power into the energy mix—produces larger results. The potential corn production lost to ozone exposure in the reference scenario is reduced by 15.7 percent, soybean losses are reduced by 8.4 percent and cotton losses are diminished by 6.7 percent.

Under the third scenario, which reflects putting a price on carbon, and achieves similar emissions reductions as the second scenario, the researchers project slightly lower reductions in ozone-induced losses for corn (12.1 percent), soybean (6.6 percent) and cotton (3.8 percent).

Members of the team are also analyzing the co-benefits of power plant carbon standards for reducing regional haze and acid rain and conducting new research on the co-benefits of the final clean power plan as compared to different energy policy futures.

—Britt Faulstick is the assistant director of media relations at Drexel University. This post originally appeared as a press release on the Drexel website.

By the European Commission Joint Research Centre

Average change in population affected per country given 4˚C global warming. Hatching indicates countries where the confidence level of the average change is less than 90 percent.
Credit: EU

A new report looks at flood risk and economic damages under different global warming scenarios with temperature increases of 1.5 degrees Celsius, 2 degrees Celsius and 4 degrees Celsius. It concludes that, if global temperatures rise by 4 degrees Celsius, the flood risk in countries representing more than 70 percent percent of the global population and global GDP will increase by more than 500 percent.

The new research, published in Earth’s Future, a journal of the American Geophysical Union, presents a global assessment of the economic costs and the population affected by river floods under different global warming scenarios. The research team analyzed a selection of high-resolution climate projections and simulations, and assessed the frequency and magnitude of river floods and their expected impacts under future scenarios.

The study reveals that, with a 4-degree Celsius temperature increase globally, countries representing 73 percent of the global population would face a 580 percent increase in flood risk. In addition, 79 percent of the global economy would face a 500 percent increase in flood damages. In the case of a 2-degree Celsius temperature increase, both the affected population and the related flood damages would rise by 170 percent compared to present levels. Even under the most optimistic scenario of a 1.5-degree Celsius temperature increase, the authors estimate that the flood-affected population would still double, and flood damages would increase by 120 percent.

The projected changes are not evenly distributed across the globe. The increase in flood risk is highest for Asia, America and Europe, while it remains low for most countries in Africa and Oceania, independent of the temperature increase.

Average change in flood damages per country given 4˚C global warming. Hatching indicates countries where the confidence level of the average change is less than 90 percent.
Credit: EU

These results support the recommendations of the Paris Agreement reached at the COP21 last year to keep a global temperature rise this century below 2 degrees Celsius above pre-industrial levels, and to pursue efforts to limit the temperature increase even further, to 1.5 degrees Celsius. The study confirms the urgent need for all countries to take active mitigation measures to limit global warming and the consequent increase in flood risk, according to the study’s authors.

As even the most optimistic warming scenario of 1.5 degrees Celsius would lead to a doubling of global flood risk, effective adaptation plans must be implemented to keep the flood risk rates at or below current levels, according to the authors. In addition, socio-economic drivers are likely to make the impacts greater in developing countries and in the regions with significant population growth. The increase in flood risk may become unsustainable in regions where the combination of socio-economic and climatic drivers trigger large-scale climatic crises involving conflicts and mass migration, according to the authors.

— This post originally appeared on the EU Science Hub website.

By Rachel Lentz

Fraction of the total rainfall, as a function of time of day, for a region including much of Indonesia and its surrounding oceans. Observations show strong peaks at early morning and mid-afternoon. IPRC modeling captures the observed modulation only when upper atmospheric forcing is included.
Credit: Takatoshi Sakazaki

No matter where you live, rain seems to fall more often at certain times of day, whether it is seen in the daily afternoon rainstorm or a typical overnight shower. Indeed, statistically, long-term average rainfall tends to cluster at certain times of the 24-hour cycle, but that time frame varies depending on location.

A team of scientists led by postdoctoral researcher Takatoshi Sakazaki, from the University of Hawaiʻi at Mānoa’s International Pacific Research Center (IPRC), has analyzed satellite-based observations and computer model simulations of tropical rainfall variation throughout the day in an effort to determine the root cause of the temporal patterns. Their results, accepted for publication in Geophysical Research Letters, a journal of the American Geophysical Union, show that daily tropical rainfall distribution is significantly shaped by heating of the upper atmosphere.

Continental settings often receive their peak rainfall in the late afternoon, after sunlight has heated the land surface throughout the day. Conversely, in tropical ocean settings, the maximum rainfall comes in the late night/early morning. In fact, detailed examination of observed tropical patterns reveals that rainfall often clusters into two uneven peaks, separated by roughly 12 hours, a pattern reminiscent of the familiar twice-daily ocean tide heights.

In fact, the atmosphere also experiences a type of daily tide. It has been long recognized that a global-scale pressure wave passes through the upper atmosphere, forced by the daily cycle of sunlight heating the ozone layer and propagating down towards the land surface. In the tropics, this wave can be seen in the daily fluctuations in barometric pressure, which peak at about 10 am and 10 pm.

Sakazaki and his team speculated that the tropical rainfall patterns are also intimately tied to this sun-driven atmospheric wave. By modeling rainfall patterns both with and without the forcing by upper atmospheric heating, they were able to show that the double peak of rainfall abundance in many tropical locations is accounted for only if the 12-hour atmospheric wave is included.

“It is exciting to find that rainfall has distinct ‘footprints’ of the stratospheric ozone heating, which occurs very far above us,” said Sakazaki. “Weather at the ground may be influenced by a much higher layer of the atmosphere than previously thought.”

Kevin Hamilton, a collaborator on this project and retired IPRC Director, noted, “Understanding the self-organization of rainfall over periods of hours to days, and over large distances, is critical for improving forecasts of our day-to-day weather in the tropics.” In addition, he emphasized that this strong link between the rainfall patterns and the atmospheric tides provides a unique feature whose presence, or absence, can be used to evaluate the accuracy of rainfall pattern forecasting in atmospheric models.

— Rachel Lentz is a Science Writer/Communications Specialist at the University of Hawaiʻi Sea Grant College Program & Pacific Islands Climate Science Center (PI-CSC) & International Pacific Research Center (IPRC). This post originally appeared on the IPRC website.

An aerial view of a Bakken formation well pad, a site of oil production, in North Dakota taken in 2014. A new study shows U.S. methane emissions are not likely an important driver of the increase in atmospheric methane levels observed worldwide after 2007, as other studies have suggested.
Credit: NOAA/Tim Newberger.

By Theo Stein

A new study shows U.S. methane emissions did not grow significantly from 2000 to 2013 and are not likely to have been an important driver of the increase in atmospheric methane levels observed worldwide after 2007, as other studies have suggested.

The new study, accepted for publication in the Journal of Geophysical Research: Atmospheres, a journal of the American Geophysical Union, provides additional insight into a question that has puzzled scientists for the past decade: what has been causing the increase in global methane levels since 2007?

To examine whether U.S. oil and gas development could be playing a role, NOAA scientist Lori Bruhwiler and an international team of researchers analyzed methane levels in air samples collected by NOAA aircraft around the U.S. They did not find evidence of large increases in methane emissions.

“Our results show that U.S. methane emissions have likely grown at a very slow rate,” said Bruhwiler, lead author of the new study. “Other scientists have proposed that large increases from the U.S. are a significant contributor to the global increase, and we just couldn’t find evidence of this from our measurements.”

Globally, methane levels in the atmosphere grew from the 1980s, when measurements began, to about 1999. Methane levels flattened between 1999 and 2007, and then resumed their growth at a time that coincided with an historic surge in U.S. oil and gas development activity. Several published studies have sought to draw a link between the increased the U.S. oil and gas activity and increases in global methane levels.

Methane is flared from a well pad in North Dakota’s Bakken formation in photo taken during a 2014 NOAA research project.
Credit: NOAA/CIRES, Jeff Peischl.

The question of whether U.S. fossil-fuel-sector methane emissions are on the rise is important because of the potential that new extraction technologies used here could be exported to exploit unconventional oil and gas reserves around the world.

Natural gas, which is composed primarily of methane, is regarded by some as a transition fuel between coal and renewable energy sources because natural gas, when burned, produces about half the carbon dioxide emissions of coal, according to the U.S. Energy Information Agency.

Methane is also the second largest human-caused contributor to global warming after carbon dioxide. Though not as abundant as carbon dioxide in Earth’s atmosphere, methane is much more potent, with 28 times the warming influence of carbon dioxide over 100 years. Because of its global warming potential, methane leakage must be limited for there to be a climate benefit in switching from coal to natural gas.

Other recent studies — including two based on the analysis of satellite estimates of atmospheric methane — have suggested that U.S. methane emissions rose by up to 30 percent from 2002-2014.  Bruhwiler and her team performed a thorough analysis of the satellite data used in the previous studies and could not identify evidence of a large increase in emissions from that data. Bruhwiler’s analysis of data from aircraft sampling across the U.S. also showed no trend of large growth in emissions.

This graph depicts the growth in atmospheric methane (CH4) as measured by NOAA from the 1980s through present.
Credit: NOAA.

NOAA scientists have contributed to several other recent studies that point to a biological, rather than fossil fuel, source for increasing global methane levels. A paper published last year found that the growth in atmospheric methane was likely due to large increases in emissions from microbial sources such as wetlands, livestock, waste and rice agriculture, especially in the tropics.

Bruhwiler’s co-author Sourish Basu, a CIRES scientist working at NOAA, said the new study was an effort to assess whether current tools and observing systems would allow scientists to evaluate the effectiveness of efforts to limit methane leaks from fossil fuel development.

“As an atmospheric scientist, my question is this: can we tell the difference between successful and unsuccessful efforts,” Basu said. “What is required to detect changes in emissions? We plan to keep refining our techniques to answer such questions.”

—Theo Stein is a public affairs specialist at NOAA in Boulder, Colorado. This post originally appeared as a news story on the NOAA website.

By Brendan Bane

The Maspalomas dune fields stretch just below the horizon of the Atlantic Ocean. Sediment flows from ocean waters and is carried across the dunes by wind, but that process can be interrupted by a developing cityscape.
Credit: Himarerme/Public Domain

Wind is powerful. Given enough time, steady gusts are strong enough to carve landscapes, from The Wave in Arizona to the limestone swirls of Texas. But putting homes and buildings in the wind’s path can disrupt this terrain-altering process, and even degrade cherished natural features, a new study suggests.

The new study, published in Earth’s Future, a journal of the American Geophysical Union, explores the impact of development on local wind patterns and dune formation on one of Spain’s Canary Islands.

By reviewing aerial photographs and topographical measurements, the study’s authors watched how a city’s expansion altered local wind patterns and ultimately changed the surrounding landscape, jeopardizing the long-term sustainability of a major tourist destination. 

The study took place on the resort island of Gran Canaria, the second-most populated of the Canary Islands. Every year, thousands of tourists flock to the island’s most popular attraction: the Maspalomas Dunes. The golden, rolling dunes span roughly 1,000 acres south of Maspalomas city, comprising a Martian-like landscape on the island’s southern coast. The dunes were designated a nature reserve in 1897, and tourists often sunbathe along the soft, sandy crests.

But some of Maspalomas’s dunes could disappear in fewer than 130 years, in part because of changes to regional wind patterns caused by city development, according to Alexander Smith, an environmental scientist at Ulster University’s School of Geography and Environmental Science in Northern Ireland, and lead author of the new study.

“The long-term sustainability of the dune field is now in question because of the negative feedback from urbanization,” Smith said. “Without major changes, I’m not sure this can be reversed.”

Smith used aerial photos of the dunes dating back to 1961, before development of Maspalomas first began. The photos revealed how the extent of vegetation and exposed sand changed over the decades. Smith supplemented those photos with topographic measurements taken between 2006 and 2011, which depicted changes in the height and shape of the dunes.

Maspalomas is home to hundreds of tourists throughout the year, who flock to the resort town to see the nationally cherished dune fields.
Credit: NASA.

Smith then plugged those measurements into a model of the Maspalomas cityscape, estimated where the wind’s course had been altered, and how that may have influenced the evolution of the dunes.

The buildings had a dual effect, intensifying wind flow upwind of the city and dulling it in the downwind area. Winds generally flow northeast to southwest across Maspalomas. But the city’s southernmost edge now acts as a shield, diverting and concentrating winds downward while blocking gusts and new sediment from reaching the city’s western side.

This dual effect degrades the dunes in two ways: the downwind area receives so little wind that plants have colonized its quieted hills, while the upwind area loses sand faster than natural processes can replenish it. According to Smith, Maspalomas’s sediment budget—the proportion of sediment flowing into a system versus the sediment leaving it—is now in a state of deficit.

Dunes that receive intensified winds could be fully depleted of sand within 130 years, Smith said. This exacerbates an already stressed area, as recent storms are eroding adjacent shores faster than incoming sediment can restore them. In contrast, dunes shielded from wind were blanketed by a 300 percent spike in plant coverage over the past 50 years.

Winds once flowed northeast to southwest across Maspalomas, as pictured in cell A. But the city’s southernmost edge redirects those gusts, concentrating them onto some dunes and blocking them from others, as pictured in cells B, C and D. Credit: Alexander Smith

Smith hopes future developers will consider his findings when designing cities alongside coastal or arid regions like Maspalomas’s dunes. By incorporating aerodynamic designs or spacing buildings farther apart, some of the buildings’ effects on wind may be negated, Smith suggested.

— Brendan Bane is a freelance science writer.

By Rachel Lentz

The view from snow-covered Mauna Kea across to a snowy Mauna Loa.
Credit: Zhang et al

Daydreams of the tropical paradise of Hawaiʻi rarely include snow in the imagery, but nearly every year, a beautiful white blanket covers the highest peaks in the state for at least a few days. However, systematic observations of snowfall and the snow cover dimensions on Mauna Kea and Mauna Loa are practically nonexistent.

A group of climate modelers led by Chunxi Zhang from the International Pacific Research Center (IPRC) at the University of Hawaiʻi at Mānoa used satellite images to quantify recent snow cover distributions patterns. They developed a regional climate model to simulate the present-day snowfalls and then to project future Hawaiian snowfalls.

Their results, accepted for publication in Earth’s Future, a journal of the American Geophysical Union, indicate that the two volcano summits are typically snow-covered at least 20 days each winter, on average, but that the snow cover will nearly disappear by the end of the century.

Long term annual snowfall on Mauna Loa and Mauna Kea on Hawaiʻi Island. a) Current average snowfall (in mm of liquid water equivalent) b) Projected snowfall by 2100, from model run with moderate emissions scenario. Topographic contour interval is 200 m.
Credit: Zhang et al

To evaluate the current situation, Zhang and his colleagues examined surface composition data retrieved from satellite imagery of Hawaiʻi Island from 2000 to 2015 to construct a daily index of snow cover. They used this data compilation to evaluate the quality of their regional atmospheric climate model, based on global climate projections that included several scenarios of anticipated climate change. Zhang then ran simulations representative of the end of the 21^st century, assuming a moderate business-as-usual scenario for greenhouse gas emissions projections, to establish how long Hawaiʻi might enjoy its occasional glimpses of white-topped mountains.

“We recognized that Hawaiian snow has an aesthetic and recreational value, as well as a cultural significance, for residents and visitors,” explained Zhang. “So, we decided to examine just what the implications of future climate change would be for future snowfall in Hawaiʻi.” Unfortunately, the projections suggest that future average winter snowfall will be 10 times less than present day amounts, virtually erasing all snow cover.

The findings were not a total surprise, with future projections showing that even with moderate climate warming, air temperatures over the higher altitudes increase even more than at sea level, and that, on average, fewer winter storm systems will impact the state. However, the group’s new method for establishing the current snow cover on these Hawaiian mountains provides another avenue for monitoring the progression of climate change in the region. Ultimately, this study also illustrates the benefits of the recent trend in model downscaling, highlighting the regional and local effects of global climate change.

— Rachel Lentz is a Science Writer/Communications Specialist at the University of Hawaiʻi at Mānoa. This post originally appeared as a press release on the IPRC webiste.