TWEET FROM SPACE: CRESCENT MOON RISING

FROM:  NASA 

On Feb. 1, 2014, Japan Aerospace Exploration Agency astronaut Koichi Wakata tweeted this view of a crescent moon rising and the cusp of Earth's atmosphere. Distinct colors are visible because the dominant gases and particles in each layer of the atmosphere act as prisms, filtering out certain colors of light.  Image Credit: NASA

AMOUNT OF WATER TREES NEED AND THE CHANGING ATMOSPHERE

On the ground: looking into Harvard Forest's trees from a less lofty perch.  Credit: NSF Harvard Forest LTER Site

FROM:  NATIONAL SCIENCE FOUNDATION
Changing Atmosphere Affects How Much Water Trees Need

Spurred by increasing levels of atmospheric carbon dioxide, forests over the last two decades have become dramatically more efficient in how they use water.

Scientists affiliated with the National Science Foundation's (NSF) Harvard Forest Long-Term Ecological Research (LTER) site report the results in this week's issue of the journal Nature.

Harvard Forest is one of 26 such NSF LTER sites in ecosystems from deserts to grasslands, coral reefs to coastal waters, around the world.

Studies have long predicted that plants would begin to use water more efficiently, that is, lose less water during photosynthesis, as atmospheric carbon dioxide levels rose.

A research team led by Trevor Keenan and Andrew Richardson of Harvard University, however, has found that forests across the globe are losing less water than expected and becoming even more efficient at using it for growth.

Using data collected in forests in the northeastern United States and elsewhere around the world, Keenan and Richardson found increases in efficiency larger than those predicted by state-of-the-art computer models.

The research was done in collaboration with scientists from the USDA Forest Service, Ohio State University, Indiana University and the Karlsruhe Institute of Technology in Germany.

"This could be considered a beneficial effect of increased atmospheric carbon dioxide," said Keenan, the first author of the Nature paper.

"What's surprising is we didn't expect the effect to be this big. A large proportion of the ecosystems in the world are limited by water--they don't have enough water during the year to reach their maximum potential growth.

"If they become more efficient at using water, they should be able to take more carbon out of the atmosphere due to higher growth rates."

While increased atmospheric carbon dioxide may benefit forests in the short-term, Richardson emphasized that the overall climate picture would remain grim if levels continue to rise.

"We're still very concerned about what rising levels of atmospheric carbon dioxide mean for the planet," Richardson said.

"There is little doubt that as carbon dioxide continues to rise--and last month we just passed a critical milestone, 400 parts per million for the first time in human history--rising global temperatures and changes in rainfall patterns will, in coming decades, have very negative consequences for plant growth in many ecosystems around the world."

How do increasing carbon dioxide levels lead to more efficient water use?

The answer, Keenan said, is in the way photosynthesis works.

To take in the carbon dioxide they need, plants open tiny pores, called stomata, on their leaves. As carbon dioxide enters, however, water vapor is able to escape.

Higher levels of carbon dioxide mean the stomata don't need to open as wide, or for as long, so the plants lose less water and grow faster.

To take advantage of that fact, commercial growers have for years pumped carbon dioxide into greenhouses to promote plant growth.

To test whether such a "carbon dioxide fertilization effect" was taking place in forests, Keenan, Richardson and others turned to long-term data measured using a technique called eddy covariance.

This method, which relies on sophisticated instruments mounted on tall towers extending above the forest canopy, allows researchers to determine how much carbon dioxide and water are going into and out of the ecosystem.

With more than 20 years of data, the towers at the NSF Harvard Forest LTER site--which have the longest continuous record in the world--are an important resource for studying how forests have responded to changes in atmospheric carbon dioxide levels, scientists say.

"A goal of the NSF LTER program is understanding forest ecosystems and the basis for predicting fluxes of energy and materials in these ecosystems," said Matt Kane, program director in NSF's Division of Environmental Biology, "as well as distributions of forest biota as a result of global climate change."

"Findings from this study are important to our understanding of forest ecosystems--and how they can be managed more effectively now and in the future."

Though more than 300 towers like Harvard Forest's have sprung up around the globe, many of the earliest--and hence with the longest data records--are in the northeastern United States.

When the researchers began to look at those records, they found that forests were storing more carbon and becoming more efficient in how they used water.

The phenomenon, however, wasn't limited to a single region. When the scientists examined long-term data sets from all over the world, the same trend was evident.

"We went through every possible hypothesis of what could be going on, and ultimately what we were left with is that the only phenomenon that could cause this type of shift in water-use efficiency is rising atmospheric carbon dioxide," Keenan said.

Going forward, Keenan, who is now at Macquarie University in Sydney, Australia, is working to get access to data collected from yet more sites, including several that monitor tropical and arctic systems.

"This larger dataset will help us better understand the extent of the response we observed," he said.

"That in turn will help us build better models, and improve predictions of the future of the Earth's climate.

"Right now, all the models we have underrepresent this effect by as much as an order of magnitude, so the question is: What are the models not getting? What do they need to incorporate to capture this effect, and how will that affect their projections for climate change?"

The research was also supported by NOAA. Field measurements at the sites, which are part of the AmeriFlux network, have also been funded by the U.S. Department of Energy and the USDA Forest Service.

-NSF-

NASA STUDIES INTERATIONS OF POLLUTION AND STORMS

FROM: NASA
NASA Flights Target How Pollution, Storms and Climate Mix

WASHINGTON -- NASA aircraft will take to the skies over the southern United States this summer to investigate how air pollution and natural emissions, which are pushed high into the atmosphere by large storms, affect atmospheric composition and climate.

NASA will conduct its most complex airborne science campaign of the year from Houston's Ellington Field, which is operated by the agency's Johnson Space Center, beginning Aug. 7 and continuing through September. The field campaign draws together coordinated observations from NASA satellites, aircraft and an array of ground sites.

More than 250 scientists, engineers, and flight personnel are participating in the Studies of Emissions, Atmospheric Composition, Clouds and Climate Coupling by Regional Surveys (SEAC4RS) campaign. The project is sponsored by the Earth Science Division in the Science Mission Directorate at NASA Headquarters in Washington. Brian Toon of the Department of Atmospheric and Oceanic Sciences at the University of Colorado, Boulder, is SEAC4RS lead scientist.

Aircraft and sensors will probe the atmosphere from top to bottom at the critical time of year when weather systems are strong enough and regional air pollution and natural emissions are prolific enough to pump gases and particles high into the atmosphere. The result is potentially global consequences for Earth's atmosphere and climate.

"In summertime across the United States, emissions from large seasonal fires, metropolitan areas, and vegetation are moved upward by thunderstorms and the North American Monsoon," Toon said. "When these chemicals get into the stratosphere they can affect the whole Earth. They also may influence how thunderstorms behave. With SEAC4RS we hope to better understand how all these things interact."

SEAC4RS will provide new insights into the effects of the gases and tiny aerosol particles in the atmosphere. The mission is targeting two major regional sources of summertime emissions: intense smoke from forest fires in the U.S. West and natural emissions of isoprene, a carbon compound, from forests in the Southeast.

Forest fire smoke can change the properties of clouds. The particles in the smoke can reflect and absorb incoming solar energy, potentially producing a net cooling at the ground and a warming of the atmosphere. The addition of large amounts of chemicals, such as isoprene, can alter the chemical balance of the atmosphere. Some of these chemicals can damage Earth's protective ozone layer.

The mission will use a number of scientific instruments in orbit, in the air, and on the ground to paint a detailed picture of these intertwined atmospheric processes. As a fleet of formation-flying satellites known as NASA's A-Train passes over the region every day, sensors will detect different features of the scene below. NASA's ER-2 high-altitude aircraft will fly into the stratosphere to the edge of space while NASA's DC-8 aircraft will sample the atmosphere below it. A third aircraft from SPEC Inc., of Boulder, Colo., will measure cloud properties.
One benefit of this thorough examination of the region's atmosphere will be more accurate satellite data.

"By using aircraft to collect data from inside the atmosphere, we can compare those measurements with what our satellites see and improve the quality of the data from space," said Hal Maring of the Earth Science Division at NASA Headquarters.

The SEAC4RS campaign is partly supported by the U.S. Naval Research Laboratory. NASA scientists involved in the mission come from NASA's Ames Research Center at Moffett Field, Calif.; Goddard Space Flight Center in Greenbelt., Md.; Jet Propulsion Laboratory in Pasadena, Calif.; and Langley Research Center in Hampton, Va.

NASA's Earth Science Project Office at Ames manages the SEAC4RS project. The DC-8 and ER-2 research aircraft are managed by NASA's Dryden Flight Research Center and based at Dryden's Aircraft Operations Facility in Palmdale, Calif

RESEARCHERS STUDY BLUE MUSSELS AND OCEAN ACIDIFICATION

Photo:  Mussel.  Credit:  Wikimedia Commons

FROM: NATIONAL SCIENCE FOUNDATION
Blue Mussels 'Hang On' Along Rocky Shores: For How Long?

Imagine trying to pitch a tent in a stiff wind. You just have it secured, when a gale lifts the tent--stakes and all--and carries it away.

That's exactly what's happening to a species that's ubiquitous along the rocky shores of both the U.S. West and East Coasts: the blue mussel.

Mussels make use of what are called byssal threads--strong, silky fibers--to attach to rocks, pilings and other hard substrates. They produce the threads using byssus glands in their feet.

Now, scientists have discovered, the effects of ocean acidification are turning byssal threads into flimsy shadows of their former selves, leaving mussels tossed about by wind and waves.

At high levels of atmospheric carbon dioxide--levels in line with expected concentrations over the next century--byssal threads become weaker, less able to stretch and less able to attach to rocks, found scientists Emily Carrington, Michael O'Donnell and Matthew George of the University of Washington.

The researchers recently published their results in the journal Nature Climate Change; O'Donnell is the lead author.

Oceans turning caustic

The pH of the seas in which these and other marine species dwell is declining. The waters are turning more acidic (pH dropping) as Earth's oceans change in response to increased carbon dioxide in the atmosphere.

As atmospheric carbon rises as a result of human-caused carbon dioxide emissions, carbon in the ocean goes up in tandem, ultimately resulting in ocean acidification, scientists have found.

To study the effects of ocean acidification on marine organisms, Carrington has been awarded an NSF SEES (Science, Engineering, and Education for Sustainability) Ocean Acidification grant.

"We need to understand the chemistry of ocean acidification and its interplay with other marine processes--while Earth's seas are still hospitable to life as we know it," says David Garrison, program director in NSF's Division of Ocean Sciences. "In the rocky intertidal zone, blue mussels are at the heart of those processes."

Land between the tides

Visit the land between the tides, and you'll see waves crashing on boulders tinged dusky blue by snapped-closed mussels.

"Their shells are a soft color, the misty blue of distant mountain ranges," wrote Rachel Carson more than 50 years ago in her best-selling book The Edge of the Sea.

For blue mussels trying to survive, the rocky intertidal zone indeed may be akin to scaling a mountain range.

The rocky intertidal is above the waterline at low tide and underwater at high tide--the area between tide marks.

It's home to such animals as starfish and sea urchins, and seaweed such as kelp. All make a living from what floats by rocky cliffs and boulders.

It can be a hard go. Rocky intertidal species must adapt to an environment of harsh extremes. Water is available when the tide washes in; otherwise residents of this no man's land between sea and shore are wide open to the elements.

Waves can dislodge them, and temperatures can run from scalding hot to freezing cold.

Hanging on for dear life

In the rocky intertidal, blue mussels hang on for dear life.

That may not always be the case.

Combining results from laboratory experiments with those from a mathematical model, Carrington and colleagues show that at high carbon dioxide concentrations, blue mussels can be dislodged by wind and wave forces 40 percent lower than what they are able to withstand today.

Mussels with this weakened ability, once dislodged from their homes, could cause ecological shifts in the rocky intertidal zone--and huge economic losses in a global blue mussel aquaculture industry valued at U.S. $1.5 billion each year.

"Mussels are among the most important species on rocky shores worldwide," says O'Donnell, "dominating ecosystems wherever they live. The properties in their byssal threads are also of interest to biochemists and have been studied as possible medical adhesives."

Blue mussels may make important contributions to the field of materials science, says Carrington.

"Some species of mussels are experts at gluing onto seagrass, some to other shells, some even adhere to rocks in the harsh conditions of deep-sea hydrothermal vents. Each may have different genes that code for different proteins, so the adhesives vary."

Will their potential be realized? Carrington, O'Donnell and George have found a disturbing answer.

The scientists allowed mussels to secrete byssal threads in a range of ocean water chemistries from present-day through predicted near-future conditions, then tested the threads to see how strong they were.

At levels considered reasonable for a near-future coastal ocean (given current rates of acidification), byssal threads were less able to stretch and therefore less able to adhere. Further testing revealed that the problem was caused by weakening of the glue where the threads attach to rocks and other hard surfaces.

Ocean acidification beyond shells and corals

"Much ocean acidification research has focused on the process of calcification," says Carrington, "through which animals and some plants make hard parts such as shells."

In acidifying oceans, marine species that depend on calcium carbonate have a more difficult time forming shells or, in the case of coral reefs, skeletons.

"But there's more to marine communities than calcified parts," says O'Donnell. Other species such as mussels and their byssal threads, he says, are equally important.

"Understanding the broader consequences of ocean acidification requires looking at a variety of biological processes in a range of species."

A need that didn't exist when Rachel Carson wrote The Edge of the Sea.

"When we go down to the low-tide line, we enter a world that is as old as the Earth itself--the primeval meeting place," mused Carson, "of the elements of earth and water."

And of mussels and rock. Fifty years hence, will the mussels still be here?