Monthly Archives: February 2010

Rising Temperatures in the Midst of Heavy Snow?

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The last few months have been a bit odd. Too much snow in the mid-Atlantic. Too little for the Winter Olympics in Vancouver. And a dusting nearly everywhere else. Meanwhile, a blizzard of confusing and often conflicting commentary has left many people asking: Is the climate really warming? Warming faster than ever? Or perhaps just weirding out?

Since NASA scientists have been tracking global temperatures and climate change for decades, we checked in with researchers from across the agency to get their take on the state of Earth’s climate (which, it’s worth noting, isn’t the same thing as Earth’s weather). The result is a collection of feature stories, videos, and web interactives that describe what we’ve found on NASA’s Global Climate Change Site. Here’s a sampling:

•     Why the Arctic Oscillation has made this winter one to remember (Article)

•     How the ocean’s natural rhythms can hide or accentuate global temperatures (Article)

•     Why the last decade has been the warmest on record (Article)

•     On the record about the temperature record (Q&A)

•     Piecing together the temperature puzzle (Video)

•    2009 Temperature update (Video)

•     Sorting out the squiqqles in the global temperature record (Interactive graphic)

•     Watching the world’s changing temperature (Data Visualization)

•     Snaps from space: The impact of a warming world (Image gallery)

–Adam Voiland, NASA’s Earth Science News Team

Richard Alley on Earth's Biggest Climate Control Knob

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Click here for a multimedia presentation of Richard Alley’s AGU talk.  (Credit: AGU)

Scientists aren’t known for being the savviest of public speakers, but Penn State’s Richard Alley is that rare researcher who knows how to give a talk. Alley — who’s willing to sing, dance, and gesticulate vigorously to get a point across — gave a lecture about carbon dioxide to an overflow crowd of scientists at the American Geophysical Union meeting this year that’s well worth watching.

Blogger and University of Toronto computer scientist Steve Easterbrook has an excellent blow-by-blow of the talk, but the heart of it came down to this point, which Alley made on his last slide:

An increasing body of science indicates that CO2 has been the most important controller of Earth’s climate. 

If you want the details, (and the details are a pleasure to sit through in this case because of Alley’s gregarious speaking style) AGU has posted video and slides of the full talk. Still want to know more about carbon dioxide? NASA’s Jet Propulsion Laboratory (JPL) released new details about the distribution of carbon dioxide in the troposphere, the region of Earth’s atmosphere that is located between 5 to 12 kilometers, or 3 to 7 miles, above Earth’s surface. (JPL also released a ten question quiz about the gas that you can access here).  

Meanwhile, Alley participated in a NASA science update back in 2005 that explored the nature of sea level rise, a topic that NASA researchers continue to investigate and that you can explore interactively using our Sea Level Viewer.

–Adam Voiland, NASA’s Earth Science News Team

Smelling the Air in Kanpur

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Winter haze piles up against the Himalayas above the Indo-Gangetic Plain.      (Credit: Earth Observatory)

“When the plane was about 30 minutes from touchdown, we could start to smell the air,” said David Giles. “It was shocking.”

Giles — a young scientist at NASA’s Goddard Space Flight Center — was en route to Kanpur, a large Indian industrial city on the banks of the Ganges river. Dust and soot tend to hover over the region, which is sandwiched between the sharp edge of the Tibetan Plateau to the north and the highlands of the Deccan Plateau to the south.

There’s so much soot in the air that satellites can routinely see a cloud of haze blanketing the region.

The bowl-like Indo-Gangetic Plain is second only to some parts of China for having the heaviest load of air pollution in the world. In the spring, when dust blows in from the deserts to the West, aerosols from factories, buses and trucks, and fires are especially heavy. So much so, in fact, that NASA researchers suggested recently that dust and soot may be driving the retreat of Himalayan glaciers by altering the monsoon.

Giles was in Kanpur to man one of NASA’s AERONET stations in the region as part of the ongoing TIGERZ campaign. He spent 17 days in Kanpur hauling the instrument around and getting harassed by local police officers, the occasional herd of roaming sheep and dust storms. In between all that, he spent the bulk of his time collecting measurements to determine whether dust and soot can glom onto one another to create new types of hybrid aerosols.

They do, he found, a seemingly mundane point but one that’s of considerable interest to the scientists trying to sort out how these two types of aerosols affect the climate. He presented his results in detail this week to colleagues at the American Geophysical Union fall meeting in San Francisco.

I nabbed him after his talk in the afternoon, to have a beer and talk through his travels. I asked him what was the most memorable part of the trip to India. “Well, it was unbelievably hot,” he said with a laugh. “Temperatures routinely hit 105 degrees.”

And how was the air? “You’d get used to it after a while,” said Giles, “but, at first, in the taxi, we were holding our sleeves over our mouths just to avoid breathing the stuff.”


Giles and colleagues using sun photometers to measure aerosols from a rooftop in Kanpur.  (Credit: Giles)

–Adam Voiland, NASA’s Earth Science News Team

The Mysteries of Muck (and the Collapse of the Laurentide Ice Sheet)

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Field assistants tromped through bogs in Harriman, NY to collect sediment cores that NASA
scientist Dorothy Peteet is using to date the retreat of the Laurentide Ice Sheet.  Credit: Peteet

I spent big chunks of my childhood mucking through the lakes and bogs of New England with my brothers and looking for any number of critters hidden in the silt.

Turtles, of course, were the main draw (minus the snappers, which we knew were capable of mangling a toe or finger with a passing chomp), but actually snagging one always was a rare treat. Bullfrogs, salamanders, and newts were our standard catch.

If only we’d had a microscope. Watching Goddard Institute for Space Studies (GISS) botanist Dorothy Peteet show images of tiny fragments of pollen, seeds, and fossils that settled to lake bottoms and sat largely unchanged for thousands of years reminded me of the extraordinary oddness–and beauty–that’s lurking in the most unsuspecting of places.

Look, for example, at this fossilized head shield of a daphnia, or water flea, which Peteet showed during presentations at GISS and the American Geophysical Union meeting last December. It’s a miniscule planktonic crustacean with a transparent body and a heart that beats visibly:



Or this statoblast, a peculiar little reproductive pod that can withstand desiccation and freezing and buds from aquatic creatures called bryozoans:

 

Or this one, a fossilized leaf of a fruit-bearing, cold-loving tundra plant, perhaps a blueberry:

 

Peteet isn’t poking around in the mud just for fun like my brothers and I did as kids, though. She’s collecting bog cores and scrutinizing the bits of fossilized plants and animals, which can be dated quite precisely using radiocarbon techniques, that turn up in the cores. Her goal is to pinpoint the timing of the collapse of the Laurentide Ice Sheet, a massive block of ice that stretched as far as Long Island during the peak of the last ice age. With Arctic ice currently undergoing rapid retreat, sorting out how the Laurentide Ice Sheet collapsed has big implications for understanding how climate change might proceed.

By analyzing material from some of the first creatures to colonize glacial lakes after the ice retreated, such as those water fleas, Peetet can estimate the date the ice sheet collapsed. Her findings suggests that the collapse occurred about 15,000 years ago, which would put it five-to-ten thousand years later than other dating techniques (particularly one influential technique that involves dating the beryllium from boulders dropped by the retreating ice sheet). 

“This was surprising, and it’s generated some controversy,” she told her colleagues. “I’d like to have your ideas about what’s going on.” To learn more about the topic, you can watch, listen, or view a pdf of Peetet’s full presentation here

Share your stories about exploring the muck in your neighborhood, your ideas on the dating controversy, and we’ll make sure that Peteet sees them and posts a reply.


Botanist Dorothy Peteet

                                                                                                                                                                 
–Adam Voiland, NASA’s Earth Science News Team       

Greenhouse Molecules Laid Bare

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The Earth is a bit like the human body; its temperature is very finely balanced, and when it gets slightly out of whack, big things can happen. In the case of our home planet, gases in the atmosphere play a vital role in maintaining this delicate equilibrium, by balancing the absorption and emission of all the electromagnetic radiation (microwaves, infrared waves, ultraviolet light and visible light, for example) reaching the surface of the Earth.

As reported recently, the Earth is getting warmer. Scientists believe the main driver behind this warming trend is rising levels of man-made greenhouse gases. These gases, which we pump out into the air, act to trap heat radiation near the surface of the Earth that would otherwise be sent back out into space. Carbon dioxide (CO2) is the Paris Hilton of greenhouse gases, and gets a lot of face time because its concentration in the atmosphere has increased relatively rapidly since the Industrial Revolution. But methane, nitrous oxide, hydrofluorocarbons (HFCs), chlorofluorocarbons (CFCs) and perfluorocarbons (PFCs) are also important agents of global warming. Some of them are actually much more potent than CO2 and they stick around for hundreds to thousands of years longer. This has some scientists concerned that these B-listers could actually impact global temperatures significantly more than CO2.

greenhouse warming cartoon

In a new paper, Partha Bera and colleagues at NASA’s Ames Research Center and Purdue University put these gases under the microscope to find out exactly why they are such powerful heat trappers. They focus on CFCs, HFCs and PFCs — all chemicals containing fluorine or chlorine — that are used in medicine, fridges, and as solvents, among other things. By probing the molecular structure of these compounds, they have found that molecules containing several fluorine atoms are especially strong greenhouse gases, for two reasons. First, unlike many other atmospheric molecules, they can absorb radiation that makes it through our atmosphere from space. Second, they absorb the radiation (and trap the heat) very efficiently, because of the nature of the fluorine bonds inside them. (In technical terms, fluorine atoms create a larger separation of electric charge within the molecule, and this helps the molecular bonds absorb electromagnetic radiation more effectively.) HFCs and other fluorine-based gases have been called “the worst greenhouse gases you’ve never heard of.” Now we know why.

Until now, scientists had not looked in detail at the underlying physical or chemical causes that make some molecules better global warmers than others. Bera and colleagues say that their work should help improve our “understanding [of] the physical characteristics of greenhouse gases, and specifically what makes an efficient greenhouse gas on a molecular level.” They hope their findings will be used by industry to develop more environmentally-friendly materials.

Amber Jenkins, NASA’s Global Climate Change team 

Tour NASA's New Climate Reel

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We’re less than two weeks away from the United Nation’s long awaited Copenhagen Climate Change Conference. In anticipation of the event, NASA has compiled a climate resource reel that highlights ten of its most compelling climate videos and visualizations. 

Video topics range from a 3-D tour of the Earth’s rapidly changing cryosphere, and the unexpected role that honey bees can play as climate data collectors, to NASA’s efforts to understand the ozone layer. 

Two of the videos offer details about NASA’s new climate satellite GloryOne of them discusses Glory’s Total Irradiance Monitor, a sensor that will help monitor the sun’s fluctuations. The other  — titled Hello Crud — delves into the perplexing world of airborne particles called aerosols

You can see all ten of the top picks at NASA’s Global Climate Change website. Additional climate-related videos and animations are available through NASA’s Scientific Visualization Studio.



–Adam Voiland, NASA’s Earth Science News Team

Can Air Pollution Cause Lightning Storms?

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Strange as it may seem, the most recent Image of the Week entry from the Climate and Radiation Branch at Goddard Space Flight Center suggests that air pollution does indeed exacerbate lightning storms. The graphic, created by Goddard meteorologist Thomas Bell, shows that rainfall and lightning rarely peaks over the weekend in the southeastern United States. In fact, lightning hasn’t peaked on a weekend during any year since 1998, Bell has shown after combing through meteorological data from 1998 to 2009. After publishing a number of scientific papers on the topic, Bell thinks he knows why: air pollution (which is at its highest levels midweek and lowest levels on the weekend) can strengthen thunderstorms, particularly in the unstable and humid air of the Southeast.

The figure shows the day of the week favored by rainfall and by lightning in each summer from 1998 to 2009 in the southeastern United States (click here for a map of the area included in the analysis). The “clock plots” on the left and right indicate the day of the week when mean activity was at a maximum. The numbers indicate the year the data comes from. The rain estimates are based on TRMM and other satellite observations. The lightning data were collected by ground stations that are part of the National Lightning Detection Network. Credit: NASA/Bell


To find out more, I ran some questions about the connection between pollution and lightning by Bell via email:

What On Earth: Why does air pollution have any bearing on lightning or rainfall, and why is the connection more noticeable over the Southeast than other parts of the country? 

Thomas Bell: Our explanation is that the storms need to start their growth in a hot, humid environment to give the pollution “something to work with.” The pollution causes the storm to climb to higher altitudes, because it causes the cloud droplets being formed in the storm to be smaller than they would be in a clean environment. They’re lighter and are carried up higher than usual, where they freeze (releasing latent heat), which pumps the storm up more than would happen in clean air.

The environment needs to be hot in order to have the capacity to push the storm up to altitudes where freezing can occur. The environment also needs to be humid because when the storm grows more vigorously it “sucks” air at its base up more strongly, pulling in more moisture, which then provides additional energy to the storm as the moisture condenses during its climb. The western half of the country is fairly dry—even though it can be hot, there isn’t much “fuel” (moisture) to feed a storm when it tries to grow more vigorously. The Southeast is especially hot and humid in the summer, so that’s where the effect shows up best, according to our theory.

What On Earth: Are there particular types of air pollution that have more or less impact on rain and lightning?

Thomas Bell: We don’t have a good answer to this as yet. The pollution should be the kind that affects cloud droplet growth. If we had to finger something, we’d probably choose the kinds of particulates that are emitted by diesel engines, because it seems that the weekly cycle in pollution is due, to a considerable extent, to the weekly cycle in transportation (probably trucking). More trucks are on the roads from Tue-Thu than they are the rest of the week. But this is more conjecture than a well-documented explanation.

For more context on Bell’s findings, see these earlier Image of Week entries, take a look at these news stories, or read these peer-reviewed journal articles. And, when you’ve done all that, head over to the Earth Science Picture of the Day page (which we’ve written about previously) and enjoy these spectacular pictures of lightning. Here’s an eerie one taken in the German town of Bad Mergentheim
Lightning over a German town.                                                    (Credit: Jens Hackmann via EPOD)


–Adam Voiland, NASA’s Earth Science News Team

An Award-Winning Scientist Who Came in from the Cold

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NASA-funded researcher Ben Smith digs a snow pit at a West Antarctic Ice Sheet Divide core
site to try to infer the annual rate of snowfall. Credit: Ben Smith

Researchers who study glaciers and polar dynamics often get into it for the love of the field work — the challenging terrain, technicological adventures, and thigh-deep snow.

Benjamin Smith, a researcher at the Polar Science Center at the University of Washington’s Applied Physics Laboratory, was no exception. As a fledgling physicist in the 1990s, his first summer job after college turned into an eye-opening adventure — a 3-month stint at the Kamb Ice Stream in Antarctica as a field assistant mapping buried crevasses with snow-penetrating radar. The rest, as they say, was history.

These days, Smith is enjoying a rare honor as one of two NASA-supported researchers to receive the Presidential Early Career Award for Scientists and Engineers (PECASE), awarded at a White House ceremony last month.

WhatOnEarth: Field work was your entry into studying glaciers. Are you involved  in Arctic or Antarctic field work now?

Smith: After a few years of field work, I discovered that though being out in cold is great, the quicker way to learn about glacier change is by doing remote sensing work. That requires a great deal of data analysis indoors. So with that notion, I got onboard as part of NASA’s ICESat I mission while working on my doctorate in physics.

WhatOnEarth: What work do you believe was the basis for your presidential award?

Smith: Well, I have a few projects that I’ve been fortunate enough to be involved in.

Not too long ago, I wrote a paper where we found that several lakes beneath the glaciers in Antarctica have gained or lost water in the last five years, and at a rate much faster than things usually happen in Antarctica. We’ve been seeing lakes that fill or drain in half a year. In one case, 3 cubic kilometers of water drained last year from one of these lakes. That’s about the size of Lake Washington in Seattle.

My main objective in all of this is to figure out where that water went and how it has affected other subglacial lakes and glaciers downstream. Have those glaciers sped up from the water flowing under them? The warmth of the surface bed beneath glaciers allows them to slide faster. If you add more water, there’s potential for glaciers to slide faster. 

I’m also part of a team that is helping to design the ICESat II satellite – a project we hope will build on the success of ICESat I. The satellite will boast several laser beams rather than one, so it’ll provide much better spatial coverage of the Earth’s surface to measure glacier mass and area.

 
President Obama honored PECASE awardees, including Ben Smith and Josh Willis, in January at the White House.
Credit: The White House


WhatOnEarth: Were you aware that you’d been nominated for the PECASE award?

Smith: No. I was completely unaware of it until I was notified by the FBI about a background check! I can tell you I was relieved when I found out the background check regarded my visit to the White House. I understand now that my nomination was put forward by colleagues at NASA. Somehow, my nomination came out on top of the pile, and that’s pretty cool.

To read a few of Ben Smith’s ICESat-related scientific papers, click the topics below.

Ice stream elevation changes observed by ICESat

Increased flow speed on an East Antarctic glacier

An inventory of subglacial lakes detected by ICESat

Gretchen Cook-Anderson, NASA’s Earth Science News Team

 

How Do Global Soot Models Measure Up?

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A image from a simulation that shows the spread of black carbon aerosols in Asia. Areas where the air was thick with
the pollution particles are white, while lower concentrations are transparent purple. (Credit:
Earth Observatory)

As NASA atmospheric scientist Eric Wilcox recently told Time magazine, emerging evidence suggests that a short-lived type of air pollution called black carbon—known popularly as soot—can exacerbate global warming by absorbing incoming solar radiation.

Yet pinning down precisely how much the black carbon exacerbates warming is no easy task, research conducted by Goddard Institute for Space Studies climatologist Dorothy Koch suggests. The study, published in Atmospheric Chemistry and Physics tracked how the predictions from 17 global black carbon models compared with actual measurements collected by airplane, satellite, and ground-based sensors. It shows, among other things, that models generally underestimate black carbon’s warming effect on climate.

Koch tested all the models in three ways. In the simplest of the three, she compared the models’ predictions to the amount of black carbon measured at the surface, finding that they matched real life reasonably well.

Her second test compared the models’ predictions to black carbon measurements made higher in the atmosphere using airplanes, and the results were much less clear cut. Though the models usually had too much black carbon over pollution sources, most had too little over remote regions such as the Arctic.

Koch’s final and most important test looked at how much solar radiation black carbon actually absorbs, an indicator of the amount of warming the particles actually produce. Again, the results were mixed. The models were largely accurate over North America and Europe, but were not for areas that have high levels of black carbon such as Central Africa, Southeast Asia, and the Amazon.

In a write-up on the Goddard Institute for Space Studies web site, Koch summarizes her findings this way:

We concluded from this study that most models have enough black carbon at ground level in polluted regions, too much in the atmosphere above source regions, but not enough in the Arctic where black carbon may play an important role in contributing to Arctic warming and ice/snow melt. The models’ soot generally does not absorb enough sunlight and therefore these models would underestimate black carbon heating effects. This probably results from underestimating the absorbing properties of the particles rather than the amount (mass) of black carbon.

Wondering how climate modelers can continue to close the gap between model predictions and reality? Koch put forward some advice on how to fine-tune the next generation of aerosols models. Her top three:

1) Account for mixing between black carbon and other components of the atmosphere,
2) Incorporate better measurements of particle size and source amount in some regions.
3) Continue to mine ongoing satellite and field campaigns for data about black carbon.

You can read more GISS science briefs and NASA news stories about black carbon here, here, and here.

–Adam Voiland, NASA’s Earth Science News Team

Deforestation: Much Ado about the Contribution to Global CO2

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CO2 is released from fires (red dots) like these near Lake Malawi in southern
Africa in
October 2009 for agricultural land clearing. Credit: NASA 

Deforestation. The environmental implications of the word are as numerous as the syllables. And scientists like Jim Collatz have the job of trying to ferret out and prove those implications. Or, as the case may be, of correcting what scientists have believed to be true.

When farmers or loggers chop or burn forest land, they set in motion the loss of biodiversity and habitat, as well as soil erosion. Collatz and other scientists are just as concerned — maybe even more so – with the carbon dioxide (CO2) deforested areas contribute to the atmosphere, warming the climate.

In 2005, the U.N. Food and Agriculture Organization announced that forest loss accounts for more than 20 percent of global emissions of CO2 from human activity. If we could stop cutting down trees, some argued, we could make a serious dent in the global carbon problem.

Not so much, a new study in the November 2009 issue of Nature Geoscience suggests. A group of Dutch and American climate scientists, including Collatz, assert that the UN’s estimate of atmospheric CO2 caused by deforestation is substantially overstated – by as much as 40 percent. Recalculating the 2005 figure with updated satellite-based estimates on carbon emissions, the researchers calculated the relative contribution of deforestation and forest degradation to be only about 12 percent.  

As a member of NASA Goddard’s Biospheric Sciences research team and co-author of the study, Collatz shared some of his thoughts with us.

What On Earth: How do you account for the change in the share of atmospheric CO2 from forest loss?

Collatz: New emission estimates from tropical deforestation are somewhat lower than in the past. At the same time, fossil fuel emissions are increasing rapidly. Deforestation is becoming a smaller proportion of total human-caused CO2 emissions. So, even if we could stop it completely, it would not be a substitute for decreasing fossil fuel emissions. If deforestation were 20 percent, then decreasing it to 10 percent may be significant and plausible. But since new analysis shows deforestation is closer to 10 percent, it’s unlikely that it can be reduced to zero percent.

 

What On Earth: What are the implications of your findings?

 

Collatz:  Some might read the paper and argue for less attention toward reducing deforestation. But we need to remain vigilant in this area. Forests provide other valuable services besides storing carbon: biodiversity, food, fiber, water resources, soil resources.  Even though current rates of deforestation may be lower than previously thought, vast amounts of carbon are stored in forests and soils all over the globe and are vulnerable to climate change and land management practices.  We need to monitor these carbon stocks and manage them for preservation and sequestration, or we may see unexpected increases in atmospheric greenhouse gases that go beyond what is emitted from fossil fuel burning.

 

To read the full paper on the Web, click here.

 –Gretchen Cook-Anderson, NASA’s Earth Science News Team

Correction: Please note the link above to the full paper has been revised. Co-author Robert Jackson of Duke University makes the paper available on the university’s site.