Edited by Barbara J. Finlayson-Pitts, University of California, Irvine, Irvine, CA, and approved November 25, 2009 (received for review October 20, 2009.
Abstract
We present laboratory studies and field observations that explore the role of aminium salt formation in atmospheric nanoparticle growth. These measurements were performed using the Thermal Desorption Chemical Ionization Mass Spectrometer (TDCIMS) and Ultrafine Hygroscopicity Tandem Differential Mobility Analyzers. Laboratory measurements of alkylammonium—carboxylate salt nanoparticles show that these particles exhibit lower volatilities and only slightly lower hygroscopicities than ammonium sulfate nanoparticles. TDCIMS measurements of these aminium salts showed that the protonated amines underwent minimal decomposition during analysis, with detection sensitivities comparable to those of organic and inorganic deprotonated acids. TDCIMS observations made of a new particle formation event in an urban site in Tecamac, Mexico, clearly indicate the presence of protonated amines in 8–10 nm diameter particles accounting for about 47% of detected positive ions; 13 nm particles were hygroscopic with an average 90% RH growth factor of 1.42. Observations of a new particle formation event in a remote forested site in Hyytiälä, Finland, show the presence of aminium ions with deprotonated organic acids; 23% of the detected positive ions during this event are attributed to aminium salts while 10 nm particles had an average 90% RH growth factor of 1.27. Similar TDCIMS observations during events in Atlanta and in the vicinity of Boulder, Colorado, show that aminium salts accounted for 10–35% of detected positive ions. We conclude that aminium salts contribute significantly to nanoparticle growth and must be accounted for in models to accurately predict the impact of new particle formation on climate.
Nature Reports Climate Change, published online 11 June 2009; doi: 10.1038/climate.2009.55
Abnormal nitrogen
by Alicia Newton, Science324, 5932 (2009)
MEREDITH HASTINGS
Nitrate concentrations in Greenland ice have almost doubled since the onset of the Industrial Revolution, according to scientists. The rise in nitrate is accompanied by a sharp drop in the isotopic signature of the nitrogen, beginning just as humans started pumping nitrogen oxides into the atmosphere.
Meredith Hastings of Brown University and colleagues used a 100-metre-long ice core from Summit, Greenland, to track changes in nitrogen composition over the past three centuries. Beginning in 1850, the isotopic ratio of the nitrogen, which in part reflects the source of the nitrate, began to decline, just as greenhouse gas concentrations were starting to rise in response to the widespread burning of fossil fuels. The sharpest jump in the isotopic ratio came between 1950 and 1980, when emissions also soared. This overall trend would be difficult to explain through changing chemical processes in the snow or atmosphere alone, leaving fossil fuel combustion as the most likely driver.
Nitrogen oxides are among the six greenhouse gases regulated under the Kyoto Protocol. The team hopes that further work will allow them to determine how changes in climate influence natural nitrogen oxide sources.
Lightning storms at mid-latitudes and in the subtropics produce more nitrogen oxides (NOx) than previously thought, finds a new study. What's more, most of the NOx pollution — a precursor to the greenhouse gas ozone — ends up in the upper troposphere, where it has a strong influence on climate.
A team led by Lesley Ott of NASA's Goddard Earth Sciences and Technology Center in Greenbelt, Maryland, used data collected during lightning storms in Germany and the United States between 1985 and 2002, along with a cloud simulation model, to estimate the amount of NOx produced by an average flash of lightning. They found that a single lightning strike produces about 7 kilograms of chemically reactive NOx. Worldwide, this amounts to an annual production of 8.6 million metric tonnes. As none of the data were collected in the tropics — where lightning may yield less NOx per flash — the global estimate may be on the high end, say the researchers.
They speculate, however, that if lightning storms become more frequent in the future, as predicted by some theoretical models, increased NOx in the upper atmosphere could affect global climate change.
See also:
Ott, L., K. Pickering, G. Stenchikov, D. Allen, A. DeCaria, B. Ridley, R.-F. Lin, S. Lang, and W.-K. Tao (2009), Production of lightning NOx and its vertical distribution calculated from 3-D cloud-scale chemical transport model simulations, J. Geophys. Res., doi: 10.1029/2009JD011880, in press.
Nuuk Climate Days 2009 -- Changes of the Greenland Cryosphere Workshop & The Arctic Freshwater Budget International Symposium, Nuuk, Greenland, 25-27 August 2009
Primary author: CHEN, Linling (Nansen-Zhu International research center/Institute of Atmospheric Physics, Chinese Academy of Sciences), lin-ling.chen@nersc.no ; Co-authors: JOHANNESSEN, Ola M. (Nansen Environmental and Remote Sensing Center); WANG, Huijun (Nansen-Zhu International research center/Institute of Atmospheric Physics, Chinese Academy of Sciences); KHVOROSTOVSKY, Kirill (Nansen Environmental and Remote Sensing Center)
Abstract ID: F4
Greenland Ice Sheet’s elevation change in winter and atmospheric circulation
Data from ERS-1, ERS-2 and Envisat Satellites are analyzed to identify the relationship between winter elevation variations of Greenland ice sheet and sea level pressure during 1993-2007. It is found that the North Pacific oscillation and the North Atlantic oscillation, the two major teleconnection patterns of surface pressure fields in North Hemisphere, both have significant impacts on the Greenland ice sheet winter elevation change by influencing accumulation. In addition, we are evaluating modeled precipitation data over Greenland based on comparison with accumulation data from all available ice core records and meteorological station, in order to better understand how the atmospheric circulation impact the Greenland Ice Sheet’s Elevation.
Nature Geoscience, published online 23 August 2009; doi: 10.1038/ngeo607
Quantification of the troposphere-to-ionosphere charge transfer in a gigantic jet
Steven A. Cummer1, Jingbo Li1, Feng Han1, Gaopeng Lu1, Nicolas Jaugey1, Walter A. Lyons2 and Thomas E. Nelson2
Abstract
Gigantic jets are the clearest manifestation of direct electrical coupling between tropospheric thunderstorms and the ionosphere. They are leaders1, 2, 3 that emerge from electrical breakdown near the top of thunderstorms4 and extend all the way to the lower edge of the ionosphere near 90-km altitude5. By contrast, blue jets6 and other related events7, 8 terminate at much lower altitudes. Gigantic jets have been observed from the ground5, 9, 10 and from orbit11. Some seem to be consistent with an upward-propagating negative discharge of 1,000-2,000 C km total charge moment change 9, but others have not been connected to distinguishable electromagnetic signatures10. Here we report simultaneous low-light video images and low-frequency magnetic field measurements of a gigantic jet that demonstrate the presence and dynamics of a substantial electric charge transfer between the troposphere and the ionosphere. The signatures presented here confirm the negative polarity of gigantic jets4 and constrain the lightning processes associated with them. The observed total charge transfer from the thunderstorm to the ionosphere is 144 C for the assumed channel length of 75 km, which is comparable to the charge transfer in strong cloud-to-ground lightning strokes.
¹Electrical and Computer Engineering Department, Duke University, Durham, NC 27708, U.S.A.
²FMA Research, Inc., Yucca Ridge Field Station, Fort Collins, CO 80524, U.S.A.
Gigantic jets blast electricity into upper atmosphere
The gigantic jet observed by Steven Cummer and his team. The thunderstorm that produced this jet was over 300 kilometres away, below the visible horizon (Image: Steven Cummer)
by Michael Marshall, New Scientist, August 23, 2009
The ancient Greeks might have thought Zeus was furious with heaven itself. The power of lightning strikes that shoot upwards from storm clouds has been measured for the first time – and they turn out to be every bit as powerful as normal lightning.
First caught on camera in 2003, "gigantic jets" shoot upwards from thunderclouds and can reach altitudes above 80 kilometres. But it wasn't until 21 July last year that Steven Cummer at Duke University in Durham, North Carolina, and his colleagues managed to measure the electrical discharge from a single gigantic jet, released from tropical storm Cristobal.
"No one had been very close to one with the right radio instrumentation before," Cummer says. "So we didn't know whether they just petered out without doing anything much, or whether they actually took some charge and dumped it somewhere."
Electric jet
The jet came out of a high storm cloud, beginning at an altitude of about 14 kilometres, and shot upwards for a further 75 kilometres.
At those heights, the atmosphere is a much better electrical conductor than at ground level because of ionising radiation from space. As a result, the jet was able to discharge 144 coulombs of charge into the upper atmosphere in about 1 second.
This is comparable to the charge transferred by a large cloud-to-ground lightning strike.
"It's fantastic that they see such a high charge transfer between the thundercloud and the ionosphere," says Victor Pasko of Pennsylvania State University in University Park.
"There is this newly identified path for discharging the thunderstorm, and a lot of charge can be moved," says Cummer. "In storms that can produce gigantic jets, it might influence what other lightning is happening in the storm."
This time, however, the team found no difference in the rate of ordinary lightning strikes around the time of the gigantic jet. "I'm surprised they saw no drop in lightning rates before or after the jet – but that might be because of the sheer size of the storm," says Pasko.
Gigantic jets are one of a host of new atmospheric phenomena discovered in recent years. Other examples are sprites and blue jets.
Proceedings of the National Academy of Sciences, published online before print August 19, 2009; doi: 10.1073/pnas.0907610106
The physical basis for increases in precipitation extremes in simulations of 21st-century climate change
Paul A. O'Gorman* (Massachusetts Institute of Technology, Cambridge, MA 02139, U.S.A.) and Tapio Schneider (California Institute of Technology, Pasadena, CA 91125, U.S.A.)
Communicated by Kerry A. Emanuel, Massachusetts Institute of Technology, Cambridge, MA; July 14, 2009 (received for review March 24, 2009).
Abstract
Global warming is expected to lead to a large increase in atmospheric water vapor content and to changes in the hydrological cycle, which include an intensification of precipitation extremes. The intensity of precipitation extremes is widely held to increase proportionately to the increase in atmospheric water vapor content. Here, we show that this is not the case in 21st-century climate change scenarios simulated with climate models. In the tropics, precipitation extremes are not simulated reliably and do not change consistently among climate models; in the extratropics, they consistently increase more slowly than atmospheric water vapor content. We give a physical basis for how precipitation extremes change with climate and show that their changes depend on changes in the moist-adiabatic temperature lapse rate, in the upward velocity, and in the temperature when precipitation extremes occur. For the tropics, the theory suggests that improving the simulation of upward velocities in climate models is essential for improving predictions of precipitation extremes; for the extratropics, agreement with theory and the consistency among climate models increase confidence in the robustness of predictions of precipitation extremes under climate change.
Mysterious, glowing clouds appear across America’s night skies
by Alexis Madrigal
Wired Science, July 16, 2009
Mysterious, glowing clouds previously seen almost exclusively in Earth’s polar regions have appeared in the skies over the United States and Europe over the past several days.
Photographers and other sky watchers in Omaha, Paris, Seattle, and other locations have run outside to capture images of what scientists call noctilucent (”night shining”) clouds. Formed by ice literally at the boundary where the earth’s atmosphere meets space 50 miles up, they shine because they are so high that they remain lit by the sun even after our star is below the horizon.
The clouds might be beautiful, but they could portend global changes caused by global warming. Noctilucent clouds are a fundamentally new phenomenon in the temperate mid-latitude sky, and it’s not clear why they’ve migrated down from the poles. Or why, over the last 25 years, more of them are appearing in the polar regions, too, and shining more brightly.
“That’s a real concern and question,” said James Russell, an atmospheric scientist at Hampton University and the principal investigator of an ongoing NASA satellite mission to study the clouds. “Why are they getting more numerous? Why are they getting brighter? Why are they appearing at lower latitudes?”
Nobody knows for sure, but most of the answers seem to point to human-caused global atmospheric change.
BLOGGER'S NOTE: This marvelous photo of the Eiffel Tower on Bastille Day with exploding fireworks and noctilucent clouds was taken by flickr user Breff. Wired Science ripped it off his flickr without asking permission, which is how it came to be posted here, because I ripped off Wired Science without asking their permission. It is not at all clear to me that those are noctilucent clouds in the background, but hey, this is a fantastic photo, any way you look at it. The original can be found at: http://www.flickr.com/photos/breff/3722358660/in/set-72157621611065989/
Not only that, but photographer Breff has a series of fab photos of the Eiffel Tower and fireworks here, and if I had money and could buy the poster and put it up in my house, I would, no kidding, they are that cool: http://www.flickr.com/photos/breff/3721417815/in/set-72157621611065989/
Noctilucent clouds were first observed in 1885 by an amateur astronomer. No observations of anything resembling noctilucent clouds before that time has ever been found. There is no lack of observations of other phenomena in the sky, so atmospheric scientists are fairly sure that the phenomenon is recent, although they are not sure why.
Over the last 125 years, scientists have learned how the clouds form. At temperatures around minus 230 °F, dust blowing up from below or falling into the atmosphere from space provides a resting spot for water vapor to condense and freeze. Right now, during the northern hemisphere’s summer, the atmosphere is heating up and expanding. At the outside edge of the atmosphere, that actually means that it’s getting colder because it’s pushed farther out into space.
It’s not hard to see how a warming Earth could change those dynamics: as the globe heats up, the top of the atmosphere should get colder.
“The prevailing theory and most plausible explanation is that CO2 buildup, at 50 miles above the surface, would cause the temperature decrease,” Russell said. He cautioned, however, that temperature observations remain inconclusive.
The global changes that appear to be reshaping noctilucent cloud distribution could be much more complex, said Vincent Wickwar, an atmospheric scientist at Utah State University whose team was first to report a mid-latitude noctilucent cloud in 2002. Temperature does not explain their observations from around 42 degrees latitude.
“To get the noctilucent clouds you need temperatures that are about 20 degrees Kelvin colder than what we see on average up there,” Wickwar said. “We may have effects from CO2 or methane but it would only be a degree or a fraction of a degree.”
Instead, Wickwar’s explanation is that a vertical atmospheric wave discovered in their LIDAR data lowered the temperature in the region above their radar installation near Logan, Utah. But then you have to ask, he noted, “Where’d the wave come from?”
They don’t really have an answer yet. Other facilities around the world with similar LIDAR capacity haven’t reported similar waves. And the Rocky Mountains, near Wickwar’s lab, can cause atmospheric waves, which could be a special feature of his location.
Other theories abound to explain the observed changes in the clouds. Human-caused increases in atmospheric methane, which oxidizes into carbon dioxide and water vapor, could be providing more water for ice in the stratosphere. Increases in the amount of cosmic or terrestrial dust in the stratosphere could also increase the number of brightly shining clouds.
Two years into Russell’s NASA project, more questions exist than firm answers. They will have at least three and a half more years, though, to gather good data on upper atmospheric dynamics.
The recent observations of noctilucent clouds at all kinds of latitudes provide an extra impetus to understand what is going on up there. Changes are occurring faster than scientists can understand their causes.
“I suspect, as many of us feel, that it is global change, but I fear we don’t understand it,” Wickwar said. “It’s not as simple as a temperature change.”
Image: 1. The sky over Omaha on July 14th, 2009, snapped by Mike Hollingshead at Extreme Instability 2. Noctilucent clouds lit up the Paris sky behind the Bastille Day fireworks show at the Eiffel Tower. Captured by flickr user, breff 3. A rendering of the noctilucent clouds created from data obtained by Russel’s NASA project, AIM. Video: NASA.
Hello, You've used one of my photos in your blog. This photo is protected under a Creative Commons Attribution-Noncommercial-No Derivative Works 2.0 Generic license. You have cropped the photo (thus removing my logo) which violates the licence. The photo doesn't link back to my site (because you copy-pasted it from WIRED). And a tiny link at the bottom of the page is definitely pushing the definition of Attribution. If you wish to continue using this photo, please use the uncropped version and link it directly to my site using the 'blog this' link creator on top of the photo in flickr (http://www.flickr.com/photos/breff/3722358660/in/set-72157621611065989/).
If you're not willing to respect the licence please stop using the photo.
I did not crop your photo. Somehow it occurred when I did a screen capture from the Wired article. I am myself very surprised that this occurred, and am only seeing it because you pointed it out to me.
Please note that this blog of mine has no commercial purpose whatsoever. I am only trying to disseminate as much information as possible concerning climate change.
I am fully aware that I violate copyright all the time.
But I would never crop out someone's watermark -- I used to be a photographer myself many years ago.
I will see if I can get the entire image onto this post, ok?
July 21, 2009 2:00 PM
N.B. It seems the cropping was caused by the allowable limit of text width on the pages of the blog.
Proceedings of the National Academy of Sciences, 2009, Vol. 106, No. 27, pp. 10949-10954; published online before print June 22, 2009; doi: 10.1073/pnas.0902817106
The large contribution of projected HFC emissions to future climate forcing
Edited by Mark H. Thiemens, University of California at San Diego, La Jolla, CA, and approved May 14, 2009 (received for review March 13, 2009)
Abstract
The consumption and emissions of hydrofluorocarbons (HFCs) are projected to increase substantially in the coming decades in response to regulation of ozone depleting gases under the Montreal Protocol. The projected increases result primarily from sustained growth in demand for refrigeration, air-conditioning (AC) and insulating foam products in developing countries assuming no new regulation of HFC consumption or emissions. New HFC scenarios are presented based on current hydrochlorofluorocarbon (HCFC) consumption in leading applications, patterns of replacements of HCFCs by HFCs in developed countries, and gross domestic product (GDP) growth. Global HFC emissions significantly exceed previous estimates after 2025 with developing country emissions as much as 800% greater than in developed countries in 2050. Global HFC emissions in 2050 are equivalent to 9–19% (CO2-eq. basis) of projected global CO2 emissions in business-as-usual scenarios and contribute a radiative forcing equivalent to that from 6–13 years of CO2 emissions near 2050. This percentage increases to 28–45% compared with projected CO2 emissions in a 450-ppm CO2 stabilization scenario. In a hypothetical scenario based on a global cap followed by 4% annual reductions in consumption, HFC radiative forcing is shown to peak and begin to decline before 2050.
Author contributions: G.J.M.V., D.W.F., J.S.D., M.M., and S.O.A. designed research; G.J.M.V. performed research; G.J.M.V. analyzed data; and G.J.M.V., D.W.F., J.S.D., M.M., and S.O.A. wrote the paper. This article contains supporting information online at www.pnas.org/cgi/content/full/0902817106/DCSupplemental.
↵* McFarland M (2008) Potential climate benefits of a global cap and reduction agreement for HFCs. Presentation at 20th meeting of the Parties to the Montreal Protocol, Doha, Qatar.
Freely available online through the PNAS open access option.
Ozone hole has unforeseen effect on ocean carbon sink
by Kate Ravilious, NewScientist, June 26, 2009
The Southern Ocean has lost its appetite for carbon dioxide, and now it appears that the ozone hole could be to blame.
The Antarctic ozone hole (Image: NASA / Goddard Space Flight Center / SVS)
In theory, oceans should absorb more CO2 as levels of the gas in the atmosphere rise. Measurements show that this is happening in most ocean regions, but strangely not in the Southern Ocean, where carbon absorption has flattened off. Climate models fail to reproduce this puzzling pattern.
The Southern Ocean is a major carbon sink, guzzling around 15% of CO2 emissions. However, between 1987 and 2004, carbon uptake in the region was reduced by nearly 2.5 billion tonnes – equivalent to the amount of carbon that all the world's oceans absorb in one year.
Premature effect
To figure out what is going on, Andrew Lenton, from the University of Pierre and Marie Curie in Paris, France, and his colleagues created a coupled ocean and atmosphere climate model, to investigate carbon absorption in oceans. Crucially, they included changes in the concentration of stratospheric ozone since 1975.
By running their model with and without the ozone depletion since 1975, Lenton and his colleagues were able to show that the ozone hole is responsible for the Southern Ocean's carbon saturation.
The effect could be down to the way decreasing stratospheric ozone and rising greenhouse gases are altering the radiation balance of the Earth's atmosphere. This has been predicted to alter and strengthen the westerly winds that blow over the Southern Ocean.
"We expected this transition to a windier regime, but it has occurred much earlier than we thought, seemingly because of the ozone hole," says Lenton.
'Unexpected effect'
Stronger surface winds enhance circulation of ocean waters, encouraging carbon-rich waters to rise from the deep, limiting the capability of surface water to absorb carbon from the atmosphere. Furthermore, the higher carbon levels in surface waters make them more acidic – bad news for many forms of ocean life, such as coral and squid.
"This result illustrates how complex the chain of cause and effect can be in the Earth system. No one would ever have predicted from first principles that increasing CFCs would have the effect of decreasing uptake of ocean carbon dioxide," says Andrew Watson, from the University of East Anglia, U.K.
by Caroline Alphonso, Toronto —Globe and Mail, April 3, 2009
Human activity is altering the world's precipitation patterns, bringing more rainfall to Canada, Northern Europe and Russia and drier weather to tropical and subtropical areas north of the equator, according to the first major international study that examines these changes over the past century.
Global warming has been blamed for higher temperatures and warmer oceans. But this is the first research paper that makes a link to rainfall patterns, with widespread implications for how people will adapt now that they've messed with Mother Nature.
"It's the first time that we've detected in precipitation data a clear imprint of human influence on the climate system," Francis Zwiers, one of the lead authors of the study and director of the climate research division at Environment Canada, said in an interview Monday.
"Temperature changes we can cope with. But water changes are much more difficult to cope with. That will have economic impacts, and impacts on food production, and could ultimately displace populations."
The study, to appear Thursday in the science journal Nature, comes as record rainfalls wreak havoc in Britain and force thousands from their homes.
The global-warming models that scientists developed to forecast climates have predicted that one effect of a warmer world would be a shift in precipitation patterns. Current observations, the study found, confirm what the models predicted.
Dr. Zwiers and his colleagues gathered global rainfall data for about 80 years, starting in 1925, and then compared it to 14 complex computer climate models.
Natural factors, such as volcanic activity, contributed to changes in precipitation patterns. But nature's work pales in comparison to what humans have done, in the form of steady increases in greenhouse gases and sulphate aerosols produced by burning fossil fuels, the study found.
Dr. Zwiers, one of Canada's most respected thinkers on global warming, explained this human activity is causing a stronger water cycle, moving more water vapour away from the warmest parts of the planet and pushing it toward the poles. This is what is making wet areas wetter, and dry areas drier.
Furthermore, higher use of fossil fuels in the Northern Hemisphere appears to be nudging the central rain band off the equator and driving it farther south, he said.
The study found that human-induced climate change has caused most of the precipitation increases in mid-latitude areas, including Canada, as well as south of the equator. Global warming has also resulted in drier conditions just north of the equator, including Mexico, Central America and northern Africa.
One of the ironies for Canada is that while there is more overall precipitation through the year, future projections show that the summers will be particularly dry for the southern Prairies, Dr. Zwiers said. That means residents will have to spend more on irrigation or switching crops.
Gordon McBean, a professor at the University of Western Ontario and the former assistant deputy minister of Meteorological Service of Canada, said the study is proof that global warming is not only about changing temperatures.
"The reality is that the climate is changing. It's not just warming, it's getting wetter in certain places and unfortunately also drier in other places," he said.
Dr. McBean said scientists are arming individuals and governments with information to make regulatory changes and plan development.
"We need strategies both within Canada and … working globally on making informed choice. The scientific community is providing information which individuals, governments at all levels need to factor into their choices," he said.
Dr. Zwiers said the results from this study have given climate scientists increased confidence in their ability to predict changes in precipitation patterns.
Proceedings of the National Academy of Sciences, published online before print June 22, 2009; doi: 10.1073/pnas.0902817106
The large contribution of projected HFC emissions to future climate forcing
Guus J. M. Velders* (Netherlands Environmental Assessment Agency, PO Box 303, 3720 AH Bilthoven, The Netherlands), David W. Fahey, John S. Daniel (National Oceanic and Atmospheric Administration, Earth System Research Laboratory, Boulder, CO 80305, U.S.A.), Mack McFarland (DuPont Fluoroproducts, Wilmington, DE 19805, U.S.A.) and Stephen O. Andersen (U.S. Environmental Protection Agency, Code 6202J, 1200 Pennsylvania Avenue NW, Washington, DC 20460, U.S.A.)
Edited by Mark H. Thiemens, University of California at San Diego, La Jolla, CA, and approved May 14, 2009 (received for review March 13, 2009).
Abstract
The consumption and emissions of hydrofluorocarbons (HFCs) are projected to increase substantially in the coming decades in response to regulation of ozone depleting gases under the Montreal Protocol. The projected increases result primarily from sustained growth in demand for refrigeration, air-conditioning (AC) and insulating foam products in developing countries assuming no new regulation of HFC consumption or emissions. New HFC scenarios are presented based on current hydrochlorofluorocarbon (HCFC) consumption in leading applications, patterns of replacements of HCFCs by HFCs in developed countries, and gross domestic product (GDP) growth. Global HFC emissions significantly exceed previous estimates after 2025 with developing country emissions as much as 800% greater than in developed countries in 2050. Global HFC emissions in 2050 are equivalent to 9–19% (CO2-eq. basis) of projected global CO2 emissions in business-as-usual scenarios and contribute a radiative forcing equivalent to that from 6–13 years of CO2 emissions near 2050. This percentage increases to 28–45% compared with projected CO2 emissions in a 450-ppm CO2 stabilization scenario. In a hypothetical scenario based on a global cap followed by 4% annual reductions in consumption, HFC radiative forcing is shown to peak and begin to decline before 2050.
Science, 19 June 2009, Vol. 324, No. 5934, pp. 1551-1554; DOI: 10.1126/science.1171477
Reports
Atmospheric carbon dioxide concentration across the mid-Pleistocene transition
Bärbel Hönisch (Department of Earth and Environmental Sciences, Lamont-Doherty Earth Observatory of Columbia University, NY 10964–8000, U.S.A.),N. Gary Hemming (Department of Earth and Environmental Sciences, Lamont-Doherty Earth Observatory of Columbia University, NY 10964–8000, U.S.A., andSchool of Earth and Environmental Sciences, Queens College, New York, NY, 11367–1597, U.S.A.), David Archer (Department of Geophysical Sciences, University of Chicago, Chicago, IL 60637, U.S.A.),Mark Siddall (Department of Earth Sciences, University of Bristol, Bristol, U.K.),and Jerry F. McManus (Department of Earth and Environmental Sciences, Lamont-Doherty Earth Observatory of Columbia University, NY 10964–8000, U.S.A.)
The dominant period of Pleistocene glacial cycles changed duringthe mid-Pleistocene from 40,000 years to 100,000 years, foras yet unknown reasons. Here we present a 2.1-million-year recordof sea surface partial pressure of CO2 (PCO2), based on boronisotopes in planktic foraminifer shells, which suggests thatthe atmospheric partial pressure of CO2 (pCO2) was relativelystable before the mid-Pleistocene climate transition. GlacialPCO2 was ~31 microatmospheres higher before the transition (morethan 1 million years ago), but interglacial PCO2 was similarto that of late Pleistocene interglacial cycles (<450,000years ago). These estimates are consistent with a close linkagebetween atmospheric CO2 concentration and global climate, butthe lack of a gradual decrease in interglacial PCO2 does notsupport the suggestion that a long-term drawdown of atmosphericCO2 was the main cause of the climate transition.
How difficult is it to recover from dangerous levels of global warming?
J A Lowe1, C Huntingford2, S C B Raper3, C D Jones4, S K Liddicoat4 and L K Gohar1 1 Met Office Hadley Centre (Reading Unit), Department of Meteorology, University of Reading, Reading RG6 6BB, UK 2 Centre for Ecology and Hydrology, Wallingford OX10 8BB, UK 3 Centre for Air Transport and the Environment, Manchester Metropolitan University, Manchester M1 5GD, UK 4 Met Office Hadley Centre, FitzRoy Road, Exeter EX1 3PB, UK
Abstract
Climate models provide compelling evidence that if greenhouse gas emissions continue at present rates, then key global temperature thresholds (such as the European Union limit of two degrees of warming since pre-industrial times) are very likely to be crossed in the next few decades. However, there is relatively little attention paid to whether, should a dangerous temperature level be exceeded, it is feasible for the global temperature to then return to safer levels in a usefully short time. We focus on the timescales needed to reduce atmospheric greenhouse gases and associated temperatures back below potentially dangerous thresholds, using a state-of-the-art general circulation model. This analysis is extended with a simple climate model to provide uncertainty bounds. We find that even for very large reductions in emissions, temperature reduction is likely to occur at a low rate. Policy-makers need to consider such very long recovery timescales implicit in the Earth system when formulating future emission pathways that have the potential to 'overshoot' particular atmospheric concentrations of greenhouse gases and, more importantly, related temperature levels that might be considered dangerous.
Reuters – Cars and tricycles can be seen along a road on a hazy day in central Beijing March 4, 2009. In recent …
WASHINGTON, March 12, 2009, Yahoo! News – The skies are dimming, for most of the world. Increases in airborne pollution have dimmed the skies by blocking sunlight over the past 30 years, researchers report in Friday's edition of the journal Science.
While decreases in atmospheric visibility — known as global dimming — have been reported in the past, the new study compiles satellite and land-based data for a longer period than had been available.
"Creation of this database is a big step forward for researching long-term changes in air pollution and correlating these with climate change," Kaicun Wang, assistant research scientist in the University of Maryland, said in a statement. "And it is the first time we have gotten global long-term aerosol information over land to go with information already available on aerosol measurements over the world's oceans."
They reported that dimming is occurring everywhere except Europe, where declines in pollution have resulted in brighter skies.
Changes in aerosols can affect weather and also may have an impact on climate, though past studies have been inconclusive. These pollutants can result in cooling by reflecting sunlight back into space, but they also can absorb solar energy, warming the atmosphere.
Researchers at the National Oceanic and Atmospheric Administration, meanwhile, warned that suggestions for a high-atmosphere "sunshade" of particles to battle global warming could reduce energy production from solar power plants.
Those proposals are aimed at blocking sunlight that can be absorbed by so-called greenhouse gases like carbon dioxide, warming climate.
But airborne particles also scatter light that does get through, and that diffuse light cannot be used by solar energy concentrating systems that produce electricity, Daniel Murphy, a scientist at NOAA's Earth System Research Laboratory in Boulder, Colo., reported in the journal Environmental Science and Technology.
Flat photovoltaic and hot water panels, commonly seen on household roofs, use both diffuse and direct sunlight, so they would be less affected.
The failure of NASA's Orbiting Carbon Observatory (OCO) is a loss to climate science, but that loss could be doubly compounded if engineers can't correct what went wrong in time for NASA's next climate satellite to fly later this year.
That satellite, known as the Glory mission, is currently set to launch in November, but it is now on hold pending the results of the OCO investigation. Whereas OCO was built to measure greenhouse gases, Glory is designed to study the effects of aerosols on clouds. This has been called the "missing link" of climate science, and it is information that is needed as soon as possible to refine global climate models.
It is well known that clouds reflect sunlight, which has a net effect of making the Earth cooler. It is also known that minute particles called aerosols often become the nuclei around which water droplets form in clouds. But what nobody understands is exactly how much humans are affecting the clouds with all the aerosols we generate through combustion, agriculture and other dust-raising activities.
So a delay in getting Glory off the ground means a delay in filling in this crucial piece of the climate puzzle. But wait -- it gets worse.
One of the instruments on Glory is the "Total Irradiance Monitor" (TIM). Its job is to measure the total light output of the Sun to a degree of precision that is simply unachievable on the ground. This is important because sunlight is the key input into global climate and it drives the whole system. The fact that some climate sceptics still site changes in the Sun's energy output as responsible for climate change speaks to the fact that we don't have a good handle on what the Sun is likely to be doing long-term and more data are urgently needed.
Solar irradiance has been measured continuously from space for about the last 30 years. But during the 1980s, coverage was insufficient and the calibration is not good between instruments that measured the Sun before and after this period. The deficit has led to disputes and to opposite conclusions about the long-term trend in solar irradiance.
Right now the best instrument for measuring solar irradiance is on the SORCE satellite, which was launched in 2003 and is now well past its nominal mission lifetime.
The TIM instrument on Glory is a descendant of this device and scientists involved with the mission say it is vital for the two instruments to observe the Sun together for at least six months to preserve the continuity of the 30-year solar record. If not, says TIM instrument scientist Greg Kopp of the University of Colorado, "it puts the whole record in jeopardy."
That would mean we might not be sure if the Sun is getting brighter, dimmer or staying the same in the coming decades, which is essential information for climate modelling and policy-making.
Glory will be launched on the same model of Taurus XL rocket that failed to place OCO into orbit today. The likely cause of the failure -- a fairing that decided not to separate -- has been established. What is not clear is whether this will require changes that could push back the launch of Glory into 2010 or beyond. Obviously scientists are hoping this will not be the case, and that any changes can be made in parallel with their own preparations for launch. On the other hand, another failure would be disastrous.
Assuming Glory launches safely, there still remains the question of whether OCO will be replaced. An ongoing concern is the shortage of climate-observing satellites on the horizon. Thanks in part to inaction during the previous US administration, there has been less investment in Earth-monitoring satellites than many climate scientists say is needed. "It looks like our capabilities will be much less in the next 5 to 10 years than they were in the previous 5 to 10 years," Drew Shindell, an atmospheric chemist with the Goddard Institute for Space Studies, told me.
With climate finally on the front burner in the White House and in Congress, it's ironic that scientists may not be in a position to provide the policy makers with the information they need at a time when they will need it most.
Impacts of climate change on stratospheric ozone recovery
Impacts of climate change on stratospheric ozone recovery
D. W. Waugh, L. Oman (Department of Earth and Planetary Sciences, Johns Hopkins University, Baltimore, MD, USA), S. R. Kawa, R. S. Stolarski, S. Pawson, A. R. Douglass, P. A. Newman (Atmospheric Chemistry and Dynamics Branch, NASA Goddard Space Flight Center, Greenbelt, MD, USA), and J. E. Nielsen (Global Modeling and Assimilation Office, NASA Goddard Space Flight Center, Greenbelt, MD, USA)
Abstract
The impact of increasing greenhouse gases (GHGs) on the “recovery” of stratospheric ozone is examined using simulations of the Goddard Earth Observing System Chemistry-Climate Model. In this model, GHG-induced climate change has a large impact on the ozone evolution and when O3 recovery milestones are reached. The two distinct milestones of “O3 returning to historical values” and “O3 being no longer significantly influenced by ozone depleting substances (ODSs)” can be reached at very different dates, and which occurs first varies between regions. GHG-induced cooling in the upper stratosphere causes O3 to increase, and O3 returns to 1980 or 1960 values several decades before O3 is no longer significantly influenced by ODSs. In contrast, transport changes in the tropical and southern mid-latitude lower stratosphere cause O3 to decrease. Here O3 never returns to 1980 values, even when anthropogenic ODSs have been removed from the atmosphere. O3 returning to 1960 (or 1980) values should not necessarily be interpreted as O3 recovery from the effects of ODSs.
(Received 4 October 2008; accepted 5 January 2009; published 5 February 2009.)
Citation: Waugh, D. W., L. Oman, S. R. Kawa, R. S. Stolarski, S. Pawson, A. R. Douglass, P. A. Newman, and J. E. Nielsen (2009), Impacts of climate change on stratospheric ozone recovery, Geophys. Res. Lett., 36, L03805, doi:10.1029/2008GL036223.
Global Warming May Delay Recovery Of Stratospheric Ozone
ScienceDaily (Feb. 4, 2009) — Increasing greenhouse gases could delay, or even postpone indefinitely the recovery of stratospheric ozone in some regions of the Earth, a new study suggests. This change might take a toll on public health.
Ozone hole around South Pole in 2003. View of the South Pole from NASA's TOMS (Total Ozone Mapping Spectrometer) satellite. Blue and green indicate relatively large amounts of ozone. Red and yellow mark the "ozone hole," an area of decreased ozone. (Credit: NASA)
Darryn W. Waugh, an atmospheric scientist at Johns Hopkins University in Baltimore, and his colleagues report that climate change could provoke variations in the circulation of air in the lower stratosphere in tropical and southern mid-latitudes — a band of the Earth including Australia and Brazil. The circulation changes would cause ozone levels in these areas never to return to levels that were present before decline began, even after ozone-depleting substances have been wiped out from the atmosphere.
"Global warming causes changes in the speed that the air is transported into and through the lower stratosphere [in tropical and southern mid-latitudes]," says Waugh. "You're moving the air through it quicker, so less ozone gets formed." He and his team present their findings in the journal Geophysical Research Letters.
Dan Lubin, an atmospheric scientist who has studied the relationship between ozone depletion and variations in the ultraviolet radiation that reaches the Earth, says Waugh's findings could bode ill for people living in the tropics and southern mid-latitudes.
If ozone levels never return to pre-1960 levels in those regions, "the risk of skin cancer for fair-skinned populations living in countries like Australia and New Zealand, and probably in Chile and Argentina too, will be greater in the 21st century than it was during the 20th century," says Lubin, who is at Scripps Institution of Oceanography in La Jolla, Calif., and did not participate in the research.
Ozone is a gas which is naturally present in the atmosphere and absorbs ultraviolet radiation from the Sun that can harm living beings—for instance, by causing human skin cancer. This protective molecule has been in decline in the stratosphere since the 1970s due to an increase in atmospheric concentrations of human-made substances (mostly chlorofluorocarbon and bromofluorocarbon compounds) that destroy ozone. Since the late 1980s, most countries have adhered to the Montreal Protocol, an international treaty to phase out production of ozone-depleting substances.
Researchers at NASA Goddard Space Flight Center in Greenbelt, Md., collaborated with Waugh in the new study. The team forecast effects on ozone recovery by means of simulations using a computer model known as the Goddard Earth Observing System Chemistry-Climate Model.
Not all regions face worse prospects for ozone recovery as a result of climate change, the scientists find.
In polar regions and northern mid-latitudes, restoration of ozone in the lower stratosphere will suffer little impact from increasing greenhouse gases, their projections indicate.
Indeed, in the upper stratosphere, climate change causes a drop in temperatures that slows down some of the chemical reactions that destroy ozone. So, recovery might be reached in those parts of the atmosphere earlier than forecast, even decades before the removal of ozone-depleting gases.
While scientists have long suspected that climate change might be altering the dynamics of stratospheric ozone recovery, Waugh's team is the first to estimate the effects of increasing greenhouse gases on the recovery of ozone by region.
Waugh says his study will help scientists attribute ozone variations to the right agent.
"Ozone is going to change in response to both ozone-depleting substances and greenhouse gases," he says, "If you don't consider climate change when studying the ozone recovery data, you may get pretty confused."
Waugh, D. W., L. Oman, S. R., Kawa, R. S. Stolarski, S. Pawson, A. R. Douglass, P. A. Newman, & J. E. Nielsen. Impacts of climate change on stratospheric ozone recovery. Geophys. Res. Lett, 36, L03805 DOI: 10.1029/2008GL036223
A couple of us (Eric and Mike) are co-authors on a paper coming out in Nature this week (Jan. 22, 09). We have already seen misleading interpretations of our results in the popular press and the blogosphere, and so we thought we would nip such speculation in the bud.
The paper shows that Antarctica has been warming for the last 50 years, and that it has been warming especially in West Antarctica (see the figure). The results are based on a statistical blending of satellite data and temperature data from weather stations. The results don't depend on the statistics alone. They are backed up by independent data from automatic weather stations, as shown in our paper as well as in updated work by Bromwich, Monaghan and others (see their AGU abstract, here), whose earlier work in JGR was taken as contradicting ours. There is also a paper in press in Climate Dynamics (Goosse et al.) that uses a GCM with data assimilation (and without the satellite data we use) and gets the same result. Furthermore, speculation that our results somehow simply reflect changes in the near-surface inversion is ruled out by completely independent results showing that significant warming in West Antarctica extends well into the troposphere. And finally, our results have already been validated by borehole thermometery — a completely independent method — at at least one site in West Antarctica (Barrett et al. report the same rate of warming as we do, but going back to 1930 rather than 1957; see the paper in press in GRL).
Here are some important things the paper does NOT show:
1) Our results do not contradict earlier studies suggesting that some regions of Antarctica have cooled. Why? Because those studies were based on shorter records (20-30 years, not 50 years) and because the cooling is limited to the East Antarctic. Our results show this too, as is readily apparent by comparing our results for the full 50 years (1957-2006) with those for 1969-2000 (the dates used in various previous studies), below.
2) Our results do not necessarily contradict the generally-accepted interpretation of recent East Antarctic cooling put forth by David Thompson (Colorado State) and Susan Solomon (NOAA Aeronomy Lab). In an important paper in Science, they presented evidence that this cooling trend is linked to an increasing trend in the strength of the circumpolar westerlies, and that this can be traced to changes in the stratosphere, mostly due to photochemical ozone losses. Substantial ozone losses did not occur until the late 1970s, and it is only after this period that significant cooling begins in East Antarctica.
3) Our paper — by itself — does not address whether Antarctica's recent warming is part of a longer term trend. There is separate evidence from ice cores that Antarctica has been warming for most of the 20th century, but this is complicated by the strong influence of El Niño events in West Antarctica. In our own published work to date (Schneider and Steig, PNAS), we find that the 1940s [edit for clarity: the 1935-1945 decade] were the warmest decade of the 20th century in West Antarctica, due to an exceptionally large warming of the tropical Pacific at that time.
So what do our results show? Essentially, that the big picture of Antarctic climate change in the latter part of the 20th century has been largely overlooked. It is well known that it has been warming on the Antarctic Peninsula, probably for the last 100 years (measurements begin at the sub-Antarctic Island of Orcadas in 1901 and show a nearly monotonic warming trend). And yes, East Antarctica cooled over the 1980s and 1990s (though not, in our results, at a statistically significant rate). But West Antarctica, which no one really has paid much attention to (as far as temperature changes are concerned), has been warming rapidly for at least the last 50 years.
Why West Antarctica is warming is just beginning to be explored, but in our paper we argue that it basically has to do enhanced meridional flow — there is more warm air reaching West Antarctica from farther north (that is, from warmer, lower latitudes). In the parlance of statistical climatology, the "zonal wave 3 pattern" has increased (see Raphael, GRL 2004). Something that goes along with this change in atmospheric circulation is reduced sea ice in the region (while sea ice in Antarctica has been increasing on average, there have been significant declines off the West Antarctic coast for the last 25 years, and probably longer). And in fact this is self reinforcing (less sea ice, warmer water, rising air, lower pressure, enhanced storminess).
The obvious question, of course, is whether those changes in circulation are themselves simply "natural variability" or whether they are forced — that is, resulting from changes in greenhouse gases. There will no doubt be a flurry of papers that follow ours, to address that very question. A recent paper in Nature Geosciences by Gillet et al. examined trends in temperatures in the both Antarctic and the Arctic, and concluded that "temperature changes in both … regions can be attributed to human activity." Unfortunately our results weren't available in time to be made use of in that paper. But we suspect it will be straightforward to do an update of that work that does incorporate our results, and we look forward to seeing that happen.
Postscript Some comment is warranted on whether our results have bearing on the various model projections of future climate change. As we discuss in the paper, fully-coupled ocean-atmosphere models don't tend to agree with one another very well in the Antarctic. They all show an overall warming trend, but they differ significantly in the spatial structure. As nicely summarized in a paper by Connolley and Bracegirdle in GRL, the models also vary greatly in their sea ice distributions, and this is clearly related to the temperature distributions. These differences aren't necessarily because there is anything wrong with the model physics (though schemes for handling sea ice do vary quite a bit model to model, and certainly are better in some models than in others), but rather because small differences in the wind fields between models results in quite large differences in the sea ice and air temperature patterns. That means that a sensible projection of future Antarctic temperature change — at anything smaller than the continental scale — can only be based on looking at the mean and variation of ensemble runs, and/or the averages of many models. As it happens, the average of the 19 models in AR4 is similar to our results — showing significant warming in West Antarctica over the last several decades (see Connolley & Bracegirdle's Figure 1).
On many occasions on this site it’s been said that cooling in Antartica is consistent with AGW, as the models show etc…. Now it appears that a warming Antarctica is also consistent with AGW. I am curious to know, is there any kind of change in temperature down there which would invalidate the AGW thesis?
[Response:Why do the critics think that everything is so simple and binary, for example that we can lump all anthropogenic forcings into a simple “AGW” forcing. Guess what, its not that simple. There are multiple anthropogenic forcings that have quite different impacts (e.g. anthropogenic greenhouse gas increases, aerosols, land-use changes and, yes, stratospheric ozone depletion). Anyone who follows the science is of course aware of this. The temperature trends in Antarctica depend on the time interval and season one looks at, because certain forcings, such as ozone depletion, are particularly important over restricted past time intervals and during particular seasons. The interval over which we expect cooling of the interior is when ozone depletion was accelerating (1960s through late 20th century) and this is precisely when we reproduce the cooling trend both in the reconstruction (primarily during the Austral fall season) and the model simulation experiments discussed in the paper. Over the longer-term, and in the annual mean, greenhouse warming wins out over the more temporary and seasonally-specific impacts of ozone depletion in our simulations, and apparently in the real world. Do you really think that all of the authors and reviewers would have overlooked a basic internal contradiction of logic of the sort you imply, if it actually existed? This is all discussed in detail in the paper. Why not go to your local library and read it and perhaps learn something? -mike]
and 
22 January 2009 at 4:32 AM
On many occasions on this site it’s been said that cooling in Antartica is consistent with AGW, as the models show etc…. Now it appears that a warming Antarctica is also consistent with AGW. I am curious to know, is there any kind of change in temperature down there which would invalidate the AGW thesis?
[Response:Why do the critics think that everything is so simple and binary, for example that we can lump all anthropogenic forcings into a simple “AGW” forcing. Guess what, its not that simple. There are multiple anthropogenic forcings that have quite different impacts (e.g. anthropogenic greenhouse gas increases, aerosols, land-use changes and, yes, stratospheric ozone depletion). Anyone who follows the science is of course aware of this. The temperature trends in Antarctica depend on the time interval and season one looks at, because certain forcings, such as ozone depletion, are particularly important over restricted past time intervals and during particular seasons. The interval over which we expect cooling of the interior is when ozone depletion was accelerating (1960s through late 20th century) and this is precisely when we reproduce the cooling trend both in the reconstruction (primarily during the Austral fall season) and the model simulation experiments discussed in the paper. Over the longer-term, and in the annual mean, greenhouse warming wins out over the more temporary and seasonally-specific impacts of ozone depletion in our simulations, and apparently in the real world. Do you really think that all of the authors and reviewers would have overlooked a basic internal contradiction of logic of the sort you imply, if it actually existed? This is all discussed in detail in the paper. Why not go to your local library and read it and perhaps learn something? -mike]