December 2004

Carbon sink or carbon source? Aerosols play significant role in shifts

by William Yeatman on December 7, 2004

Researchers used data from six sites within NASA’s AERONET (AErosol RObotic NETwork). Sites represented a wide variety of landscapes, including forests, cropland and grassland. This site in Walker Branch, Tenn., shows a sun photometer over a broadleaf deciduous forest. The sun photometer measures radiation and aerosol properties that impact light.
Photo courtesy of NASA.

Researchers at North Carolina State University have shown that the amount of aerosols dust particles, soot from automobile emissions and factories, and other airborne particles in the atmosphere has a significant impact on whether the surface area below either absorbs or emits more carbon dioxide (CO₂).

The researchers discovered that changes in the levels of airborne aerosols resulted in changes to the terrestrial carbon cycle, or the cycle in which CO₂ is absorbed by plant photosynthesis and then emitted by the soil.

Besides documenting the effects of aerosols on the carbon cycle, the research also showed that the type of landscape also influenced whether a surface area served as a carbon sink, an area that absorbs more CO₂ than it emits, or as a carbon source, an area that emits more CO₂ than it absorbs. In the research project, six locations across the United States encompassing forests, croplands and grasslands were studied. Increased amounts of aerosols over forests and croplands resulted in surface areas below becoming carbon sinks, but increased amounts of aerosols over grasslands resulted in surface areas becoming carbon sources.

Dr. Dev Niyogi, research assistant professor of marine, earth and atmospheric sciences at NC State and lead author of the study, hypothesizes that the differences among landscapes can be attributed to the amount of shade provided by tree and plant leaves in forests and croplands. The lack of shading in grasslands changes the ground surface temperature, which alters the rate of photosynthesis in plants and the CO₂ emissions by soil. Since plants want to take in CO₂ but also preserve water at the same time, Niyogi believes the lack of shade and increased temperatures may cause plants to slow the rate of photosynthesis, causing less CO₂ to be absorbed and thus more CO₂ to be effectively emitted. That would make the surface area a carbon source.

The research was published in Geophysical Research Letters, a journal of the American Geophysical Union. Niyogis co-authors on the research paper include NC State graduate student Hsin-I Chang; Dr. Vinod Saxena, professor of marine, earth and atmospheric sciences at NC State; Dr. Randy Wells, professor of crop science at NC State; Dr. Fitzgerald Booker, associate professor of crop science at NC State and USDA-ARS plant physiologist; Dr. Teddy Holt, adjunct professor of marine, earth and atmospheric sciences at NC State and a scientist at Naval Research Laboratory-Monterey; and colleagues from across the country.

Aerosols have been known to affect the climate by changing the radiation that reaches the earth surface. Increase in aerosols is often considered one possible reason that the earths surface has not seen as much warming as previously projected by climate models.

Previous studies have shown that many factors affect the carbon cycle, including rainfall and changes in land cover. But this study is believed to be the first multisite, observational analysis demonstrating that aerosols affect the carbon cycle. The study shows aerosols affect the earths regional climate in an even more profound manner by affecting its biological and chemical exchanges of the greenhouse gases.

The study examined six sites across the United States in the summertime; these locations were chosen because data on aerosols and carbon fluxes, or the changes in the carbon absorption and emission rates, were readily available. Sites ranged from grassland in Alaska to mixed forestland in Wisconsin to cropland in Oklahoma.

Before showing the effects of aerosols on the carbon cycle, the paper first showed the effects of diffuse radiation radiation that is not direct sunlight but radiation scattered by clouds, haze, or something else on carbon fluxes. The research showed that higher levels of diffuse radiation resulted in higher rates of carbon sink.

Although common sense would suggest that areas with plants receiving more constant direct sunlight would result in a surface becoming a carbon sink, that is not necessarily the case, Niyogi says. In fact, more radiation means plants more quickly reach a level of photosaturation. As Niyogi explains it, Plants absorb CO₂ very efficiently. At very high levels of radiation, as is the case with direct radiation, additional increases do not necessarily cause increased photosynthesis. It doesnt matter how much more radiation you add, the plant is not going to absorb more CO₂. But at lower levels of radiation, as is the case with diffuse radiation, any increase in radiation translates to additional photosynthesis.

The study then examined the effects of cloudiness on the carbon cycle. Cloudiness, which increased the amount of diffuse radiation, resulted in a greater amount of carbon sink in surface areas.

The study team then linked aerosols and diffuse radiation, and showed strong relationships between high amounts of aerosols and high amounts of diffuse radiation and between low amounts of aerosols and low amounts of diffuse radiation.

Finally, the study yielded its most important findings: Aerosols affect the carbon cycle in different types of landscapes, with forests and croplands serving as carbon sinks while grasslands served as carbon sources.

When you have more carbon being absorbed, it means that plants and forests there are going to grow faster, Niyogi said. And so it has the potential to alter the landscape. And when you have a change in landscape, or a change in the biogeochemical properties like the carbon cycle you have a landscape that is actively vulnerable to climate change.

Studies like these can really start putting forward the right processes in trying to quantify the carbon sink more accurately. Once we start introducing these reality-based processes into our models, well get better estimates of carbon budget, Niyogi said.

Niyogi now plans to add other variables to studying the carbon cycle, such as the effects of different types of aerosols, and factors like soil moisture. He is also planning regional and global analyses using satellite remote sensing and models to see if results square with the field studies.

The research was funded by NASA, the National Science Foundation, the Office of Naval Research, and an NC State Faculty Research and Professional Development Award.

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An abstract of the paper follows.

Direct Observations of the Effects of Aerosol Loading on Net Ecosystem CO₂ Exchanges Over Different Landscapes
Authors: Dev Niyogi, Hsin-I Chang, V. K. Saxena, and Randy Wells, North Carolina State University; Teddy Holt, Naval Research Laboratory; Kiran Alapaty, University of North Carolina-Chapel Hill; Fitzgerald Booker, USDA-ARS Air Quality-Plant Development Unit and NC State; Fei Chen, National Center for Atmospheric Research; Kenneth J. Davis, Penn State University; Brent Holben, NASA Goddard Space Flight Center; Toshihisa Matsui and Roger A. Pielke Sr., Colorado State University; Tilden Meyers and Kell Wilson, National Oceanic and Atmospheric Administration; Walter C. Oechel, San Diego State University; Yongkang Xue, University of California, Los Angeles
Published: Nov. 2004, in Geophysical Research Letters

Abstract: We present the first direct, multisite observations in support of the hypothesis that atmospheric aerosols affect the regional terrestrial carbon cycle. The daytime growing season (summer) CO₂ flux observations from six sites (forest, grasslands and croplands) with collected aerosol and surface radiation measurements were analyzed for high and low diffuse radiation; effect of cloud cover; and effect of high and low aerosol optical depths (AOD). Results indicate that aerosols exert a significant impact on net CO₂ exchange, and that their effect may be even more significant than that due to clouds. The response appears to be a general feature irrespective of the landscape and photosynthetic pathway. The CO₂ sink increased with aerosol loading for forest and crop lands, and decreased for grassland. The cause for the difference in response between vegetation types is hypothesized to be canopy architecture.

U.S. Has Three-Pronged Climate Change Strategy, Envoy Says

by William Yeatman on December 6, 2004

in Kyoto Negotiations, Politics

The United States is pursuing a three-pronged climate change strategy that is equal to the efforts of any other nation to address this environmental issue, which is the focus of attention at a major international meeting underway in Buenos Aires, Argentina.

“We believe we match or exceed what any other country in the world is doing to address” climate change and the need to control greenhouse gas emissions, said Harlan Watson, senior climate negotiator for the U.S. State Department, speaking at a press briefing on the sidelines of the conference of the parties to the U.N. Framework Convention on Climate Change (UNFCCC).

The first prong in the U.S. strategy is to reduce carbon intensity — that is, the amount of carbon emissions generated per dollar of economic output — and consequently to reduce emissions.

“Second, we are making substantial investments in science and technology and institutions designed to address both climate change in the near term and in the long term,” Watson said to the international press. The senior official, also the alternate head of the U.S. delegation to the meeting, said the United States is spending about $5 billion annually on science and technology projects, including solar and renewable energy technologies, and advanced, still-developing technologies such as nuclear fission and fusion.

The United States has established partnership arrangements with other nations in pursuit of those technological breakthroughs, and that is the third element of the U.S. strategy.

“We have well over 200 projects with our partners addressing climate change science, clean energy technologies, earth observations, and so forth,” said Watson. The United States and partners are working to develop a new generation of nuclear reactors, new methods for the capture and storage of fossil fuel emissions, and the technologies and support structure to move society toward a hydrogen-energy based economy.

The looming implementation of the Kyoto Protocol is the main agenda item at the UNFCCC. The United States is not a party to that agreement, which called for compulsory reductions in greenhouse gas emissions. Watson said the United States may not be in accord on the Kyoto agreement, but it has taken actions to reduce emissions and control climate change.

“Much more focus ought to be put on the action,” he said.

The following terms are used in the transcript:

DOE: U.S. Department of Energy

EURATOM: European Atomic Energy Community

The transcript of the press briefing follows:

[U.S. Department of State]

Press Briefing by
Dr. Harlan L. Watson
Senior Climate Negotiator and Special Representative,
U.S. Department of State, and
Alternate Head of the United States Delegation,
Tenth Conference of the Parties [COP] to the
UN Framework Convention on Climate Change [UNFCCC]

Buenos Aires, Argentina
December 7, 2004

Dr. Watson: We welcome and congratulate the government of Argentina on hosting the meeting here and for the excellent arrangements they have made. We are certainly committed to working constructively and to having positive outcomes of this Conference of the Parties.

The United States does remain committed to the Framework Convention and to achieving its ultimate objective. However, we are taking a different path than Kyoto, which many of the parties here are taking. With regard to the actions the United States is taking, they are many, and I would challenge many of the Kyoto Protocol Parties to match us in the activities we are taking both domestically and internationally.

First of all, we have three prongs in our climate policy which President Bush announced in February 2002. The first is to reduce our greenhouse gas intensity at home, thereby slowing the growth of our greenhouse gas emissions. Second, we are making substantial investments in science and technology and institutions designed to address both climate change in the near term and in the long term. And, third, we are engaging actively in international cooperation — both on a bilateral basis and on a multilateral basis.

With regard to our domestic program, we are committed to reducing our greenhouse gas intensity by 18% over the ten-year period 2002-2012. This is a domestic commitment the President made. We are doing this through a number of programs through both incentives and voluntary programs, and through some mandatory programs such as improving the fuel economy of our automobiles, improving the efficiency of our appliances and so on.

With regard to science, the United States is spending some $2 billion annually on the science of climate change, to address the uncertainties and help reduce these uncertainties. We spent some $23 billion dollars since 1990 when the U.S. Global Change Research Program was first initiated.

On the technology side, we spend approximately $3 billion dollars annually on a variety of technologies, the implementation of which would allow us to reduce our greenhouse gases over the long term. This includes both near-term options such as solar, and other renewable energy technologies, energy efficiency technologies, advanced fossil technologies — and some longer-term technologies, such as advanced nuclear, both in fission and fusion, as well as strong investments in hydrogen and in carbon capture and storage.

Internationally — we are engaged both, as I mentioned before, on a bilateral basis as well as multilaterally. Bilaterally, we have established partnerships with 14 countries and regional organizations — many of which are Kyoto parties and some of which are not. We have well over 200 projects with our partners addressing climate change science, clean energy technologies, earth observations and so forth. We have also initiated, as I mentioned yesterday, some five multilateral initiatives — science and technology initiatives:

The Group on Earth Observations — which is involving over 50 nations and 30 international organizations, as well as the European Commission, I might add, on helping to design and implement, over the next ten years, a comprehensive earth observation system which will provide data not only on climate change but also on other environmental issues.

We have a very strong partnership among 10 countries and the EURATOM on the Generation IV International Forum which is working to develop a new generation of nuclear reactors, which will be safer and more economic and secure, from a proliferation standpoint.

The Carbon Sequestration Leadership Forum, with some 16 countries and the European Commission, is working on technologies that will allow the capture and storage, in a safe and environmental manner, of emissions from fossil fuel burning plants.

The International Partnership for the Hydrogen Economy — where again we have 16 countries and the European Commission — is working to advance the global transition to a hydrogen economy.

And most recently, the Methane-to-Markets Partnership where 13 countries joined the United States this summer to launch an innovative program that will be targeted on reducing methane emissions, which is the second most important greenhouse gas. With regard to this latter partnership, the U.S. committed some $53 million to the Partnership over the next five years.

I want to close my opening remarks by referring to President Bushs commitment he made in June 2001 to develop with friends and allies and nations throughout the world an effective and science-based response to address climate change. The United States supports the development of an integrated approach to partnerships among governments, the private sector and NGOs that promotes economic growth, improves economic efficiency and productivity, enhances energy security, increases the availability of cleaner, more efficient energy resources and, of course, reduces pollution — all in ways that have the effect of reducing nations’ greenhouse gas intensity.

We believe that economic development is absolutely key to addressing this issue, because without economic development and economic growth around the world we are not going to be able to afford the new technologies that we need to address the problem in the long term.

And with that, I will be happy to stop and take any questions that you might have. Thank you.

Reuters: Dr. Watson, you told us about the goal of reducing the GHG intensity by 18% over the next 10 years. I wanted to know where U.S. emissions will stand in 2012 relative to 1990, because I understand that your emissions rose since 1990 right now, are up 13% and well, I’d rather you do the math for me.

Dr. Watson: Well, I quite frankly don’t have off the top of my head — maybe my colleagues of the DOE can address what our latest projection is. I believe we are forecasted, under a business-as-usual scenario, to be up approximately 20% by 2010. But, Dave, do you have that figure at the top of your head?

David Conover [Director, Climate Change Technology Program, U.S. Department of Energy]: No, I don’t.

Dr. Watson: O.K. I think the projections, again under the latest business-as-usual [scenario], we would expect a 4% reduction from that, which would get us about 15% or 16% above 1990 levels.

German Radio: Can you please tell us how would an international climate change protection regime from the time after 2012 have to look so it could be ratified by the U.S.?

Dr. Watson: Quite frankly, we don’t believe it’s time to address the post-2012 time frame. We are very focused on implementing the President’s program domestically. We think there are many lessons that will be learned from that process, which can inform the international process. We believe the same is true for those who will be working to implement the Kyoto Protocol. Of course, what is still to be decided among the Kyoto Parties is the type of compliance regime that will be agreed to; whether, of course, the Kyoto mechanisms – exactly how all those will work out. Of course, European trading systems and other trading systems under development still have to be implemented. Again, we will learn many, many lessons from that. And, quite frankly, whether or not the Kyoto Parties will be willing to take on what we believe would be non-growth economic policies; [they will be] required to meet the targets. So, for all of these reasons, we do not believe that it is the appropriate time to talk about post-2012 negotiations.

Agence France-Presse: I just want to understand your figures on what you’re spending this fiscal year. Can one add $3 billion this year and $2 billion annually to say that you’re spending $5 billion on climate change science and on new technologies? I mean, to simplify matters, can I do that or how would you do the arithmetic? Thank you.

Dr. Watson: Yes. Actually, Congress, by the way, is still working on our 2005 budget. The President’s overall request for climate change programs was $5.8 billion, $5 billion of which were spent on science and technology – $2 billion on the science and $3 billion on the technology. We also have some significant amounts requested before Congress with regard to tax incentives to encourage the use of clean energy technologies as well as, of course, our assistance to developing countries through our contributions to GEF and other international bodies.

Energy Daily: You mentioned the President’s statement in June 2001 committing to a science-based response to the problem of global warming. Can we infer that the U.S. does not consider the Kyoto Protocol to be based on sound science?

Dr. Watson: The Kyoto Protocol was a political agreement. It was not based on science.

German Press Agency: You’ve been telling us all the efforts the U.S. is making concerning climate change. Can you tell us when the world can expect that GHG emissions will really decrease? In which year will this be – in 2020 or when would that be? And a second question, if you allow me, what went wrong in American way of life that you have almost doubled GHG emissions in comparison to countries in Europe with the same living standard, more or less? What went wrong in the States?

Dr. Watson: Let me address the last part first, and I’ll turn to my colleague in the Department of Energy to perhaps provide some more detail on some of our technology programs. Nothing went wrong in the U.S. We are blessed with economic growth. In most developed countries and developing countries economic growth implies more energy use, which typically implies more emissions. I might say, by the way, that your sweeping statement about European reductions does not hold across-the-board, because you should know there have been substantial increases in a number of countries in Europe. I’m not going to name any countries, but I think you all know who they are.

David, would you like to address the first question?

David Conover: Thank you. We are making substantial investments in both near-term deployment of energy-efficiency and renewable energy. The total budget for our program is over $3 billion, as Harlan indicated, and fully a quarter of that is deployment of technologies today that will have an impact on reductions of greenhouse gas emissions.

The larger efforts that we have going will phase in over the near, the mid-term and long-term. The Partnership for the Hydrogen Economy [and the Presidents Hydrogen Fuel Initiative are aiming for] the 2015 time-frame [for commercialization of] hydrogen-powered vehicles.

The FutureGen program is clean coal with sequestration producing hydrogen and electricity, and is also on schedule for that time frame.

The GEN IV nuclear programs that Harlan mentioned are aiming at the 2035 time-frame. And, ITER and the fusion effort…… is aiming to the middle of the century, in the 2050 time-frame.

So we are phasing these technologies as we move forward. We have strong investments in the near term, and we believe that the intensity metric that we are using is the appropriate metric to recognize both reductions in greenhouse gas emissions and continued economic growth.

Question: My question is, beyond climate itself, which consequences does the U.S. perceive that is suffering from the dependence on fossil carbon? Now, the reason for my question is that in today’s local “Buenos Aires Herald”, which is in English, there’s a reproduction of an article by Thomas Friedman. He points out that, in effect, the National Science Foundation will be funded less by 105 million dollars next year. That means that there’s a reduction of 2%, and he also points out that by paying these high amounts of money for imports of oil we are actually funding terrorism that’s going to the U.S…and the question was simply that beyond climate itself, what other consequences does the U.S. have now from the dependence on fossil carbon?

Dr. Watson: You’re getting way beyond my area of expertise. But, clearly, it is having an impact in the increased oil prices and obviously has had an impact in what we have seen at the fuel pumps and so on. And I believe that all of the forecasts are that we are going to have lower economic growth than we otherwise would have – as will the rest of the world. Beyond that you are getting way beyond my realm of expertise. I really don’t want to comment.

O Globo, Brazil: My question is if the U.S. is doing so many things to reduce emissions as they say here, why do you think there are so many negative opinions about the Bush administration that seems to be like the bad boy. Why is that if you’re doing so much and … [inaudible]?

Dr. Watson: Thank you for your question. I’m not sure why we are considered the “bad boys.” Let me just say that perhaps there’s a perception that it is more important to agree to things rather than taking actions. We believe the focus ought to be on the actions. But, agreeing to Kyoto does not necessarily mean that you’re going to meet those commitments. And again, much more focus ought to be put on the actions… Again, our focus there is highlighting our actions. We believe we match or exceed what any other country in the world is doing to address the issue.

BBC News: There’s been quite a lot of criticism of your attempts yesterday to keep discussion off the agenda of the various conferences coming up next year – on Disaster Relief and on the problems of Small Island States. The interpretation that some of the NGO’s are putting on this is that you are very concerned not to admit the causal link between climate change and some of the problems being discussed there because of the possible liability issues that might arise if that link was admitted. Can you comment on that?

Dr. Watson: Yes, let me say that our intervention there was to make sure that there is appropriate input from the Framework Convention on Climate Change into those other two meetings that are coming up — in Mauritius on the Barbados Plan of Action – as well as the Kobe World Conference on Disaster Reduction. And then, of course, the input in the Commission on Sustainable Development process, which will be from 2006 to 2007.

Each of the upcoming meetings that will occur in January of next year has their own negotiating sessions. Certainly, climate is featured in the current negotiating text. We believe that those are the appropriate fora to negotiate those texts. Quite frankly, one of our concerns here is that this meeting will be used as an opportunity to try to negotiate things here in a forum which is really not appropriate. Again, those negotiations will take place, and the results of those will take place both in Mauritius and in Kobe at the end of January.

We also have a problem with the Framework Convention, trying to provide inputs into meetings in general. Our time here is very limited, and there are many, many issues on the plate. Procedurally, if the Conference of the Parties starts to provide input to every meeting that is occurring, nothing else will get done. In fact, we won’t even work through the list of meetings.

Lastly, we want to make sure that, again, the attention is focused on what it is that the Convention is actually doing to contribute to those processes. There are many, many activities which are being carried out under the Framework Convention which are relevant to both the meetings in Mauritius and Kobe — particularly our work on adaptation is certainly very relevant, and we expect a very positive outcome on adaptation as well as other major steps that have been undertaken under the Convention processes.

There is an agreement that was reached that the focus [of the COP plenary discussion] will be on an exchange of views on what UNFCCC activities are underway or have been accomplished that are appropriate for the Executive Secretary to report on to those meetings. Those bodies can then take those into account and complete their negotiations ultimately successfully on their text there.

New York Times: I wanted to go back to the issue of post-2012 goals. Dr. Watson, you made reference to the February 2002 speech by President Bush in which he said that within 10 years the U.S. would reassess its position. So, I have two questions that flow from that. Why not, even in an informal fashion, discuss now some of those issues, post-2012 issues and plan ahead? That’s the first question. Secondly, if not now, when?

Dr. Watson: Why not?’ Because we are still implementing the President’s program and we want to be informed by the results. The President said the current U.S. plan is to review the results of that in 2012. And, if not [now], when?’ Well, again, 2012 is when the U.S. has to reassess its current program. Obviously, we will be informed along the way by science and make adjustments as needed. But we do not intend to change our overall approach.

BBC: In the session yesterday, the opening session, this is Joke Waller Hunter when she was speaking about the future and after 2012 about the possibility of different rules and different speeds. Did you interpret that as an opening towards the United States’ willingness to discuss different ways of doing things?

Dr. Watson: Listening carefully and reading her comments, I think she put that more as a hypothetical and certainly something that needs to be on the table – different approaches and so on. And, particularly if you have the desire to bring in developing countries more into the process than they currently are, there will have to be different approaches because expecting developing countries, whose focus is on poverty reduction, to agree to targets and timetables that might impede that desire to reduce poverty in their countries is just not going to be something that is agreeable to them.

Thank you.

New report undermines climate change claims

by William Yeatman on December 6, 2004

in Science

As the 10th Conference of the Parties (COP) begins in Buenos Aires this week – the first COP since the ratification of the Kyoto protocol – scientists have published new research that calls into question many of the scientific assumptions driving global climate change policy.

The report, produced by the George C. Marshall Institute in Washington DC and the Scientific Alliance in London, suggests that calls for global action on climate change are often based on poor or uncertain science. In particular, the report sets out nineteen key questions and assumptions underpinning the climate change debate and global climate policy, highlighting a number of important areas where scientific uncertainty remains, as well as those where sound scientific evidence throws the Kyoto process into doubt.

Mark Adams, Director of the Scientific Alliance, said: The debate over the state of climate science and what it tells us about past and future climate has been going on for at least 15 years. It is not close to a conclusion, in spite of assertions to the contrary. The purpose of our paper is to subject the fundamentals of climate change science to the highest level of scientific scrutiny and to highlight those areas where further research is still needed.

William OKeefe, President of the George C. Marshall Institute, said: Climate change science has fallen victim to heated political and media rhetoric and as a consequence, the quality of science and rigors of the scientific process have suffered. The result is extensive misunderstanding over what we know about the climate system and what influences it, and the impact of human activity on future climate. The world will be ill served if global climate policy, planned out at events such as COP10, continues to be driven by politicized science instead of scientific facts and reality. The aim of our paper is to go some way towards restoring accuracy and clarity to the debate.

There are key issues that must be better understood if policy is to more closely match current knowledge levels. Examples of issues that are not adequately understood in the climate debate include:

– The assertion that there is a direct causal relationship between increased atmospheric concentrations of CO2 and other green house gases, and increased temperature during the 20th century, greenhouse gases CO2 rose steadily, while temperatures rose fell and rose in a pattern that showed no direct relation to increased greenhouse gases.

– Whether global warming over the past century is unique to the past 1000 years or longer the IPCC Third Assessment Report conclusion that the warming of the 20th century is unique to at least the past 1000 years was based on a study (by Mann, et al.) that has been shown to be incorrect by three studies recently published in peer-reviewed literature. These studies show that many parts of the world have experienced warmer temperatures at some time during the last 1000 years than they did during the later part on the 20th century.

– The influence of the sun on global climate new studies indicate that changes in the Suns magnetic field may be responsible for shorter-term changes in climate, including for much of the 20th century.

– The influence of human activity on the possibility of abrupt climate change all available evidence indicates that ice ages are caused by changes in the amount of solar energy reaching the Earths surface rather than changes in greenhouse gas concentrations.

– The accuracy of climate change modelling the estimates from current climate change models are highly uncertain and large differences between the results from different modelling methods remain. No climate model has been scientifically validated

– Understanding about major climate processes and their importance in terms of understanding future climate change – key uncertainties about the influence of ocean circulation, the hydrological (water) cycle, cloud formation and the properties of aerosols on the climate system remain. The cumulative effect of these and other uncertainties in our understanding of the climate system is an inability to accurately model the climate system and therefore accurately project future climate.

The George C. Marshall Institute, a non-profit research group founded in 1984, is dedicated to fostering and preserving the integrity of science in the policy process. The Institute conducts technical assessments of scientific developments with a major impact on public policy and communicates the results of its analyses to the press, Congress and the public.

The Scientific Alliance, formed in 2001, is a non-profit membership-based organisation based in London. The Alliance brings together both scientists and non-scientists committed to rational discussion and debate on the challenges facing the environment today.

The nineteen questions addressed by the report are as follows:

1. How is the atmospheric concentration of carbon dioxide (CO2) determined and how accurate are the measurements?

2. How much of todays atmosphere is CO2?

3. What has been the history of atmospheric CO2 concentrations?

4. Do we know why CO2 concentrations are rising?

5. What do we know about the relation between increases in the atmospheric concentrations of CO2 and other greenhouse gases and temperature?

6. If temperature changes cannot be correlated with the increase in atmospheric concentrations of CO2 and other greenhouse gases, what is causing them?

7. What influence does the Sun have on global climate?

8. What is known with a high degree of certainty about the climate system and human influence on it?

9. What major climate processes are uncertain and how important are these processes to understanding future climate?

10. What tools are available to separate the effects of the different drivers that contribute to climate change?

11. How accurate are climate models?

12. What is the basis for forecasts of large temperature increases and adverse climate impacts between 1990 and 2100?

13. How accurate are the parameters used in climate models?

14. How well have models done in back-casting past climate?

15. Is global warming over the past century unique in the past 1000 years of longer?

16. How much does the global climate vary naturally?

17. What do we know about the extent of human influence on climate? To what extent has temperature increase since 1975 been the result of human activities?

18. Could climate change abruptly?

19. Will sea level rise abruptly?

NASA study links wind, current changes to Indian Ocean warming

by William Yeatman on December 1, 2004

in Science

A NASA study suggests changing winds and currents in the Indian Ocean during the 1990s contributed to the observed warming of the ocean during that period. The findings, published in a recent issue of Geophysical Research Letters, have potential implications for long- term regional climate variability.

“Establishing this correlation provides an important missing piece to the global ocean-warming puzzle and provides vital information for regional governments and climate modelers,” said Dr. Tong Lee, study author and researcher at NASA’s Jet Propulsion Laboratory (JPL), Pasadena, Calif. “These findings from satellite data also advance space exploration by increasing understanding of how complex planetary system elements, such as winds and currents, in our home planet interact to drive climate change. Such technologies, which have been demonstrated to be critical in understanding Earth’s climate system, may someday prove useful in studying climate systems on other planets,” he said.

Lee’s findings are based on sea level measurements from NASA’s Topex/Poseidon oceanographic satellite, sea-surface temperature data from the National Oceanic and Atmospheric Administration’s Advanced Very High Resolution Radiometer satellite, and wind data from the European Space Agency’s European Remote Sensing satellites. Collected between 1992 and 2000, the combined data reveal weakening of southeasterly trade winds over the South Indian Ocean caused a major circulation of this ocean to wane by nearly 70 percent of its average strength.

The atmosphere heats the upper Indian Ocean. The circulation of this ocean counteracts the atmospheric heating by exporting warm surface water and importing colder subsurface water.

The slowdown of this circulation tends to prevent warm surface water from exiting and colder subsurface water from entering the upper Indian Ocean, raising its average temperature. During this period, the average sea-surface temperature of the Indian Ocean increased by approximately 0.25 C (0.45 F).

“This is a very important and intriguing element of climate observations, suggesting convincingly that a major piece of the world ocean has significantly changed its circulation during the last decade,” said Professor Jochem Marotzke, director of the Max Planck Institute for Meteorology in Germany. “While it is too early to say whether the underlying cause is natural variability or human-induced global warming, this result poses an interesting challenge to global climate modelers all over the world,” he added.

Multi-decadal warming of the Indian Ocean in the past has affected the North Atlantic climate and was blamed for a devastating drought along the southern edge of the Sahara Desert in the 1970s and ’80s. Understanding the cause of this warming and predicting its future evolution are major challenges to the climate community, as the ocean’s warming is tied into a much larger global cycle of events. This research suggests the Indian Ocean is subject to the same type of long-term ocean-circulation oscillations that drive weather and climate patterns in the Pacific and Atlantic Oceans.

“The waning wind and ocean currents of the Indian Ocean might be a manifestation of decadal and longer climate variability. This could have significant effects on the ocean’s ability to absorb atmospheric carbon dioxide and the region’s marine food web,” Lee said.

Like vegetation, the ocean is a natural carbon dioxide “sink” that absorbs variable amounts of carbon dioxide from the atmosphere, depending on winds, ocean currents and temperatures. The weakened wind and ocean currents, along with rising ocean temperatures, could hamper the Indian Ocean’s ability to absorb carbon dioxide. Ocean phytoplankton, the base of the marine food web, relies on the nourishment brought up by cooler, nutrient-rich subsurface water to survive and reproduce. The slowed cycling of warm and cold water could also bring fewer nutrients from the depths of the ocean to the surface, resulting in a decrease in the region’s biological productivity.

To review the full text of Lee’s study on the Internet, visit:

http://www.agu.org/pubs/current/gl.shtml/

For information about Topex/Poseidon and its follow-on satellites on the Internet, visit:

http://sealevel.jpl.nasa.gov/index.html

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