Science Current Events | Science News | Brightsurf.com
 

World to be even hotter by century's end

May 25, 2006
BERKELEY - If Earth's past cycles of warming and cooling are any indication, temperatures by the end of the century will be even hotter than current climate models predict, according to a report by University of California, Berkeley, researchers.

The scientists based their conclusion on a study of Antarctic ice cores containing a 360,000-year record of global temperature and levels of carbon dioxide and methane-two of the major greenhouse gases implicated in global warming. They found that during periods of warming, greenhouse gas levels rose and created significantly higher temperatures than would be expected solely from the increased intensity of sunlight that triggered these warm periods.

Though the ice core data do not point to specific processes that amplify the warming, the researchers suspect that it is due to warmer soils and oceans giving off more CO2 and methane, which add to the greenhouse effect of CO2 from fossil fuel burning and other human activities.

Thus, while current models predict temperature increases of 1.5 to 4.5 degrees Celsius (2.7 to 8.1 degrees Fahrenheit) from a doubling of atmospheric carbon dioxide levels, the natural processes injecting more CO2 into the atmosphere will lead to temperature increases of 1.6 to 6 degrees Celsius (2.9 to 10.8 degrees Fahrenheit), with the higher temperatures more likely, the researchers said.

"We are underestimating the magnitude of warming because we are ignoring the extra carbon dioxide dumped into the atmosphere because of warming," said John Harte, UC Berkeley professor of energy and resources and of environmental science, policy & management. "Warming gets an extra kick from CO2 feedback."

"The warming caused by our release of CO2 triggers changes in the Earth system that lead to release of more CO2 to the atmosphere," added co-author Margaret Torn, a UC Berkeley adjunct associate professor of energy and resources and staff scientist at Lawrence Berkeley National Laboratory. "If that is the case, then every bit of CO2 release now is actually committing us to a larger CO2 change in the atmosphere."

The result, Harte and Torn conclude in their paper, is "that the upper value of warming that is projected for the end of the 21st century, 5.8°C [10.4°F], could be increased to 7.7°C [13.9°F], or nearly 2°C additional warming."

The report is scheduled for publication in the May 26 issue of Geophysical Research Letters. That issue also will contain an article that looks at the same effect over a shorter time scale, confirming the amplification reported by Harte and Torn and suggesting that it may be even greater.

Current climate models, called General Circulation Models, start from fundamental physical processes to calculate a probable temperature increase based on likely atmospheric carbon dioxide levels, typically a doubling of today's CO2 concentration. These models also include feedback mechanisms that boost or moderate warming, such as the increased heat absorption expected when highly reflective ice sheets and glaciers melt; or the effect of more atmospheric water vapor on the formation of clouds, which both reflect sunlight and insulate the Earth.

But models are only now beginning to take into account the extra carbon dioxide and methane injected into the atmosphere as global temperatures increase. Though this is expected because warmer soils decompose faster, releasing more CO2, and because warmer oceans outgas more CO2, scientists have yet to quantify the full impact of these processes.

"Without a mechanism, people feel uncomfortable putting these processes in a model. I think that's a big mistake," Harte said.

Luckily, it's possible to estimate the effect of CO2 feedback by looking at how the Earth responded to past cycles of warming and cooling, which were caused by natural variations in the strength of sunlight hitting Earth, rather than by human production of greenhouse gases. Ice cores drilled in the Vostok ice sheet in 1998 and 1999 by Russia, France and the United States span nearly 420,000 years and carry information about four major climate cycles and many smaller temperature swings. In 1999, scientists measured CO2 and methane levels from gas trapped in bubbles in the ice, and have estimated global temperature based on oxygen isotope and deuterium ratios. UC Berkeley's Kurt Cuffey, professor of geography and earth and planetary science, updated these measurements in 2001.

Climate scientists immediately saw that the ice core data imply a strong positive feedback to global CO2 and methane levels, but how much this impacted warming trends was unclear.

Harte, a physicist by training, and Torn devised a way to use these data and current global climate models to estimate the effect of increased CO2 entering the atmosphere as a result of warming, called the "gain," analogous to the gain of an electronic amplifier-the factor by which output power increases. From Cuffey's data, Harte and Torn were able to extract the effect of temperature on CO2 and methane levels. They calculated the reverse-the effect of CO2 and methane levels on temperature, or the so-called climate sensitivity-from climate models, using a number consistent with a new estimate published in the April 20 issue of Nature.

Harte and Torn added the resultant gains from CO2 and methane to the gain already known for other climate feedbacks, in particular the largest source, increased atmospheric water vapor, to get a total gain that they used to calculate the temperature increase that would result from a doubling of current CO2 levels.

Both researchers emphasize that the large temperature range they predict-1.6 to 6 degrees Celsius-does not mean that we have an equal chance of ending up with less warming as with greater warming. In other words, it doesn't mean that the uncertainties are symmetric about an average increase of 3.8°C.

"People see this uncertainty and think that we have an equal probability of dodging a bullet as catching it. That is a fallacy," Torn said.

"By giving the appearance of symmetric feedback, people have an excuse to say, 'Maybe we don't have to worry so much,'" Harte said. "But while there are uncertainties in the feedbacks, all the major feedbacks are positive, meaning they would increase warming, and we know of no significant negative feedbacks that would slow warming."

While Harte acknowledges that the future may not look like past periods of global warming, "in the absence of contradictory evidence, we have to assume the future will respond like the past."

"Whatever the mechanisms that cause temperature to create a change in CO2 and methane, they are repeatable again and again and again over many cooling and warming cycles. So, although the world is different today than it was then, we don't have a basis for ignoring them," Torn added.

Harte has been conducting studies on experimental plots in the Rocky Mountains that would quantify the effect of warmer temperatures on soil carbon. He and his colleagues found that artificially heated plots lost significant soil carbon to the atmosphere as CO2, compared to control plots. Thus, he said, the effect of heating on the carbon cycle in his plots is to generate a positive feedback, though he noted that this might be a short-term effect. The long term effect, however, is unknown, as is the effect of warming in other habitats.

"We need to know the effect of warmer temperatures in all different habitats, not just temperate Rocky Mountain forests but also the tropics and European boreal forests and Eastern U.S. deciduous forests and savanna and prairie. There are huge data gaps," he said.

Torn noted, however, that humans are the biggest unknown.

"To predict the future, you have to guess how much CO2 levels will go up. That depends on the biggest uncertainty of all-what humans decide to do. Do we get smart and prevent CO2 emissions? Do we continue with business as usual? Or will we end up somewhere in between?"

The work was supported by the U.S. Department of Energy's Climate Change Research Division and by the National Science Foundation.

University of California, Berkeley


Related Climate Models Current Events and Climate Models News Articles


Warming slow-down not the end of climate change, study shows
A slow-down in global warming is not a sign that climate change is ending, but a natural blip in an otherwise long-term upwards trend, research shows.

Atmospheric mysteries unraveling
It's been difficult to explain patterns of toxic mercury in some parts of the world, such as why there's so much of the toxin deposited into ecosystems from the air in the southeastern United States, even upwind of usual sources.

Understanding subduction zone earthquakes: the 2004 Sumatra earthquake example
The 26 December 2004 Mw ~9.2 Indian Ocean earthquake (also known as the Sumatra-Andaman or Aceh-Andaman earthquake), which generated massive, destructive tsunamis, especially along the Aceh coast of northern Sumatra, Indonesia, clearly demonstrated the need for a better understanding of how frequently subduction zone earthquakes and tsunamis occur.

New study favors cold, icy early Mars
The high seas of Mars may never have existed, according to a new study that looks at two opposite climate scenarios of early Mars and suggests that a cold and icy planet billions of years ago better explains water drainage and erosion features seen on the planet today.

Big dinosaurs steered clear of the tropics
For more than 30 million years after dinosaurs first appeared, they remained inexplicably rare near the equator, where only a few small-bodied meat-eating dinosaurs made a living.

Warmer, lower-oxygen oceans will shift marine habitats
Modern mountain climbers usually carry tanks of oxygen to help them reach the summit. The combination of physical exertion and lack of oxygen at high altitudes creates a major challenge for mountaineers.

EARTH: Flames fan lasting fallout from Chernobyl
In the years following the 1986 Chernobyl nuclear disaster, forest fires billowed plumes of contaminated smoke, carrying radioactive particles throughout Europe on the wind.

Exposure of US population to extreme heat could quadruple by mid-century
U.S. residents' exposure to extreme heat could increase four- to six-fold by mid-century, due to both a warming climate and a population that's growing especially fast in the hottest regions of the country, according to new research.

New link between ocean microbes and atmosphere uncovered
Few things are more refreshing than the kiss of sea spray on your face.

Climate change's future impact uncertain on Midwest water cycle, Dartmouth-led study finds
Will climate change make the U.S. Midwest drier or wetter during the summer growing season? A new Dartmouth-led study finds that the answer remains uncertain.
More Climate Models Current Events and Climate Models News Articles

Climate Models Fail

Climate Models Fail


Climate Models Fail exposes the disturbing fact that climate models being used by the IPCC for their 5th Assessment Report have very little practical value because they cannot simulate critical variables of interest to the public and policymakers. Using easy-to-read graphs, this book compares data (surface temperature, precipitation, and sea ice area) with the computer model simulations. It is very easy to see that the model outputs bear little relationship to the data. In other words, climate models create imaginary climates in virtual worlds that exhibit no similarities to the climate of the world in which we live.
This book was prepared for readers without scientific backgrounds. The terms used by scientists are explained and non-technical “translations” are provided....

System Zoo 2 Simulation Models. Climate, Ecosystems, Resources

System Zoo 2 Simulation Models. Climate, Ecosystems, Resources
by Hartmut Bossel (Author)


Mathematical modeling and computer simulation make it possible to understand and control the dynamic processes taking place in complex systems. Simulation provides insights into the often surprising diversity of possible behaviors, and allows identifying possibilities for intervention and options for alternative development. About one hundred simulation models from all areas of life are fully documented in the three volumes of the 'System Zoo'. They can be quickly implemented and easily operated using freely available system dynamics software. Volume 2 of the System Zoo contains simulation models of the regional water cycle and global carbon cycle, the photosynthesis of vegetation, forest growth, the water, nutrient, and energy dynamics of agriculture, the interaction of plants,...

Mathematical and Physical Fundamentals of Climate Change

Mathematical and Physical Fundamentals of Climate Change
by Zhihua Zhang (Author), John C. Moore (Author)


Mathematical and Physical Fundamentals of Climate Change is the first book to provide an overview of the math and physics necessary for scientists to understand and apply atmospheric and oceanic models to climate research.  The book begins with basic mathematics then leads on to specific applications in atmospheric and ocean dynamics, such as fluid dynamics, atmospheric dynamics, oceanic dynamics, and glaciers and sea level rise.  Mathematical and Physical Fundamentals of Climate Change provides a solid foundation in math and physics with which to understand global warming, natural climate variations, and climate models. This book informs the future users of climate models and the decision-makers of tomorrow by providing the depth they need. Developed from a course that the authors...

A Vast Machine: Computer Models, Climate Data, and the Politics of Global Warming (Infrastructures)

A Vast Machine: Computer Models, Climate Data, and the Politics of Global Warming (Infrastructures)
by Paul N. Edwards (Author)


Global warming skeptics often fall back on the argument that the scientific case for global warming is all model predictions, nothing but simulation; they warn us that we need to wait for real data, "sound science." In A Vast Machine Paul Edwards has news for these skeptics: without models, there are no data. Today, no collection of signals or observations -- even from satellites, which can "see" the whole planet with a single instrument -- becomes global in time and space without passing through a series of data models. Everything we know about the world's climate we know through models. Edwards offers an engaging and innovative history of how scientists learned...

Stochastic Climate Theory: Models and Applications

Stochastic Climate Theory: Models and Applications
by Serguei Dobrovolski (Author)


The author describes the stochastic (probabilistic) approach to the study of changes in the climate system. Climatic data and theoretical considerations suggest that a large part of climatic variation/variability has a random nature and can be analyzed using the theory of stochastic processes. This work summarizes the results of processing existing records of climatic parameters as well as appropriate theories: from the theory of random processes (based on the results of Kolmogorov and Yaglom) and Hasselmann's "stochastic climate model theory" to recently obtained results.

Climate System Modeling

Climate System Modeling
by Kevin E. Trenberth (Editor)


This interdisciplinary volume aimed at graduate students and researchers provides a thorough grounding in the tools necessary for an appreciation of climate change and its implications. It discusses not only the primary concepts involved but also the mathematical, physical, chemical and biological basis for the component models and the sources of uncertainty, the assumptions made and the approximations introduced. Climate System Modeling addresses all aspects of the climate system: the atmosphere and the oceans, the cryosphere, terrestrial ecosystems and the biosphere, land surface processes and global biogeochemical cycles. As a comprehensive text it will appeal to students and researchers concerned with any aspect of climatology and the study of related topics in the broad earth and...

This Changes Everything: Capitalism vs. The Climate

This Changes Everything: Capitalism vs. The Climate
by Naomi Klein (Author)


The most important book yet from the author of the international bestseller The Shock Doctrine, a brilliant explanation of why the climate crisis challenges us to abandon the core “free market” ideology of our time, restructure the global economy, and remake our political systems.

In short, either we embrace radical change ourselves or radical changes will be visited upon our physical world. The status quo is no longer an option.

In This Changes Everything Naomi Klein argues that climate change isn’t just another issue to be neatly filed between taxes and health care. It’s an alarm that calls us to fix an economic system that is already failing us in many ways. Klein meticulously builds the case for how massively reducing our greenhouse emissions is our best chance...

The Brain-Targeted Teaching Model for 21st-Century Schools

The Brain-Targeted Teaching Model for 21st-Century Schools
by Mariale M. Hardiman (Author)


A powerful guide for applying brain research for more effective instruction The Brain-Targeted Teaching Model for 21st-Century Schools serves as a bridge between research and practice by providing a cohesive, proven, and usable model of effective instruction. Compatible with other professional development programs, this model shows how to apply educational and cognitive neuroscience principles into classroom settings through a pedagogical framework. The model’s six components are: (1) Establish the emotional connection to learning 
(2) Develop the physical learning environment
(3) Design the learning experience 
(4) Teach for the mastery of content, skills, and concepts 
(5) Teach for the extension and application of knowledge
(6) Evaluate...

Climate Shock: The Economic Consequences of a Hotter Planet

Climate Shock: The Economic Consequences of a Hotter Planet
by Gernot Wagner (Author), Martin L. Weitzman (Author)


If you had a 10 percent chance of having a fatal car accident, you'd take necessary precautions. If your finances had a 10 percent chance of suffering a severe loss, you'd reevaluate your assets. So if we know the world is warming and there's a 10 percent chance this might eventually lead to a catastrophe beyond anything we could imagine, why aren't we doing more about climate change right now? We insure our lives against an uncertain future--why not our planet?In Climate Shock, Gernot Wagner and Martin Weitzman explore in lively, clear terms the likely repercussions of a hotter planet, drawing on and expanding from work previously unavailable to general audiences. They show that the longer we wait to act, the more likely an extreme event will happen. A city might go underwater. A rogue...

Informing Energy and Climate Policies Using Energy Systems Models: Insights from Scenario Analysis Increasing the Evidence Base (Lecture Notes in Energy)

Informing Energy and Climate Policies Using Energy Systems Models: Insights from Scenario Analysis Increasing the Evidence Base (Lecture Notes in Energy)
by George Giannakidis (Editor), Maryse Labriet (Editor), Brian Ó Gallachóir (Editor), GianCarlo Tosato (Editor)


This book highlights how energy-system models are used to underpin and support energy and climate mitigation policy decisions at national, multi-country and global levels. It brings together, for the first time in one volume, a range of methodological approaches and case studies of good modeling practice on a national and international scale from the IEA-ETSAP energy technology initiative. It provides insights for the reader into the rich and varied applications of energy-system models and the underlying methodologies and policy questions they can address. The book demonstrates how these models are used to answer complex policy questions, including those relating to energy security, climate change mitigation and the optimal allocation of energy resources. It will appeal to energy...

© 2015 BrightSurf.com