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Climate effects of global land cover change
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When changing from grass and croplands to forest, there are two competing effects of land cover change on climate: an albedo effect which leads to warming and an evapotranspiration effect which tends to produce cooling. It is not clear which effect would dominate. We have performed simulations of global land cover change using the NCAR CAM3 atmospheric general circulation model coupled to a slab ocean model. We find that global replacement of current vegetation by trees would lead to a global mean warming of 1.3°C, nearly 60% of the warming produced under a doubled CO2 concentration, while replacement by grasslands would result in a cooling of 0.4°C. It has been previously shown that boreal forestation can lead to warming; our simulations indicate that mid- latitude forestation also could lead to warming. These results suggest that more research is necessary before forest carbon storage should be deployed as a mitigation strategy for global warming.
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Climate Impacts
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Climate negotiations under scientific uncertainty
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How does uncertainty about “dangerous” climate change affect the prospects for international cooperation? Climate negotiations usually are depicted as a prisoners’ dilemma game; collectively, countries are better off reducing their emissions, but self-interest impels them to keep on emitting. We provide experimental evidence, grounded in an analytical framework, showing that the fear of crossing a dangerous threshold can turn climate negotiations into a coordination game, making collective action to avoid a dangerous threshold virtually assured. These results are robust to uncertainty about the impact of crossing a threshold, but uncertainty about the location of the threshold turns the game back into a prisoners’ dilemma, causing cooperation to collapse. Our research explains the paradox of why countries would agree to a collective goal, aimed at reducing the risk of catastrophe, but act as if they were blind to this risk.
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Climate Outlook Looking Much The Same, or Even Worse
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Climate scientists have been feverishly preparing analyses for inclusion in the fifth climate assessment report (AR5) of the Intergovernmental Panel on Climate Change (IPCC) due out in 2013. At the meeting, they gave colleagues a peek at where climate science stands 5 years after their last push to inform the authoritative international evaluation . The climate models are bigger and more sophisticated
than ever, speakers reported, but they are yielding the same wide range of possible warming and precipitation changes as they did 5 years ago. But when polled on other areas of concern, researchers say they see more trouble ahead than the previous IPCC assessment had, though less than some scientists had feared
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Climate Science PDFs
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Climate Science PDFs Collection
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Climate Videos and Webinars
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Videos and Webinars
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Climate, carbon cycling, and deep-ocean ecosystem
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Climate variation affects surface ocean processes and the production of organic carbon, which ultimately comprises the primary food supply to the deep-sea ecosystems that occupy 60% of the Earth’s surface. Warming trends in atmospheric and upper ocean temperatures, attributed to anthropogenic influence, have occurred over the past four decades. Changes in upper ocean temperature influence stratification and can affect the availability of nutrients for phytoplankton production. Global warming has been predicted to intensify stratification and reduce vertical mixing. Research also suggests that such reduced mixing will enhance variability in primary production and carbon export flux to the deep sea. The dependence of deep-sea communities on surface water production has raised important questions about how climate change will affect carbon cycling and deep-ocean ecosystem function. Recently, un- precedented time-series studies conducted over the past two decades in the North Pacific and the North Atlantic at >4,000-m depth have revealed unexpectedly large changes in deep-ocean ecosystems significantly correlated to climate-driven changes in the surface ocean that can impact the global carbon cycle. Climate-driven variation affects oceanic communities from surface waters to the much-overlooked deep sea and will have impacts on the global carbon cycle. Data from these two widely separated areas of the deep ocean provide compelling evidence that changes in climate can readily influence deep-sea processes. However, the limited geographic coverage of these existing time-series studies stresses the importance of developing a more global effort to monitor deep- sea ecosystems under modern conditions of rapidly changing climate.
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Climate-induced changes in the small mammal communities of the Northern Great Lakes Region
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We use museum and other collection records to document large and extraordinarily rapid
changes in the ranges and relative abundance of nine species of mammals in the northern
Great Lakes region (white-footed mice, woodland deer mice, southern red-backed voles,
woodland jumping mice, eastern chipmunks, least chipmunks, southern flying squirrels,
northern flying squirrels, common opossums). These species reach either the southern or
the northern limit of their distributions in this region. Changes consistently reflect
increases in species of primarily southern distribution (white-footed mice, eastern
chipmunks, southern flying squirrels, common opossums) and declines by northern
species (woodland deer mice, southern red-backed voles, woodland jumping mice, least
chipmunks, northern flying squirrels). White-footed mice and southern flying squirrels
have extended their ranges over 225 km since 1980, and at particularly well-studied sites
in Michigan’s Upper Peninsula, small mammal assemblages have shifted from numerical
domination by northern species to domination by southern species. Repeated resampling
at some sites suggests that southern species are replacing northern ones rather than
simply being added to the fauna. Observed changes are consistent with predictions from
climatic warming but not with predictions based on recovery from logging or changes in
human populations. Because of the abundance of these focal species (the eight rodent
species make up 96.5% of capture records of all forest-dwelling rodents in the region and
70% of capture records of all forest-dwelling small mammals) and the dominating
ecological roles they play, these changes substantially affect the composition and
structure of forest communities. They also provide an unusually clear example of change
that is likely to be the result of climatic warming in communities that are experienced by
large numbers of people.
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CLIMATE’S SMOKY SPECTRE
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With their focus on greenhouse gases, atmospheric scientists have largely overlooked lowly soot particles. But black carbon is now a hot topic among researchers and politicians.
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Climate: Sawyer predicted rate of warming in 1972
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Excerpt: "In four pages Sawyer summarized what was known about the role of carbon dioxide in enhancing the natural greenhouse effect, and made a remarkable prediction of the warming expected at the end of the twentieth century.He concluded that the 25% increase in atmospheric carbon dioxide predicted to occur by 2000 corresponded to an increase of 0.6 °C in world temperature..... In fact the global surface temperature rose about 0.5 °C between the early 1970s and2000. Considering that global temperatures had, if anything, been falling in the decades leading up to the early 1970s, Sawyer’s prediction of a reversal of this trend, and of the correct magnitude of the warming, is perhaps the most remarkable long-range forecast ever made.
Despite huge efforts, and advances in the science, the scientific consensus on the amount of global warming
expected from increasing atmospheric carbon dioxide concentrations has changed little from that in Sawyer’s time.
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