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 Collection: Environmental Policy Collection
Weather and Climate Extremes in a Changing Climate. Regions of Focus: North America, Hawaii, Caribbean, and U.S. Pacific Islands

Weather and Climate Extremes in a Changing Climate. Regions of Focus: North America, Hawaii, Caribbean, and U.S. Pacific Islands

Date: June 2008
Creator: U.S. Climate Change Science Program and the Subcommittee on Global Change Research.
Description: This document is part of the Synthesis and Assessment Products described in the U.S. Climate Change Science Program (CCSP) Strategic Plan. Changes in extreme weather and climate events have significant impacts and are among the most serious challenges to society in coping with a changing climate. This Synthesis and Assessment Product (SAP 3.3) focuses on weather and climate extremes in a changing climate. Many extremes and their associated impacts are now changing. For example, in recent decades most of North America has been experiencing more unusually hot days and nights, fewer unusually cold days and nights, and fewer frost days. Heavy downpours have become more frequent and intense. Droughts are becoming more severe in some regions, though there are no clear trends for North America as a whole. The power and frequency of Atlantic hurricanes have increased substantially in recent decades, though North American mainland land-falling hurricanes do not appear to have increased over the past century. Outside the tropics, storm tracks are shifting northward and the strongest storms are becoming even stronger. It is well established through formal attribution studies that the global warming of the past 50 years is due primarily to human-induced increases in heat-trapping gases. Such ...
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Trends in Emissions of Ozone-Depleting Substances, Ozone Layer Recovery, and Implications for Ultraviolet Radiation Exposure

Trends in Emissions of Ozone-Depleting Substances, Ozone Layer Recovery, and Implications for Ultraviolet Radiation Exposure

Date: November 2008
Creator: US Climate Change Science Program and the Subcommittee on Global Change Research.
Description: This Synthesis and Assessment Product (SAP 2.4) focuses on the Climate models. Depletion of the stratospheric ozone layer by human-produced ozone-depleting substances has been recognized as a global environmental issue for more than three decades, and the international effort to address the issue via the United Nations Montreal Protocol marked its 20-year anniversary in 2007. Scientific understanding underpinned the Protocol at its inception and ever since. As scientific knowledge advanced and evolved, the Protocol evolved through amendment and adjustment. Policy-relevant science has documented the rise, and now the beginning decline, of the atmospheric abundances of many ozone-depleting substances in response to actions taken by the nations of the world. Projections are for a return of ozone-depleting chemicals (compounds containing chlorine and bromine) to their "pre-ozone-depletion" (pre-1980) levels by the middle of this century for the midlatitudes; the polar regions are expected to follow suit within 20 years after that. Since the 1980s, global ozone sustained a depletion of about 5 percent in the midlatitudes of both the Northern Hemisphere and Southern Hemisphere, where most of the Earth's population resides; it is now showing signs of turning the corner towards increasing ozone. The large seasonal depletions in the polar regions are ...
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Atmospheric Aerosol Properties and Climate Impacts

Atmospheric Aerosol Properties and Climate Impacts

Date: January 2009
Creator: U.S. Climate Change Science Program and the Subcommittee on Global Change Research
Description: This report critically reviews current knowledge about global distributions and properties of atmospheric aerosols as they relate to aerosol impacts on climate. It assesses possible steps to substantially reduce uncertainties in aerosol radiative forcing estimates.
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Climate Projections Based on Emissions Scenarios for Long-Lived and Short-Lived Radiatively Active Gases and Aerosols

Climate Projections Based on Emissions Scenarios for Long-Lived and Short-Lived Radiatively Active Gases and Aerosols

Date: September 2008
Creator: U.S. Climate Change Science Program and the Subcommittee on Global Change Research
Description: This report focuses on the Climate Projections Based on Emissions Scenarios. The influence of greenhouse gases and particle pollution on our present and future climate has been widely examined. While both long-lived (e.g., carbon dioxide) and short-lived (e.g., soot) gases and particles affect the climate, other projections of future climate, such as the IPCC reports focus largely on the long-lived gases. This U.S. Climate Change Science Program Synthesis and Assessment Product provides a different emphasis. The authors examine the effect of long-lived greenhouse gases on the global climate based on updated emissions scenarios produced by another CCSP Synthesis and Assessment Product (SAP 2.1a). In these scenarios, atmospheric concentrations of the long-lived greenhouse gases leveled off, or stabilized, at predetermined levels by the end of the twenty-first century (unlike in the IPCC scenarios). However, the projected future temperature changes fall within the same range as those projected for the latest IPCC report. The authors confirm the robust future warming signature and other associated changes in the climate.
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The North American Carbon Budget and Implications for the Global Carbon Cycle

The North American Carbon Budget and Implications for the Global Carbon Cycle

Date: November 2007
Creator: U.S. Climate Change Science Program and the Subcommittee on Global Change Research.
Description: A primary objective of the U.S. Climate Change Science Program (CCSP) is to provide the best possible scientific information to support public discussion, as well as government and private sector decision making, on key climate-related issues. To help meet this objective, the CCSP has identified an initial set of 21 Synthesis and Assessment Products (SAPs) that address its highest priority research, observation, and decision support needs. This report-CCSP SAP 2.2-addresses Goal 2 of the CCSP Strategic Plan: Improve quantification of the forces bringing about changes in the Earth's climate and related systems. The report provides a synthesis and integration of the current knowledge of the North American carbon budget and its context within the global carbon cycle. In a format useful to decision makers, it (1) summarizes our knowledge of carbon cycle properties and changes relevant to the contributions of and impacts upon North America and the rest of the world, and (2) provides scientific information for decision support focused on key issues for carbon management and policy. Consequently, this report is aimed at both the decision-maker audience and to the expert scientific and stakeholder communities.
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Future Climate Change Research and Observations:  GCOS, WCRP and IGBP Learning from the IPCC Fourth Assessment Report

Future Climate Change Research and Observations: GCOS, WCRP and IGBP Learning from the IPCC Fourth Assessment Report

Date: 2008
Creator: International Geosphere-Biosphere Programme
Description: Learning from the authors of the IPCC Fourth Assessment Report and its findings to help guide future strategies for climate change observations and research was the key objective of a workshop organised jointly by the Global Climate Observing System (GCOS), the World Climate Research Programme (WCRP), and the International Geosphere-Biosphere Programme (IGBP) in Sydney, Australia, 4-6 October 2007.
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Temperature Trends in the Lower Atmosphere: Steps for Understanding and Reconciling Differences

Temperature Trends in the Lower Atmosphere: Steps for Understanding and Reconciling Differences

Date: April 2006
Creator: U.S. Climate Change Science Program and the Subcommittee on Global Change Research
Description: This Synthesis and Assessment Product is an important revision to the conclusions of earlier reports from the U.S. National Research Council and the Intergovernmental Panel on Climate Change. Previously reported discrepancies between the amount of warming near the surface and higher in the atmosphere have been used to challenge the reliability of climate models and the reality of human-induced global warming. Specifically, surface data showed substantial global-average warming, while early versions of satellite and radiosonde data showed little or no warming above the surface. This significant discrepancy no longer exists because errors in the satellite and radiosonde data have been identified and corrected. New data sets have also been developed that do not show such discrepancies. This Synthesis and Assessment Product is an important revision to the conclusions of earlier reports from the U.S. National Research Council and the Intergovernmental Panel on Climate Change. For recent decades, all current atmospheric data sets now show global-average warming that is similar to the surface warming. While these data are consistent with the results from climate models at the global scale, discrepancies in the tropics remain to be resolved. Nevertheless, the most recent observational and model evidence has increased confidence in our understanding ...
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Past Climate Variability and Change in the Arctic and at High Latitudes

Past Climate Variability and Change in the Arctic and at High Latitudes

Date: January 2009
Creator: U.S. Climate Change Science Program and the Subcommittee on Global Change Research
Description: This Climate Change Science Program Synthesis and Assessment Product addresses current capabilities to integrate observations of the climate system into a consistent description of past and current conditions through the method of reanalysis. In addition, the Product assesses present capabilities to attribute causes for climate variations and trends over North America during the reanalysis period, which extends from the mid-twentieth century to the present. This Product reviews Past Climate Variability and Change in the Arctic and at High Latitudes. Paleoclimate records play a key role in our understanding of Earth's past and present climate system and in our confidence in predicting future climate changes. Paleoclimate data help to elucidate past and present active mechanisms of climate change by placing the short instrumental record into a longer term context and by permitting models to be tested beyond the limited time that instrumental measurements have been available. Recent observations in the Arctic have identified large ongoing changes and important climate feedback mechanisms that multiply the effects of global-scale climate changes. As discussed in this report, paleoclimate data show that land and sea ice have grown with cooling temperatures and have shrunk with warming ones, amplifying temperature changes while causing and responding to ...
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NOAA Reports Potent Greenhouse Gas Levels Off

NOAA Reports Potent Greenhouse Gas Levels Off

Date: November 17, 2003
Creator: NOAA News Online
Description: This document provides a summary of a study by NOAA researchers and National Institute for Space Research in the Netherlands. According to the study, one of the atmosphere's most potent greenhouse gases, methane, may now have leveled off. Scientists aren't sure yet if this "leveling off" is just a temporary pause in two centuries of increase or a new state of equilibrium.
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Reanalysis of Historical Climate Data for Key Atmospheric Features: Implications for Attribution of Causes of Observed Chan

Reanalysis of Historical Climate Data for Key Atmospheric Features: Implications for Attribution of Causes of Observed Chan

Date: 2008
Creator: U.S. Climate Change Science Program and the Subcommittee on Global Change Research
Description: This Climate Change Science Program Synthesis and Assessment Product addresses current capabilities to integrate observations of the climate system into a consistent description of past and current conditions through the method of reanalysis. In addition, the Product assesses present capabilities to attribute causes for climate variations and trends over North America during the reanalysis period, which extends from the mid-twentieth century to the present. This Product reviews the strengths and limitations of current atmospheric reanalysis products. It finds that reanalysis data play a crucial role in helping to identify, describe, and understand atmospheric features associated with weather and climate variability, including high-impact events such as major droughts and floods. Reanalysis data play an important role in assessing the ability of climate models to simulate the average climate and its variations. The data also help in identifying deficiencies in representations of physical processes that produce climate model errors.
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