Reconciling Observations of Global Temperature Change
Reconciling Observations of Global Temperature Change

Author: National Research Council

Publisher: National Academies Press

Published: 2000-01-07

Total Pages: 101

ISBN-13: 0309183723

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An overall increase in global-mean atmospheric temperatures is predicted to occur in response to human-induced increases in atmospheric concentrations of heat-trapping "greenhouse gases." The most prominent of these gases, carbon dioxide, has increased in concentration by over 30% during the past 200 years, and is expected to continue to increase well into the future. Other changes in atmospheric composition complicate the picture. In particular, increases in the number of small particles (called aerosols) in the atmosphere regionally offset and mask the greenhouse effect, and stratospheric ozone depletion contributes to cooling of the upper troposphere and stratosphere. Many in the scientific community believe that a distinctive greenhouse-warming signature is evident in surface temperature data for the past few decades. Some, however, are puzzled by the fact that satellite temperature measurements indicate little, if any, warming of the lower to mid-troposphere (the layer extending from the surface up to about 8 km) since such satellite observations first became operational in 1979. The satellite measurements appear to be substantiated by independent trend estimates for this period based on radiosonde data. Some have interpreted this apparent discrepancy between surface and upper air observations as casting doubt on the overall reliability of the surface temperature record, whereas others have concluded that the satellite data (or the algorithms that are being used to convert them into temperatures) must be erroneous. It is also conceivable that temperatures at the earth's surface and aloft have not tracked each other perfectly because they have responded differently to natural and/or human-induced climate forcing during this particular 20-year period. Whether these differing temperature trends can be reconciled has implications for assessing: how much the earth has warmed during the past few decades, whether observed changes are in accord with the predicted response to the buildup of greenhouse gases in the atmosphere based on model simulations, and whether the existing atmospheric observing system is adequate for the purposes of monitoring global-mean temperature. This report reassesses the apparent differences between the temperature changes recorded by satellites and the surface thermometer network on the basis of the latest available information. It also offers an informed opinion as to how the different temperature records should be interpreted, and recommends actions designed to reduce the remaining uncertainties in these measurements.

Thriving on Our Changing Planet
Thriving on Our Changing Planet

Author: National Academies of Sciences, Engineering, and Medicine

Publisher: National Academies Press

Published: 2019-01-20

Total Pages: 717

ISBN-13: 0309467578

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We live on a dynamic Earth shaped by both natural processes and the impacts of humans on their environment. It is in our collective interest to observe and understand our planet, and to predict future behavior to the extent possible, in order to effectively manage resources, successfully respond to threats from natural and human-induced environmental change, and capitalize on the opportunities â€" social, economic, security, and more â€" that such knowledge can bring. By continuously monitoring and exploring Earth, developing a deep understanding of its evolving behavior, and characterizing the processes that shape and reshape the environment in which we live, we not only advance knowledge and basic discovery about our planet, but we further develop the foundation upon which benefits to society are built. Thriving on Our Changing Planet presents prioritized science, applications, and observations, along with related strategic and programmatic guidance, to support the U.S. civil space Earth observation program over the coming decade.

Understanding Earth's Deep Past
Understanding Earth's Deep Past

Author: National Research Council

Publisher: National Academies Press

Published: 2011-08-02

Total Pages: 153

ISBN-13: 0309209196

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There is little dispute within the scientific community that humans are changing Earth's climate on a decadal to century time-scale. By the end of this century, without a reduction in emissions, atmospheric CO2 is projected to increase to levels that Earth has not experienced for more than 30 million years. As greenhouse gas emissions propel Earth toward a warmer climate state, an improved understanding of climate dynamics in warm environments is needed to inform public policy decisions. In Understanding Earth's Deep Past, the National Research Council reports that rocks and sediments that are millions of years old hold clues to how the Earth's future climate would respond in an environment with high levels of atmospheric greenhouse gases. Understanding Earth's Deep Past provides an assessment of both the demonstrated and underdeveloped potential of the deep-time geologic record to inform us about the dynamics of the global climate system. The report describes past climate changes, and discusses potential impacts of high levels of atmospheric greenhouse gases on regional climates, water resources, marine and terrestrial ecosystems, and the cycling of life-sustaining elements. While revealing gaps in scientific knowledge of past climate states, the report highlights a range of high priority research issues with potential for major advances in the scientific understanding of climate processes. This proposed integrated, deep-time climate research program would study how climate responded over Earth's different climate states, examine how climate responds to increased atmospheric carbon dioxide and other greenhouse gases, and clarify the processes that lead to anomalously warm polar and tropical regions and the impact on marine and terrestrial life. In addition to outlining a research agenda, Understanding Earth's Deep Past proposes an implementation strategy that will be an invaluable resource to decision-makers in the field, as well as the research community, advocacy organizations, government agencies, and college professors and students.

Review of the U.S. Climate Change Science Program's Synthesis and Assessment Product on Temperature Trends in the Lower Atmosphere
Review of the U.S. Climate Change Science Program's Synthesis and Assessment Product on Temperature Trends in the Lower Atmosphere

Author: National Research Council

Publisher: National Academies Press

Published: 2005-06-10

Total Pages: 74

ISBN-13: 030909674X

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The U.S. Climate Change Science Program (CCSP), established in 2002 to coordinate climate and global change research conducted in the United States and to support decision-making on climate-related issues, is producing twenty-one synthesis and assessment reports that address its research, observation, and decision-support needs. The first report, produced by the National Oceanic and Atmospheric Administration (NOAA) in coordination with other agencies, focuses on understanding reported differences between independently produced data sets of temperature trends for the surface through the lower stratosphere and comparing these data sets to model simulations. To ensure credibility and quality, NOAA asked the National Research Council to conduct an independent review of the report. The committee concluded that the report Temperature Trends in the Lower Atmosphere: Understanding and Reconciling Differences is a good first draft that covers an appropriate range of issues, but that it could be strengthened in a number of ways.

Attribution of Extreme Weather Events in the Context of Climate Change
Attribution of Extreme Weather Events in the Context of Climate Change

Author: National Academies of Sciences, Engineering, and Medicine

Publisher: National Academies Press

Published: 2016-07-28

Total Pages: 187

ISBN-13: 0309380979

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As climate has warmed over recent years, a new pattern of more frequent and more intense weather events has unfolded across the globe. Climate models simulate such changes in extreme events, and some of the reasons for the changes are well understood. Warming increases the likelihood of extremely hot days and nights, favors increased atmospheric moisture that may result in more frequent heavy rainfall and snowfall, and leads to evaporation that can exacerbate droughts. Even with evidence of these broad trends, scientists cautioned in the past that individual weather events couldn't be attributed to climate change. Now, with advances in understanding the climate science behind extreme events and the science of extreme event attribution, such blanket statements may not be accurate. The relatively young science of extreme event attribution seeks to tease out the influence of human-cause climate change from other factors, such as natural sources of variability like El Niño, as contributors to individual extreme events. Event attribution can answer questions about how much climate change influenced the probability or intensity of a specific type of weather event. As event attribution capabilities improve, they could help inform choices about assessing and managing risk, and in guiding climate adaptation strategies. This report examines the current state of science of extreme weather attribution, and identifies ways to move the science forward to improve attribution capabilities.

Review of the Draft Fourth National Climate Assessment
Review of the Draft Fourth National Climate Assessment

Author: National Academies of Sciences, Engineering, and Medicine

Publisher: National Academies Press

Published: 2018-06-18

Total Pages: 207

ISBN-13: 0309471699

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Climate change poses many challenges that affect society and the natural world. With these challenges, however, come opportunities to respond. By taking steps to adapt to and mitigate climate change, the risks to society and the impacts of continued climate change can be lessened. The National Climate Assessment, coordinated by the U.S. Global Change Research Program, is a mandated report intended to inform response decisions. Required to be developed every four years, these reports provide the most comprehensive and up-to-date evaluation of climate change impacts available for the United States, making them a unique and important climate change document. The draft Fourth National Climate Assessment (NCA4) report reviewed here addresses a wide range of topics of high importance to the United States and society more broadly, extending from human health and community well-being, to the built environment, to businesses and economies, to ecosystems and natural resources. This report evaluates the draft NCA4 to determine if it meets the requirements of the federal mandate, whether it provides accurate information grounded in the scientific literature, and whether it effectively communicates climate science, impacts, and responses for general audiences including the public, decision makers, and other stakeholders.