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7711 results in Climatology and Climate Change

Page 143 of 386

  • Preface

  • Intergovernmental Panel on Climate Change (IPCC)
  • Book:
    Climate Change 2013 – The Physical Science Basis
    Published online:
    05 June 2014
    Print publication:
    24 March 2014, pp vii-x

  • Summary

    The Working Group I contribution to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change (IPCC) provides a comprehensive assessment of the physical science basis of climate change. It builds upon the Working Group I contribution to the IPCC's Fourth Assessment Report in 2007 and incorporates subsequent new findings from the Special Report on Managing the Risks of Extreme Events and Disasters to Advance Climate Change Adaptation, as well as from research published in the extensive scientific and technical literature. The assessment considers new evidence of past, present and projected future climate change based on many independent scientific analyses from observations of the climate system, paleoclimate archives, theoretical studies of climate processes and simulations using climate models.

    Scope of the Report

    During the process of scoping and approving the outline of its Fifth Assessment Report, the IPCC focussed on those aspects of the current understanding of the science of climate change that were judged to be most relevant to policymakers.

    In this report, Working Group I has extended coverage of future climate change compared to earlier reports by assessing near-term projections and predictability as well as long-term projections and irreversibility in two separate chapters. Following the decisions made by the Panel during the scoping and outline approval, a set of new scenarios, the Representative Concentration Pathways, are used across all three Working Groups for projections of climate change over the 21st century.

  • Chapter 11 - Near-term Climate Change: Projections and Predictability

  • Intergovernmental Panel on Climate Change (IPCC)
  • Book:
    Climate Change 2013 – The Physical Science Basis
    Published online:
    05 June 2014
    Print publication:
    24 March 2014, pp 953-1028

  • Summary

    Executive Summary

    This chapter assesses the scientific literature describing expectations for near-term climate (present through mid-century). Unless otherwise stated, ‘near-term’ change and the projected changes below are for the period 2016–2035 relative to the reference period 1986–2005. Atmospheric composition (apart from CO2; see Chapter 12) and air quality projections through to 2100 are also assessed.

    Decadal Prediction

    The nonlinear and chaotic nature of the climate system imposes natual limits on the extent to which skilful predictions of climate statistics may be made. Model-based ‘predictability’ studies, which probe these limits and investigate the physical mechanisms involved, support the potential for the skilful prediction of annual to decadal average temperature and, to a lesser extent precipitation.

    Predictions for averages of temperature, over large regions of the planet and for the global mean, exhibit positive skill when verified against observations for forecast periods up to ten years (high confidence). Predictions of precipitation over some land areas also exhibit positive skill. Decadal prediction is a new endeavour in climate science. The level of quality for climate predictions of annual to decadal average quantities is assessed from the past performance of initialized predictions and non-initialized simulations. {11.2.3, Figures 11.3 and 11.4}

    In current results, observation-based initialization is the dominant contributor to the skill of predictions of annual mean temperature for the first few years and to the skill of predictions of the global mean surface temperature and the temperature over the North Atlantic, regions of the South Pacific and the tropical Indian Ocean for longer periods (high confidence).

  • Chapter 7 - Clouds and Aerosols

  • Intergovernmental Panel on Climate Change (IPCC)
  • Book:
    Climate Change 2013 – The Physical Science Basis
    Published online:
    05 June 2014
    Print publication:
    24 March 2014, pp 571-658

  • Summary

    Executive Summary

    Clouds and aerosols continue to contribute the largest uncertainty to estimates and interpretations of the Earth's changing energy budget. This chapter focuses on process understanding and considers observations, theory and models to assess how clouds and aerosols contribute and respond to climate change. The following conclusions are drawn.

    Progress in Understanding

    Many of the cloudiness and humidity changes simulated by climate models in warmer climates are now understood as responses to large-scale circulation changes that do not appear to depend strongly on sub-grid scale model processes, increasing confidence in these changes. For example, multiple lines of evidence now indicate positive feedback contributions from circulation-driven changes in both the height of high clouds and the latitudinal distribution of clouds (medium to high confidence). However, some aspects of the overall cloud response vary substantially among models, and these appear to depend strongly on sub-grid scale processes in which there is less confidence. {7.2.4, 7.2.5, 7.2.6, Figure 7.11}

    Climate-relevant aerosol processes are better understood, and climate-relevant aerosol properties better observed, than at the time of AR4. However, the representation of relevant processes varies greatly in global aerosol and climate models and it remains unclear what level of sophistication is required to model their effect on climate. Globally, between 20 and 40% of aerosol optical depth (medium confidence) and between one quarter and two thirds of cloud condensation nucleus concentrations (low confidence) are of anthropogenic origin.

  • Technical Summary

  • Intergovernmental Panel on Climate Change (IPCC)
  • Book:
    Climate Change 2013 – The Physical Science Basis
    Published online:
    05 June 2014
    Print publication:
    24 March 2014, pp 31-116

  • Summary

    TS.1 Introduction

    Climate Change 2013: The Physical Science Basis is the contribution of Working Group I (WGI) to the Fifth Assessment Report (AR5) of the Intergovernmental Panel on Climate Change (IPCC). This comprehensive assessment of the physical aspects of climate change puts a focus on those elements that are relevant to understand past, document current and project future climate change. The assessment builds on the IPCC Fourth Assessment Report (AR4) and the recent Special Report on Managing the Risk of Extreme Events and Disasters to Advance Climate Change Adaptation (SREX) and is presented in 14 chapters and 3 annexes. The chapters cover direct and proxy observations of changes in all components of the climate system; assess the current knowledge of various processes within, and interactions among, climate system components, which determine the sensitivity and response of the system to changes in forcing; and quantify the link between the changes in atmospheric constituents, and hence radiative forcing (RF), and the consequent detection and attribution of climate change. Projections of changes in all climate system components are based on model simulations forced by a new set of scenarios. The Report also provides a comprehensive assessment of past and future sea level change in a dedicated chapter. Regional climate change information is presented in the form of an Atlas of Global and Regional Climate Projections (Annex I). This is complemented by Annex II: Climate System Scenario Tables and Annex III: Glossary.

  • Chapter 6 - Carbon and Other Biogeochemical Cycles

  • Intergovernmental Panel on Climate Change (IPCC)
  • Book:
    Climate Change 2013 – The Physical Science Basis
    Published online:
    05 June 2014
    Print publication:
    24 March 2014, pp 465-570

  • Summary

    6.3.4.3 Global Nitrogen Budget

    For base year 2010, anthropogenic activities created ~210 (190 to 230) TgN of reactive nitrogen Nr from N2. This human-caused creation of reactive nitrogen in 2010 is at least 2 times larger than the rate of natural terrestrial creation of ~58 TgN (50 to 100 TgN yr−1) (Table 6.9, Section 1a). Note that the estimate of natural terrestrial biological fixation (58 TgN yr−1) is lower than former estimates (100 TgN yr−1, Galloway et al., 2004), but the ranges overlap, 50 to 100 TgN yr−1 vs. 90 to 120 TgN yr−1, respectively). Of this created reactive nitrogen, NOx and NH3 emissions from anthropogenic sources are about fourfold greater than natural emissions (Table 6.9, Section 1b). A greater portion of the NH3 emissions is deposited to the continents rather than to the oceans, relative to the deposition of NOy, due to the longer atmospheric residence time of the latter. These deposition estimates are lower limits, as they do not include organic nitrogen species. New model and measurement information (Kanakidou et al., 2012) suggests that incomplete inclusion of emissions and atmospheric chemistry of reduced and oxidized organic nitrogen components in current models may lead to systematic underestimates of total global reactive nitrogen deposition by up to 35% (Table 6.9, Section 1c). Discharge of reactive nitrogen to the coastal oceans is ~45 TgN yr−1 (Table 6.9, Section 1d). Denitrification converts Nr back to atmospheric N2. The current estimate for the production of atmospheric N2 is 110 TgN yr−1 (Bouwman et al., 2013).

  • Chapter 5 - Information from Paleoclimate Archives

  • Intergovernmental Panel on Climate Change (IPCC)
  • Book:
    Climate Change 2013 – The Physical Science Basis
    Published online:
    05 June 2014
    Print publication:
    24 March 2014, pp 383-464

  • Summary

    Executive Summary

    Greenhouse-Gas Variations and Past Climate Responses

    It is a fact that present-day (2011) concentrations of the atmospheric greenhouse gases (GHGs) carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O) exceed the range of concentrations recorded in ice cores during the past 800,000 years. Past changes in atmospheric GHG concentrations can be determined with very high confidence from polar ice cores. Since AR4 these records have been extended from 650,000 years to 800,000 years ago. {5.2.2}

    With very high confidence, the current rates of CO2, CH4 and N2O rise in atmospheric concentrations and the associated radiative forcing are unprecedented with respect to the highest resolution ice core records of the last 22,000 years. There is medium confidence that the rate of change of the observed GHG rise is also unprecedented compared with the lower resolution records of the past 800,000 years. {5.2.2}

    There is high confidence that changes in atmospheric CO2 concentration play an important role in glacial–interglacial cycles. Although the primary driver of glacial–interglacial cycles lies in the seasonal and latitudinal distribution of incoming solar energy driven by changes in the geometry of the Earth's orbit around the Sun (“orbital forcing”), reconstructions and simulations together show that the full magnitude of glacial–interglacial temperature and ice volume changes cannot be explained without accounting for changes in atmospheric CO2 content and the associated climate feedbacks. During the last deglaciation, it is very likely that global mean temperature increased by 3°C to 8°C.

  • Foreword

  • Intergovernmental Panel on Climate Change (IPCC)
  • Book:
    Climate Change 2013 – The Physical Science Basis
    Published online:
    05 June 2014
    Print publication:
    24 March 2014, pp v-vi

  • Summary

    “Climate Change 2013: The Physical Science Basis” presents clear and robust conclusions in a global assessment of climate change science—not the least of which is that the science now shows with 95 percent certainty that human activity is the dominant cause of observed warming since the mid-20th century. The report confirms that warming in the climate system is unequivocal, with many of the observed changes unprecedented over decades to millennia: warming of the atmosphere and the ocean, diminishing snow and ice, rising sea levels and increasing concentrations of greenhouse gases. Each of the last three decades has been successively warmer at the Earth's surface than any preceding decade since 1850.

    These and other findings confirm and enhance our scientific understanding of the climate system and the role of greenhouse gas emissions; as such, the report demands the urgent attention of both policymakers and the general public.

    As an intergovernmental body jointly established in 1988 by the World Meteorological Organization (WMO) and the United Nations Environment Programme (UNEP), the Intergovernmental Panel on Climate Change (IPCC) has provided policymakers with the most authoritative and objective scientific and technical assessments. Beginning in 1990, this series of IPCC Assessment Reports, Special Reports, Technical Papers, Methodology Reports and other products have become standard works of reference.

  • 1 - Introduction

  • Roger G. Barry, University of Colorado Boulder, Eileen A. Hall-McKim, University of Colorado Boulder
  • Book:
    Essentials of the Earth's Climate System
    Published online:
    28 May 2018
    Print publication:
    17 March 2014, pp 1-13

  • Summary

    We begin by defining climate and weather and then explaining their significance in everyday life. This helps clarify the scope and importance of climatology and its place in environmental sciences. Following a brief introduction to climatic data and frequently used statistics, we review the history of world climatology over the last two centuries. Finally, we examine the contribution of weather satellites to the study of weather and climate beginning in the 1960s.

    Climate and weather

    The word climate is derived from the Greek word “klima,” meaning slope, and was linked to temperature gradients from Equator to Pole. It entered the English language from French in the thirteenth century. Its modern meaning evolved in the sixteenth century.

    Climate is the sum total (or composite) of the weather conditions that generally prevail at a place or over a region. It encompasses the statistics (means, variability, and extremes) of temperature, humidity, atmospheric pressure, wind velocity, cloud cover, precipitation, and other meteorological variables over a long period of time. In contrast, weather is the condition of these same elements and their variations over time intervals of a few days. Conventionally, weather extends out to about 10–15 days – the limit of numerical weather prediction – while longer intervals, typically a month, are considered as part of climate. The “standard” interval used to define climatic characteristics by the World Meteorological Organization (WMO) is 30 years, and these data are called “normals.” This term was first used for 1901–1930; the current normal is 1961–1990 or 1981–2010, depending on data availability. However, world weather records were earlier published for 1881–1920. The 30 years must be consecutive and the averages are unweighted. The normals are updated by national climate organizations and the WMO each decade

  • 11 - Future climate

  • Roger G. Barry, University of Colorado Boulder, Eileen A. Hall-McKim, University of Colorado Boulder
  • Book:
    Essentials of the Earth's Climate System
    Published online:
    28 May 2018
    Print publication:
    17 March 2014, pp 194-205

  • Summary

    As we noted in the last chapter, the last 30 years have seen significant global warming, with nearly universal retreat of mountain glaciers, and major losses of Arctic sea ice cover in the 2000s, especially in late summer. Ice shelves have collapsed off northern Ellesmere Island, Canada, and in the Antarctic Peninsula. The Intergovernmental Panel on Climate Change (IPCC) issued its Fourth Assessment Report in 2007, concluding that increased concentration of greenhouse gases (GHGs) was almost certainly the cause. The report also projected global climatic conditions by AD 2100 using the results of simulations with coupled global climate models.

    We begin with a brief review of global climate models, and then consider the major projected changes during this century, their impacts, and finally related economic and socio-political issues.

    Global climate models

    A large number of model projections of GHG concentrations in AD 2100 have been made using different scenarios of population growth and economic activity, These scenarios have been applied in global climate models since the third IPCC report in 2001. Global climate models are coupled atmosphere and ocean general circulation models (GCMs) that treat mathematically almost all climatic processes at high temporal and spatial resolutions.

  • 2 - The elements of climate

  • Roger G. Barry, University of Colorado Boulder, Eileen A. Hall-McKim, University of Colorado Boulder
  • Book:
    Essentials of the Earth's Climate System
    Published online:
    28 May 2018
    Print publication:
    17 March 2014, pp 14-46

  • Summary

    The elements of climate involve external forcing factors – notably solar radiation – response functions such as air temperature, and moisture variables like precipitation and moisture content. It is not possible to follow a totally logical sequence due to the interactions between many of the variables. Nevertheless, we shall begin with solar energy and other forms of energy, then temperature, and proceed from there to moisture variables such as clouds, precipitation, and evaporation.

    Weather variables are measured at a global network of about 7000 stations every six hours and these data are collected and analyzed to produce climatic statistics for hourly, daily, monthly, and annual intervals. These and other historical data are available at: www.ncdc.noaa.gov/oa/climate/climatedata.html

    Climatic variables such as solar radiation are recorded by much more limited specialized networks.

    Energy

    Solar radiation

    The energy that warms the Earth and its atmosphere, thereby supporting life, and also drives the atmospheric circulation, is supplied by solar radiation. The sun emits electromagnetic energy from its photosphere (the lowest layer of the solar atmosphere, effectively the visible solar surface), which has a temperature of about 6000 °C. Solar energy is emitted at a rate proportional to the fourth power of the absolute temperature, meaning that the sun emits enormous quantities of energy. The short wavelength of this radiation is in the range 0.1–3 μm, or micrometers (μ = 10−6, this Greek letter is pronounced “mew”) with a maximum in the visible light band at 0.5 μm(see Box 2A.1). Ultraviolet radiation is shorter than 0.4 μm, andmost of this is absorbed by atmospheric ozone (O3) gas between 10 and 50 km in the upper atmosphere (see Box 2B.1). Visible radiation (light) is emitted between 0.4 μm (blue light) and 0.8 μm (red light) (see Box 2B.2), and infrared (or thermal) radiation between 0.8 and 3 μm. The amount received at the top of the atmosphere (ToA) on a surface at right angles to the beam is ~1366 W m−2.

  • Preface

  • Roger G. Barry, University of Colorado Boulder, Eileen A. Hall-McKim, University of Colorado Boulder
  • Book:
    Essentials of the Earth's Climate System
    Published online:
    28 May 2018
    Print publication:
    17 March 2014, pp ix-x

  • Summary

    This textbook seeks to provide a modern global overview of the world’s climates on all space and time scales. It addresses microclimates to global scale processes and phenomena. It spans climate changes over geologic time and the future climates of the late twenty-first century. It is designed to serve as an introductory course in climatology, suitable for students in environmental sciences, geography, meteorology, and related disciplines. The purpose of the book is first to provide a firm foundation of the physical principles that underpin climatology; second, to describe the spatial climatic characteristics over the globe including local and microclimatic scales; third, to detail the past and projected future climates of the Earth; and fourth, to introduce some applications of climatic information.

    The book is organized into 11 parts following a brief introduction on definitions, statistics, and the history of climatology. These are: a global view of the major climatic elements of energy and moisture followed by pressure, wind and storms, local and microclimates, the general circulation, circulation modes, synoptic climatology, the regional effects of land and sea, climatic types on land, past climates, future climate and its impacts, and different examples of applied climatology. Chapters 2, 3, 5, 6, and 7 are more meteorological in content. Chapters 8 and 9 provide detailed accounts of oceanic and land climates.

  • 10 - Past climates

  • Roger G. Barry, University of Colorado Boulder, Eileen A. Hall-McKim, University of Colorado Boulder
  • Book:
    Essentials of the Earth's Climate System
    Published online:
    28 May 2018
    Print publication:
    17 March 2014, pp 172-193

  • Summary

    Although geologists recognized the occurrence of past ice ages in the 1840s, the study of climate change only began in earnest in the 1950–1960s. Since the 1980s there have been major advances in our understanding of the nature of, and reasons for, climatic changes. These advances have been made possible through the development of new observational tools and hypotheses, and the use of global climate models to simulate past climatic conditions.

    Knowledge of the climate of the past is of vital importance for a full understanding of present and potential future world climates. Analysis of past changes can help to reveal the underlying causes of global climate patterns. In this chapter we will summarize our knowledge of geologic time, the Cenozoic era, the Quaternary period, and the Anthropocene, when human influences on the environment became significant.

    It is worth pointing out that climate variability refers to the variation of global or regional climate about its mean state. The time scale may be decades or millennia and the variation may be cyclical or irregular. Climate change refers to changes in the long-term statistics of climatic elements (the mean state, standard deviation, or frequency distribution). The time scale is at least several decades, but may be thousands of years or more. Climatic changes may be due to changes in external forcings (solar output, changes in the Earth’s orbit, volcanic eruptions), internal variability in the atmosphere–ocean–cryosphere system), or anthropogenic (human-induced) forcing. Changes may involve an abrupt shift in the mean state, an increasing or decreasing trend over time, or a change in the degree of variation about the mean without a change in the mean value.

  • 12 - Applied climatology

  • Roger G. Barry, University of Colorado Boulder, Eileen A. Hall-McKim, University of Colorado Boulder
  • Book:
    Essentials of the Earth's Climate System
    Published online:
    28 May 2018
    Print publication:
    17 March 2014, pp 206-224

  • Summary

    In this chapter we examine various examples of the application of climatic information. We begin by examining climatic extremes and disasters. Then we examine climate and soils, and climate and agriculture. This is followed by a consideration of water resources, renewable energy, and climate and transportation. The chapter concludes with a brief summary of insurance and climate-related disasters and a section on climate forecasts and services.

    Climatic extremes and disasters

    Much attention has been given to weather extremes – severe thunderstorms, tornadoes, windstorms and tropical cyclones. These events typically last from a few hours to a few days. However, climatic extremes have time scales from a month to decades, with long-lasting consequences. They include persistent intense rains giving rise to floods, protracted droughts, heat waves, and freezes.

    For the United States a Climate Extremes Index (CEI) has been developed by NOAA, which is based on an aggregate set of conventional climate extreme indicators. These include the following types of data:

  • monthly maximum and minimum temperature;

  • daily precipitation;

  • monthly Palmer Drought Severity Index (PDSI);

  • the wind velocity in land-falling tropical storm and hurricanes.

    • Temperature and precipitation data are taken from 1220 stations in the US Historical Climatology Network (USHCN) covering the contiguous United States. The values are based on the percentage of the area of the United States with much below/much above normal maximum and minimum temperatures and, similarly, of severe drought or extreme moisture surplus. The details may be found at www. ncdc.noaa.gov/extremes/cei

    Between 1910 and 2011 the CEI ranged from 9 to 40. It was lowest over 1942– 1980 and has subsequently been consistently higher.

  • Profiting from Antarctic science

  • D.W.H. Walton
  • Journal:
    Antarctic Science / Volume 26 / Issue 2 / April 2014
    Published online by Cambridge University Press:
    17 March 2014, p. 113
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