IPCC Third Assessment Report

IPCC Third Assessment Report

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The IPCC Third Assessment Report, Climate Change 2001, is an assessment of available scientific and socio-economic information on climate change by the IPCC
IPCC may refer to:*Intergovernmental Panel on Climate Change, of the United Nations*Independent Police Complaints Commission, of England and Wales*Irish Peatland Conservation Council...

. The IPCC was established in 1988 by the United Nations Environment Programme
United Nations Environment Programme
The United Nations Environment Programme coordinates United Nations environmental activities, assisting developing countries in implementing environmentally sound policies and practices. It was founded as a result of the United Nations Conference on the Human Environment in June 1972 and has its...

 (UNEP) and the UN's World Meteorological Organization
World Meteorological Organization
The World Meteorological Organization is an intergovernmental organization with a membership of 189 Member States and Territories. It originated from the International Meteorological Organization , which was founded in 1873...

 (WMO) "... to assess scientific, technical and socio-economic information relevant for the understanding of climate change, its potential impacts and options for adaptation and mitigation."[IPCC website] The Third Assessment Report (TAR) is the third of a series of assessments; it has been superseded by the IPCC Fourth Assessment Report
IPCC Fourth Assessment Report
Climate Change 2007, the Fourth Assessment Report of the United Nations Intergovernmental Panel on Climate Change , is the fourth in a series of reports intended to assess scientific, technical and socio-economic information concerning climate change, its potential effects, and options for...

 (AR4), released in 2007.

Statements of the IPCC or information from the TAR are often used as a reference showing a scientific consensus
Scientific opinion on climate change
The predominant scientific opinion on climate change is that the Earth is in an ongoing phase of global warming primarily caused by an enhanced greenhouse effect due to the anthropogenic release of carbon dioxide and other greenhouse gases...

 on the subject of global warming
Global warming
Global warming refers to the rising average temperature of Earth's atmosphere and oceans and its projected continuation. In the last 100 years, Earth's average surface temperature increased by about with about two thirds of the increase occurring over just the last three decades...

, although a small minority of scientists take issue with the UN assessments (see also Global warming controversy
Global warming controversy
Global warming controversy refers to a variety of disputes, significantly more pronounced in the popular media than in the scientific literature, regarding the nature, causes, and consequences of global warming...

 and Politics of global warming
Politics of global warming
The politics of global warming have involved corporate lobbying, funding of special interest groups and public relations campaigns by the oil and coal industries which have affected policy decisions and legislation worldwide...


Working groups

The IPCC is organized as three working group
Working group
A working group is an interdisciplinary collaboration of researchers working on new research activities that would be difficult to develop under traditional funding mechanisms . The lifespan of the WG can last anywhere between a few months and several years...

s (WG) and a task force
Task force
A task force is a unit or formation established to work on a single defined task or activity. Originally introduced by the United States Navy, the term has now caught on for general usage and is a standard part of NATO terminology...

  • WGI: Scientific aspects of climate (see ).
  • WGII: Vulnerability, consequences, and options (see ).
  • WGIII: Limitation and mitigation options (see ).
  • Task Force: National Greenhouse Gas Inventories Programme http://www.ipcc-nggip.iges.or.jp

WG I covers the same areas as the Second Assessment Report (SAR) of 1995, but WG II & III cover slightly different areas in the TAR.


The key conclusions of Working Group I (The Scientific Basis, Summary for Policymakers, in ) were:
  1. An increasing body of observations gives a collective picture of a warming world and other changes in the climate system (The global average surface temperature
    Instrumental temperature record
    The instrumental temperature record shows fluctuations of the temperature of the global land surface and oceans. This data is collected from several thousand meteorological stations, Antarctic research stations and satellite observations of sea-surface temperature. Currently, the longest-running...

     has increased over the 20th century by about 0.6°C; Temperatures have risen during the past four decades in the lowest 8 kilometres of the atmosphere; Snow cover and ice extent have decreased)
  2. Emissions of greenhouse gases and aerosols due to human activities continue to alter the atmosphere in ways that are expected to affect the climate (Anthropogenic aerosols are short-lived and mostly produce negative radiative forcing; Natural factors have made small contributions to radiative forcing over the past century)
  3. Confidence in the ability of models to project future climate has increased (Complex physically based climate models are required to provide detailed estimates of feedbacks and of regional features. Such models cannot yet simulate all aspects of climate (e.g., they still cannot account fully for the observed trend in the surface-troposphere temperature difference since 1979) and there are particular uncertainties associated with clouds and their interaction with radiation and aerosols. Nevertheless, confidence in the ability of these models to provide useful projections of future climate has improved due to their demonstrated performance on a range of space and time-scales http://www.grida.no/climate/ipcc_tar/wg1/007.htm.)
  4. There is new and stronger evidence that most of the warming observed over the last 50 years is attributable to human activities
  5. Human influences will continue to change atmospheric composition throughout the 21st century
  6. Global average temperature and sea level are projected to rise under all IPCC SRES scenarios
    Special Report on Emissions Scenarios
    The Special Report on Emissions Scenarios was prepared by the Intergovernmental Panel on Climate Change in 2000, based on data developed at the Earth Institute at Columbia University. The emissions scenarios described in the Report have been used to make projections of possible future climate...


The TAR estimate for the climate sensitivity
Climate sensitivity
Climate sensitivity is a measure of how responsive the temperature of the climate system is to a change in the radiative forcing. It is usually expressed as the temperature change associated with a doubling of the concentration of carbon dioxide in Earth's atmosphere.The equilibrium climate...

 is 1.5 to 4.5 °C; and the average surface temperature is projected to increase by 1.4 to 5.8 Celsius degrees over the period 1990 to 2100, and the sea level is projected to rise by 0.1 to 0.9 metres over the same period. The wide range in predictions is based upon several different scenarios that assume different levels of future CO2 emissions. Each scenario then has a range of possible outcomes associated with it. The most optimistic outcome assumes an aggressive campaign to reduce CO2 emissions, while the most pessimistic is a "business as usual" scenario. The more realistic scenarios fall in between.

Basis of predictions

IPCC predictions are based on the same models used to establish the importance of the different factors in global warming.
These models need data about anthropogenic emissions of greenhouse gases and aerosols.
These data are predicted from economic models based on 35 different scenarios.
Scenarios go from pessimistic to optimistic, and predictions of global warming depend on the kind of scenario considered.

IPCC uses the best available predictions and their reports are under strong scientific scrutiny.
The IPCC concedes that there is a need for better models and better scientific understanding of some climate phenomena, as well as the uncertainties involved.
Critics assert that the available data is not sufficient to determine the real importance of greenhouse gas
Greenhouse gas
A greenhouse gas is a gas in an atmosphere that absorbs and emits radiation within the thermal infrared range. This process is the fundamental cause of the greenhouse effect. The primary greenhouse gases in the Earth's atmosphere are water vapor, carbon dioxide, methane, nitrous oxide, and ozone...

es in climate change.
Sensitivity of climate to greenhouse gases may be overestimated or underestimated because of some flaws in the models and because the importance of some external factors may be misestimated. The predictions are based on scenarios, and the IPCC did not assign any probability to the 35 scenarios used.

See also

  • Attribution of recent climate change
    Attribution of recent climate change
    Attribution of recent climate change is the effort to scientifically ascertain mechanisms responsible for recent changes observed in the Earth's climate...

  • Avoiding Dangerous Climate Change
    Avoiding Dangerous Climate Change
    The related terms "avoiding dangerous climate change" and "preventing dangerous anthropogenic interference with the climate system" date to 1995 and earlier, in the Second Assesment Report of the International Panel on Climate Change and previous science it cites.In 2002, the United Nations...

    , and an international conference on the topic.
  • Climate change
    Climate change
    Climate change is a significant and lasting change in the statistical distribution of weather patterns over periods ranging from decades to millions of years. It may be a change in average weather conditions or the distribution of events around that average...

  • Carbon dioxide equivalent
    Carbon dioxide equivalent
    Carbon dioxide equivalent and Equivalent carbon dioxide are two related but distinct measures for describing how much global warming a given type and amount of greenhouse gas may cause, using the functionally equivalent amount or concentration of carbon dioxide as the reference.- Global warming...

  • Effects of global warming
    Effects of global warming
    This article is about the effects of global warming and climate change. The effects, or impacts, of climate change may be physical, ecological, social or economic. Evidence of observed climate change includes the instrumental temperature record, rising sea levels, and decreased snow cover in the...

  • Energy conservation
    Energy conservation
    Energy conservation refers to efforts made to reduce energy consumption. Energy conservation can be achieved through increased efficient energy use, in conjunction with decreased energy consumption and/or reduced consumption from conventional energy sources...

  • Energy policy
    Energy policy
    Energy policy is the manner in which a given entity has decided to address issues of energy development including energy production, distribution and consumption...

  • Global warming controversy
    Global warming controversy
    Global warming controversy refers to a variety of disputes, significantly more pronounced in the popular media than in the scientific literature, regarding the nature, causes, and consequences of global warming...

  • Global climate model
    Global climate model
    A General Circulation Model is a mathematical model of the general circulation of a planetary atmosphere or ocean and based on the Navier–Stokes equations on a rotating sphere with thermodynamic terms for various energy sources . These equations are the basis for complex computer programs commonly...

  • World energy resources and consumption
    World energy resources and consumption
    ]World energy consumption in 2010: over 5% growthEnergy markets have combined crisis recovery and strong industry dynamism. Energy consumption in the G20 soared by more than 5% in 2010, after the slight decrease of 2009. This strong increase is the result of two converging trends...

External links