IPCC Fifth Assessment Report

The Fifth Assessment Report (English Fifth Assessment Report, AR5 ) of the IPCC is the latest report from the Intergovernmental Panel on Climate Change ( Intergovernmental Panel on Climate Change) of the United Nations. The reports summarize regularly the state of scientific knowledge on global warming. The issued at intervals of five to six years IPCC reports are widely regarded as a consensus position within the climatological experts when it comes to the human influence on climate. Previous reports published in 1990 (FAR ), 1995 (SAR ), 2001 (TAR ) and 2007 ( AR4 ).

The summary ( Summary for Policymakers ) the results of Working Group I ( The Physical Science Basis, " Physico- scientific basis " ) for the fifth World Climate Report was published on 27 September 2013 a final draft ( final draft ) of the full report on September 30, 2013, the editorial edited final version on 30 January 2014.

The presentation of the summary of the report of Working Group II ( Impacts, Adaptation and Vulnerability) on March 31, 2014 in Yokohama was accompanied by an urgent call from the Chairman of the IPCC, Rajendra Pachauri, for more climate protection and broad media coverage; the German Federal Government reiterated the climate goal to reduce CO2 emissions by 40 percent below 1990 levels by the year 2020.

The Report of Working Group III ( Mitigation of Climate Change) and a synthetic band to appear in the course of 2014.

  • 4.1 Climate models
  • 4.2 Secondary Summaries
  • 5.1 author lists
  • 5.2 reports
  • 5.3 Secondary Summaries

IPCC

The English Intergovernmental Panel on Climate Change (IPCC; Intergovernmental Panel on Climate Change), the German often referred to as the IPCC, was launched in November 1988 by the United Nations Environment Programme (UNEP ) and the World Meteorological Organization ( WMO) is an intergovernmental institution to life, to summarize the state of scientific research for policy makers. The main task of the Framework Convention on Climate Change (UNFCCC) Associate Committee is to assess the risks of global warming as well as to gather mitigation and adaptation strategies.

Overview

The report of the Working Group I comprises 2216 pages and consists of a comprehensive summary ( Technical Summary, 127 pages ), an introduction, thirteen substantive chapters and three appendices. The Summary for Policymakers is 36 pages long and includes an introduction and the sections entitled " Observed changes in the climate system ", " Drivers of Climate Change", " understanding of the climate system and its recent changes ", " Future global and regional climate changes ." The current UN climate report is based on the Fourth Assessment Report, have been incorporated into the new results. In the bibliography 9,200 peer -reviewed studies are cited. In order to document scientific uncertainty, the statements have been evaluated by the team of authors qualitatively ( " very low " to "very large " trust ) or either - if possible - quantitative probabilities specified. These range from " almost certain " ( 99-100 % probability) over "very likely" (90-100 % probability), "likely" ( 66-100 % probability ) to " extremely unlikely" (0-1 % probability). Where applicable, statements were also presented as facts (no indication of probabilities ).

Main findings of the Working Group I " Physico -technological foundations "

Observed changes in the climate system

  • A warming of the climate system is unequivocal: the atmosphere and the ocean have become warmer, ice and snow have fallen, the sea level and the concentration of carbon dioxide in the atmosphere have risen. Changes such since the 1950s have not yet occurred for decades to millennia. The average temperature at the Earth's surface has risen from 1880 to 2012 by 0.85 ° C.
  • It is likely that was on the northern hemisphere the period 1983 to 2013, the warmest 30-year period of the last 1400 years.
  • Extreme weather events such as heat waves have become very common and probably prolonged.
  • With great confidence can be assumed that the oceans between 1971 to 2010 was added 90 % of the additional energy due to global warming. The strongest heated the layers near the surface. In the upper 75 meters, the temperature rose from 1971 to 2010 by an average of 0.11 ° C per decade. Almost surely, heated the upper 700 meters from 1971 to 2010.
  • With great confidence, it is assumed that the Greenland ice sheet and the Antarctic ice sheet have lost in the last two decades mass. The mass loss was 2002-2011 when the Greenland ice sheet is 215 billion tons / year, the Antarctic ice sheet is 147 billion tons / year. The glaciers in the world lost probably 1993-2009 275 billion tons of ice / year.
  • The extent of Arctic sea ice in summer was very likely to be from 9.4 to 13.6 percent per decade back, which corresponds 730000-1070000 km ².
  • The north polar snowpack went since the mid of the 20th century ( great confidence ).
  • Sea level rise in the period 1901-2010 was 19 ± 2 cm. It is likely that the increase has accelerated since the beginning of the 20th century; 1993 to 2010, the increase was very likely 3.2 mm / year.
  • The current concentration of greenhouse gases in the atmosphere is the highest in 800,000 years. Human activities 555 billion tons of carbon have been released since 1750; in comparison to the concentration of the pre-industrial level has increased by 40% of carbon dioxide. The rate of increase of the concentration of greenhouse gases in the 20th century was the highest of the past 22,000 years with very high probability. 155 billion tonnes of carbon released were taken from the ocean; The pH of the top layer has decreased to 0.1 (corresponding to an increase in the hydrogen ions of 26 percent, great confidence ).

Drivers of climate change

  • The radiative forcing of the climate system has increased by 2.29 watts / m² compared to 1750; the largest share of which has atmospheric CO ₂. The share of changes in the sunlight is only 0.05 Watt / m² and had thereby, as well as volcanic eruptions, only a small proportion of the climate changes in the last century.
  • It is extremely likely (> 95 %) that human influence is the main reason for the observed global warming since 1950.

Future global and regional climate changes

  • The further release of greenhouse gases will lead to further global warming and the associated changes to the climate system.
  • The estimation of future climate change based on the application of climate models at four concentration paths ( engl. representative concentration pathways ( RCPs ), "representative concentration pathways "). These present the results of new emission scenarios represent, including for the first time a scenario, the ambitious climate protection measures into account (RCP 2.6). The paths are named after the change in radiative forcing, which would be accompanied by the year 2100 about with them: RCP 2.6 - change in radiative forcing 2.6 W / m², RCP 4.5 - 4.5 W / m², RCP 6.0 - 6 W / m² and RCP 8.5 - 8.5 W / m². Regardless of the concentration path, the temperature of the atmosphere is likely to 0.3-0.7 ° C over the period 2016-2035 are higher than 1985-2005.
  • The further increase in temperature depends on the concentration Path: It is for the period 2081-2100 probably between 0.3-1.7 ° C (RCP 2.6) to 2.6 to 4.8 ° C (RCP 8.5).
  • It is almost certain that extreme weather events will increase.
  • Extreme precipitation in the middle latitudes and humid tropical regions will most likely frequent and intense.
  • The ocean will continue to warm, the heat will move from the upper water layers in the depth and influence ocean currents. It is very likely that the Atlantic ocean currents ( Gulf Stream ) will weaken. A collapse or a shift in the 21st century is very unlikely, but can not be excluded later on further warming.
  • The Arctic Ocean is the concentration path RCP 8.5 ( further increase in the emission of greenhouse gases ), probably in the summer before mid-century ice-free.
  • The volume of the glacier takes until the end of this century between 15-55 % (RCP 2.6) and 35-85 % (RCP 8.5 ) from ( medium confidence ).
  • The sea level is up to the period 2081-2100 according to the concentration path probably between 26-55 cm (RCP 2.6) and 45 to 82 cm (RCP 8.5) increase. In the latter case, the increase is by the year 2100 98 cm ( medium confidence ).
  • The collapse of ice sheets could lead to an additional increase of some 10 cm.
  • It is almost certain that the rise in sea level already will continue after 2100 alone due to the thermal expansion of the water for a few hundred years. With a further increase of the concentration of carbon dioxide in the atmosphere, the increase can be up to the year 2300, more than three meters ( medium confidence ).

Understanding of the climate system and its recent changes

  • Our understanding of the climate system contribute observations, studies of feedback and simulations with climate models. Climate models have been developed and are able to simulate long-term climate changes well.
  • For shorter periods of time (from 10 to 15 years ) and at the regional level, which are more strongly influenced by random events, the climate models are less reliable.
  • A doubling of carbon dioxide levels in the atmosphere would lead to a warming of 1.5-4.5 ° C ( great confidence ).

More information

Climate models

The new climate simulations on which the statements about future climate change in the AR5 materially based, were partly in the Coupled Model Intercomparison Project Phase 5 ( CMIP5 ) conducted an international collaboration of climate model community.

Secondary summaries

The key messages in German were published jointly by the Federal Ministry for the Environment, together with the Federal Ministry of Education and Research, the German IPCC Coordination Office and the Environmental Protection Agency and.

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