Klimaänderung5. Informationen aus Paleoklima-Archiven

Robert SausenDeutsches Zentrum für Luft- und RaumfahrtInstitut für Physik der AtmosphäreOberpfaffenhofen

Vorlesung WS 2018/19LMU München

Contents of IPCC 2013Working Group I: the Physical Science Basis

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Contents of IPCC 2013Working Group I: the Physical Science Basis

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The basis for the confidence levelS

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Likelihood termsS

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IPCC 2013, Chap. 1

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Geologische Zeitskala

Summary of past periodsfor which climate information is assessed

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Reconstructions of volcanic forcing and total solar irradiance (TSI)

Statements in the Executive Summary Greenhouse-Gas Variations and Past Climate Responses (1)

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.

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IPCC 2013, Chap. 5

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Reconstructions of CO2 and climate parameters

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IPCC 2013, Chap. 5

Reconstructions of CO2 and climate parameters

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IPCC 2013, Chap. 5

Reconstructions of CO2 and climate parameters

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Orbital parameters and proxy records over the past 800 kyr

Statements in the Executive Summary Greenhouse-Gas Variations and Past Climate Responses (1)

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.

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 high confidence that changes in atmospheric CO2 concentration play an important role in glacial–interglacial cycles.

New estimates of the equilibrium climate sensitivity based on reconstructions and simulations of the Last Glacial Maximum (21,000 years to 19,000 years ago) show that values below 1oC as well as above 6oC for a doubling of atmospheric CO2concentration are very unlikely.

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IPCC 2013, Chap. 5

Statements in the Executive Summary Greenhouse-Gas Variations and Past Climate Responses (2)

With medium confidence, global mean surface temperature was significantly above pre-industrial levels during several past periods characterised by high atmospheric CO2 concentrations.

New temperature reconstructions and simulations of past climates show with high confidence polar amplification in response to changes in atmospheric CO2concentration.

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IPCC 2013, Chap. 5

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Observations and multi-model mean simulations of sea surface temperature anomalies and surface air temperature anomalies

Statements in the Executive Summary Global Sea Level Changes During Past Warm Periods

The current rate of global mean sea level change, starting in the late 19th-early 20th century, is, with medium confidence, unusually high in the context of centennial-scale variations of the last two millennia.

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IPCC 2013, Chap. 5

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Global mean sea level

Statements in the Executive Summary Global Sea Level Changes During Past Warm Periods

The current rate of global mean sea level change, starting in the late 19th-early 20th century, is, with medium confidence, unusually high in the context of centennial-scale variations of the last two millennia.

There is very high confidence that the maximum global mean sea level during the last interglacial period (129,000 to 116,000 years ago) was, for several thousand years, at least 5 m higher than present and high confidence that it did not exceed10 m above present.

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IPCC 2013, Chap. 5

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Sea level during the Last Interglacial (LIG) period

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Greenland Ice Sheet at the Last Interglacial

Statements in the Executive Summary Global Sea Level Changes During Past Warm Periods

The current rate of global mean sea level change, starting in the late 19th-early 20th century, is, with medium confidence, unusually high in the context of centennial-scale variations of the last two millennia.

There is very high confidence that the maximum global mean sea level during the last interglacial period (129,000 to 116,000 years ago) was, for several thousand years, at least 5 m higher than present and high confidence that it did not exceed10 m above present.

There is high confidence that global mean sea level was above present during some warm intervals of the mid-Pliocene (3.3 to 3.0 million years ago), implying reduced volume of polar ice sheets.

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IPCC 2013, Chap. 5

Statements in the Executive Summary Observed Recent Climate Change in the Context of Interglacial Climate Variability (1)

New temperature reconstructions and simulations of the warmest millennia of the last interglacial period (129,000 to 116,000 years ago) show with medium confidence that global mean annual surface temperatures were never more than 2°C higher than pre-industrial.

There is high confidence that annual mean surface warming since the 20th century has reversed long-term cooling trends of the past 5000 years in mid-to-high latitudes of the Northern Hemisphere (NH).

There is medium confidence from reconstructions that the current (1980–2012) summer sea ice retreat was unprecedented and sea surface temperatures in the Arctic were anomalously high in the perspective of at least the last 1450 years.

There is high confidence that minima in NH extratropical glacier extent between 8000 and 6000 years ago were primarily due to high summer insolation (orbital forcing).

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IPCC 2013, Chap. 5

Statements in the Executive Summary Observed Recent Climate Change in the Context of Interglacial Climate Variability (2)

For average annual NH temperatures, the period 1983–2012 was very likely the warmest 30-year period of the last 800 years (high confidence) and likely the warmest 30-year period of the last 1400 years (medium confidence).

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IPCC 2013, Chap. 5

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Reconstructed annual temperatures during the last 2000 years

Statements in the Executive Summary Observed Recent Climate Change in the Context of Interglacial Climate Variability (2)

For average annual NH temperatures, the period 1983–2012 was very likely the warmest 30-year period of the last 800 years (high confidence) and likely the warmest 30-year period of the last 1400 years (medium confidence).

Continental-scale surface temperature reconstructions show, with high confidence, multi-decadal periods during the Medieval Climate Anomaly (950 to 1250) that were in some regions as warm as in the mid-20th century and in others as warm as in the late 20th century.

There is high confidence for droughts during the last millennium of greater magnitude and longer duration than those observed since the beginning of the 20th century in many regions.

With high confidence, floods larger than those recorded since 1900 occurred during the past five centuries in northern and central Europe, western Mediterranean region and eastern Asia.

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IPCC 2013, Chap. 5

Floods in Germany 1

Passauwww.sueddeutsche.de, 2. Juni 2013

Kolbermoorwww.ovb-online.de, 4. Juni 2013

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Floods in Germany 2

postcard showing the Isar flood in September 1899

Sammlung M. Deutsch, Erfurt/Göttingen

so called “Thüringer Sintflut” (Deluge of Thuringia)

29 Mai 1613Deutsch et al., 2013

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Flood frequency in selected European rivers

Statements in the Executive Summary Past Changes in Climate Modes

New results from high-resolution coral records document with high confidence that the El Niño-Southern Oscillation (ENSO) system has remained highly variable throughout the past 7000 years, showing no discernible evidence for an orbital modulation of ENSO.

With high confidence, decadal and multi-decadal changes in the winter North Atlantic Oscillation index (NAO) observed since the 20th century are not unprecedented in the context of the past 500 years.

The increase in the strength of the observed summer Southern Annular Mode since 1950 has been anomalous, with medium confidence, in the context of the past 400 years.

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IPCC 2013, Chap. 5

Statements in the Executive Summary Abrupt Climate Change and Irreversibility

With high confidence, the interglacial mode of the Atlantic Ocean meridional overturning circulation (AMOC) can recover from a short-term freshwater input into the subpolar North Atlantic.

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Selected paleoenvironmental and climate model data for the abrupt

Holocene cold event at 8.2 ka

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IPCC 2013, Chap. 5

Statements in the Executive Summary Abrupt Climate Change and Irreversibility

With high confidence, the interglacial mode of the Atlantic Ocean meridional overturning circulation (AMOC) can recover from a short-term freshwater input into the subpolar North Atlantic.

Confidence in the link between changes in North Atlantic climate and low-latitude precipitation patterns has increased since AR4.

It is virtually certain that orbital forcing will be unable to trigger widespread glaciation during the next 1000 years.

There is high confidence that the volumes of the Greenland and West Antarctic ice sheets were reduced during periods of the past few million years that were globally warmer than present.

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6. Kohlenstoff- und andere biogeochemische Kreisläufe

Contents of IPCC 2013Working Group I: the Physical Science Basis

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Contents of IPCC 2013Working Group I: the Physical Science Basis

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