Réf. IPCC 2007 - R (SP)

Référence bibliographique complète
Climate Change 2007 : The Physical Science Basis - Summary for Policymakers - Contribution of Working Group I to the Fourth Assesment Report of the IPCC. IPCC (International Panel for Climate Change). Genêve,2007, 18 p.

Mots-clés
 

Organismes / Contact
Partenaires
Sécrétariat du GIEC, c/o Organisation météorologique mondiale, 7 bis, avenue de la Paix, Case Postale 2300, 1211 Genève 2, Suisse
Phone: +41 22 730 8208/8254/8284 ; Fax: +41 22 730 8025/8013 ; IPCC-Sec@wmo.int
United Nations Environmental Program
World Meteorological Organization

Principaux rapports scientifiques sur lesquels s'est appuyé le rapport
 

(1) - Paramètre(s) atmosphérique(s) modifié(s)
(2) - Elément(s) du milieu impacté(s)
(3) - Type(s) d'aléa impacté(s)
(3) - Sous-type(s) d'aléa
Temperature, precipitations Snow cover, glaciers    

Pays / Zone
Massif / Secteur
Site(s) d'étude
Exposition
Altitude
Période(s) d'observation
Wolrd         1901-2006 / Last 1300 years

(1) - Modifications des paramètres atmosphériques
Reconstitutions
Average Northern Hemisphere temperatures during the second half of the 20th century were very likely higher than any other 50-years period in the last 500 years and likely the highest in at least the past 1300 years.
Observations
Temperatures :
Warming of the climate system is unequivocal, as is now evident from observations of increases in global average air and ocean temperatures, widespread melting of snow and ice, and rising global average sea level.

11 of the last 12 years (1995-2006) rank amongst the 12 warmest years in instrumental records of global surface temperature since 1850. The updated linear trend (1906-2005) of 0.74°C is larger than the TAR linear trend (1901-2000) of 0.6°C. The linear trend for the last 50 years (0.13°C per decade) is nearly twice that for the last 100 years. The total temperature increase from 1850-1899 to 2001-2005 is 0.76°C.

Widespread changes in extreme temperatures have been observed over the last 50 years. Cold days, cold nights and frost have become less frequent, while hot days, hot nights, and heat waves have become more frequent.

Updated observations reveal that the Diurnal Temperature Range (DRT) has not changed from 1979 to 2004 as both day- and night-temperature have risen at about the same rate.

Precipitations :
The frequency of heavy precipitations events has increased over most land areas, consistent with warming and observed increase of atmospheric water vapour.

Long-term trends from 1900 to 2005 have been observed in precipitation amount over many large regions. Significantly increased precipitations has been observed in northern Europe. Drying has been observed in the Mediterranean. Precipitation is highly variable spatially and temporally, and data are limited in some regions.

Winds :
Mid-latitude Westerly winds have strenghtened in both hemispheres since the 1960s.
Modélisations
Temperatures :
The global average surface warming following a doubling of carbon dioxide concentrations is likely to be in the range 2 to 4.5°C with a best estimate of about 3°C, and is very unlikely to be less than 1.5°C. Values substantialy higher than 4.5°C cannot be excluded but agreement of model with observations is not good for those values.

For the next two decades, a warming of about 0.2°C per decade is projected from a range of SRES emission scenarios. The likely range of the SRES scenarios is between 1.1 and 6.4°C (for 2090-2099 reative to 1980-1999) and the best estimate are between 1.8°C and 4.0°C.
Hypothèses
It is very likely that hot extremes, heat waves, and heavy precipitations events will continue to become more frequent.

Since the TAR there is an improving understanding of projected patterns of precipitation. Increase in the amount of precipitation are very liekly in high latitudes, wile decrease are likely in most subtropical land regions (by as much as 20 % in the A1B scenario in 2100) continuing observed trends in recent trends.

Informations complémentaires (données utilisées, méthode, scénarios, etc.)
 

(2) - Impacts du changement climatique sur le milieu naturel
Reconstitutions
 
Observations
Mountains glaciers and snow cover have declined on average in both hemispheres.
Modélisations
 
Hypothèses
Snow cover is projected to contract. Widepsread increase in thaw depth are projected over most permafrost regions.

Sensibilité du milieu à des paramètres climatiques
Informations complémentaires (données utilisées, méthode, scénarios, etc.)
   

(3) - Impacts du changement climatique sur l'aléa
Reconstitutions
 
Observations
 
Modélisations
 
Hypothèses
 

Paramètre de l'aléa
Sensibilité du paramètres de l'aléa à des paramètres climatiques
Informations complémentaires (données utilisées, méthode, scénarios, etc.)
 
 

(4) - Remarques générales
 

(5) - Préconisations et recomandations
Destinataires et portée du rapport Policy makers
Types de recommandations et / ou préconisations