Global climate system

Hoelzmann, P., Jolly, D., Harrison, S. P., Laarif, F., Bonnefille, R., and Pachur, H.-J. (1998). Mid-Holocene land-surface conditions in northern Africa and the arabian peninsula a data set for the analysis of bio-geophysical feedbacks in the climate system. Global Biogeochem. Cycles 12,35-51. 

Fig. 17-1 The global climate system, (a) Energy fluxes, including incoming solar radiation, reflected radiation, emitted longwave radiation (from an effective altitude of ca. 6 km), and atmospheric and oceanic heat flux toward the polar regions, (b) The atmospheric circulation corresponding to part (a). Refer back to Fig. 7-4 and associated text for a discussion of the general circulation.

Fig. 17-2 The web of interactions in the atmospheric part of the global climate system. The strength of the interactions is qualitatively depicted by the thickness of the line. Bidirectional interactions have two arrowheads, unidirectional ones have only one. (From Houghton (1984), reprinted with permission from Cambridge University Press.)...

Climate is clearly "global" in both causes and consequences moreover, the emissions of GFIG have effects on global warming independently of their location, and local climatic changes are completely linked with the world climate system. 

The main tools used to provide global projections of future climate are general circulation models (GCMs). These are mathematical models based on fundamental physical laws and thus constitute dynamical representations of the climate system. Computational constraints impose a limitation on the resolution that it is possible to realise with such models, and so some unresolved processes are parameterised within the models. This includes many key processes that control climate sensitivity such as clouds, vegetation and oceanic convection [19] of which scientific understanding is still incomplete. 

C Earth s surface temperature (adapted from IPCC Report 2001 [1]). The global climate will depend on natural changes and the response of climate system to human activities. Four human activity models are indicated A1F1, A1B, AIT, Bl. 

Current concentrations of GHG have already caused the mean global temperature to increase by 0.76 °C in the period from 1850 to 2005 owing to the inertia of the climate system this will lead to at least a further half-degree warming over the next few decades. Eleven of the twelve years from 1995 to 2006 rank among the 12 warmest years in the instrumental record of global surface temperature (since 1850). 

The global mean temperature at equilibrium is different from expected global mean temperature at the time of stabilisation of GHG concentrations owing to the inertia of the climate system. In most scenarios, stabilisation of GHG concentrations occurs between 2100 and 2150. 

Solomon, S. (1997) Mid-Latitude Ozone Depletion, in G.P. Brasseur (ed.), The Stratosphere and Its Role in the Climate System, NATO ASJ Series Series I Global Environmental Charge, Vol. 54, Springer-Verlag... 

It should be added that in order to understand the physical laws governing present and future climates, studies of paleoclimate are also important, especially of sudden short-term changes. The intensive development of space-borne remote sensing has not provided adequate global information about the diagnostics of the climate system because the way the existing system of space-borne and conventional observation works remains far from optimal. 

Volcanic eruptions cause changes in RF from 0.2 Wm 2 to 0.5 W m 2 (these values, however, are very conditional). To analyze the possible anthropogenic impacts on global climate, estimates of the sensitivity of the climate system to external forcings are very important. Hansen et al. (1998) assumed that a change in global mean SAT with a doubled C02 concentration should constitute 3 1°C. The unreliable character of RF estimates makes it worthwhile to use different scenarios of RF changes. Developments in this field can be exemplified by the work of Tett et al. (1999). 

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