Scenarios Of The Arctic Climate In The 21st Century

Both observations and model studies have shown that the Arctic is a region of high climate sensitivity to increased concentration of greenhouse gases (see e.g. Houghton et al. 1990, 1992, 1996, 2001). Most climate model simulations suggest that a doubling of C02 will cause a rise in global mean surface air temperature from 1,4°C to 5.8°C (Houghton et al. 2001) with a two-to three-fold amplification in the Arctic. Atkinson (1994) gives the following reasons for this enhanced warming in the Arctic: 1) snowline-albedo feedback, 2) release of CO, and CH4 from soil carbon and methane hydrates from sea bed sediments, 3) strong surface inversion which gives reduced vertical mixing, 4) increased absolute humidity which reduces radiative cooling, 5) low atmospheric H.,0 increase which enhances the CO, effect and 6) Arctic haze which enhances springtime warming. The first three reasons are the most important. The final three factors play lesser, contributory roles.

How can we predict climatic change in the Arctic? Most scientists distinguish two main approaches which are used to estimate a climatic change associated with a wanner world (see e.g. Jäger and Kellogg 1983; Palutikof etal. 1984; Palutikof 1986; Wigley et al. 1986; Salinger and Pittock 1991). The first approach uses the general circulation models (GCMs) or global chemical models to construct scenarios of the future climate. The second one uses past warm periods as analogues of a future, warm, high carbon dioxide world. In the present paper the results based on these approaches are presented.

0 0

Post a comment