Climate change update
E. Linacre and B. Geerts
Twentieth-century climate changes discerned by 2002 include the following -
- global surface warming of the air,
and increase of the mean sea surface temperature - screen temperatures
rose by an average 0.8°C - most of the warming has occurred in late winter
and spring, and at night;
- cooling of the lower stratosphere by
about 1°C since 1950, consistent with GCM predictions;
- a global increase of rainfall over
land of 1%, implying greater evaporation caused by warming (1); the
increase in rainfall (and temperature) is larger in winter at high
northern latitudes; and a slight decrease has occurred in some regions,
such as in northern Africa and on the west coast of South America;
- an increased atmospheric vapour pressure
over the tropics, at least since 1973 (1);
- more cloud over the oceans,
especially convective clouds and cirrus clouds - this, in turn, enhances
- a rise of sea level by 10-25 cm, of
which 2 - 7 cm is due to thermal expansion of the layer above the
- a general retreat of glaciers,
responsible for raising the sea level by 2 - 5 cm (3);
- tropical cyclones are fewer and weaker in
the north Atlantic (compared to the middle of the century) but more
numerous in the north west Pacific;
- fewer snowfall events in the Snowy Mountains
of southeast Australia, at least since 1970, and shorter periods each year
with enough snow for skiing (4).
- fewer frosts in many places,
e.g. the southeastern USA, Alberta (Canada), northwestern Europe and
Australia. At Roma in southern Queensland in Australia, for instance,
there around 10 frosts each year now, instead of about 25 in 1900 (5).
- Schimel, D. et al. 1996.
Radiative forcing of climate change. In Houghton et al. 1996, 65 -131 (2).
- Houghton, J.T. et al., L.G.
Meira Filho, B.A. Callander, N. Harris, A. Kattenberg and K. Maskell (eds)
1996. Climate Change 1995: the science of climate change. Contribution
from the Working Group I to the Second Assessment Report of the
Intergovernmental Panel on Climate Change. (Cambridge Univ. Press) 572pp.
- Warwick, R.A. et al. 1996.
Changes of sea level. In Houghton et al. 1996, 359 - 405.
- Clem Davis 1997. Priv.
- Karl, T.R., N. Nicholls and
J. Gregory 1997. The coming climate. Scientific American 276