Hervé Le Treut
13 October 2005, Helsinki, Mörkky
Social and scientific problems. Hard facts, their repercutions.
Carbon dioxide, methane, nitrous oxyde (among others)
1957: first measurements - Hawai
Exponential growth since the industrial revolution.
Bubbles in the ice.
5000 years of stability - end of an inter-glacial era
Records from the ice of Antarctica
Perturbations due to astronomical effects - large planets
Abrupt change unprecedented over 100000 years.
Growth of energy consumption since 1950. Disruption of an equilibrium by otherwise limited human intervention.
Less than 1% of the mass of the atmosphere;
water vapor, other gases, clouds play an important role.
Without them, the average temperature would be 30 degrees lower.
CO2 etc. remain for long durations (100 years), thus accumulate.
Evolution of the average temperature, of the size of glaciers.
Anticipation of the level of the sea (40-50 cm in 2100):
slowly reacting component of the climate system - irreversible
Vegetation - natural moderator
Ocean circulation.