The oceans,the climate and people (with a view from mars)*

Abstract

If the Earth is looked at as a planet, the first really significant influence that man has had is the increase in atmospheric CO₂ which has occurred over the past Century. Models based on projected uses of fossil fuels and the behaviour of the ocean and the biosphere, in so far as they are understood, lead to predictions of a doubling of the atmospheric CO₂ by the middle of the next Century and an increase by a factor of from five to eight within two centuries. Models of the climatic impact of such a CO₂ increase predict an increase of surface temperature of about 2°C for doubling and 5 to 10°C for a factor of eight. 2°C is twice the magnitude of temperature fluctuations over the past Century, and 10°C is greater than the change between present conditions and a full ice age.

Thus, increasing CO₂ may very well dramatically affect mankind. However, there are many uncertainties in the models, in particular in the way in which the ocean is treated concerning both its ability to absorb CO₂ and its response as part of the climate system. Within the next few decades we may need to make some very important social decisions with respect to national and international response to a climate change, which is likely still to be uncertain because of the difficulty of separating any change in climate produced by CO₂ increase from purely natural fluctuations. It is not evident that we have mechanisms in place either to gain enough knowledge to reduce the uncertainties or to make appropriate decisions in the face of the uncertainties.