Climate and health

A minority of the Scandinavian public, even fewer of the health professionals, and almost none of the climate experts, are in doubt that we are experiencing a global warming, that this warming is due to greenhouse gases, that the emission of these is human made, and that it is our combustion of fossil fuels that causes the increased atmospheric concentration of these gases. Fewer are aware of the long lag-time from the time of our emissions, over the increase in temperature -, to the final climate consequences of more unstable weather, spreading droughts, melting glaciers and increasing sea level. In the northern part of the world, we have so far primarily felt the climate changes in higher temperatures. But the retreat of glaciers, the increasing icefree arctic areas and the greener vegetation are also quite evident. Perhaps due to these relatively harmless changes, many have difficulty in understanding and accepting how profound an influence climate changes will bring through the coming decades. And how dramatic changes in our life style we have to accomplish, if the development does not pass important tipping points, beyond which we may loose control over the climate. Thawing of the permafrost tundra in artic Canada, Greenland, Norway, Sweden, Finland and Siberia will release huge amounts of methane and CO2, further accelerating the global warming. The inertia in these changes could easily be mistaken for stability. The world geological history proves that although climate changes are slow processes in a human time scale, the climate system is indeed very sensitive to even small changes in the physical conditions. Last time the amount of greenhouse gases was at the present level, and we had equilibrium between CO2, temperature and sea level, was during the Pliocene epoch 3/2 million years ago. At that time the global mean temperature was about three degrees higher than today, and the sea level was 25 m above present level, just an outlook on to what we should expect if the present level of greenhouse gases remains unchanged (1). Not by tomorrow, not in 2050, but within some hundreds of years from now. Before these end-point scenarios become true, the world population will have experienced devastating changes in their life conditions, with lack of fresh water for billions, floods in some areas and droughts in others, a higher frequency of cyclones, disruption of infrastructure, climate refugees, and local and regional conflicts as one consequence of these changes, all things we will see in this century, although less dramatic if we act appropriately and in a determined way now. The health consequences of such changes are not difficult to imagine. The poorest societies in Africa and Southern Asia will suffer first and most, the same populations which have contributed least to the present greenhouse gas level. In principle, two strategies exist for averting these climate threats. The first is mitigating further aggravation of the changes by cutting out 80-90% of our emissions in the industrialised world before the year 2050 in order to reach the United Nations goal of an average emission of 1-2 tonnes of CO2 per capita per year. Our present emission in Scandinavia is now about 15 tonnes, in the USA 24 tonnes, in China 5 tonnes, in India 2 tonnes and in Africa /2 a tonne per capita per year, just to get an impression of the huge global differences. The other is to adapt to the changes already present, and to those to come. These two strategies are of course complementary, due to the fact that many of the mentioned changes are already inevitable by now. While the cut-down of greenhouse gas emission in one country in the first instance is to the advantage of all other countries, local adaptation, such as by reinforcing dikes, primarily helps the very country making this effort. The global consequences of focusing on