Climate change – will it affect our health?
What is climate change?
Climate change, often inaccurately called the greenhouse effect, will affect our health in many ways. The true greenhouse effect is an ancient phenomenon, and in fact a prerequisite for life on earth. It makes our planet a tolerable place with an average temperature of about 15 ºC (35 ºF). Without the greenhouse effect, the world would be freezing cold, on average about -18 ºC (-2 ºF), but there would also be variations, roasting hot during the day and freezing cold at night.
Our atmosphere with its gases prevents the escape of heat into outer space, and therefore the average temperature increases by over 30 ºC, from -18 to +15 ºC. It works like the windows in our car, they let sunshine (energy) in, but the same amount of energy is lost to the environment as infrared radiation (heat radiation) only after considerable warming of the car. The atmosphere also circulates heat, preventing excessive variations between day and night in most regions.
The most important greenhouse gases are water vapour, carbon dioxide, methane, nitrous oxide (laughing gas), chlorofluorocarbons (also called "freons"), and tropospheric (lower atmospheric) ozone. The chlorofluorocarbons are totally man made; the concentrations of the other gases depend in part on human activities.
Climate change in fact, is a reinforcement of the greenhouse effect. When the concentration of carbon dioxide increases, escape of heat into the space is further prevented, and therefore the average surface temperature will tend to increase. How much it will increase is somewhat more difficult to forecast. If calculated directly from the increase of carbon dioxide concentration, a doubling of carbon dioxide would increase the average temperature by about 5 ºC. This was already calculated in 1896 by a Swedish chemist, Svante Arrhenius.
How certain are the predictions?
There are some uncertainties in the calculations; the most important is the effect of water vapour. When the temperature increases, there is more evaporation of water, and this will make it more cloudy. The effects of clouds are somewhat difficult to predict, because on one hand water vapour is a greenhouse gas, but on the other hand clouds will reflect off part of the radiation from the sun. This is called the albedo effect. The most recent prediction of the Intergovernmental Panel on Climate Change (IPCC) from the year 2007 is in the worst case scenario the temperature will rise by somewhere between 2.4 to 6.4 ºC, and even in the best case scenario it will increase by between 1.1 to 2.9 ºC. This difference between scenarios illustrates how much human beings can influence the future by their own efforts. Unfortunately, the human race seems to intent on even exceeding the worst case scenario in their hunger for energy.
This prediction is only an average over the whole globe. There will be major differences between different areas. By and large, the closer to polar regions you are, the greater will be changes, and towards the equator the increase will be less. In Northern Europe, the increase could be several degrees, if the carbon dioxide concentration were to double from the pre-industrial level of 0.028 % to 0.056 %. What will impact hugely in Europe is the fate of the Gulf Stream. In some predictions, it has been calculated that the Gulf Stream might change course before reaching Europe. This would mean much of Europe would experience a climate similar to that of Alaska, Labrador, or Northern Siberia. In this respect, the latest predictions are reassuring; this is not likely to happen for at least 100 years.
How then about our health?
With so many uncertainties about the degree of climate change itself, it is even more difficult to predict its health effects. Some effects are, however, quite likely to occur. Crop yields will decrease in many areas, causing starvation, refugee problems, and consequently a plethora of health effects. Food prices are predicted to increase, and this means its impact will be worst in the poorest countries. The fact that somewhere else the conditions for farming might improve will not be of any immediate help, because the starving population does not live there. It will take time to start new production and to create the infrastructure for distribution. Malnutrition due to decreasing crop yields is predicted to be the biggest health consequence of climate change. This is probably what is already happening in northern Africa.
Secondly the warming climate will favour the spread of several infectious diseases, for example the vector-born diseases such as malaria. Malaria carrying species of mosquitoes are predicted to spread from the tropical areas to more temperate regions, and also higher up the mountains. Although dryness will probably worsen the living conditions for mosquitoes in other regions, it seems likely that the net effect will be an increase in malaria. Some other infectious diseases are also predicted to increase, some of them vector-borne, some related to food and water hygiene.
A third predicted and in part already materialized group of health effects is due to extreme weather events. An increase in average temperature will without doubt also increase the likelihood of heat episodes. During the two first weeks of August 2003, much of Central Europe suffered an extreme heat wave. In France, an estimated 15,000 more people died than during the previous three years at the same time. During the worst day of the heat wave, mortality was more than fivefold compared to the same day in previous years. In the whole of Europe, the excess mortality estimate was 35,000 deaths.
High temperatures and dryness will also lead to forest fires as bitterly experienced in Australia in 2009. These kinds of uncontrollable fires have become more common in the Mediterranean countries from Portugal to Greece. These have also been responsible for a number of deaths in addition to huge material losses.
Even if increased temperatures will decrease some risks in cold regions, the negative impact of heat waves is clearly more important than the positive effect of a few less cold-related deaths.
In 2005, Hurricane Katrina devastated the city of New Orleans, and many other locations in the southern United States. Are these storms related to climate change? In individual cases it is hard to tell, but the likelihood of storms and floods will increase, because of the surface warming of the oceans. Even insurance statistics are showing a clear increase in the number, ferocity and destructiveness of storms.
What could and should be done?
When discussing the risks of climate change, the most important point is not to expect a 100 % proof of some effects. The important point is how large risks we are willing to take. If the effect is disastrous, even a 5 % chance is completely unacceptable, to say nothing of a 95 % chance. When one considers carcinogenic chemicals, some people are unwilling to accept an even one in a million risk. Putting it very mildly, we are now talking of a multitude of risks that are much more likely to happen than not to happen. Who would take that risk with cancer?
It was a little disturbing to note that it appears that only the predicted economic consequences of climate change published in 2006 by British economist Nicholas Stern woke up many governments. Perhaps this means that many politicians were not really persuaded by health and environmental issues, but the economic consequences clearly shocked them.
There is one good point in the mitigation of climate change. The same measures that decrease the emissions of carbon dioxide will also decrease the emissions of the air pollutants most dangerous to our health. The most important of these are fine particulate matter, oxides of nitrogen, carbon monoxide, and sulphur dioxide.
The emissions of carbon monoxide and sulphur dioxide can already be reduced effectively with modern technology. The most important problem here is the developing countries using coal and oil with less developed technology. The control of fine particulate matter is only moderately good even in the developed countries, and oxides of nitrogen remain a problem. For these reasons, it will be important to find ways to limit, even restrict the use of fossil energy production as soon as possible. This will impact both in abating climate effects and in improving the health of the population.
In recent years, there has been a growing awareness that climate change will have major impacts on human health. Thus, there is every reason to try to reduce our dependence on fossil-based energy. A reduction in combustion of fossil fuels will improve health also by lowering the levels of other emissions deleterious to health.
Notes and references
- See the chapter "What’s wrong with the air in our cities?"
One level up: The air that we breathe
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