Rising carbon dioxide levels are encouraging the growth of ragweed and poison ivy and boosting the proliferation of fungal spores. As a result, climate change makes allergies worse, and as such is one of many allergy causes to look out for. Climate change is leading to more ragweed pollen in the air, according to Lewis Ziska, a plant physiologist with the United States Department of Agriculture. 'Climate change is affecting plants and human health, especially that of allergy sufferers,' he said at a recent meeting of the American College of Allergy, Asthma, and Immunology. Moreover, leaves fed by increased levels of carbon dioxide allow mould to reproduce more rapidly and spread more allergenic spores.
Climate change is also likely to increase indoor air pollution in homes, schools, and offices. This is because it increases indoor humidity which is known to allow house dust mite and mould to thrive. Also, higher temperature and humidity decompose discarded food faster, which encourages insect allergens such as cockroaches.
Allergy is not the only health problem arising from climate change. Medical experts from the Climate and Health Council, writing in the British Medical Journal, say that an increase in car and plane use and the advent of cheap, energy-dense food from intensive agriculture have not just increased carbon emissions - they have also led to increased levels of obesity, diabetes and heart disease because people are relying on their cars too much. Some, but not all, studies also show a link between obesity and asthma. Meanwhile, rising temperatures also lead to malnutrition, childhood diarrhoea and malaria.
All these are good reasons to put health at the centre of climate change negotiations. For instance, curbs on traffic would increase walking and cycling and people would get fitter and slimmer. Reduce livestock production, and people would eat less meat, which may decrease rates of colorectal cancer (currently the second most common cancer among men, after lung cancer).
(1) 'Climate change and its impact on respiratory health' Symposium at the scientific meeting of the American College of Allergy, Asthma and Immunology, November 2010
(2) Richards I and Stott R Doctors and climate change BMJ 2010;341:c6357