Feature

We’re on the road to Kyoto

Cathy Read explains why global warming will have profound effects on health – and why we have to look to Kyoto to discover whether governments will take it seriously

In December representatives from almost every country in the world are due to meet in Kyoto, Japan to set legally binding reduction targets for emissions of greenhouse gases after the year 2000. The Kyoto conference is the most important on climate change since the Rio ‘Earth Summit’ five years ago, and will be a critical test of the will of the international community to act on firm evidence that global warming is already underway.

The climate system includes the atmosphere, oceans, land surface and cryosphere (snow, glaciers, sea-ice, etc.). In a balanced climate system the amount of energy gained from the sun is equivalent to the amount of energy lost into space. The naturally occurring greenhouse gases — water vapour, carbon dioxide (CO2), methane, nitrous oxide and ozone — are more efficient at absorbing outgoing terrestrial radiation than incoming solar radiation, causing the earth’s surface and lower atmosphere to warm.

This natural ‘greenhouse effect’ keeps the earth some 30° warmer than it would otherwise be, and has enabled life to develop on earth. But now the climate system is out of balance. As a result of human activity, there is more energy entering the climate system than leaving. Of all the greenhouse gases, CO2 has made the largest contribution to this ‘greenhouse effect’.

Further climate change depends critically on emissions of greenhouse gases to the atmosphere. The Intergovernmental Panel on Climate Change (IPCC) forecasts an increase in average world temperature within the range 1-3.5°C over the next century. Climate models predict rates of global warming between ten and 100 times faster than any natural change in world climate experienced by human society to date.

Health effects of climate change

We can be certain that climate change poses a serious threat to health in the next century. We are far less certain of the precise nature, extent and distribution of adverse health effects.

Some populations and some people will be more vulnerable to the effects of climate change. Vulnerability will to a large extent be determined by region, but it is likely that the poor everywhere will be least able to adapt and therefore most susceptible.

Direct effects of temperature on health. Global warming will increase the frequency of very hot days and increase the amount of ill health and death related to thermal stress. A study of deaths during three heat waves in Los Angeles in which temperatures were around 41°C found that the peak death rate was 172 per cent of that expected at all ages and that people aged over 85 were the most vulnerable. In temperate countries a potential increase in heat-related deaths due to climate change would probably be offset by decreases in cold related deaths. A model based on the UK calculated that even if the temperature increased by an average of 3° the additional heat-related deaths would be more than offset by fewer winter deaths.

Effects on respiratory healthdue to changes in concentrations of aeroallergens (spores, moulds etc.) and air pollutants such as ozone dependent on temperature-sensitive photochemistry.

Extreme weather events. Climate change may affects the variability of rainfall and temperature and increase the frequency of floods, droughts and storms. Extreme weather events often trigger natural disasters that result in deaths, injury and psychological ill health.

Infectious diseases. Many of the world’s major infectious diseases are caused by parasites or viruses transmitted by insects such as mosquitoes and ticks that are extremely sensitive to climate factors. Diseases likely to become more common due to future climate change include malaria, dengue, African trypanosomiasis (sleeping sickness), American trypanosomiasis (Chagas disease), leishmaniasis, onchocerciasis (river blindness) and lymphatic filariasis (elephantiasis).

Malaria is the vector-borne disease likely to be most affected by climate change. Some 300-500 million people are currently infected with malaria and two million people (mostly young children) die of malaria every year. Approximately 45 per cent of the world’s population lives in climate-defined zones of potential malaria transmission. This may increase to 60 per cent by later next century.

Climate change would also influence certain vector-borne diseases in temperate regions including arboviral haemorrhagic fevers and encephalitis, leishmaniasis and lyme disease.

World-wide, diarrhoeal diseases caused by microbiological contamination of drinking water and food are a major cause of ill health and deaths. Climate change may affect the availability of local water supplies and result in the use of more easily contaminated sources of water. The incidence of food poisoning is often related to ambient temperature, even where refrigeration is available, and it has been estimated that by 2050 the UK could expect a 20 per cent increase in food poisoning in the spring and autumn months. Climate change may also increase the spread and transmission of cholera by creating favourable conditions for algal blooms, a natural host organism reservoir for the cholera germ.

Food production. Climate change would affect food production with regional gains and losses dependent on factors including temperature, rainfall and plant diseases and pests. One recent study incorporating several climate change scenarios predicts an extra 40-300 million at risk of hunger by the year 2060.

Sea-level rise. IPCC forecasts that sea level will rise (due to thermal expansion of the oceans and the melting of glaciers) by approximately 40 centimetres a year by the year 2100, a rate of rise several times faster than over the previous century. A half-metre rise would approximately double the number of people—currently about 46 million—who experience flooding annually. Besides the injuries and deaths caused by flooding, sea-level rise would displace coastal populations, disrupt food production and local economies and increase the risk of communicable disease.

The politics of climate change

The UN Framework Convention on Climate Change, signed at Rio in June 1992, is intended to minimise climate change and has now been ratified by 165 countries. As a ‘framework convention’, it is simply the foundation for a process to develop over time. It was anticipated that protocols could be added to specify reduction targets and timetables for different greenhouse gases.

The convention’s ultimate objective is ‘the stabilisation of greenhouse gas concentrations in the atmosphere at a level that would prevent dangerous anthropogenic interference with the climate system’. It committed signatories to agree measures to protect the climate rapidly enough to allow ecosystems to adapt naturally to climate change, to ensure that food production is not threatened and to enable economic development to proceed in a sustainable manner. As a first step, this meant a non-binding commitment on developed countries to return CO2 emissions to 1990 levels by the year 2000. The convention recognises that industrialised countries bear the greatest responsibility for past and present emissions and so they must take a lead in reducing emissions. But the commitment does not require developed countries to actually achieve the goal, and a second conference in Geneva in July 1996 made little progress despite definitive evidence of global warming reported by IPCC.

The UK and Germany are the only countries that expect CO2 emissions to fall (by between 4 and 8 per cent) by 2000. In Germany this is due to the closure of inefficient industries in the East, while the UK reductions will follow the last government’s move from coal to gas for electricity generation, rather than because of any primary commitment to reduce CO2 emissions.

Although the UK claims to be an international leader in halting climate change, its current energy policies are not compatible with sustainable development. The Labour government has inherited a number of subsidies to the oil, gas and coal industries which force down the price of fossil fuels, encouraging consumers to use more. And the UK’s lax offshore tax regime (effectively a subsidy on the fossil fuel supply) is allowing oil companies to expand into the ‘Atlantic Frontier’ off the north-west coast of Scotland.

If the UK is to move towards a healthy and sustainable energy policy it must discourage the use of fossil fuels and promote energy efficiency and the use of renewable energy sources. To date, the government has paid little attention to alternative clean sources of energy although the potential is enormous. For example, the British solar industry has an annual turnover of some £40m but only a tiny home market. Yet each year the UK receives 30 times more energy from the sun than that contained in all proven UK oil reserves. The Department of Trade and Industry’s own research shows that widespread application of solar photovoltaic technology could generate up to two-thirds of our electricity. If the government redirected fossil fuel subsidies to alternative energy sources such as solar power, some of this potential could be realised.

About 25 per cent of our CO2 production comes from traffic exhaust. An expanded, integrated public transport system together with measures to encourage walking and cycling and discourage car use would reduce air pollution and CO2 emissions, improving health now and in the future.

Prime Minister Tony Blair’s strong words on climate change at the recent UN Earth Summit gives some hope that Labour is prepared to commit itself to tackling this urgent problem. But we must continue to lobby the powerful and raise awareness so as to focus minds on the importance of the task ahead.

This is an edited version of an article which first appeared in Global Security, the magazine of MEDACT (Medical Action for Global Security). MEDACT, 601 Holloway Road, London N19 4DJ. 0171 272 2020.