We tend to think of climate change as an environmental issue, which, of course, it is. Current scientific findings on Arctic ice melting, rising sea levels, greenhouse gas emissions, and ocean acidity suggest that during this century, the earth's average surface temperature will surpass the supposedly "safe" threshold of 2 degrees celsius above preindustrial level.
But climate change is also a public health issue, one whose profound effects on the lives and wellbeing of billions of people are just beginning to be understood. A major new report launched jointly by The Lancet and University College London, which I coauthored, has concluded that climate change is the biggest global health threat of the 21st century. Our findings strongly suggest that health experts and advocates ought to be at the forefront of calling for action on climate change. Their help is urgently needed: plans need to be put in place immediately to manage the worst effects, requiring unprecedented levels of international cooperation.
Some of the effects are already being felt. The heat waves of 2003 resulted in 70,000 deaths, mostly from respiratory and cardiovascular diseases. Increased mortality from heat stroke should be expected soon. As temperatures rise, there will be an increased risk of transmission of insect-borne diseases like dengue fever and malaria. As many as 260 to 320 million more people may be affected by malaria by 2080 as mosquitoes spread into newly warm areas. Pathogens also mutate faster at higher temperatures, making treatment more difficult.
A 2-3 degree temperature rise may not not sound too threatening, but temperatures do not rise uniformly. A 3 degree rise overall means a 5-6 degree rise at the polar caps, with the inevitable melting of Greenland and Antarctic ice sheets, leading to up to 13 meters of sea level rise over the next 200 years. More worryingly, the release of methane, a much more powerful greenhouse gas than carbon dioxide, from below the permafrost in Canada, Siberia, and the arctic tundra, could set up a tipping point leading to catastrophic warming and more rapid rises in sea level.
Food supply is another area of concern. One group of U.S. researchers predicts serious crop yield declines and food shortages before 2030, which will put great pressure on prices and demand. Rising food prices have hurt many poor people in the past 2 years, and hunger in south Asia is at a 40-year high. Some estimates suggest that up to half the world's population could face food shortages by the end of the century because of disruptions caused by climate change.
Then there's water. In Africa, 250 million people are already deprived of a secure water supply -- and the numbers are growing. There are serious droughts in China, Australia, the Middle East, Africa, and parts of the United States. Several cities, wealthy as well as poor, such as Barcelona, Adelaide, Kathmandu, Mexico, and New Delhi have precarious supplies and may need to import water. And the spread of water-borne diseases is likely to increase as populations are forced to rely on less-clean water sources.
This is to say nothing of the increasing frequency and severity of hurricanes and cyclones, greater vulnerability in developing world shanty towns to extreme weather events, and large-scale population migration that will worsen existing health crises and in some cases create new ones.
The health effects of climate change -- with the rich causing most of the problem (the poorest billion account for only 3 percent of the world's carbon footprint) and the poor suffering most of the consequences (Africans will lose 500 times more healthy life years than Americans) -- will forever shame our generation if nothing is done to address them.
Governments must appreciate that there are major health benefits and cost-savings from low-carbon living, with potential reductions in obesity, heart disease, diabetes, stress, accidents, and respiratory illnesses. Any effective response requires greater coordination and accountability by international institutions and governments. Unilateral responses simply won't suffice.
It is encouraging that U.S. President Barack Obama has made climate change a priority, that the Chinese government has announced ambitious emissions reductions and massive investment in renewable energy sources, and that the climate debate is recognizing this is not just an environmental issue but one that threatens our health and survival.
don't have much time. Current climate developments are at the very
worst end of the computer model predictions. Every year of delay
increases the costs and difficulties of effective action. Unless this
challenge finds its way to the top of the international agenda, this
century could be a disaster movie without a happy ending.