As Sari Kovats and Andrew Haines have pointed out in a recent commentary,1 our world is warming up. Climate models predict that this increase in mean annual temperature will continue for the rest of the 21st century. Whatever the reasons for the temperature increase, climate change may have a greater impact on ecological processes than previously realized.2
There is mounting evidence that global climate change has extended growing seasons, changed distribution patterns and altered the phenology of flowering, breeding and migration. For migratory birds, the timing of arrival on breeding territories and overwintering grounds is a key determinant of reproductive success, survivorship and fitness.3
The Arctic Climate Impact Assessment (ACIA) report — the most comprehensive assessment of regional climate change ever undertaken — was released in November 2004.4 The report documents that the Arctic has experienced dramatic warming over the past 50 years, with winter temperatures increasing by as much as 3–4°C. Over the past 30 years, the Arctic has lost almost a million square kilometres of sea ice, an area larger than Norway, Sweden and Denmark combined.4
Indigenous peoples and livelihoods are already severely affected by rising temperatures and sea levels, as are human settlements and economic infrastructure by thawing permafrost. These serious impacts will not occur decades in the future — they are being felt now. And they are being felt not just in remote islands halfway around the world, but also in some of the world's richest countries. Glacier retreat in Nepal, Peru and Switzerland, anomalous heat waves in France, and increasing sea-level and salt-water encroachment in Kiribati, Bangladesh and the United States are just a few examples of impacts related to climate change.
For several decades now we have been acutely aware of the increasingly intensifying effect that environmental degradation has on human health. Health experts are becoming more and more concerned about the potential impact on public health.5 The medical community must become more aggressively involved in combating future global environmental problems.