Global warming is the most serious of all the problems facing our species and therefore deserves the highest priority response now. Although the future is uncertain, global warming is happening already and we cannot afford to ignore it.

This question reveals a lack of understanding of the seriousness of the impacts that climate change is already having on human health and well-being, and on biodiversity. Climate change is already making the poorest poorer in developing countries, via droughts and heat waves, and these are the people who suffer the brunt of the extreme weather events that appear to be becoming more frequent. Indirectly climate change is the greatest threat to future global economic development.

Regional and international conflicts caused or made worse by climate change threaten the very existence of civilisation. Even the viability of the human race, at least in its current numbers, may be threatened by the end of the 21st century.

In addition, the relatively rapid poleward and upward migration of climatic and vegetation zones and drastic decreases in habitability of the oceans, together with ocean acidification, and of many habitats on land, mean that climate change has been rated as the greatest threat to biodiversity. This is even above habitat destruction by man, pollution, over exploitation, and the effects of invasive species.

Even if there is some uncertainty about its exact scale and impact and the rate of change we cannot afford to take the risk of ignoring climate change.