LONDON – The United Nations climate change conference, to be held in Copenhagen this December, should provide the climax to two years of international negotiations over a new global treaty aimed at addressing the causes and consequences of greenhouse-gas emissions.
A global deal on climate change is urgently needed. Concentrations of carbon dioxide and other greenhouse gases in the atmosphere have reached 435 parts per million (ppm) of CO2-equivalent, compared with about 280 ppm before industrialization in the nineteenth century.
If we continue with business-as-usual emissions from activities such as burning fossil fuels and cutting down forests, concentrations could reach 750 ppm by the end of the century. Should that happen, the probable rise in global average temperature relative to pre-industrial times will be 5˚C or more.
It has been more than 30 million years since the earth’s temperature was that high. The human species, which has been around for no more than 200,000 years, would have to deal with a more hostile physical environment than it has ever experienced. Floods and droughts would become more intense and global sea levels would be several meters higher, severely disrupting lives and livelihoods, and causing massive population movements and inevitable conflict around the world. Some parts of the world would be under water; other would become deserts.