The UN climate change conference, to be held in Copenhagen in 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 19th century.
If we continue with business-as-usual emissions from activities such as burning fossil fuels and cutting down forests, concentrations could reach 750ppm by the end of the century. Should that happen, the probable rise in global average temperature relative to pre-industrial times would 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.
Developing countries recognize and are angered by the inequity of the current situation. Current greenhouse-gas levels are largely due to industrialization in the developed world since the 19th century. Yet developing countries are the most vulnerable to the consequences of climate change, which threaten the economic growth that is necessary to overcome poverty. At the same time, emissions cannot be reduced at the extent required without the central contribution of the developing world.
Climate change and poverty, the two defining challenges of this century, must be tackled together. If we fail on one, we will fail on the other. The task facing the world is to meet the environment’s “carbon constraints” while creating the growth necessary to raise living standards for the poor.
To avoid the severe risks that would result from a rise in global average temperature of more than 2˚C, we must get atmospheric concentrations below 450ppm. This will require a cut in annual global emissions from about 50 gigatonnes of CO2-equivalent today to below 35 gigatonnes in 2030, and less than 20 gigatonnes by 2050.
Today, per-capita annual emissions in the EU are 12 tonnes and 23.6 tonnes in the US, compared to 6 tonnes for China and 1.7 tonnes for India. As the projections for 2050 suggest that the world’s population will be about 9 billion, annual per-capita emissions must be reduced to approximately 2 tonnes of CO2-equivalent, on average, if the global annual total is to be less than 20 gigatonnes.
Most developed countries are targeting reductions in annual emissions of at least 80 percent — relative to levels in 1990 — by 2050. If they are to convince developing countries that the 2050 goal is credible, they must be both ambitious and realistic about the domestic political challenges they face in adopting and implementing demanding targets for 2020, 2030 and 2040.
Developing countries need substantial help and support from rich nations in order to implement their plans for low-carbon economic growth, and to adapt to the effects of climate change that are now inevitable over the next few decades. Developed countries should also provide strong support for measures to halt deforestation in developing countries, and for reducing emissions substantially, quickly and at reasonable cost.
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