MILAN – Most people recognize that human activity, primarily the use of fossil fuels, is contributing mightily to an increasing level of greenhouse gases in the atmosphere. These gases, particularly CO2, increase the risk of damage to the world’s climate. This means that limits on our consumption of fossil fuels cannot be measured only by the availability of supplies, but must also take account of the environmental costs.
Yet considerable uncertainty remains about the magnitude of the impact of rising levels of atmospheric greenhouse gases on temperatures and climate. This uncertainty must be taken seriously when formulating strategies to combat climate change.
The high-growth developing countries – Brazil, Russia, India, China, and others in the G-20 – now include more than half the world’s population. If they continue their current strong growth trajectories, as seems likely, they will approach advanced-country levels of income by mid-century or shortly thereafter.
At that point, the part of the world’s population with advanced-country income levels ($20,000 dollars or above in today’s dollars) would increase from 16% to 66%. And, if the newly affluent follow the patterns of consumption, energy use, and carbon emissions that accompany high income levels now, the climate change battle will have been lost.