Carbon dioxide emissions have been growing steadily for 200 years, since fossil fuel burning began on a large scale at the start of the Industrial Revolution. But the growth in emissions is now accelerating despite unambiguous evidence that carbon dioxide is warming the planet and disrupting ecosystems around the globe. In 2000, the Intergovernmental Panel on Climate Change (IPCC) laid out projections of how greenhouse gas emissions were likely to evolve during the twenty-first century due to economic, demographic, and technological changes.
The high-end scenario combined rapid economic growth and globalization with intensive fossil fuel use and was used as the IPCC’s upper limit for estimates of future climate change in its recent 2007 report. Yet this upper-limit projection predicted annual emissions growth of only 2.3 percent between 2000 and 2010—far less than the 3.1 percent annual increase observed so far this century. With CO2 emissions currently exceeding the worst-case scenario, we can expect that temperature and sea level rise will likely do the same. Five countries are responsible for over half of fossil-fuel-related CO2 emissions, and the United States and China alone account for more than a third. The United States has been the world’s largest emitter for over a century, releasing 1.66 GtC in 2006, or 19.8 percent of global emissions.