Climate Change Proceeds Down Worrisome Path

John Mulrow | Dec 03, 2009

Global temperature dropped slightly in 2008, but two other climate indicators—emissions of carbon dioxide (CO2) and its concentration in Earth’s atmosphere—continued their worrisome upward trends. The concentration of carbon dioxide increased to 385 parts per million (ppm), extending the past decade’s trend of rising 1.9 ppm per year on average.1 (See Figure 1.) Meanwhile, some 31,794 million tons of CO2 from fossil fuels were emitted—up 2 percent from the previous year despite high oil prices and the economic downturn of 2008, which reduced fossil fuel demand significantly.2 (See Figure 2.) The International Energy Agency predicts that in 2009 emissions will drop by 3 percent, the largest decline in 40 years, owing mostly to the recession but also to national climate action policies.3

Worldwide, per capita CO2 emissions averaged 4.71 tons in 2008, with great variation among countries.4 It has long been true that developing countries have much lower per capita emission rates than industrial countries. To give one dramatic example, the average Haitian caused 0.1 tons of CO2 emissions in 2008 while the average American was responsible for 18 tons.5 Emissions are rising rapidly in the developing world, however, even if per capita emissions remain lower there. China’s CO2 emissions have risen almost 6 percent a year since 1971, a trend that is expected to continue.6

Though CO2 concentrations and emissions continued their steady rise, global mean temperature actually dropped slightly, to 14.44 degrees Celsius.7 (See Figure 3.) This is the lowest recorded temperature since the beginning of the twenty-first century, causing some advocacy groups to claim a “halt” to global warming.8 But the dip is actually a result of interannual climate variability rather than a shift in the long-term warming trend.9 The Pacific was much colder than normal in 2008 owing to the climate phenomenon known as La Niña, which caused equatorial surface water temperature to fall due to changes in air pressure and circulation.10 Experts warn that the warm counterpart phenomenon El Niño is likely to return next year, bringing back higher temperatures.11

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