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Last year, 2001, was the second warmest year since recordkeeping began in 1867. Following the all-time high of 1998, last year's near-record extends a strong trend of rising temperatures that began around 1980. The 15 warmest years since 1867 have all come since 1980.
This new year of temperature data provides further evidence that a trend of rising temperature is bringing to an end the period of relative climate stability that has prevailed since agriculture began some 11,000 years ago.
Monthly global temperature data compiled by NASA's Goddard Institute for Space Studies, in a series based on meteorological station estimates going back to 1867, show that September 2001 was the warmest September on record. November also set an all-time high. And six recent months—August and December 2001 and January, March, April, and May 2002—were each the second warmest respective months on record.
The global average temperature for 2001 is calculated at 14.52 degrees Celsius (58.1 degrees Fahrenheit). The all-time high in 1998 was 14.69 degrees Celsius. Over the last century, the average global temperature climbed from 13.88 degrees Celsius in 1899-1901 to 14.44 degrees in 1999-2001, an increase of 0.56 degrees. But four fifths of this gain came in the century's last two decades.
The rise of nearly 0.6 degrees Celsius during the last century is quite small compared with projections by the Intergovernmental Panel on Climate Change (IPCC) of the temperature rise for this century of 1.4-5.8 degrees Celsius (2.5-10.4 degrees Fahrenheit). Even the lower figure in that range would be more than double the increase of the last century. And the upper-end projection would be nearly 10 times as much.
The contrast in sea level rise for the last century and that projected for this one is similarly worrying. During the last century, sea level rose an estimated 10-20 centimeters (4-8 inches). The IPCC projects that during this century sea level will rise 9-88 centimeters (4-36 inches).
Rising temperature is not an irrelevant abstraction. It brings countless physical changes—from more intense heat waves, more severe droughts, and ice melting to more powerful storms, more destructive floods, and rising sea level. These changes in turn affect not only food security and the habitability of low-lying regions, but also the species composition of local ecosystems.
Climate change affects food security in many ways. In 2000, the World Bank published a map of Bangladesh showing that a 1-meter rise in sea level would inundate half of that country's riceland. Bangladesh would lose not only half its rice supply but also the livelihoods of a large share of its population. The combination of a population of 134 million expanding by 2.7 million a year and a shrinking cropland base is not a reassuring prospect for Bangladesh.
Widespread changes in ecosystems are also being triggered. Recent years have brought heavy investments by governments and environmental organizations to protect particular ecosystems by converting them into parks or reserves. But if the rise in temperature cannot be checked, there is not an ecosystem on the earth that can be saved. Everything will change.
An additional year of temperature data reinforces the concerns expressed by the team of eminent scientists who produced the latest IPCC report, Climate Change 2001. They make clear what is now becoming obvious even to nonscientists: fossil fuel burning is changing the earth's climate.
The bottom line is that altering the earth's climate is serious business—not something to be taken lightly. We can curb climate change by shifting from a carbon-based energy economy to one based on hydrogen. We have the technologies to do it. The economics are falling into place. Do we have the wisdom and the will to restructure the energy economy before climate change spirals out of control?
Copyright © 2002 Earth Policy Institute