This additional year of temperature data provides further evidence that a new trend of rising temperature is bringing to an end the period of relative climate stability that has prevailed since shortly after the last Ice Age ended and 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.August and October temperatures in 2001 were each the second warmest on record.
Based on data for the first 10 months, the global average temperature for 2001 is calculated at 14.51 degrees Celsius (58.1 degrees Fahrenheit). The all-time high in 1998 was 14.68 degrees Celsius. (See figure http://www.earth-policy.org/Updates/Update4_data.htm.)
Looking back over the last century, the average global temperature climbed from 13.88 degrees Celsius in 1899-1901 to 14.45 degrees in 1999-2001, an increase of 0.57 degrees. Fully two thirds of this gain--more than 0.4 degrees--occurred in the century's two closing decades.
After fluctuating around 14 degrees Celsius (57.2 degrees Fahrenheit) during most of the century, the temperature has been above this level every year since 1976. During the last several years, the earth's temperature has fluctuated around 14.4-14.6 degrees Celsius.
The rise of nearly 0.6 degrees Celsius during the last century is quite small compared with the projected temperature rise over the next century of 1.4-5.8 degrees Celsius (2.5-10.4 degrees Fahrenheit) according to the Intergovernmental Panel on Climate Change (IPCC). Even the lower figure in that range would be more than double the increase of the last century. The upper-end projection of 5.8 degrees Celsius 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 0.1-0.2 meters (4-8 inches). The IPCC projects that during this century sea level will rise from 0.1-0.9 meters (4-36 inches).
The temperature rise of recent decades follows on the heels of rising atmospheric concentrations of carbon dioxide (CO2), the principal greenhouse gas responsible for global warming. During the first two centuries of the Industrial Revolution from 1760 to 1960, atmospheric CO2 levels climbed from an estimated 277 parts per million (ppm) to 317 ppm--a rise of 40 ppm. But
during the four decades from 1960 to 2001, CO2 concentrations climbed from 317 ppm to 371 ppm, a gain of 54 ppm. (See figure http://www.earth-policy.org/Updates/Update4_data.htm.) This accelerating rise in recent decades corresponds closely with the growth in fossil fuel
burning during this period.
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 such obvious things as food security and the habitability of low-lying regions, but also the species composition of local ecosystems.
Agriculture is particularly vulnerable to climate change. For example, in the summer of 1988, record heat and drought in the American Midwest pulled the U.S. grain harvest below consumption for the first time in history.
Fortunately for the scores of countries that import grain from the United States, the nation had a large grain reserve at the time and was able to satisfy importers' needs by drawing down these reserves.
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.
Climate change is also triggering widespread changes in ecosystems. 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 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 non-scientists: that 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 now have the technologies to do it. The economics are falling into place. At issue is whether we can restructure the energy economy before climate change
spirals out of control.
Earth Policy Institute
Lester R. Brown
Additional data and information sources http://www.earth-policy.org or
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For more information on climate change or the emerging solar/hydrogen
economy, see chapters 2 and 5, respectively, of Eco-Economy: Building an
Economy for the Earth (available for free download).
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