China Finds No "Unprecedented" Global Warming
December 10, 2002
by Dennis T. Avery
Chinese climate researchers say today’s world climate shows no unprecedented warming. After analyzing nine separate Chinese historic temperature sources, they’ve concluded that China’s warmest temperatures occurred nearly 2000 years ago—when Europe was in the well-documented Roman Warming.
Global warming activists want us to believe the world had nice, stable temperatures until humans came along in the twentieth century and created the “greenhouse effect” with auto exhausts and heavy industry.
Greenpeace claims that the Dunde glacial ice cap in central Asia yields temperature information for the last 12,000 years, and the warming since 1850 has been “unprecedented.”
Jonathon Overpeck of the U.S. National Oceanographic and Atmospheric Administration called 1998 “the warmest year in at least 1200 years.” He even suggested that the famed Medieval Warming Period (recorded in Europe between A.D. 900 and 1300, with temperatures 4–7 degrees Fahrenheit warmer than today) happened only in Europe!
Chinese researchers sharply disagree. Chinese temperature history, collected from such sources as peat bogs, lakebed sediments, ice cores, and tree rings, shows the following:
China was warmest between the year A.D. 1 and the year A.D. 240 (during Europe’s Roman Warming).
China then had a colder period from A.D. 240–800, coinciding with the cold European weather of the Dark Ages.
China had warmer weather from A.D. 800–1400, essentially the years of Europe’s Medieval Climate Optimum.
China cooled again between 1400 and 1820 (roughly the period of Europe’s Little Ice Age; that’s when the Vikings who had settled Greenland during the Medieval Warming starved or froze to death.)
China’s current warming cycle began in the early 1800s, as did the recent warming in Europe and North America.
Overpeck’s suggestion that the Medieval Warming was a Europe-only event is controversial, but a number of climate researchers have said, “Research has failed to identify any known natural climate-forcing mechanism that could have generated all of the ‘unprecedented warming’ of the twentieth century.”
Of course, it is at least as unlikely that Europe could have maintained a temperature substantially higher than the rest of the planet for more than 300 years.
Fortunately, recent U.S. research breaks the theoretical deadlock. A team led by Dr. Gerard Bond of the Lamont-Doherty Earth Observatory (affiliated with New York’s Columbia University) recently released its analysis of seabed cores from the North Atlantic that go back 12,000 years. Looking at iceberg debris, the Bond team found nine global warmings and nine global coolings in a cycle that averaged 1340 years—and coincided exactly with a known cycle in the sun’s magnetic activity.
The Chinese climate history, published recently in Geophysical Research Letters, further validates the Bond team’s seabed core findings. It also tosses into a cocked hat both the idea of stable earth temperatures and the idea that Europe could have a climate separate from the rest of the Earth.
Dr. Sally Baliunas, an astrophysicist at the Harvard–Smithsonian Center for Astrophysics, has long warned that the main greenhouse effect is natural. She says water vapor, clouds, and such variables as sea ice are at least ten times as important as carbon dioxide levels in atmospheric warming or cooling. Dr. Baliunas also notes that virtually all of today’s warming occurred before 1940. A slight cooling from 1940 to 1970, with a slight warming trend since then, followed the pre-1940 warming. None of this lends much credence to the theory that human industries are making the planet warmer.
This article appeared in the Knight-Ridder Tribune on November 5, 2002, and is reprinted with permission.
Dennis T. Avery is based in Churchville, VA, and is director of the Hudson Institute's Center for Global Food Issues.