1997 Global Temperature Review

For the 3 million Canadians without electricity after last week's ice storm, Israelis shoveling the foot of snow that fell on Jerusalem on Monday, and anyone else who may have been out of the loop, Tom Karl, chief climatologist with the National Oceanic and Atmospheric Administration (NOAA), claimed last Thursday that 1997 was the warmest year on record and that nine of the warmest years have occurred in the last 11, according to ground-based and sea surface temperature data. Afterwards, Associate NOAA Administrator Elbert W. "Joe" Friday put a room full of reporters into a tizzy with statements to the effect that global warming was definitely here -- this time for sure, almost no doubt about it.

But also on January 8, down at the University of Alabama at Huntsville, atmospheric scientists John Christy and Roy Spencer, the nation's top experts on global temperature data taken from weather satellites, reported a somewhat different story -- that 1997 was actually a bit on the cool side, continuing the downward trend evident since the satellite readings began in 1979. Said Christy, in a quote buried in the Washington Post, "From the satellite's point of view it was a very normal year."

Citizens might well ask, what's going on here? Satellite readings are the most reliable and the only global temperature data scientists have. Like global climate computer models, satellites look at a range of temperatures in the lower atmosphere above the Earth's surface. In contrast, surface temperature stations are not global; they are overwhelmingly in the northern hemisphere (United States and western Europe). Surface data are not only skewed by the urban heat island effect and by climate events like El Niño, but the myriad and often low-tech ways in which the data are collected -- particularly sea surface data -- give a result that can only be described as fruit salad.

And let's not overlook the bottom line. Global climate fluctuates naturally, so simply claiming a warm year isn't enough. As one of our scientist colleagues pointed out last week, global warming proponents have to prove that the warming has the distinctive "fingerprint" of a human-enhanced greenhouse effect, namely slight-to-no warming in the tropics and rampant warming at the poles.

That's not the profile of NOAA's warming. Their warming is largely in the tropics (thanks to El Niño), with little-or-no warming at the poles. Rural ground-based stations near the Arctic circle show no warming trend; last July, the Antarctic set a record low temperature of - 86.8 degrees fahrenheit, beating the old record of - 83.7 degrees set in 1965.

Not surprisingly then, although administrator Joe Friday tried to make hay with a "temperature record" press conference (on the last sultry day here in Washington of a Bermuda high-pressure system), much of what NOAA climatologist Tom Karl said was cautious, carefully worded, and innocuous enough to stand up to the scrutiny of his scientific peers. Here are his views, as reported by the Associated Press:

"The trend of global temperatures is never due to a single source," commented Karl, noting that factors can include periodic cycles of climate change, ocean circulation, and even volcanoes. (Note: Studies of ocean sediment cores have shown numerous natural swings in surface temperatures over the last 3000 years, some more than 3 degrees celsius, or well on the high side of climate model forecasts.)

Karl said continued warming could produce "a lot of surprises," including changes in rain and snowfall patterns, though not necessarily a disaster. "Based on the data we see, we certainly couldn't predict a catastrophic event," he said.

(According to the UN Intergovernmental Panel on Climate Change report, hurricanes have steadily weakened in frequency and intensity since about 1940, and global average precipitation has dropped slightly since about 1955. An analysis of U.S. flood records from 1914 through the mid-1990s by scientists with the U.S. Geological Survey shows no abnormal weather patterns emerging.)

"The increasing trend of temperatures that we see, we believe, is at least partially attributed to human activities."

(The key word here is "partially," without any speculation as to whether that is 1 percent, 5 percent, 25 percent, or ?)

"The odds that we would be wrong, that there is no relation to human activity, is in the area of 5 to 10 percent."

(To the key word "partially" add the key phrases "human activities" and "no relation." Human activities do affect climate. Farm irrigation increases humidity, which could affect climate and temperature around ground stations. Diverting rivers for irrigation raises ocean salinity and can affect ocean circulation and weather patterns. Commercial airline traffic, spreading ice particles from contrails, may create a regionally enhanced greenhouse effect. Notice, however, that none of these human activities relate to CO₂ concentrations in the atmosphere.)

In short, for all the heavy breathing on the part of reporters, particularly television reporters with the main networks, Karl's statements were rather non-alarmist. Even the statements by NOAA Associate Administrator Joe Friday were less than hair-raising, compared to what we often see in print. Asked about possible effects of global warming, Friday noted "reports" of a softening of the Alaskan permafrost, which he said could adversely affect building foundations, and a 6-inch rise in overall sea levels over the last century (which many scientists believe is typical of the last several centuries).

Did that sound like sea level halfway up the Washington Monument, islands disappearing, mounting death tolls from heat waves, searing drought, plagues, pestilence, etc? Well, some reporters thought so apparently. (Recall that during the Kyoto conference, reporters with the Toronto Star, the only newspaper providing worse coverage on this issue than the Washington Post, told their Canadian readers that global warming would bring "150 million environmental refugees" flooding over the Canadian border from you know where!) With few exceptions (New York Times, UPI, and possibly Fox News Network), the news coverage was so off the mark that three bona-fide scientists wore out their dialing fingers the next day to get on radio programs to set the record straight.

--Made available through the Science and Environmental Policy Project

Candice Crandall writes for the Science & Environmental Policy Project.