But if the press and public have acquiesced to the idea of climate change, they have not begun to grapple with the implications. This is the new battle line. There is broad agreement that it's coming--but little agreement on what that means, how that matters or even how to pursue such questions.
But the pace of incoming evidence is accelerating, and with it may soon come the first hints of actual public concern. Questions must be articulated before they can be answered. What "change" should be expected? How much, how soon, and where? If it happens as expected, who stands to be hurt? What can they/we do about it in advance? And is this coming change now inevitable, or can it be slowed, reduced, forestalled, reversed?
A large number of scientists, a growing number of environmental and other public interest organizations, a small number of politicians and scattered members of the general public are now asking such questions in earnest. Answers have barely begun to trickle in. But if new studies announced in recent months are any indication, the real challenges of climate change can only grow in coming months and years. Among the latest findings:
· Warmest winter: The winter of 1999-2000 was the warmest in the United States since official records began 105 years ago, according to a March 10 announcement from the National Oceanic and Atmospheric Administration (NOAA). It was the third winter in a row that set a new U.S. record. Scientists said the unusual warmth was linked to La Niña, characterized by cooler than normal ocean temperatures in the eastern and central Pacific, and that links to a long-term pattern of global warming were still inconclusive. However, since 1980, two thirds of all winters have been warmer than average, NOAA said. And this year's winter average temperature of 38.4 degrees Fahrenheit was 0.6 of a degree higher than the previous record set last year--a huge jump.
Worldwide, temperatures this winter were the sixth warmest on record, following the two warmest winter seasons on record set in the two previous years, NOAA scientists said.
· Ocean evidence: In the March 21 online edition of the Proceedings of the National Academy of Sciences, scientists at Scripps Institution of Oceanography at the University of California, San Diego, reported evidence of pronounced changes in the earth's climate that can be tracked in cycles of ocean conditions over thousands of years. These cycles reveal that Earth is currently in a period in which a natural rise in global temperatures combined with warming from the greenhouse effect will push the planet through an era of rapid global warming.
This report is the first comprehensive study of the effects of "tidal mixing" on climate change spanning millennia. Researchers Charles Keeling and Timothy Whorf propose that strong oceanic tides drive changes in climate due to their ability to increase vertical mixing in the ocean and thereby transport cold ocean water to the surface. While strong tides elicit cooler climate conditions around the planet, weak tides lead to less cold water mixing and result in warmer periods on earth. The current phase in the cycle suggests that a natural warming trend began a hundred years ago, picked up in the 1970s, and should continue over the next five centuries.
"We have discovered an 1,800-year tidal cycle that appears to match with recent climate change," said Keeling, the study's main author. "If this is a correct mechanism for understanding climate change over millennia, then temperatures will rise both because of weaker tidal mixing and because of the greenhouse effect, which is on the increase as well."
· Low snow, possible drought ahead for U.S.: Among anticipated consequences of global warming and climate change are dramatic changes in precipitation in many parts of the world. While it is still unclear what role, if any, climate change is having on this year's weather, it cannot be ignored that unprecedented storms and flooding have hit many parts of the world. Western Europe experienced two of the most destructive storms on record in December. Venezuela was hit by catastrophic floods in the same month. Australia has seen unusually powerful cyclones and flooding since January. Mozambique and its neighbors in southern Africa are struggling to cope with the worst floods of the century that began last month.
Meanwhile, the lowest snowfall on record in the U.S. Midwest this year could bring the Great Lakes to their lowest level on record this summer and may also portend a second year of major drought throughout much of the east and central states.
The Monthly Bulletin of Great Lakes Water Levels for March showed that Lakes Superior and Erie are already nine inches below average and Lakes Huron and Michigan 18 inches below average. Those levels will keep dropping as summer approaches, since snowfall that normally recharges the lakes during the spring simply did not occur. Normally, about 40 percent of Lake Superior's annual water supply comes from melting snow.
On March 13, U.S. Geological Survey (USGS) Director Charles G. Groat warned that continued below-normal streamflows and low groundwater levels may signal a continuation of last summer's drought that devastated the eastern U.S. This year, Groat says, the drought pattern is likely to move west into the Appalachians, the Ohio River basin, the central Midwest, the lower Mississippi basin and the southeast.
· Biggest iceberg breaks off Antarctica: Current models of global warming predict that the strongest effects, at least in the near term, are likely to be felt in the planet's high-latitude zones. If warming is occurring, visible signs should appear in the Arctic and Antarctic. Without doubt, such signs are increasingly obvious.
Of particular concern to scientists is the apparent weakening of the massive Ross Ice Shelf of Antarctica. On March 22, an iceberg that may be the largest ever recorded broke away from the Ross Ice Shelf and is now adrift in the Ross Sea, heading for the shipping lanes of the southern Pacific Ocean. According to the U.S. National Science Foundation, the iceberg has a surface area measuring 183 miles by 22 miles, more than twice as large as the state of Delaware. In recent years, scientists have observed numerous large cracks or fissures in the ice shelf which suggest that the entire mass of floating ice may eventually disintegrate.
