The Changing Earth--Science Grapples With Huge Challenge

Recent scientific evidence has removed all doubt that the Earth is undergoing dramatic changes that could have a profound effect on the planet’s habitability. But the effort to measure those changes and determine their impact has left scientists with an equally profound challenge.

Oceanographers, climatologists and other researchers who are exchanging ideas at the fall meeting of the American Geophysical Union here are in general agreement that such changes as a global warming trend either have already begun or are inevitable, but they all share a common frustration.

To clearly understand the rate of change and its consequences, they need to know what conditions on the Earth were like hundreds and even thousands of years ago. And that, they all agree, is an enormously difficult task that will require major new commitments on a global scale.

The Earth’s atmosphere, for example, “is changing much more quickly than anyone had imagined,” said Ralph Cicerone, an atmospheric chemist with the National Center for Atmospheric Research. “We’re looking at the effects, but we aren’t doing it very well.”

Furthermore, changes in such things as sea level would be so subtle that they almost defy detection. Some scientists have argued that global warming is pushing sea level up by about 1 millimeter a year.

“That’s the diameter of a human hair,” exclaimed a frustrated Tim Barnett, a research meteorologist at Scripps Institution of Oceanography. “Come on,” he pleaded, “give me a break.”

Barnett, an oceanographer, argued that if the sea level is rising, it has been largely immeasurable over the last century and is probably insignificant. And if anyone thinks a change in sea level at one location means the world’s oceans are rising, Barnett has a blunt reply.

“Horsefeathers,” he snorted. “The data’s not taken on a global level.”

Measuring sea level is compounded by the fact that the solid Earth is also changing in ways that could affect where the tides fall on the beach. But that does not mean the overall sea level is changing.

Much of the planet is still “rebounding” from the last ice age, meaning the ground is rising ever so slowly because of the retreat of the glaciers so long ago. That removed an enormous weight from the land, but it takes thousands of years for the ground to rebound fully and that process is still going on.

Such things as oil extraction can cause coastal areas to drop, giving the impression of a rising sea.

All of those elements make changes in sea level very hard to predict, and Barnett argues that significant changes will have to be measured over decades, if not centuries.

He told reporters that if anyone has land on the beach that they want to sell cheaply before it becomes flooded, he would be glad to buy it.

One way to predict changes would be to accurately chart increases in ocean temperatures, an area where there is somewhat of a historical record.

“People have been keeping records for over 130 years,” Barnett said. Fishermen, for instance, measured water temperatures more than a century ago, but they scooped water out of the sea in a canvas bucket. Barnett believes their readings were probably about half a degree too low because water would evaporate quickly from the canvas bucket, lowering the temperature.

While the reliability of such early measurements is questioned, the results suggest that ocean temperatures rose slightly until about 1950, and then leveled off, Barnett said.

As an atmospheric scientist, Cicerone has a little better historical record than Barnett’s, but his task is no less challenging.

“We have a record from 160,000 years,” Cicerone said. The record is in ice cores taken from both polar caps, which amount to frozen time capsules that tell much about the atmosphere many years ago. Cicerone believes the evidence is indisputable.

“These (ice cores) are not leaky buckets,” he said. “Changes have occurred. It’s real.”

The cores show, for example, that the level of carbon dioxide in the atmosphere has more than doubled over that period. Carbon dioxide, produced by everything from automobiles to factories, lowers the planet’s ability to radiate heat out into space, thus raising the temperature in the so-called “greenhouse effect.”

And scientists using satellites, aircraft and ground instruments have documented the holes in the ozone layer over the north and south poles. Ozone helps shield the planet from harmful solar radiation, and the holes have been caused by the release of chemicals considered important to many industrial processes.

But what frustrates scientists like Cicerone is the fact that while the ozone holes have been documented, the effort to determine the effect has been woefully inadequate.

Lack of Data Told

“There are reasons to believe plankton will be reduced, but there is absolutely no data to base that on,” he said. Plankton are a vital part of the food chain.

Scientists missed a choice opportunity to study the effect in 1987 when the ozone hole over Antarctica broke up and parts of it drifted over New Zealand and Australia, he said. Had they been ready, it might have been possible to measure the direct impact on populated areas.

There is some fear, for example, that certain types of cancers might have increased, but there is no data to support that.

The task of the atmospheric scientist is further complicated by the fact that changes there can occur vary rapidly, especially at high altitudes where the air is very thin.

“Nobody can predict what the impact will be,” Cicerone said. “But it will be large, quick and inescapable.”

Richard Somerville, head of the Climate Research Group at Scripps, described the effort that will be required as colossal.

Somerville’s group is part of a new program put together by the University of California. The program will unite researchers from the university as well as Scripps and the two federal laboratories managed by UC at Los Alamos and Livermore.

Understanding Changes

The multidisciplined approach is what is needed if humans are to understand the changes that may well determine the planet’s future, scientists contend.

But many attending the meeting here said they see little evidence of the level of the commitment demanded by the scope of the problem.

“All these changes are happening more quickly than we can understand them,” Cicerone said.