Science under the microscope.

Our planet is definitely getting warmer and so is the debate about what's causing the heating up

No one is arguing about whether or not there is a Greenhouse Effect -- scientists agree that greenhouse gases warm Earth. Carbon dioxide, water vapour, nitrous oxide, methane; they're all up there trapping heat from the sun.

The debate is about how much human activities contribute to, or enhance, the Greenhouse Effect that occurs naturally.

In their book It's a Matter of Survival, published in 1990, David Suzuki and Anita Gordon sound the alarm. They say a warmer world in 2040 will have no forests, that fisheries will be affected, and there will be widespread starvation as agricultural productivity declines. As sea waters rise, they see coastal towns being destroyed. The authors go so far as to name the year 2040 Despair -- a time of "new famines, new droughts, new flooding, as the Earth's climate inexorably warms."

If you look at the 1980s, things certainly were very hot. In fact, it was the hottest decade since climate experts began keeping records more than a century ago. According to the Meteorological Office of the United Kingdom, the world's oldest keeper of climatic data, the decade included six of the 10 hottest years on record. But not everyone pushed the alarm button when this information hit the press. Researchers who released the data stressed that temperatures fluctuate for many reasons and that changes over one year, or even one decade, do not necessarily point to a trend.

In 1990, when the report was released, even scientists who think global warming is part of our climate problems -- the non-skeptics -- were cautious in their responses. For example, James Hansen of the U.S. National Aeronautics and Space Administration's Goddard Institute for Space Studies in New York said: "It's not conclusive, but it's one more strong piece of evidence." And, Stephen Schneider, a climatologist at the National Center for Atmospheric Research, said: "I think the Greenhouse Effect began in the 1980s. But, it will take 20 years before it can be proven beyond a doubt."

While some ground-based instruments show the world getting hotter, weather satellites have not detected a warming trend. In fact, they show a slight cooling since 1979. Weather-balloon records have shown the same thing. When ground-level readings are adjusted to account for local "heat island" effects that come from all the energy burned in major cities they also indicate minor cooling.

Still, there are cries of despair, and perhaps nobody would be taking any notice without them. So, environmentalists warn of disaster. Those who worry about the human contribution to global warming say we're upsetting the natural balance of greenhouse gases. In It's a Matter of Survival, climatologist Stephen Schneider says: "... there is much better than an even betting-odds chance that by 2040 the world will be in a climatic regime unprecedented in the era of civilization. That means more than, say, two degrees Celsius (3.6 [degrees] F) warmer than it was during the average of the past several thousand years. That rate of change is what has most of us concerned.

"...the low end of what humans are talking about is one degree of warming over the next century. The high end is five to 10 [degrees] C (9 [degrees] F to 18 [degrees] F). So we're looking at changes that are degrees a century, whereas the natural rate of change is degrees, at most, a millenium."

Environmentalists say we have to stop relying so much on burning fossil fuels to drive our industry and accommodate our consuming lifestyles. And, to save our planet, we have to act now. Otherwise, our legacy to future generations won't be pretty. The potential disasters are more than a little frightening.

Warmer air means more humid air -- water vapour in the air can increase by 6% for every degree Celsius the temperature rises. This would mean higher than average rainfall and more intense storms, causing increased damage in flood-prone areas. Weather forecasters say global warming could trigger the formation of megastorms. Huge and intense hurricanes, typhoons, and cyclones could be on the loose in the world's oceans bringing massive death and destruction when they come ashore.

Heat waves could produce even higher temperatures and last longer. In June 1998, a heat wave in India with temperatures reaching 50 [degrees] C left 3,000 dead. Scores of people died in Chicago in June 1995 when a week-long heat wave brought highs in excess of 40 [degrees] C. An increase in the world's temperature of 3 [degrees] C would trigger such killer heat waves once every four years instead of the current average of once every 20 years.

Vegetation zones would move dramatically. Plains, steppes, and prairies could turn into sweltering deserts. This is particularly bad news because those are the world's major grain growing areas.

Based on these predictions, it looks as though we could be in for a pretty nasty future. However, there is by no means universal agreement that this unpleasant world is what lies ahead.

Critics say most of the evidence used by the Greenhouse Effect theorists is circumstantial. Many of the predictions of future catastrophes are mostly guesswork; we just don't know enough about the very complex interactions of solar energy, clouds, Earth's rotation and tilt, ocean currents, and a host of other variables.

How many times is your local weather forecast wrong? If we can't get that right 100% of the time how can we put much trust in climate predictions that look ahead centuries?

The Fraser Institute, which generally supports the concerns of corporate Canada, says the public hasn't been getting the full picture. It says the popular media tend to summarize scientific reports to the point of oversimplification -- they have overstated the scientific "consensus" that the enhanced Greenhouse Effect is occurring and that it is significant, and they've understated the uncertainty, disagreement, and debate surrounding the issue.

If there's any scientific consensus, it's that there is a lot of uncertainty about predicting future climate changes. In fact, many scientists are concerned that governments are basing their environmental policies on highly uncertain scientific theories. They say governments are mistakenly making decisions on the "unsupported assumption that catastrophic global warming follows from the burning of fossil fuel and requires immediate action."

The current 200-year-old warming trend may be part of a natural cycle of heating and cooling that planet Earth has been going through since the beginning of time. We know that over the last 150,000 years the average air temperature on Earth has varied by as much as 6 [degrees] C.

A big problem is that the computer General Circulation Models used to help predict climate change have turned out to be unreliable. Models used in the early 1990s predicted that by latter half the decade, Earth's temperature would have warmed from between 1.3 [degrees] C and 2.3 [degrees] C due to changes in greenhouse gases caused by human activity.

It didn't happen.

The surface temperature history of the northern hemispheres since 1990 -- where the higher temperature was predicted -- tells a different story. The actual warming by 1997 was about 0.6 [degrees] C, almost four times less than what was predicted. One estimate suggests that at least half of that warming was prior to major changes in the Greenhouse Effect, before 1945. This leaves the enhanced Greenhouse Effect increase at 0.3 [degrees] ;800% lower than the high computer prediction. Furthermore, the land-surface records of the past decade show no warming at all.

And, climate-change skeptics point out that the warming that did occur was followed by three decades of climate cooling. The cooling took place when greenhouse-gas emissions actually increased. Some scientists think the warming was a natural recovery from an earlier natural cooling.

Clearly, sorting out our climate is not an easy task. The trend of global temperatures can't be traced to a single source.

In 1998, our federal government formed a national forum on climate change. It brought together a group of 25 "eminent Canadians" (mostly Order-of-Canada recipients) to look at the whole issue of climate change. About six months later, in June, the group released its conclusion that the balance of scientific evidence supports the view that global warming poses a real threat. It did acknowledge the uncertainties surrounding the issue and said the skeptical voices could be right and should continue to be heard. The group also was concerned about the limitations of the computer models used to predict the seriousness of climate change and the costs of action. Nevertheless, it rejected these uncertainties as an excuse for doing nothing.

So, in the end, they accepted the view of those who think we should act on cutting back greenhouse-gas emissions just in case the doomsayers are right.

Even if things don't turn out so badly, the end result will be less pollution, better urban air quality and a more efficient economy. It's a kind of insurance. There may not be a disaster. But, if there is, we'll be better prepared.

The skeptics still argue that the next decade could root out some of the uncertainties and result in policies that are based on fact rather than theory.

SUGGESTED ACTIVITIES:

1. According to the Fraser Institute, environmentalists are against economic growth because they believe such progress causes environmental degradation. The Institute quotes Michael M'Gonigle, a Greenpeace activist, as saying that "the very nature of the free market (along with economic growth and free trade) -- is inherently anti-environmental." This belief, says the Institute, "prompts environmental activists to demand increased regulations that will stifle economic growth and reduce economic activity." And, to make their case, they go along with the global disaster scenario even if they don't believe that global warming is a serious threat caused by humans. Do you agree or disagree? Give reasons for your answer.

2. Do a book report on Hot Talk, Cold Science: Global Warming's Unfinished Debate, by S. Fred Singer. Dr. Singer is a respected astrophysicist and university professor. His book, published in 1997, has been described by one reviewer as a "concise yet masterful discussion of the climate record; computer models; the effects of clouds, oceans, aerosol cooling, solar variability, and greenhouse gases; crop yields; climate-change mitigation; and much more.