Global Warming: The Evidence and the Debate

Revolutionary Worker #942, February 1, 1998

Starting in the late 1700s, huge changes happened in the way human beings organized production. This so-called "industrial revolution" was triggered by the emergence of capitalism in a few countries of Europe and North America. Modern industry expanded as those first capitalist countries imposed their domination over people throughout the world. Over two centuries, as capitalism spread across the planet, people have been drawn into larger and larger urban areas, where hundreds of millions of pe ople have been exploited by capitalists in factories. This new industrial production needed huge amounts of energy, which the capitalists got by sending coalminers into the earth and oil workers to pump petroleum from the ground.

The Rise in Greenhouse Gases

Carbon dioxide is one of the "greenhouse gases" that stop the earth's heat from escaping into outer space. Without the "greenhouse effect" caused by these gases the earth would be much colder, frozen and most likely lifeless.

Scientific study of bubbles in glaciers shows that there was very little change in the levels of carbon dioxide gas (CO2) in the 10,000 years before industrialization. Then, 200 years ago, something started to happen. There is considerable evidence that there has been a 30 percent rise in the amount of carbon dioxide in the air since the late 1700s, as a result of the capitalist industrialization of human production. (See the accompanying chart.)

Human beings have always released carbon dioxide into the air by burning wood in cooking fires. But industrialization produced a huge and sudden leap in the amount of CO2 released by human activity. Research shows that the release of CO2 increased exponentially between 1800 and 1974--because of the rapid increase in the burning of coal in electrical plants, gasoline in cars and trucks, and diesel fuel in locomotives.

Meanwhile, capitalism has also led to a massive deforestation of the earth--as logging companies cut down timber, and as capitalist farming has created large numbers of landless peasants who move into forested areas to farm. Trees absorb CO2--and the cutting down of the earth's forests means that more of this gas stays in the air. Finally, capitalist industry and agriculture are producing major amounts of other "greenhouse gases"--including methane (CH4), nitrous oxide (NO2), and the chloroflorocarbo ns (CFCs).

The danger of this is that, at a certain point, the rise in these "greenhouse gases" will start to cause major effects in the climate. At first the rise in average temperature would be slow. But eventually, these small increases would cause more water vapor and clouds in the air--and that would cause an escalation in the warming process. The Report from the UN's Intergovernmental Panel on Climate Change (IPCC) estimated that the "enhanced greenhouse effect" of doubling CO2 from pre-industrial l evels would cause global surface temperatures to rise between 1.8 degrees and 6.3 degrees Farenheit (between 1 and 3.5 degrees Centigrade).

That global warming would be relatively small compared to the normal variations in weather--but they would be large enough to trigger major changes in the climate throughout the world. This is shown by the earth's past. In the depths of the last ice age, when mile-high ice sheets reached down to today's Great Lakes, the earth's average temperature was only 5 to 9 degrees Farenheit (3 to 5 degrees Centigrade) colder than it is today.

The IPCC suggests that at current trends of capitalist industrialization and gas release--the so-called "business as usual scenario"--the doubling of CO2, and accompanying climate change, could arrive late in the next century. The expansion of capitalist industrial production, and the extreme inability of this system to restrict pollution suggest that the tripling and even quadrupling of greenhouse gases is a possibility. This would mean almost certain climatic catastrophe.

Climate Change and
Human Impact

"Climate change is expected to occur at a rapid rate relative to the speed at which ecosystems can adapt and re-establish themselves."

United Nations Intergovernmental Panel on Climate Change

If the CO2 level doubles above the pre-industrial levels, it has been predicted that the earth's average surface temperature would warm considerably. Such changes in average temperature, if they happen, would cause major changes in climate. Scientists estimate that temperature zones could shift toward the poles by 100 to 400 miles. Climate models predict that rainfall and storms would increase. The changes would affect different regions differently. Some areas may become wetter, while others will become more dry. Warming would reduce the amount of ice contained in glaciers or polar caps and raise ocean levels--perhaps as much as three feet (95 centimeters). This would flood many low-lying areas and ocean islands.

The plants and climate of large parts of the world would change--forcing many people to move. Many of the world's current breadbaskets would face flooding or big changes in temperature and rainfall that make them less productive.

Forests don't adapt or "move" at the speed such heating would occur. Some models predict that between a third and two-thirds of the world's remaining forest systems could be impacted in major ways--along with the species of plants and animals they contain. The higher temperatures could cause organisms that are living near their temperature tolerance limits to become extinct.

Many plants thrive in higher CO2 concentration, and warming could improve the climate in some regions. But for the world's poor people who often live close to the edge of disaster in "normal" times--there would be intense dangers of starvation and disease from major climate shifts. For example, it has been estimated that rises in temperature could reduce India's wheat yield by 20 percent.

Storm surges already affect 46 million people in an average year. If the oceans rose three feet, twice that many people could be affected. Many island countries would lose much of their land below the ocean waves, including Kiribati, the Marshall Islands, Tonga, Palau, Nauru, Niue, the Federated States of Micronesia and Tuvali (all in the Pacific), and the Maldives (in the Indian Ocean). An ocean rise of three feet would displace an estimated 70 million Chinese people and 32 million people in Bangladesh .

There have been some detailed scientific analyses of the potential impact that such climate changes could have on the spread of diseases and availability of drinking water. Over one billion people already don't have adequate supplies of safe drinking water, and many others are dependent on so-called "single-point systems" such as bore holes or isolated reservoirs--such people would be sharply affected by changes in global rain patterns.

A Corporate-Subsidized Controversy

Everything about predictions of global warming has been challenged by the "Global Climate Coalition" (GCC) which is funded by more than 50 companies and trade associations in the oil, coal, utility, chemicals and auto industries in the U.S. Corporate opponents of greenhouse reductions reportedly spent over $13 million last year to publicize the argument that "proposals to limit CO2 emissions are premature and not justified by the scientific evidence." The GCC promotes a small group of scientists who are generally called "climate skeptics." As a result, the bourgeois press gives these same "skeptics" widespread "equal time" to argue against the predictions of global warming.

These "skeptics" claim there is no evidence that the past rise in CO2 caused the simultaneous rise in temperature--or that human activity can cause global warming. They say the earth's climate is relatively stable--and that any changes that happen are likely to be natural warmings from a previous ice age. If the earth warms slightly, they say, the changes in climate are likely to be minor or even beneficial. They argue that technological innovations in the next century, especially the improveme nt and spread of nuclear power, are likely to make actions now unnecessary.

At the heart of the "skeptic" argument is the claim that restricting the release of greenhouse gases would be so expensive for corporations and especially the U.S., that it is unjustified unless there is irrefutable proof that human activity is causing global warming. Many of these skeptics charge that the whole discussion of global warming is a hoax perpetrated by forces hostile to capitalism and industrial development.

These pro-capitalist "experts" have a familiar ring: Other "experts" paid by corporations argue that there is no proof that smoking causes cancer. In the past, corporate-financed medical clinics once "proved" that coal dust didn't cause black lung in coalminers.

On one level, the arguments the "climate skeptics" raise have nothing to do with science, and everything to do with class interests. In this society it is always possible to find "experts" willing to defend the status quo.

But on another level, the "skeptics" are exploiting a real problem surrounding the issue of global warming: There will only be overwhelming proof of climate change when it actually starts to happen. And by then it will be too late to stop disaster. CO2 cannot be removed from the atmosphere once it is there. Global warming can be prevented--but it can't be reversed by any foreseeable means once it has developed far enough to cause major climate changes.

Scientists believe that, to prevent global warming, the rise in CO2 must be stopped before it reaches critical levels. At current rates, this means there may only be a few decades to act.

Available Facts,
Rational Conclusions

"I'm not 99 percent sure, but I'm 90 percent. Why do we need 99 percent certainty when nothing else is that certain. If there were only a 5 percent chance the chef slipped some poison in your dessert, would you eat it?"

Climatologist Stephen Schneider

It is hard to make long-term predictions about climate changes--because the weather of the earth is extremely complex and dynamic and the science of climatology is still relatively new. There are wide variations in weather and temperature--from year to year, and from century to century--for reasons that are completely natural.

Several key facts about the situation are clearly documented and rarely disputed:

  1. The physics of the "greenhouse effect" is well known: "Greenhouse gases," including CO2 and especially water vapor, reduce the amount of heat the earth releases into outer space.
  2. The global average surface temperature has risen between 0.5 and 1.1 degree F (0.3 and 0.6 C.) since 1860.
  3. Rises in average temperatures cause increased evaporation of water into the air. And greater water vapor in turn causes higher temperatures. Exactly when that would happen on a global scale is the subject of intense debate.
  4. CO2 in the air has risen 30 percent over the last 200 years. Methane, another greenhouse gas, has doubled over the same period. The New York Times reported (December 1, 1997), "Precise monitoring of carbon dioxide concentrations since the 1950s has shown a relentless upward trend." This rise is clearly the result of human activity--the burning of fossil fuels and wood.
  5. Global sea levels have risen between 10 and 25 centimeters over this same period, which is significantly higher than the rate averaged over the last several thousand years.

It is extremely difficult to prove that the rising CO2 has caused the rising temperature. But the evidence is strong enough that a great many scientists are convinced: industrial society has not yet caused major climate change--but it has already changed the earth's average surface temperatures by small amounts. A fact sheet from the United Nations Environment Program says that "the pattern of change seems to point to some human influence on climate similar to that projected b y climate models and larger than expected from natural fluctuations." It is simply not known if the many kinds of "odd weather" the earth seems to have been experiencing over the last decade are related to human activity.

There remain different estimates of precisely at what point greenhouse gases would trigger climate changes and how large those changes would be. These estimates vary depending on the computer "climate model" used. These models are being refined constantly as new understandings emerge, but they are still relatively untested. But despite differences in estimates, there is a widespread scientific conviction that if the amount of CO2 keeps rising in the air, it will at some point almost ce rtainly trigger disastrous climate changes--probably over the next century, or possible soon thereafter--if radical changes do not happen in the way modern industry extracts and uses energy.

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