GLOBAL WARMING IS an increase in the temperature of the Earth due to an increase in greenhouse gases that reduce natural cooling.
Periodically, the natural changes in the Earth's climate have produced increases 376 global warming and decreases in average temperature and the changes have altered the climate of the Earth.
The current debate over global warming centers around the likelihood that industrial greenhouse gases are triggering global warming outside the Earth's natural cycle.
The debate is both scientific and political, and the consequences are economic, social, and ecological.
For example, during the presidential debates of 2000, candidate George W.
Bush indicated that the scientific evidence for global warming was inconclusive at best, and that conclusions still needed to be established.
As president in the summer of 2001, he withdrew the UNITED STATES from the Kyoto Protocol, an international agreement seeking national limits on greenhouses gases.
Then he asked the National Academy of Sciences to examine the science of climate change.
The academy reported in 2002 that industrial factors were, in fact, altering the climate.
EVIDENCE FOR GLOBAL WARMING Since around 1900, the Earth's temperature has risen about 1.1 degrees F (0.6 degrees C).
The increase over the final 40 years of the 20th century was almost half of the total rise over a century.
The rate of warming was greater than at any period in the preceding 400- 600 years.
The 1990s experienced 7 of the 10 warmest years of the century, including the hottest year- 1998-since record keeping began over a century before.
Mountain glaciers were receding, the Arctic ice pack decreased 40 percent in four decades, and sea levels rose during the previous century at a rate three times as fast as the rates of the preceding 3,000 years.
Animals and plants were altering their ranges and behavior.
Extreme weather (drought and storms and floods) became more prevalent and more extreme.
The Intergovernmental Panel on Climate Change reported in 2001 that regional climate changes, especially rising temperatures, had already begun to affect many parts of the world.
Freezes came later in the year, permafrost was melting, and rivers and lakes were thawing earlier.
Growing seasons increased in the midto high latitudes as plant and animal ranges shifted poleward and upward and animals and plants changed mating times.
The panel's report rested on the examination of long-term studies, normally 20 years or more.
The studies consistently confirmed the models.
The study rejected chance as a cause in the direction of change, but it did not discount as a reason for magnitude.
The projected impacts, as warming continues, varies by REGION.
Ocean and sea levels continue to rise, heat waves and droughts become more common.
as does conflict over water, weather such as floods is more severe, and heat-related illnesses and death and insect- and rodent-borne infectious diseases spread to areas previously without them.
Greenhouse gases also damage the world's forests, increasing the amount of carbon dioxide as the forests cleanse less.
Some of the measures to counter the emission of carbon dioxide, methane, and nitrous oxides include cleaner cars, alternative fuels, renewable energy sources, and an end to clear-cutting.
SKEPTICISM AND DEBATE Richard S.
Lindzen, Alfred P.
Sloan Professor of Meteorology at the Massachusetts Institute of Technology, says that there seems to be a consensus among the informed populace that global warming is real, as indicated by the upsurge in diplomatic activity.
He acknowledges that greenhouse gases have increased, with carbon dioxide increasing 50 percent over the past century; he does challenge the implications and assumptions.
He contends that there is little scientific evidence for the popular scenarios of catastrophe.
In fact, the literature from hydrologists, economists, and agronomists indicates that adjustments would be fairly simple.
He grants that carbon dioxide levels have risen since 1800, based on evidence from ice cores and atmospheric sampling.
The rate has slowed since the 1970s though.
And the future depends on human choice-increased use of coal could cause a doubling by 2030.
The solution is technology, and Lindzen advocates better nuclear reactors.
After all, the surface temperature has fluctuated within that one degree for billions of years.
And the Earth has long had periods with higher carbon dioxide levels than the dire predictions forecast for the coming centuries.
A skeptic's history of global warming acknowledges that 19th-century studies did note the possibility of industrial gases increasing warming.
But the methodological problems were also noted.
And climatologists discounted the theory.
In fact, cooling in the 1950s and 1960s caused a concern in the 1970s that the world could be entering a period of cooling, not the warming of the 1980s and 1990s.
Mostly, the crisis of cooling passed with little political or scientific interest.
Rising temperatures ended the hysteria.
The Geophysical Fluid Dynamics Laboratory at Princeton and other institutions continued to model change and predict warming, but it remained an academic exercise until 1988.
In the summer of 1988, James Hansen of the Goddard Institute for Space Studies testified before the Senate Committee on Science, Technology and Space, saying that he was sure that temperatures had risen and greenhouse warming was occurring.
It was a warm summer, and temperatures had risen in the 1970s faster than an even increase in carbon dioxide would warrant.
Hansen cited no cause and effect relationship.
Initially the climate-modeling experts criticized Hansen for trying to use shaky modeled data as the basis for public policy.
Still, the community acknowledged that the warming model wasn't impossible.
Environmental groups seized on Hansen's testimony, making "global warming" a battle cry, a marketing tool.
The Green lobby in the United States soon had a budget of several hundred million dollars and 50,000 employees.
The media went along because the Green catchphrases were easier to understand and sold more papers than the abstruse technical debate.
For the Greens, the burden of proof was absolute.
They construed the scientific inability to disprove warming as validation of their nightmare scenarios.
And scientists other than Hansen supported the model by acknowledging that increasing carbon dioxide probably would cause warming, but most remained skeptical about huge amounts and huge impacts.
Politicians joined the effort, as did performers and other media personalities.
The media in Europe and the United States by 1989 were declaring a scientific consensus.
As the movement grew, with politicians and others clamoring for saving Mother Earth, more skeptical scientists attempted to redress the balance.
Reports in Forbes and Reader's Digest indicated that there really wasn't the scientific consensus the advocacy groups professed.
The Bulletin of the American Meteorological Society's series supporting the environmentalists generated counterarguments from skeptics.
A Gallup poll of climate scientists in the American Meteorological Society and in the American Geophysical Union indicated that 49 percent doubted man-made warming data, 18 percent accepted that some had occurred, and a third didn't know.
The warming advocates countered.
A geologist at Greenpeace, Jeremy Legett, attacked the critics.
Popular writings proliferated.
George Mitchell, Senate majority leader and father of a prominent environmental activist, produced World on Fire: Saving an Endangered Earth; Senator Al Gore wrote Earth in the Balance: Ecology and the Human Spirit.
The Union of Concerned Scientists, originally a nuclear disarmament group, then a nuclear power opponent, turned to the global warming issue.
Its petition citing global warming as the greatest risk to humanity got 700 signers, including members of the National Academy of Sciences and Nobel laureates.
Most were not climatologists.
And the petition called for renewed work on nuclear power.
Skepticism increased among the scientists even as consensus grew among the environmentalists and politicians kept the bandwagon rolling, reiterating the claims of scientific unanimity.
SCIENTIFIC DOWNSIDE The downside of making a political issue out of science is that it weakens the science in question.
Funding for climate research actually decreased as the growth of researchers and programs was faster than the growth in funding.
And one string attached was that the research must have the right result.
Government money and government power were tied to one side of the debate.
And industry got onto the bandwagon, especially industries that stood to profit by enhancing their image as environmentally responsible or industries such as waste management companies that had a direct economic benefit.
Utilities could broaden the base on which they got profits.
And environmental improvement was a $1.7-trillion-a-decade enterprise.
As a final note, the whole question of modeling is confused by the tendency of many to believe that the great increases in computing power over the past decade or so have allowed the models to be accurate.
The experts know that the complexity of the system is such that even this great computing capacity is insufficient to even approximate an accurate model.
Without a good model, there is no solid basis for any conclusion.
Just a vast waste of resources that could be better employed elsewhere.
THE KYOTO PROTOCOL In December 1997, more than 150 nations signed the first legally binding treaty aimed at cutting emissions of the main greenhouse gases believed to contribute to global warming.
The meeting in Kyoto, JAPAN, though, left much of the detail about how it would be implemented to future talks.
These dragged on, reaching a crisis in The Hague, NETHERLANDS, in November 2000 when the United States and the EUROPEAN UNION failed to agree and talks broke down.
President Bush soon afterward announced that he was pulling the United States out of the deal altogether.
Since America produced a quarter of greenhouse gases, that was a big blow, but the other nations decided to carry on, and they finally reached agreement in Marrakech, MOROCCO, in November 2001.
Under the terms of the protocol, industrialized nations committed themselves to a range of targets to reduce emissions between 1990, the base year, and 2010.
The world targets ranged from an average 8 percent cut for most of Europe up to a 10 percent increase for ICELAND and an 8 percent increase for AUSTRALIA.
(The United States originally committed itself to a 7 percent cut.) The members of the European Union agreed to parcel out their entitlement so that countries such as IRELAND and GREECE could increase their emissions, while Britain, GERMANY, and others faced cutbacks.
Global warming is a highly charged political and economic issue.
Third-world and developing nations contended that only the developed nations were in a position to afford reforms and technology; developing nations were not.
Besides, the developed nations generated most of the gases and were the beneficiaries.
Why should developing nations be penalized for following the industrialization path that brought wealth to the developed ones? Industrialized nations argued that the controls would be futile unless all nations cut back, even the developing ones.
The United States contended that unequal standards would give developing nations a trade advantage.
Domestic companies might desert the United States for countries without limits.
Developing nations did win their demand for an exemption.
Senate voted 95-0 not to ratify any treaty that would not apply the same standards to all signatories.
THE TIPPING POINT In 2004, the U.S.
Department of Defense jumped onto the global warming bandwagon.
It reported evidence that the ocean-atmosphere system that determines the world climate, rather than shifting gradually over long periods of time, had historically moved quickly, within a decade or less, from one condition to another.
The question for the department became how close the climate system might be to the threshold of another rapid shift.
The explanation was that the current that brings tropical water and warm air to northern Europe and the eastern United States might be diluting because of increased cold water as glaciers melt and alter the ocean's salinity.
Potentially, the current could collapse.
Earlier global warming, not caused by human impacts of course, replicated the human industrial centuries.
As the Ice Age ended 13,000 years before, Greenland began warming, the current apparently shut down, and a mini Ice Age ensued, lasting 1,300 years.
That was the Younger Dryas period.
Although the Younger Dryas ice age was natural, the climatologists in 2001 were more inclined to attribute similar conditions during the previous half century of global warming to human influence.
They cited shrinking Arctic ice, melting glaciers in the ALPS, earlier springs in northern regions.
They attributed these to the burning of fossil fuels (coal and petroleum), which releases heat-trapping carbon dioxide.
When the climate experts met in 2001, they were worried about the consequences for future generations.
Then came the tipping point theory.
At some point in a process, the threshold is reached, and gradual change tips abruptly in the new direction.
THE DAY AFTER TOMORROW The National Academy of Sciences in 2002 reported that human activity could be the trigger of a new ice age from global warming.
At the World Economic Forum at Davos, Switzerland, in 2003, Robert Gagosian of the Woods Hole Oceanographic Institution in Massachusetts strongly encouraged examination of the implications of a tipping point that could occur within two decades.
Others alarmed at the possibility included billionaire Gary Comer of Land's End, who made climate change one of his philanthropies.
In Hollywood, 20th Century Fox was preparing to release The Day After Tomorrow, a disaster movie set in the Ice Age caused by global warming.
Not all scientists agreed, of course, but the momentum was shifting; even the cautious Department of Defense discerned a real threat from global warming.
While the scientists disputed with each other, the Pentagon defined climate change as a national security threat that could arrive as early as 2020.
Megadroughts, nuclear war, mass starvation-these were some of the consequences of wars for river valleys and other sources of water and food.
Once past the tipping point, change could occur within three to five years, bringing on another ice age.
The Pentagon ceded that the probability of such consequences is unknown, probably quite small, but the risk is so severe that there is no option of assuming that it's a myth or bad science.#