reprint from green.yahoo.com

GLOBAL WARMING MYTHS/FACTS

Myth: The science of global warming is too uncertain to act on.

Fact: There is no debate among scientists about the basic facts of global warming.

The most respected scientific bodies have stated unequivocally that global warming is occurring, and people are causing it by burning fossil fuels (like coal, oil and natural gas) and cutting down forests.

The U.S. National Academy of Sciences, which in 2005 the White House called "the gold standard of objective scientific assessment," issued a joint statement with 10 other National Academies of Science saying:

"the scientific understanding of climate change is now sufficiently clear to justify nations taking prompt action. It is vital that all nations identify cost-effective steps that they can take now, to contribute to substantial and long-term reduction in net global greenhouse gas emissions." (Joint Statement of Science Academies, 2005)

The only debate in the science community about global warming is about how much and how fast warming will continue as a result of heat-trapping emissions. Scientists have given a clear warning about global warming, and we have more than enough facts — about causes and fixes — to implement solutions right now.

Myth: Even if global warming is a problem, addressing it will hurt American industry and workers.

Fact: A well designed trading program will harness American ingenuity to decrease heat-trapping pollution cost-effectively, jumpstarting a new carbon economy.

Claims that fighting global warming will cripple the economy and cost hundreds of thousands of jobs are unfounded. In fact, companies that are already reducing their heat-trapping emissions have discovered that cutting pollution can save money.

The cost of a comprehensive national greenhouse gas reduction program will depend on the precise emissions targets, the timing for the reductions and the means of implementation. An independent MIT study found that a modest cap-and-trade system would cost less than $20 per household annually and have no negative impact on employment.

Experience has shown that properly designed emissions trading programs can reduce compliance costs significantly compared with other regulatory approaches. For example, the U.S. acid rain program reduced sulfur dioxide emissions by more than 30 percent from 1990 levels and cost industry a fraction of what the government originally estimated, according to EPA. Furthermore, a mandatory cap on emissions could spur technological innovation that could create jobs and wealth.

Letting global warming continue until we are forced to address it on an emergency basis could disrupt and severely damage our economy. It is far wiser and more cost-effective to act now.

Myth: Water vapor is the most important, abundant greenhouse gas. So if we’re going to control a greenhouse gas, why don’t we control it instead of carbon dioxide (CO₂)?

Fact: Although water vapor traps more heat than CO₂, because of the relationships among CO₂, water vapor and climate, to fight global warming nations must focus on controlling CO₂.

Atmospheric levels of CO₂ are determined by how much coal, natural gas and oil we burn and how many trees we cut down, as well as by natural processes like plant growth.

Atmospheric levels of water vapor, on the other hand, cannot be directly controlled by people; rather, they are determined by temperatures. The warmer the atmosphere, the more water vapor it can hold. As a result, water vapor is part of an amplifying effect.

Greenhouse gases like CO₂ warm the air, which in turn adds to the stock of water vapor, which in turn traps more heat and accelerates warming. Scientists know this because of satellite measurements documenting a rise in water vapor concentrations as the globe has warmed.

The best way to lower temperature and thus reduce water vapor levels is to reduce CO₂ emissions.

Myth: Global warming and extra CO₂ will actually be beneficial — they reduce cold-related deaths and stimulate crop growth.

Fact: Any beneficial effects will be far outweighed by damage and disruption.

Even a warming in just the middle range of scientific projections would have devastating impacts on many sectors of the economy. Rising seas would inundate coastal communities, contaminate water supplies with salt and increase the risk of flooding by storm surge, affecting tens of millions of people globally.

Moreover, extreme weather events, including heat waves, droughts and floods, are predicted to increase in frequency and intensity, causing loss of lives and property and throwing agriculture into turmoil.

Even though higher levels of CO₂ can act as a plant fertilizer under some conditions, scientists now think that the "CO₂ fertilization" effect on crops has been overstated; in natural ecosystems, the fertilization effect can diminish after a few years as plants acclimate. Furthermore, increased CO₂ may benefit undesirable, weedy species more than desirable species.

Higher levels of CO₂ have already caused ocean acidification, and scientists are warning of potentially devastating effects on marine life and fisheries. Moreover, higher levels of regional ozone (smog), a result of warmer temperatures, could worsen respiratory illnesses. Less developed countries and natural ecosystems may not have the capacity to adapt.

The notion that there will be regional “winners” and “losers” in global warming is based on a world-view from the 1950’s. We live in a global community. Never mind the moral implications — when an environmental catastrophe creates millions of refugees half-way around the world, Americans are affected.

Myth: Global warming is just part of a natural cycle. The Arctic has warmed up in the past.

Fact: The global warming we are experiencing is not natural. People are causing it.

People are causing global warming by burning fossil fuels (like oil, coal and natural gas) and cutting down forests. Scientists have shown that these activities are pumping far more CO₂ into the atmosphere than was ever released in hundreds of thousands of years. This buildup of CO₂ is the biggest cause of global warming.

Since 1895, scientists have known that CO₂ and other greenhouse gases trap heat and warm the earth. As the warming has intensified over the past three decades, scientific scrutiny has increased along with it. Scientists have considered and ruled out other, natural explanations such as sunlight, volcanic eruptions and cosmic rays. (IPCC 2001)

Though natural amounts of CO₂ have varied from 180 to 300 parts per million (ppm), today's CO₂ levels are around 380 ppm. That's 25% more than the highest natural levels over the past 650,000 years. Increased CO₂ levels have contributed to periods of higher average temperatures throughout that long record. (Boden, Carbon Dioxide Information Analysis Center)

As for previous Arctic warming, it is true that there were stretches of warm periods over the Arctic earlier in the 20th century. The limited records available for that time period indicate that the warmth did not affect as many areas or persist from year to year as much as the current warmth. But that episode, however warm it was, is not relevant to the issue at hand. Why? For one, a brief regional trend does not discount a longer global phenomenon.

We know that the planet has been warming over the past several decades and Arctic ice has been melting persistently. And unlike the earlier periods of Arctic warmth, there is no expectation that the current upward trend in Arctic temperatures will reverse; the rising concentrations of greenhouse gases will prevent that from happening.