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.

ter;">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.

The only debate in the science community about global warming isabout 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 ofimplementation.

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.

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 can't be happening because some glaciers and ice sheets are growing, not shrinking.

FACT:

In most parts of the world, the retreat of glaciers has been dramatic. The best available scientific data indicate
that Greenland's massive ice sheet is shrinking.


Between 1961 and 1997, the world's glaciers lost 890 cubic miles of ice. The consensus among scientists is that rising air temperatures are the most important factor behind the retreat of glaciers on a global scale over long time periods.

Some glaciers in western Norway, Iceland and New Zealand have been expanding during the past few decades. That expansion is a result of regional increases in storm frequency and snowfall rather than colder temperatures — not at all incompatible with a global warming trend.


In Greenland, a NASA satellite that can measure the ice mass over the whole continent has found that although there is variation from month to month, over the longer term, the ice is disappearing.

In fact, there are worrisome signs that melting is accelerating: glaciers are moving into the ocean twice as fast as a decade ago, and, over time, more and more glaciers have started to accelerate.

What is most alarming is the prediction, based on model calculations and historical evidence, that an approximately 5.4 degree Fahrenheit increase in loca temperatures will result in a sea-level rise of over 20 feet.

Since the Arctic is warming 2-3 times faster than the global average, this tipping point is not far away.


The only study that has shown increasing ice mass in Greenland only looked at the interior of the ice sheet, not at the edges where melting occurs. This is actually in line with climate model predictions that global warming would lead to a short-term accumulation of ice in the cold interior due to heavier snowfall.

(Similarly, scientists have predicted that Antarctica overall will gain ice in the near future due to heavier snowfall.) The scientists who published the study were careful to point out that their results should not be used to conclude that Greenland's ice mass as a whole is growing.

In addition, their data suggested that the accumulation of snow in the middle of the continent is likely to decrease over time as global warming continues.

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