US Governments Enviromental Protection Agency wrote:
What's Known
Scientists know with virtual certainty that:
* Human activities are changing the composition of Earth's atmosphere. Increasing levels of greenhouse gases like carbon dioxide (CO2) in the atmosphere since pre-industrial times are well-documented and understood.
* The atmospheric buildup of CO2 and other greenhouse gases is largely the result of human activities such as the burning of fossil fuels.
* A warming trend of about 0.7 to 1.5°F occurred during the 20th century. Warming occurred in both the Northern and Southern Hemispheres, and over the oceans (NRC, 2001).
* The major greenhouse gases emitted by human activities remain in the atmosphere for periods ranging from decades to centuries. It is therefore virtually certain that atmospheric concentrations of greenhouse gases will continue to rise over the next few decades.
* Increasing greenhouse gas concentrations tend to warm the planet.
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What's Likely?
The Intergovernmental Panel on Climate Change (IPCC) has stated "There is new and stronger evidence that most of the warming observed over the last 50 years is attributable to human activities" (IPCC, 2001). In short, a number of scientific analyses indicate, but cannot prove, that rising levels of greenhouse gases in the atmosphere are contributing to climate change (as theory predicts). In the coming decades, scientists anticipate that as atmospheric concentrations of greenhouse gases continue to rise, average global temperatures and sea levels will continue to rise as a result and precipitation patterns will change.
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What's Not Certain?
Important scientific questions remain about how much warming will occur, how fast it will occur, and how the warming will affect the rest of the climate system including precipitation patterns and storms. Answering these questions will require advances in scientific knowledge in a number of areas:
* Improving understanding of natural climatic variations, changes in the sun's energy, land-use changes, the warming or cooling effects of pollutant aerosols, and the impacts of changing humidity and cloud cover.
* Determining the relative contribution to climate change of human activities and natural causes.
* Projecting future greenhouse emissions and how the climate system will respond within a narrow range.
* Improving understanding of the potential for rapid or abrupt climate change3.
Addressing these and other areas of scientific uncertainty is a major priority of the U.S. Climate Change Science Program (CCSP)4. The CCSP is developing twenty-one Synthesis and Assessment products to advance scientific understanding of these uncertainty areas by the end of 2008. More information5.
Throughout the science section of this Web site, use of "virtual certainty" (or virtually certain) conveys a greater than 99% chance that a result is true. Other terms used to communicate confidence include "very likely" (90-99% chance the result is true) and "likely" (66-90% chance the result is true). These judgmental estimates originate from the Intergovernmental Panel on Climate Change (IPCC, 2001).
What does all that mean? I'll sum it up:
That greenhpuse gases exist and that they help keep the earth nice and cosy is a FACT. That CO2 is one of those gases is a FACT, water vapor and methane are also greenhouse gases. if you want other sources than the EPA, there's plenty on net and libraries.
We humans are burning billions os barrels of oil every day, that is a FACT. These billions of barrels produce millions of tons of CO2 (and also carbon monoxide, a poisous side effect of ineficien iol burning), that is also a FACT.
That this CO2 we humans a producing contribute to to global warning SEEMS PRETTY GODAMN PLAUSIBLE, considering the rate we are burning oil and the first fact I stated.
Scientists COULD BE WRONG, but at the moment NOONE (except maybe ATG and his goverment lobbied sources) know for sure. We will only know for sure 50 or a 100 years from now when it it will be TOO DAMN LATE to do much.
So we can sit on our asses and keep buying hummers, or we can make and effort to polute less. The WORST thing that could happen if we became a little less poluting is that we would have a cleaner world. But some powerful people think otherwise...
Last edited by EVieira (2006-12-09 10:32:06)
"All truths are easy to understand once they are discovered; the point is to discover them."
Galileo Galilei (1564-1642)