What is Global Warming?
The claim that nothing is happening is very difficult to defend in light of the vast amounts of visual, land-based, and satellite data that clearly show rising average ocean and land temperatures and shrinking ice sheets.
The claim that observed global warming is natural or at least not the result of human carbon emissions (see Climate Skeptic below) highlights data that show that global temperatures and atmospheric CO2 levels have been as high or higher in the past. They also point to the well-understood effects of solar activity on the amount of radiation hitting the Earth and the fact that the Sun has been particularly active in recent times.
In general, climate scientists and environmentalists either (1) dispute the data based on, for example, new ice core data or (2) suggest that the timing issue - that is, how quickly the globe has warmed and the climate has changed - simply does not fit the model of past natural events. They also note that compared to other stars, the Sun is actually very stable, varying in energy output by only 0.1% and over a relatively short 11- to 50-year cycle quite unrelated to global warming as a whole. The data strongly suggest that solar activity influences global climate in many important ways, but is not a factor in the systemic change over time that we call global warming.
As for the ultimate position that global warming and climate change are due to human activity (are “anthropogenic”), scientists attribute today’s atmospheric warming to human activities that have increased the amount of carbon-containing gases in the upper atmosphere and to increased amounts of small particles in the lower atmosphere. (NASA offers a good course module on “The Carbon Question.”) Specifically, gases released primarily by the burning of fossil fuels and the tiny particles produced by incomplete combustion trap the Sun’s energy in the atmosphere. Scientists call these gases “greenhouse gases” (GHGs) because they act like false reflectors in our global greenhouse.
Scientists call the tiny particles “black carbon” (you call it soot or smoke) and attribute their warming effect to the fact that the resulting layer of black particles in the lower atmosphere absorbs heat like a black blanket.
Scientists date the beginning of the current warming trend to the late 18th or early 19th century when coal first came into common use.
This warming trend has accelerated as we have increased our use of fossil fuels to include gasoline, diesel, kerosene, and natural gas, as well as the petrochemicals (plastics, pharmaceuticals, and fertilizers) that we now make from oil.
Scientists attribute the current warming trend to the use of fossil fuels because their use releases into the atmosphere stores of carbon that were sequestered (buried) millions of years ago.
The addition of this “old” carbon to the world’s current carbon stock, scientists have concluded, is what is warming our planet, causing global warming.
What are the main greenhouse gases? The most common and most talked about greenhouse gas is CO2, or carbon dioxide. Because it is so common, scientists use it as a yardstick or measure of things that are warming the atmosphere. Methane, for example, another important greenhouse gas, is 28-36 times
Create Your Own Website With Webador