Now, those that would have you believe that mankind is not capable to changing his environment to such a degree to change the planet's climate, would also have you believe that smoking cigarettes does not cause cancer.
They look at the globe and see a great big world..... but forget only a very thin layer of that globe is where everything lives on the planet.
Now.... global warming, or climate change, is the effect that pumping huge quantities of greenhouse gases into the atmosphere has had on the Earth's atmospheres ability to retain solar radiation ---- thus heat. This began, by some studies, with the agricultural revolution, which put more methane in the air --- but this was a minor bounce ---, but really got a kick with the Industrial Revolution.
We are thickening the atmosphere, which is warming the planet a few degrees, which warms the world's oceans a few degrees (not a minor feat), which in turn melts the glaciers, sea ice, and shelf ice around the world.
There is one notable cycle still in effect here.... we are in the middle of an interglacial period, and the thermal pulse of coming out of the last ice age is still migrating down through the glaciers, which probably makes them a little more susceptible to melting than they would be otherwise.
This causes sea levels to rise, as well as become less salty (which can stall out the "great oceanic conveyor" flow of warm equatorial waters to the North Atlantic..... which is how global warming can cause an mini-ice age for the American NE and Northern Europe. Lack of pack ice in the Arctic is already starting to drown Polar Bears in significant numbers, which may go extinct in a decade or two at this rate. Shelf ice breaking up in the Antarctic has already cause low lying island nations to begin to evacuate to higher ground. Serious loss of the ice shelfs or Greenland's glaciers can raise sea levels between 10 feet and 40 feet.
Now 10 to 40 feet may not sound like much, but that has nearly half the world's population running for higher ground. That shuts down every port around the world, where goods are shipped in and out, every fishing processing plant, and probably drowns out 1/3rd of the industrial centers around the world. A serious lack of industrial goods and food shortages (read: famine). Oil terminals and refineries mostly gone as well.
Another worry is the permafrost in Siberia, and the methane stored in the deep sea beds. Either of these starts to "defrost" (which has started in Siberia) and more methane (a powerful greenhouse gas), can be released into the atmosphere than humanity could ever hope to release by it's activities. This will cause a relatively strong rise in world-wide temperatures. ALOT more melting of ice would result, and a rise in sea levels of 50 to 200 feet.
Now, I prefer climate change or shift to global warming because of the effects it would have:
Further desertification around the world, and the warmer air dries out the ground. All that extra heat in the oceans creates more and stronger storms around the world. Severe winds. Tornadoes. Hurricanes. Lightening storms. Drought in more locations around the world. Areas dependent on seasonal snow pack and glacier melt off for their water go without water.
Higher temperatures also bring more tropical diseases to higher latitudes (we are seeing this now already). This will only continue to increase.
Human factor.... War. War over resources, water, territory.
And all the evidence is there. From species migrating to northern attitudes and higher altitudes around the world, to rising sea levels, to data collected around the world on temperatures, ice thickness, and so forth.
Some would prefer to ignore it. Others worry that acknowledging it would cause them financial loss. Many just can't get their itty-bitty minds around the numbers or concepts involved.
