As you may know, the causes of global warming and climate change are debated in

Question

As you may know, the causes of global warming and climate change are debated in scientific circles. Some say greenhouse gases are to blame; others say the earth regularly experiences cycles of warming and cooling. Some point to our recent record cold temperatures and snowfall, and ask how can we blame global warming? Still other scientists are predicting that our present global warming trend will result in a new Ice Age. Try to locate the physics principle(s) which provide a logical progression from warmer temperatures to an Ice Age. You don't have to believe the theory, just merely repeat it here and discuss its merits or deniability. Please don't use the same answer as before. Please answer this on your own. Thank you!

Explanation / Answer

Climate data show that Earth’s average temperature has risen at least 0.7 oC (1.3 oF) over the 20th century. Temperature increases over the 21st century will probably be two and a half to five times as large,because greenhouse gases like carbon dioxide allow sunlight to penetrate the atmosphere but make it harder for outgoing infrared radiation to escape. What’s more, just as carbonated soda fizzes when it warms up, warmer temperatures cause the ocean to release carbon dioxide taken up during colder periods. Analyses of air trapped in glacial ice over the last 800,000 years show that atmospheric carbon dioxide generally ranged between 200 and 300 parts per million by volume (ppmv); increases in these levels were slightly preceded by increases in temperature caused by natural orbital shifts. During this period, global temperature varied by about 12 oC. Now, carbon levels are approaching 400 ppmv as the burning of fossil fuels pumps more and more carbon dioxide into the atmosphere. Even if the rate of growth could be moderated enough to stabilize levels at about 550 ppmv, average temperatures might well rise by about 5 oC–with devastating effects for us earthlings, such as rising sea levels and dramatic changes in weather patterns.

But even that warming will not stave off the eventual return of huge glaciers, because ice ages last for millennia and fossil fuels will not.In about 300 years, all available fossil fuels may well have been consumed.Over the following centuries, excess carbon dioxide will naturally dissolve into the oceans or get trapped by the formation of carbonate minerals. Such processes won’t be offset by the industrial emissions we see today, and atmospheric carbon dioxide will slowly decline toward preindustrial levels. In about 2,000 years, when the types of planetary motions that can induce polar cooling start to coincide again, the current warming trend will be a distant memory.

This means that humanity will be hit by a one-two punch the likes of which we have never seen.Scientists have shown that CO2 and climate moved in lock-step throughout the Pleistocene ice ages. The ice ages were actually many pulses of cold glacial phases interspersed with warmer interglacials. These pulses had a distinct regularity caused by wobbles in Earth’s orbit around the Sun (Milankovitch cycles). When Earth’s orbit reduced the intensity of sunlight in the northern hemisphere, the Earth went into a glacial phase. When the orbital cycle brought increased the intensity of insolation in the northern hemisphere, ice sheets melted and we went into a warm interglacial. Because warmer oceans can dissolve less CO2, the CO2 levels see-sawed extremely closely with Earth’s temperature. It was a slow pace of change, taking tens to hundreds of thousands of years, and yes as the myth states, in the last million years the biggest orbit-induced cycles were every 100,000 years.The Earth was indeed cooling over the last 6,000 years due to Earth's orbit, heading into the next glacial phase scheduled for about the year 3500 AD. But all that changed when we got to the industrial era. Global temperatures departed from that cooling trend, and instead rose parallel with our greenhouse gas emissions.

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