Extreme weather stories always seem to receive extensive new coverage. The polar vortex, wildly oscillating/fluctuating temperatures in the Midwest and East Coast, horrific drought in California, flooding in the United Kingdom, etc. make interesting news. But these reports have left many perplexed, particularly about global warming. How can global warming cause such cooling?
The warming of our planet's surface and a possible correlation with rising carbon dioxide (CO2) levels has sparked considerable controversy about the origin of this warming (human-induced or an unpredictable act of nature?). What's not debatable is that evidence abounds that warming is indeed real. Nine out of 10 of the warmest years on record occurred in the past decade, and 2006 (just the first half!) was the warmest year for the U.S. In fact, fact average global temperatures have been increasing (by about one degree during this past century).
Despite many claims to the contrary, natural and human activity can alter the Earth's atmosphere and modify our environment. All of the oxygen we breathe (21 percent of our atmosphere) was produced by life via photosynthesis. Smog is a more direct effect of human/industrially-induced atmospheric alteration. Indeed, many past societal catastrophes, such as the Dust Bowl of the 1920s, were likely caused by over-farming. With our great potential to create and learn, we also have great potential to cause our own self-destruction.
Our atmosphere is akin to stretching a rubber glove over a bowling ball -- it is very thin. But our atmosphere protects us from the extremes of temperature that Mercury and the Moon have. It isn't as thick or dense as Venus, so we don't suffer from oppressive heat (850 K) due to greenhouse warming that prevents water from condensing there. Earth is in a very fortunate (for life) state of quasi-equilibrium that allows water to condense, removes most of the carbon dioxide from the air, and allows liquid water to become a solvent. Thus, life evolved.
However, human activity is probably altering this equilibrium by producing greenhouse gases, most notably carbon dioxide. These gases trap heat, warming Earth's surface which leads to further release of carbon dioxide (trapped in melting glaciers or warming oceans). This warms Earth's surface even more, creating a new equilibrium state in which all life may not survive.
Addressing this cycle can take patience. Unlike water, which readily condenses into liquid and solid (ice/snow) form, carbon dioxide remains in the atmosphere roughly 100 years before being naturally removed. Thus, any effort initiated today to reverse the warming trend will not bear fruit until some decades later.
Though carbon dioxide levels have cyclically varied from about 180 ppm to 280 ppm over the past 650,000 years, we have never measured higher carbon dioxide concentrations than during our current period. At 370 ppm, carbon dioxide levels are roughly 27 percent higher than at any other point in the Earth's "recent" history.
Though many argue that greenhouse gas release via human activity pales by comparison with volcanoes and other geothermal releases, these events are very short term; they may have created problems for life in the past but were rapidly (in geological terms) corrected.
Though carbon dioxide produced by all life not including humans may be larger than that created by human activity, without humans, it has been in equilibrium/balance for much time via the carbon cycle. Humans continue to add enormous additional quantities of carbon dioxide and other greenhouse gases and are also removing the ability of life to remove/sequester carbon dioxide (e.g. by decimating rain forests). This alters the Earth's natural homeostatic balance, and we may only be beginning to see the negative results.
To give some perspective of the sheer quantity of CO2 introduced by humans, consider that one gallon of gasoline releases about 20 pounds of CO2 (among other greenhouse gases) and given that our nation consumes over 20 million barrels of oil every day, this implies that about 9 billion tons of carbon dioxide are released into the atmosphere every day.
Whenever rapid change occurs, all life suffers as it struggles to adapt. The Earth's natural equilibrium can only take so many shocks before it irreversibly enters a new state, one that, like the rest of the planets in our solar system, may not support life.
Tragically, most of the voices from whom the public have heard discuss global warming (such as author Michael Crichton or politician Al Gore) are not scientists. Some of these voices have spun or misunderstood the science behind this phenomenon to suit their own political or dogmatic needs. Scientists, such as James Hanson who has been studying global warming for decades, have been censored/muzzled by political bosses who have no little or no scientific training. Other scientists such as Peter Doran have had their data misinterpreted and misrepresented for political aims.
Unfortunately for humans, there is no politics in nature, only absolute natural laws. We cannot go on pretending these laws of nature don't exist and can be violated without disastrous consequences. Whether it is warming, pollution, dwindling natural resources, pestilence and disease, or overpopulation, the human race is on a collision course with reality and only science can avoid the likely catastrophes that loom ahead.
