No doubt you probably read about the latest updated report on global warming or saw it discussed on television news. Few could have missed the summary report released by the U.N.-sponsored Intergovernmental Panel on Climate Change. If you are shivering in some of the coldest weather of this winter, it may seem unimportant right now, but that could change.
There seems to be a growing consensus among scientists that something harmful is happening with the weather (and that it is likely to be caused by reliance on burning fossil fuels – oil, gas, and coal – including heating and cooling buildings). Combustion creates lots of greenhouse gases, notably carbon dioxide (CO2), plus various other toxic pollutants to be emitted into the atmosphere that anyone can see on a typical day in most large cities. This pollution is suspected of causing a greenhouse effect in the upper atmosphere where excess heat is being trapped. Its greatest impact seems to be at the north and south poles, with resulting accelerated melting of the icecaps that have taken thousands of years to build up. Another fear is destruction of the protective layer of ozone that insulates the earth from biologically harmful ultraviolet (UV) radiation emitted from the sun. Ozone levels over the northern hemisphere have been dropping by 4 percent per decade. Much larger declines have been seen from space over approximately 5 percent of the earth’s surface around the North and South Poles.
Consequences of this trend bring forecasts of some serious threats to habitats in the affected areas. Melting icecaps could raise the ocean levels, flooding low-lying coastal plains (including some very densely populated areas). A rising ocean level could be serious for the United States, where half the population lives within 50 miles of the shoreline. Climate changes could upset agriculture or even stimulate massive animal migrations. The timetable and extent of all this is uncertain, but authors of the report indicate that the trends soon may be irreversible if nations do not take action to curtail further global warming. In second and third installments, additional details on the consequences and possible strategies for mitigating global-warming impacts are scheduled for release in April and May, respectively.
The problem with this doomsday forecast by a couple thousand renowned international scientists is that some respected scientists disagree. The basis of their argument is that correlations, no matter how probable, do not necessarily prove causation. Everyone seems to agree that global warming and CO2 concentrations are connected, but not all agree that the cause is manmade – at least not entirely. For example, cores deep-drilled into the arctic tundra have disclosed that the earth likely has experienced a series of warming and cooling cycles in the past on a fairly regular schedule that were accompanied by like changes in CO2. Critics also wonder how much of the motivation for the warnings about global warming is politically or economically driven. A group of some 45 countries has been organized by France into a new effort to stifle expanded combustion of fossil fuels, with the United States, China, and India noticeably absent for good reason.
These countries rely heavily on use of fossil fuels for conversion of energy into their gross national production (GNP), as do most industrialized nations. Environmental protection laws have helped tremendously to reduce air and water pollution in America, and energy-efficiency measures have greatly improved productivity, but China and India are far behind on both scores. Consequently, they rely on rapid growth in fossil-fuel combustion to provide the economic growth needed to support their exploding populations. In addition, some economists claim any curtailment of fossil fuels will assure that the most undeveloped countries will continue suffering from all the ills created by sluggish economies and lack of technology that requires increasing fossil-carbon energy use.