Even though the global temperature has been changing for millions of years, this is the first cen­tury in which we are seeing global changes occur quickly relative to the time that human and ani­mal life activity has been documented. Human- induced changes to global temperature are now evident, whereas the changes in the past were seen as natural phenomena. For example, in the prein­dustrial era the concentration of CO₂ measured 280 parts per million; by 2005, that had increased to 382 parts per million.

Despite mounting empirical evidence of global temperature change over the past few centuries, it is only relatively recently that scientists have taken note of global temperature changes and publicized them. The 1970s was the first decade in which the general public began to take note of environmental issues. In the United States this occurred through the efforts of environmentalists and scientists who pressured government to institute sweeping changes to U.S. environmental policy. Subsequently, more than 15 national acts of environmental legislation have focused on a range of issues from clean water to endangered species. These new forms of environmental legislation did not, however, take into account increases in fossil fuel emissions that occur with increased global dependence on manufacturing, energy generation, and automobile use. The U.S.

Environmental Protection Agency, created in 1970, did not provide the U.S. auto industry with fuel emission or miles-per-gallon standards, which eventually resulted in millions of tons of carbon entering the atmosphere every year. By not recognizing this serious emission problem, policymakers did not acknowledge changes in potential carbon loads to the atmosphere. Scientists now estimate that global warming will continue, despite our actions to slow the changes. There is concern that we will quickly near what is said to be the ultimate carbon threshold of 480 parts per million in our planet’s atmosphere.

The science behind global climate change is complicated. It takes time to establish patterns and understanding of the problem. The U.S. Congress heard first testimony on global warming in 1973; following that, an international cam­paign was launched to explain the future dangers if such a problem were to be ignored. Scientists predicted global catastrophes such as the melting of the polar ice caps, coastal flooding, and wide­spread migration of affected populations. We have finally begun to acknowledge the connection between fossil fuel emissions and increased global temperature. However, there remains ongoing debate over whether the problem exists as fact or is a theory.

Increased media coverage of global warming has been due in part to former Vice President Al Gore’s 3-decade-long research and investigation into climate change, which culminated in the Academy Award-winning documentary, An Inconvenient Truth, a national theatrical film release; a book of the same title; and an interna­tional lecture series. Public awareness of this issue has increased, and individual and community efforts to help reduce the impact of global climate change are more widespread. It is not yet clear to what extent social behavior is following public sentiment that now supports societal action to curb the impacts of global climate change. Longitudinal, empirical research will be needed to determine these outcomes.

It has been projected that even if we decrease our carbon output now, it would have very little impact on current and future climate change trends. Notwithstanding, action is still encour­aged in order not to escalate the problem. It has taken decades of data collection to determine if a global climate change pattern even exists. Even given this evidence, some still question the valid­ity of the global climate change claims and data. Those who doubt the conclusions argue that longitudinal evidence has not shown that global warming is occurring, let alone creating serious environmental harm. This position, opponents claim, is being fueled by those who are closely allied with the fossil fuel industry and other manufacturers who stand to lose money if their primary source of business is replaced with less environmentally damaging alternatives. Proponents of alternative fuels have been encour­aging these companies to invest in alternative, environmentally friendly technology, but with lim­ited success to date.

Much of this debate is centered on time. On the one hand, advocates who support the need to recognize global warming argue that time is of the essence. They advocate for change now, given the likelihood that a planetary overload of carbon will reach dangerous levels in the next 20 years. In 2007, U.S. automobile fuel efficiency standards were 22 miles per gallon (mpg), and the U.S. government requires only a slight increase to 23.5 mpg by 2010. In November 2007, the U.S. Court of Appeals demanded that the Bush administration change the standards and answer some basic questions about why not all vehicles have to meet the current standard; for example, minivans and sport utility vehicles are allowed to be less fuel efficient than cars. The gathering of world leaders for the Kyoto Protocol of 1997 and in Bali, Indonesia, in 2007 indicated an urgent need to establish limits on carbon output to at least slow the effects of global climate change.

On the other hand, opponents argue that more time is needed to establish data trends that sup­port the reality and consequences of global warm­ing. U.S. energy policy does not support the global guidelines set forth in Kyoto, nor are current U.S. policymakers, along with China, willing to sup­port any kind of mandatory carbon and fossil fuel emission reductions. However, there are move­ments toward tax incentives for voluntary reduc­tion actions.

The full consequences of global warming will emerge only with time. Recognition of the impor­tance of research in this area is reflected in the awarding of the 2007 Nobel Peace Prize to Al Gore and the scientists working with the United Nations International Panel on Climate Change. If momentum toward curbing global warming continues, perhaps the potential disastrous effects on human populations and the environment will be avoided. Yet, even with acknowledgment of the problem, significant changes to the national energy infrastructure have been slow in coming.

Scientists often rely on time through longitudi­nal studies to develop data trends over which people come to conclusions and take action. In response to the question of how quickly we need to begin to change our lifestyles and behaviors to make a difference in carbon output, some leading scientists claim that we have only 10 remaining years to reverse the effects of global climate change. Many others are calling for an 80% reduction in carbon emissions by 2050. The suc­cess of such reforms requires not only the time but also the will to implement far-reaching policy changes such as fuel economy standards, manu­facturing caps on carbon, and clean energy options.

Erin E. Robinson-Caskie

See also Ecology; Extinction and Evolution; Glaciers; Ice Ages; Nuclear Winter; Values and Time

Further Readings

Godrej, D. (2001). The no-nonsense guide to climate change. Oxford, UK: Verso.

Gore, A. (2006). An inconvenient truth: The planetary emergency of global warming and what we can do about it. New York: RoDalíe Press.

McKibben, B. (2007). Fight global warming now. New York: Holt Paperbacks.

Michaels, P. (2005). Shattered consensus: The true state of global warming. Lanham, MD: Rowman & Littlefield.