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Global Warming

A landmark study has moved the existence of global warming from a subject of debate to a commonly accepted scientific principle.  The report from the National Academy of Sciences - National Research Council (NAS/NRC) entitled CLIMATE CHANGE SCIENCE, AN ANALYSIS OF SOME KEY QUESTIONS marks the first time a study commissioned by the federal government has publicly concluded that global warming exists.  The study says that global warming "is real and particularly strong within the past 20 years."  A total of 14 specific questions were addressed by the study, ranging from "Is climate change occurring?  If so, how?" to "What are the specific areas of science that need to be studied further, in order of priority, to advance our understanding of climate change?"  The report states "greenhouse gases are accumulating in Earth's atmosphere as a result of human activities, causing surface air temperatures and subsurface ocean temperatures to rise.  Temperatures are, in fact, rising."  The report notes that "changes observed over the last several decades are likely mostly due to human activities," but the NAS/NRC could not rule out the possibility that a significant part of the climate changes could be the result of natural variability.  Regardless of the reason for the climate change, global warming is expected to continue through the 21^st century.  While in some areas, the rising temperatures will cause a rise in sea level, computer model simulations also project "an increased tendency towards drought over semi-arid regions, such as the U.S. Great Plains."

The NAS/NRC also looked for substantive differences between the Intergovernmental Panel on Climate Change (IPCC) Report and its published summary.  According to the NAS/NRC, the IPCC summary "largely represents the consensus scientific views and judgments of the committee members, based on the accumulated knowledge that these individuals have gained – both through their own scholarly efforts and through formal and informal interactions with the world's climate change science community."  One of the specific questions asked of the NAS/NRC was "By how much will temperatures change over the next 100 years and where?"  The highest estimate of the atmospheric temperature increase is 10.4^oF.  While this may not seem to be a particularly large change when looking on the short term, the long-term impact of such a change is significant.  According to their report, "Higher evaporation rates would accelerate the drying of soils following rain events, resulting in lower relative humidities and higher daytime temperatures, especially during the warm season."  There is evidence to suggest that droughts as severe as the "dust bowl" of the 1930's were much more common during the 10^th and 14^th centuries than they have been in recent record.  Another major question the study addressed was, "What will be the consequences (e.g., extreme weather, health effects) of increases [in temperature] of various magnitude?"  The study concludes "Hydrologic impacts could be significant over the western United States, where much of the water supply is dependent on the amount of snow pack and the timing of the spring runoff."

While global warming presents concerns for everyone, water and wastewater professionals need to be especially aware of the environmental impact of this issue.  If the water supply is threatened, or reduced in volume, the quality of any recharge to the water supply becomes critical.  Onsite wastewater treatment systems will have an increasing impact in maintaining water quality, primarily by preventing pollution of aquifers that may be reduced in size.  Even without the future impact of global warming, much of the potable water supply of the country is currently dependent upon management of onsite sewage treatment and disposal systems.  As recently as 1997, the NAS/NRC was asked to provide a scientific evaluation of how to best protect the drinking water supply for the 9 million people in the New York City area.  The study contains conclusions and recommendations regarding the technologies being used for onsite sewage treatment and disposal systems and their effect on the New York watershed.  To view a summary of the New York watershed report, visit our Regional Guidelines page.

To purchase a copy of the publication CLIMATE CHANGE SCIENCE, AN ANALYSIS OF SOME KEY QUESTIONS from the National Academies Press, or read it online for free, use the following hyperlink www.nap.edu/catalog/10139.html?srchtop.

Background of the National Academy of Sciences - National Research Council report

On May 11, 2001, the White House made a request to the National Academies to identify areas where there are the greatest certainties and uncertainties in the science of climate change.  Because of the critical nature of this issue, the Administration asked for a response "as soon as possible" but no later than early June, 2001.  A committee with broad expertise and diverse perspectives on the scientific issues of climate change was appointed by the National Research Council and they issued their report June 6, 2001.

To find out more about the National Academies, visit our National Academy of Sciences - National Research Council page.