landmark study has moved the existence of global warming from a
subject of debate to a commonly accepted scientific
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
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 21st
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.
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 10.4oF.
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 10th and 14th 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."
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
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