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Re: Human vs. natural influences on the environment
: > Try reading several sources in the non-specialist science press.
: > I can recommend Scientific American, New Scientist, Science News
: > and Discover. These will often cite sources in the peer-reviewed
: > journals, which is about as uncompromising as you can get. I
: > often see them print critical letters.
Dan Evens <dan.evens@hydro.on.ca> wrote:
: UHG! I can recommend NOT trusting any of these.
Then you are a fool who is incapable of identifying accurate
scientific reporting. I have been a regular reader of Scientific
American for several decades, and while the article quality has suffered
in the last few years, the magazine does a very good job of reporting on
the sciences.
Dan Evens <dan.evens@hydro.on.ca> wrote:
: Sample: Sci. Am. published,
: several times over the last couple years, a graph purporting to show the
: rise in average global temp. over the last century.
Which issue? I don't remember seeing any such graph.
Dan Evens <dan.evens@hydro.on.ca> wrote:
: Environmental reporting is some of the WORST journalism you are ever
: likely to find.
Like a typical conservative, you blame the messenger when you don't
like the news.
******************************************************************
THE IPCC SECOND ASSESSMENT REPORT
Dr. Daniel A. Lashof, Senior Scientist, NRDC
More than two years of work by the international scientific community
culminated on December 16, 1995, when the Intergovernmental Panel on
Climate Change (IPCC) adopted the final component of its Second
Assessment Report (SAR). The landmark report consists of detailed
reports on the basic science of global climate change, on potential
impacts and mitigation measures, and on the socio-economics of climate
change, capped by a synthesis relating the findings of these reports to
the objective of the Rio Climate Treaty. The IPCC has determined that
global climate change has begun, that the impacts of climate change
could be severe if unchecked, and that significant opportunities exist
to reduce emissions of greenhouse gases. Although the IPCC itself is
barred from making policy recommendations, by pulling an enormous wealth
of material together in a manner accessible to policymakers, the IPCC
Second Assessment Report creates a compelling case for more vigorous
action to reduce greenhouse gas emissions. The IPCC Second Assessment
Report was written and reviewed by some 2000 leading scientists and
technical experts from about 130 countries. Each section of the report
was extensively peer reviewed by both independent and government
experts. The Summary for Policy Makers of each of the three Working
Group reports and the Synthesis Report were each approved line-by-line
by government representatives in consultation with the lead authors.
Thus the IPCC report represents the most comprehensive and authoritative
source of information on global climate change.
The final line-by-line approval process was marred by an intense effort
by oil-producing countries and industry lobbyists to delete or water
down key conclusions in each of the documents. These countries, led by
Saudi Arabia and Kuwait in close consultation with the Climate Council
and the Global Climate Coalition (two U.S.-based organizations
representing coal and oil interests), exploited the IPCC's consensus
process by dragging out the debate over sentence-after-sentence in an
attempt to win concessions. In one remarkable example, the comments of
Kuwait were identical to those of the Dow Chemical Company (a Global
Climate Coalition member), but Kuwait could not explain the rationale
for its comments.
Ultimately this effort failed to suppress the key findings of the report
due to the diligence of the lead authors in assuring the scientific
integrity of the final product. Nonetheless, in addition to slowing down
the process and forcing late night sessions to complete the work, the
oil producer's efforts did succeed in weakening some aspects of the
report. For example, because of time constraints the original Summary
for Policy-makers of the Working Group I report on science had to be
recast as a <Technical Summary> that does not have to be approved
line-by-line and will not be bound with the overall summary material of
the Second Assessment Report. Similarly, the discussion in the Synthesis
Report of what would be required to stabilize the concentration of
carbon dioxide in the atmosphere at various levels omits the observation
that stabilizing concentrations at a level below an equivalent-doubling
of atmospheric CO2 requires cumulative emis-sions during the next
century that are substantially less than in any of the IPCC IS92
scenarios (this fact can be inferred by closely examining the tables,
however).
Major Findings of the Report Include:
- Humans are Changing the Global Climate
Greenhouse gas concentrations are increasing: Since preindustrial times
the concentration of carbon dioxide (CO2) in the atmosphere has
increased by 30 percent, methane has increased by 145 percent, and
nitrous oxide has increased by 15 percent. CFCs, HFCs, and PFCs were
introduced into the atmosphere for the first time. The buildup in the
concentration of these gases is due to human activities, particularly
fossil fuel combustion and land-use change.
Sulphate particles are masking part of the greenhouse warming: Some of
the warming affect of greenhouse gas increases is currently being masked
by sulphate particles from burning coal and oil. Unlike the greenhouse
gases, which remain in the atmosphere for decades to centuries and are
distributed nearly uniformly, sulphate particles remain in the
atmosphere for only a few weeks and their concentrations vary from
region to region. Therefore, sulphate particles cannot be considered a
simple offset to the greenhouse gases with respect to climate change at
the regional level. Furthermore, if sulphate emissions were reduced, due
to their local or regional environmental effects or to changes in
technology, for example, their concentrations would fall quickly,
unmasking additional greenhouse warming.
Stabilizing greenhouse gas concentrations would require emission
reductions: If carbon dioxide emissions were maintained near current
levels the atmospheric concentration of carbon dioxide would continue to
increase at a nearly constant rate for at least two centuries, reaching
about 500 ppmv by 2100. To stabilize the concentration of carbon dioxide
at 450 ppmv would require that cumulative emissions over the next
century be limited to about 640 gigatons of carbon, compared to
emissions of 1500 gigatons in the mid-case business-as-usual scenario,
IS92a. To stabilize concentrations at a given level, higher emissions in
early decades require lower emissions later on.
The balance of evidence suggests a discernible human influence on global
climate: Global mean surface temperature has increased by between about
0.5 and 1.1< F during the last century, a change that is unlikely to be
entirely natural in origin. The balance of evidence, from changes in
global mean surface air temperature and from changes in geographical,
seasonal and vertical patterns of atmospheric temperature, suggests a
discernible human influence on global climate.
Climate is projected to change faster than it has in 10,000 years: For
the range of IPCC IS92 emission scenarios and the range of climate
sensitivity to changes in radiative forcing adopted by the IPCC, global
mean temperature is projected to increase by 1.8 to 6.3< F between 1990
and 2100, accounting for the increases in sulphate emissions assumed in
most of these scenarios. If sulphate emissions are assumed to be
constant at 1990 levels, the global temperature increase is projected to
be 1.4 to 8.1< F. Sea level is projected to rise by 15 to 95 cm. In all
cases the average rate of warming would probably be greater than any
seen in the last 10,000 years, but the actual annual to decadal changes
would include considerable natural variability.
Climate change may involve "surprises": Future unexpected, large and
rapid climate system changes (as have occurred in the past) are, by
their nature difficult to predict. This implies that future climate
changes may also involve "surprises". In particular these arise from the
non-linear nature of the climate system. When rapidly forced, non-linear
systems are especially subject to unexpected behavior.
- Climate Change will have Significant Consequences
Rising sea levels: Average sea level has been rising throughout the last
100 years, and global warming is expected to increase the annual rate by
two to five times. Projected global impacts include increased flooding
and storm damage, increased shoreline erosion, decreased marine and
coastal biodiversity, and contamination of drinking and irrigation water
with salt water. Significant expense to adapt to sea level rise will be
required and some areas may have to be abandoned.
In the U.S., sandy beaches nationwide would be degraded, particularly
beaches on outer coasts exposed to ocean waves, such as Monmouth County,
NJ and Long Island, where submersion rates may exceed 100 feet of beach
per one foot of sea level rise. This one-foot rise of sea level could
occur as soon as 50 years from now. Protecting parts of the
Louisiana/Mississippi River delta may prove impossible.
Human health: Increases in mortality from heat waves, compounded by more
severe urban air pollution, are projected. Increases are also expected
in infectious diseases such as malaria, dengue and yellow fever, and
schistosomiasis, due to the spread of conducive climate conditions and
changes in the lifecycle of disease vectors and infectious organisms.
For example, a temperature increase of 5P7 degrees (possible over the
next 100 years) doubles the rate of transmission of the dengue virus.
Indeed dengue fever has recently reemerged in Mexico and Central
America, and even Texas, where 14 cases were confirmed, one of those
endemic.
A study for Atlanta projects that the number of heat-related deaths
would rise from an average of less than 80 per year currently to 150P440
per year in 2050. Local transmission of malaria could occur in much of
the U.S. by the middle of the next century, with local epidemics
possible despite our strong public health infrastructure.
Forest decline: The consequences of global warming on forests may be
severe. Fully one-third of forest ecosystems are expected to be
disrupted. Further, in a rapidly changing climate, a seedling could
become established in a location which, 50 years later, when the seeding
has matured, can no longer support it. This could lead to replacement of
slow-growing, mature forests of beech, hemlock, maple and oak with
fast-growing trees and shrubs associated with disturbed areas like
clearcuts and roadsides. In New England, some familiar trees may
disappear from much of the region, affecting fall foliage displays,
animal populations, and the timber, tourism and hunting industries. In
the Pacific Northwest, Douglas fir and Ponderosa pine forests at the
southern parts of their range could become grasslands, while the Sierra
NevadaUs west side forests may become more like those on the drier east
side, affecting tourist, lumber and recreational industries.
Insurance losses: The historical probabilities of extreme events, such
as windstorms, floods and wildfires, may no longer provide a sound basis
for predicting future losses. A series of unanticipated losses could
lead to higher premiums, major bankruptcies in the insurance industry
and/or the withdrawal of insurance coverage from vulnerable areas. For
example, even today, a class-5 hurricane hitting Miami or a class-4
hurricane hitting New York would cost $50 billion in losses
Freshwater resources: Already scarce fresh water supplies in many
regions, particularly arid and semi-arid, would be even more at risk.
Some areas would experience both more droughts AND more floods, such as
the western United States. In the West, where winter precipitation falls
largely as snow, higher temperatures will increase rain and decrease
snow, contributing to high winter/spring runoff (when flood risk is
already highest) while summer runoff will drop because of the decline in
snowpack and accelerated spring melting.
- Climate Change can be Curbed through Cost-Effective Policies
Significant emission reductions are feasible: Significant reductions in
net greenhouse gas emissions are technically possible and can be
economically feasible. These reductions can be achieved by utilizing an
extensive array of technologies and policy measures that accelerate
technology development, diffusion, and transfer in all sectors,
including the energy, industry, transportation, residential/commercial
and agricultural/forestry sectors.
Alternative energy options: The IPCC estimates that $10 billion in R&D
and $7-12 billion in initial deployment incentives, spread over a couple
of decades, would be sufficient to support commercialization of a range
of renewable energy technologiesQa small sum compared with the $5-6
trillion over the same period that would be spent to subsidize
conventional energy sources if current practices continue.
Action now to cut emissions is prudent: The literature indicates that
significant Rno regretsS opportunities are available in most countries
and that the risk of aggregate net damage due to climate change,
consideration of risk aversion and the precautionary approach, provide
rationales for actions beyond Rno regretsS. The challenge is not to find
the best policy today for the next 100 years, but to select a prudent
strategy and to adjust it over time in the light of new information.
Appropriate long run signals are required to allow producers and
consumers to adapt cost-effectively to constraints on greenhouse gas
emissions and to encourage investment, research, development and
demonstration.
NOTE: A volume containing the Synthesis Report and the three Summaries
for Policy-makers will be published by the IPCC Secretariat. The IPCC
also plans to post these documents on the Internet at the following web
sites: http://www.unep.ch/ipcc/ipcc-0.html; http://www.wmo.ch/. The full
report will be published by Cambridge University Press in early 1996.
******************************************************************
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