Neocon, there are three things I would like to say about your post. First, it is the opinion of one person only. Secondly, the general environmental degradation and loss of small low lying island nations and the melting of the polar ice caps and the measurable depletion of the ozone layer are concrete events that are actually occurring.
Now you can argue whether these are the results of a general global warming, but you cannot dispute in scientific terms that these alarming events are actually happening. Oh, and there are many other opinions which refute yours. Here is just one, from a group of academic scientists:
April 22, 1998
UMass Scientists Lead Team Reconstructing
Global Temperature Over Past Six Centuries
Study is most definitive to date on global warming
[Images] [Study FAQ] [Study]
AMHERST, Mass. --Climatologists at the University of Massachusetts have
reconstructed the global temperature over the past 600 years, determining that
three recent years, 1997, 1995, and 1990, were the warmest years since at least
AD 1400. The study, which was conducted by Michael Mann and Raymond
Bradley of the geosciences department, along with University of Arizona colleague
Malcolm Hughes, is detailed in the April 23 issue of the journal Nature.
The researchers were able to estimate temperatures over more than half the surface
of the globe, pinpointing average yearly temperatures in the northern hemisphere to
within a fraction of a degree, going back to AD 1400. The study places in a new
context long-standing controversy over the relative roles of human and natural
changes in the climate of past centuries, according to Mann. Scientists were
particularly interested in natural "forcings," that is, factors that can affect the climate
significantly, but which are not part of the climate system itself. Based on statistical
comparisons of reconstructed northern hemisphere temperatures, the best estimates
indicate that natural changes in the brightness of the sun and volcanic emissions
both played an important role in governing climate variations over the period
studied.
However, over the past few decades, greenhouse gases produced by human
activities appear to have had an increasing influence on temperatures. "The
anomalous warmth of several recent years appears likely to be related to human
influences on climate," said Mann.
The study bears out concerns voiced by scientists in recent years regarding global
warming, Bradley said. It is known that industrialization during the past century has
increased levels of carbon dioxide in the Earth's atmosphere by more than 25
percent over its pre-industrial level. Several so-called greenhouse gases have the
potential to heat the atmosphere, Mann said, "but the one we're most concerned
about is carbon dioxide, because carbon dioxide is the primary greenhouse gas
resulting from industrialization." These greenhouse gases form a sort of blanket
around the Earth, trapping in heat that would otherwise be radiated back to space,
Mann explained. This causes the Earth's atmosphere to heat up.
If the amount of carbon dioxide in the atmosphere were to continue to increase at
its current rate, it could rise to double its pre-industrial level during the next century,
leading to a magnification of the already observed warming, according to Mann.
For example, melting ice caps could raise sea levels, threatening coastal regions
with more frequent flooding. The planet as a whole might expect to see frequent
extreme weather events, Mann said. "Heat waves and droughts could become
more common, and more intense," he said.
Climatologists are also concerned about the degrees of uncertainty surrounding
increased or accelerated global warming, Mann said. "We have a sense of what
might happen to the planet as a whole, but the fact is, we don't really know what
the regional impacts might be."
Weather instruments were introduced only in the mid-1800s, so to go back 600
years, scientists reconstructed the climate records by relying on the small number of
very long historical records, along with annually recorded "proxies" – natural
archives that actually chronicle climate variations, said Bradley. Among these
archives are: the density and width of tree rings, samples of centuries-old layered
ice, and corals, which incorporate chemicals into their skeletons depending on
water temperature and salinity, both of which are affected by climate.
The researchers relied on proxies from more than 100 sites across the globe,
ranging from Arctic regions, to South American mountaintops, to locations
throughout North America and Europe. In certain cases they used historical
temperature estimates, which had previously been translated into an estimate of
seasonal climate conditions. These were based on diary accounts of events such as
crop yields, dates of first frosts, wine harvests, and famines. Several documents
were lengthy weather station records which relied on conventional, though cruder,
versions of meteorological instruments, such as early thermometers. These were
used to supplement the network of proxy climate records. Advanced statistical
techniques were used to translate the proxy information into surface temperature
patterns, so that past centuries could be compared with the 20th century.
Researchers found certain individual years particularly intriguing. For example,
historical documents from 1791 suggested conditions consistent with a strong El
Nino event that year; the proxy-reconstructed temperature pattern bore out these
suspicions. The weather was much cooler than usual over most of the globe in
1816 following the eruption of the Indonesian volcano, Tambora, the year before.
Warming observed in certain regions, however, was consistent with changes in
atmospheric circulation also expected to result from a strong volcanic eruption.
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