Global Warming, Another Look
In
the ongoing debate over global warming media attention
has focused on a growing chorus of alarming predictions
coming from the scientific and environmental communities
and denials by the economic and political sectors
founded on lack of firm proof. Proponents point to
growing evidence of increasing temperature and point out
that waiting for unequivocal proof will leave it too
late to avoid catastrophe. Opponents claim that the
economic costs of greenhouse gas reduction would be too
high to bear without clear evidence of necessity.
While the media chooses to concentrate on controversy
and threats of calamity there is a significant and
credible minority opinion in science that presents a
quite different perspective. In this view the purported
warming has been exaggerated. The extent to which it
does exist is largely due to natural causes, and it is
more likely to be beneficial than detrimental. Many
geologists in particular adhere to this persuasion but
it receives little notice from the media.
Geologists now have powerful tools for looking at past
climate records preserved in sediments and ice cores.
They have clear evidence that the recent epoch of
glacial cycles involves over a hundred glacial periods
spanning the past several million years. Looking at such
records we are now nearing the end of a warm
interglacial period when temperature peaks, just before
the plunge into a new glacial cycle.
These cycles correspond to cycles in the Earth’s orbit
that affect how much sunlight the planet receives.
Superimposed on this pattern are shorter term cycles of
solar activity that also effect climate on a shorter
time scale. These latter cycles correspond to sunspot
activity and they are recorded in the formation of the
isotope Beryllium10 which can be read in ice
and sediment cores. Comparing temperature and sunspot
activity over the past 1000 years we find that the
record high temperatures of the past decade corresponds
to a record high level of solar activity.
The general consensus among those knowledgeable in this
area is that certainly most of the recently observed
temperature increase is attributable to natural cycles
and any contribution from increased greenhouse gases
must be minor. It also means that contrary to the
global warming scenario we are probably close to
entering another ice age. Whether "close" in this sense
means decades or centuries is uncertain but one piece of
evidence indicates it may begin sooner rather than
later.
Ice age sediments from the Arctic Ocean contain abundant
remains of open water plankton. Contrary to what one
might expect, the Artic Ocean is mostly open water
during glacial periods. This is not as unreasonable as
it may seem. The ice covered Artic is now a polar desert
in terms of atmospheric moisture. An open water Arctic
Ocean would greatly increase moisture and snowfall
leading to greatly increased ice buildup on land and
accelerated cooling by reflection of solar radiation
from ice, snow, and clouds. This could only maintain of
course, if the sea remained open and this could only
happen with an inflow of warmer water. This in turn
would most likely involve a diversion of a portion of
the Gulf Stream into the Artic Ocean. Thinning of Arctic
Ocean ice and increasing ice free areas in summer has
been noticeable in recent decades. If continued for
another decade or two this will result in much of the
sea being open in summer. It seems reasonable that some
point in this process may be the threshold for a shift
in current patterns and the turning point into the next
glacial cycle.
In the meantime another study just released has found
evidence of past bleaching events in coral cores over
the last 1000 years so the recently observed bleaching
events are not unprecedented but may also just be
something that occasionally happens in our dynamic
world.
How all of this may play out in the real world will
probably be argued until actuality settles it. We have
neither the will to change ourselves nor the means to
change the world and only a very limited ability to
predict it. We can however enjoy the ride. It should be
a most interesting one.
Walter Starck
Editor/Publisher
wstarck@goldendolphin.com |