| Global
Warming
SOLAR
ACTIVITY INFLUENCE TO WEATHER
QUESTION: Is there a significant correlation between
solar activity, e.g., magnetism, and earth's weather, say,
for the northern hemisphere?
RESPONSE: From Dr. Rodney Viereck,
SEC Research Scientist, NOAA
"The earth has warmed about 1 degree C in the last
150 years. This is
an estimate and may be as small as 0.5 degrees or 1.5 degrees.
The
warming trend is not a smooth curve but rather it has ups
and downs.
There was a cold period between 1900 and 1920. There was
also a cooling period between 1940 and 1970. Since 1970,
the global climate has really started to warm up quickly.
There is no obvious reason why the climate should have cooled
during the last 150 years if the main forcing is man's activities
(anthropogenic). The sun however did get brighter and dimmer
over the
same period. In fact, based on estimates of the solar activity,
the sun
was less active during the early 1900s and during the 1940
to 1970
period. These less active periods correspond to the colder
climate
period that I mentioned above. Therefore, there is reason
to believe
that the sun has contributed to climate variability.
Certainly, if you look at the climate of the last 500,000
years, changes
in the distribution of the sunlight on earth (how much sun
reaches the
polar regions) caused vearly large changes in the past.
During the last
500,000 years there have been four short periods (about
10,000 years
long) where the climate was as warm as it is now. The rest
of the time,
the global temperature was 2-8 degrees C colder than it
is now. These
were the ice ages when the ice over Canada and Russia was
up to a mile thick. If you calculate the amount of time
the climate is warm vs.
cold, it has been colder than now for about 90% of the time.
We are in
a very warm period and according the cyclic behavior of
the climate, we should start to get colder in the next 2000
years or sooner. We will
then head into another ice age."
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