The Eartlh's Energy Imbalance --
The facts, just the
facts, as we know them:
There is some
recent scientific work that asserts the following(*):
-
The "energy balance" of the earth, on the overall, is
increasing - it is now "out of balance". That
means that we are getting more energy in (from the sun)
than we are releasing. This is due largely to changes
in atmospheric composition. The "energy imbalance"
is now about 0.85 watts/M2.
-
Some of this "extra energy" is raising the surface temperature
of the earth. Over the past 150 years, the overall surface
temperature of the earth has risen by about 2 degrees
F (about 1 degree C). Of this, the surface temperature
has increased by 0.5 degrees F in the last decade.
-
Most of this increased "energy balance" is not going into
the surface temperature, though. Most of the extra energy
is going into the oceans. Results confirmed by ocean-
temperature sensing equipment along with satellite studies
shows that the heat capacity of the ocean is increasing,
with a total increase of about 1.8 watts/year/M3 in the
1993-2003 decade. (Note from website author: The last figure
is taken from notes made of Dr. Hansen's presentation on C-SPAN3
on 5 May 05; have not yet been able to verify in web literature.)
A more well-quoted figure is an increase in energy distribution over
the earth's surface of approximately 0.85 watts/M2.
(*) Data Source:
Dr. James Hansen, Chief, NASA Institute for Space Studies,
NASA Release April 28, 2005
At the same time, there are other scientists who are saying that the "error margins"
for the claims put forth are larger in reality than what the scientists who've
published the previous assertions will allow. This means, the entire foregoing
set of comments (and even data items and mathematical projectiosn) may be in error.
One of these scientists is Lubos Motl, Assistant Professor of Physics at Jefferson Labs,
and also affiliated with Harvard University. Motl is a researcher in string theory (an aspect of theoretical physics) at ,
who makes
the following points(**):
-
"You can see that their advertised error margin is
roughly 100 times smaller than the error margin of any
conceivable calculation that someone may want to do today
or in the near future.
-
"... but when we make a contact with reality,
we must also include the errors and uncertainties of the
model itself - the model uncertainties which are large.
The scientific significance of the number "0.85" is zero.
"
The upshot of all of this sturm und drang in scientific circles
is that we are not absolutely sure of anything right now except
for data itself. Models, especially predictive models, in areas
that include multiple interacting effects are subtle and delicate
matters.
(**)
Motl also recommends an interesting article by
Ahilleas Maurellis and Jonathen Tennyson on The Climatic
Effects of Water Vapor. Yes, this is a bit like reading
a Scientific American article, but it's important. Please
read if you want to discuss this issue intelligently. Read
several times if need be. Even if it's been a long time since
you've been in chemistry class, this will start to make sense.
It's well-written enough, so do read. Also, if you go to this
effort, please do read
Hansen's article as well. Both just pretty interesting
and surprisingly readable.
This does not mean that we still know nothing, and can infer nothing. And it
most certainly does not mean that we should do nothing. Rather, we need to be
careful rather than overreactive in our approach.
