Re: comments guys
- From: Alastair <al@xxxxxxxxxxxxxxxxxxxxxxxxxx>
- Date: Thu, 31 Jan 2008 14:29:45 -0800 (PST)
On Jan 31, 8:15 pm, Weatherlawyer <Weatherlaw...@xxxxxxxxxxx> wrote:
On Jan 31, 7:05 pm, Alastair <a...@xxxxxxxxxxxxxxxxxxxxxxxxxx> wrote:
In fact surface measurements have shown that global warming
is happening faster than the models predict.
I can't see how global warming can be considered a fact since the
insulation concerned fractions, small fractions, of a chemical that
may or may not be adding to the atmosphere is as open to shedding heat
eventually, as is any other fragment of the atmosphere.
Global warming is a fact because the last ten years have been the
hottest since records began. But you only need to look at the early
daffodils, reports of retreating glaciers from Kilimanjaro to Alaska,
and wild fires and droughts being reported from Southern Europe, North
America and Australia to realise something is up.
The greenhouse effect of carbon dioxide has been know about since John
Tyndall's experiments in Victorian times when he found that it was
only the trace gases such as water vapour, carbon monoxide, carbon
dioxide, ozone and methane that absorbed the thermal radiation emitted
by the Earth's surface. However, there are enough molecules of water
vapour and carbon dioxide to trap most of the radiation within the
lowest 100 feet of the atmosphere. These molecules do emit radiation
but at a lower intensity than the ground. The difference in energy
between that absorbed and emitted heats the other air molecules so
raising the temperature of the air near the surface. It has been
calculated that without this "greenhouse effect" global temperature
would be 33 C lower than they are at present.
Even if the earth were magically covered in a dual layer of highly
reflective envelope with a vacuum sandwich in between, the nett result
would be an equilibrium matching that of the atmosphere in prehistoric
times. Or historic times come to that.
The global temperature of the Earth has varied during geological
times, and crocodiles flourished in the Arctic 50 million years ago.
In fact hippos and lions lived in the Thames valley during the last
interglacial only 100,000 years ago. But during those times carbon
dioxide levels were higher than during glacial periods. It is
probably the evolution of grasses which that reduced the global CO2
levels and was responsible for the current ice age.
There is no law of science that says the planet has to be at the
temperature of the planet has to remain as it was over the last one
hundred/thousand years. Carbon dioxide levels have been measured and
they shows that over the last 150 years CO2 has risen from 280 ppm to
380 ppm, a rise of over a third.
No system can contain its heat indefinitely.
The Earth is being warmed by the Sun, and the Earth's temperature
rises until it can emit as much radiation as it receives from the Sun.
If you add more CO2, less radiation can escapes, the surface warms,
the ice melts and more solar radiation is absorbed.
The science is even more complicated than I have described, but
remember that the only way hte Earth can lose heat is by radiation.
There is nothing in space to convect or conduct heat away from the
Earth.
.
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