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| naebad... |
 Posted: Thu Oct 29, 2009 12:09 pm |
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http://www.globalwarminghoax.com/comment.php?comment.news.113
Leonard Weinstein, ScD
In this paper, former NASA Senior Research Scientist Leonard
Weinstein, ScD uses the melting of Arctic and Greenlandish ice to show
how CO2 can not cause catastrophic melting in the future. In fact,
both areas are well within the norm of natural variation.
One of the issues most harped upon by the media and the focus of Dr.
Weinstein's analysis is the melting of the polar ice caps in relation
to atmospheric CO2 content. Dr. Weinstein analyzes and deflates each
claim using proven scientific data from the area and focused reasoning
instead of taking it at face value from the feeding hand of the
societal grapevine. He reinserts many intentionally forgotten
variables and factors into the hackneyed mass ice-melting formula we
are all familiar with such as the reflectivity of the snow-cover, the
axial tilt of the Earth, the emissivity of water, and other melt(and
hysteria)-damping factors that are often swept from the public's view.
There is an interesting story going around that Anthropogenic Global
Warming (AGW) is resulting in unusual melting of the polar and near
polar ice caps, especially the Arctic sea ice and Greenland ice cap,
and this is going to contribute to the Earth’s problems in a big way
(flooding, feedback temperature increase, etc.). In order to
understand the issue, a few simple facts and recent observations need
to be shown. The following discussion is restricted to the Arctic and
Greenland, since these are the main regions of contention. It should
be noted that the Antarctic is presently cooling (and has been for
several years) and sea ice extent is expanding.
We first need to examine the external energy balance for the Arctic.
Due to the axial tilt of the Earth, the Arctic is in full dark about
half of the year, and in partial to full Sunlight about half of the
year. The maximum Sun angle at the North Pole is about 24 degrees
above the horizon. This angle only occurs for a relatively short time,
and smaller angles occur most of the daylight time. The maximum Solar
insolation from this (due to the angle and atmospheric absorption) is
about 400 W/m2. The high reflectivity of clean snow (always present on
ice) results in only about 40 W/m2 being absorbed into the ice. The
maximum air temperature near the surface is just a small amount above
freezing, so the maximum thermal heat transfer from air to ice is
generally just a few 10’s of W/m2. The ice (or snow) gray-body
emissivity (about 0.9) is much higher than the low absorption (about
0.1) at the short wavelengths of Sunlight, so the reemitted long
wavelength radiation is about 280 W/m2. The result is that solid ice
cannot normally melt from Solar radiation plus air warming from the
top, even at peak summer. The rest of the year has even less energy
input, so ice is strongly cooled all year long.
The actual cause of the significant melting of summer ice has been
shown to not be possible from the top. However, there is considerable
summer melting. It is clear from the physics that the summer melting
has to have been caused by water flowing under the ice. The water
flows from lower latitudes, so has a higher temperature than the ice.
If the water is warm enough it melts the ice from below. However, if
the ice is cold enough and the water cool enough, this flow will
freeze and add thickness of solid ice to the underside. This is the
source of new solid ice. Snow on the top also adds to the thickness,
but is not solid ice.
The summer melting can result in some Arctic open water. Open water
can absorb much more of the Solar insolation than ice or snow, but
even at the maximum summer level, absorbs only about 350 W/m2 near the
pole. The water emissivity is slightly higher than ice, and radiates
about 300 W/m2. These result in a maximum excess of absorption in open
water of only about 50 W/m2 for a very short part of the peak of
summer, and a large net cooling over the full year. Thus to claim that
a temporary full melting of Arctic ice (from underneath) will keep the
ice from reforming is incorrect based on Solar insolation and
reasonable air temperature variations.
The following figure is show as an example of the very rapid
temperature rise experienced at the Artic in recent years. This is
supposed to prove the model predictions of unusual temperature rise
rates are valid, and that we are heading for big problems:
(see link)
The temperature variations are shown relative to the temperature
during 2000. The temperature has been as much as 2C higher than at
present, and the last several years have a dropping temperature. The
zero line actually corresponds to –30C, so even a temperature rise of
10C or even 20C would not even start to melt the ice.
The result is a clear demonstration that the present models and scare
claims are not valid, and that using a short selected time history can
give a very misleading indication of longer trends.
Naebad |
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