Global warming advocates went to Antarctica to prove that Antarctic sea ice had disappeared because of man.  They got stuck in ten foot thick sea ice they knew wasn't there.  The rescue ship was also stuck for a while, but it was eventually able to back out to safer water.

This all happens in the heat of summer.  A hundred years ago, the entire region, right up to the shore, was completely clear of ice.  

Oh, the irony!  

Given the embarrassment of such "political" scientists, it is worth examining the issue: does man have a major impact on the climate?

How does a physicist, such as myself, address this topic?  I look at the physical evidence and see what it says.

Let's start with the computer models.  How well do the warming models predict?  Climate models predicted that we would now be experiencing an exponential rise in Earth's temperature.  Unfortunately, for the last seventeen years the climate has shown no such growth.

Well, then, how well do the models account for past climate?  We know from the chronicles of witnesses that the mean temperature fluctuated by several degrees.  The Bronze-Age warmth was followed by a cold climate-caused dark age.  The later Roman warm optimum was followed, at the end of the Western Empire, by cold sufficient to freeze the Rhine and Danube rivers and propel the starving Germanic tribes into Roman territory.  Then, after the medieval warming, when Greenland was green and wine was exported from England, came the post-medieval Little Ice Age.

The models account for none of this.  Climate oscillates; the models do not.  For a considerable while, the warming advocates even denied the eyewitness testimony -- there were no Little Ice Ages, the advocates said.

From the written records of the last thousand years, we find that cold correlates with sunspot minima.  This is happening today.  Correlation does not prove cause, and causation is still hypothetical, but the correlation is suggestive.

Then there are the ice age glaciations.  Warming advocates claim that increases in atmospheric carbon dioxide caused the melting of the glaciers.  Indeed, there is a correlation.  Unfortunately, the increase in carbon dioxide always came after the glaciers started melting.  This might have had something to do with the oceans warming.  More about this in a bit.

Carbon dioxide does warm the Earth.  So what happens when we add more of it to the atmosphere?  The early warming models assumed that the heating was taking place in the lower atmosphere -- the troposphere.  Adding carbon dioxide here was said to be bad.

There is an easy test for this: go outside and look at the house across the street.  In the infrared portion of the spectrum, where carbon dioxide light absorption takes place, that house would be invisible, or at best barely discernible.  The fact is that carbon dioxide absorption is so strong that the troposphere is already opaque with carbon dioxide.  Adding more carbon dioxide is much like adding bricks to thicken a brick wall.  The added bricks don't affect the transparency of the wall in the least.

The climate modelers overlooked this gross error until just a few years ago.  If the problem is not tropospheric, they said, it must be in the stratosphere.  Unfortunately for the modelers, we can see stratospheric carbon dioxide from satellites.  Satellites show an anomaly: industrial areas, where man is injecting the most carbon dioxide, show little increase in stratospheric carbon dioxide.  Why?  One idea is that these places have lots of greenery, and plants love to eat carbon dioxide -- it's their food.  On the other hand, downwind of hot, salty sea water, such as the Red Sea and the Gulf of California, and even the Mediterranean, there are vast plumes of stratospheric carbon dioxide.  This makes sense.  The warmer the water, the less carbon dioxide it can dissolve.  The same is true of salt.  Increase saltiness, and you decrease dissolved carbon dioxide.  Cold water, with lots of dissolved carbon dioxide, is sucked into these constrained areas.  The sea warms, evaporates water, and becomes more salty.  Carbon dioxide is released.

Warm water means evaporation.  Evaporation means increased water vapor in the atmosphere.  Water vapor is an even better greenhouse gas than carbon dioxide.  Therefore, carbon dioxide, by increasing water vapor, induces a positive feedback which increases the Earth's temperature still further.

Such reasoning is embedded in most of the models.  This is familiar.  Nights with low clouds generally are warmer than clear nights, because the clouds form a blanket that traps and reflects back the Earth's radiation.  But cloud tops also reflect sunlight and thereby act to cool the Earth.  Which is more important? 

For a long time, the argument was that cloud warming beats cooling.  Then the argument shifted to the notion that the effects cancel.  But there is an easy test for this.  In equatorial regions, evaporated water vapor forms lots of clouds.  These regions are hot, even at night, so one might argue that the clouds cause warming.  However, just north and south of these cloudy regions, the air is clear.  Here we find the Earth's great deserts -- sometimes cooler at night, but very much hotter during the day.  The evidence is that, on balance, clouds cause cooling.  The feedback is negative.  Carbon dioxide-induced evaporation of water vapor actually results in moderation of the greenhouse effect.

All the foregoing is at the micro-level of Earth's history.  Deep time tells us even more.  Throughout most of Earth's history, the atmosphere contained much more carbon dioxide than today, with periods of great carbon dioxide variation.  Yet, despite this, the basic climate has been remarkably stable and relatively cool. 

Start at the beginning.  About four billion years ago, the temperature of the Earth had fallen sufficiently for oceans to form and life to begin.  If the warming advocates are right, the Earth should have become like Venus -- dry and hot enough to melt lead.  It didn't. 

For billions of years after the oceans were created, the atmosphere remained mostly a very thick blanket of carbon dioxide.  Nitrogen, which today makes up 78 percent of Earth's atmosphere, was only a trace gas in the original thick carbon dioxide atmosphere.  Oxygen was practically nonexistent.  The sun may have been cooler then, or it may have been hotter.  Still, the temperature had to have been moderate, and much like today, or forms of life other than extremophiles would not have evolved.  Stromatolites, which originated early on in that carbon-thick atmosphere, continue to thrive in today's cool environment.

With the evolution of photosynthesizing plankton and algae, most of the carbon dioxide in the atmosphere was converted to calcium carbonate, and oxygen was released.  The atmosphere became what we have today, but generally with a much higher concentration of carbon dioxide.  Temperatures stayed about the same.  Obviously some powerful negative feedback mechanism was moderating the temperature, and still is.

That is the bottom line: negative feedback keeps the Earth's climate relatively stable despite large variations in solar flux and atmospheric composition. 

Man may have some influence over the climate, but the effect is likely to be very small.  There is no cause for economy-disrupting control of carbon dioxide.  Be very suspicious of those who advocate, and carry out, such a policy.  They have something most unpleasant in mind.