Global Climate Change - Solar Activity and Clouds

Well, we've pretty much established that it's not CO2 that's causing the temperature variations, so what else could it be?  Well, what's the only object that provides us with light and heat?  Hmm....the Sun perhaps?  It amazes me that eminent (and perhaps not so eminent?) scientists have for years been discounting the sun as a major influencer of our climate.  A nuclear furnace which provides us with every single erg of energy falling on the surface of our planet and which projects a variable solar wind which wraps an envelope of active particles around the Earth is not suspected of having anything to do with our climate?  OK - maybe they think they're right, but I think they should be members of the Flat Earth Society.

We can measure the effects directly, because the solar wind is directly related to solar activity and this activity has been measured for a long time.  We can construct a chart showing whether there is a relationship between solar activity and global temperature.  When we do we get a fascinating result, as you can see in the chart below for data between the years 1870 and 1990.

Chart Reference: The Carbon Dioxide Thermometer and the Cause of Global Warming; Nigel Calder,-- Presented at a SPRU (Science and Technology Policy Research) seminar, University of Sussex, Brighton, England, October 6, 1998. Solar wind is used here as a measure of sun intensity.

In this chart you can see very clearly the tight relationship between solar wind (solar activity) and global temperature.  You can also see that as the temperature rises with the solar activity, so does the CO2 level.

So, if it can't be CO2 that's making our global temperature fluctuate, what else could it be?  Let's look at the sun in more detail, because as I said above, it is becoming increasingly clear that the sun plays a fundamental role in the changes which we see, and we will now investigate one of the most important ways in which it is believed this happens.  It is all associated with the solar wind and the effect it is believed to have on our upper atmosphere.  The theory is that at times of high solar activity the sun effectively "wraps" our planet in a sheath of ionised particles which shield us against cosmic rays, which are bombarding us all the time from outer space.  This is important because it is suggested that cosmic rays play a key role in cloud formation by creating "aerosols" around which clouds can form.  We saw a few pages back that water vapour is a very effective greenhouse gas, and so it is easy to see why clouds, which are all water vapour can (and do) play a big part in controlling temperatures.  They do this in two ways:

It has been shown conclusively that the oceans, which make up two thirds of the surface of the Earth, absorb heat from the sun and distribute it around the planet.  The ocean currents are crucial, both in storing the heat for extended periods and in distributing it to areas which do not receive much solar heat (the Gulf Stream is one such example of a warm current which pumps warm water from the tropics to the western coasts of northern Europe).  It has been shown that the oceans warm primarily via solar short wave radiation, and the effectiveness of this process is of course affected by cloud cover - more clouds equals less heating and cooler temperatures.  The International Satellite Cloud Climatology Project produced compelling evidence of a direct link between cloud cover and temperature, and calculations show that the increased SW radiation which would have warmed the oceans in the late 20th century would have easily been enough to drive the observed warming which occurred.  

The second way in which clouds affect temperature is because they act as reflectors, sending back into space a proportion of the solar energy falling on them.  This is called in science an increase in "albedo" for our planet.  Again, we have reliable evidence from satellite observations that cloud cover (and hence albedo) increase during periods of low solar activity.  The suggestion is that cosmic rays can penetrate deeper into our atmosphere, creating more aerosols around which clouds can form.  There are numerous experiments underway at the moment to try to validate this theory, but in my opinion it has much greater credibility than suggesting 350ppm of carbon dioxide can have any significant effect on global temperatures.

Quoting Peter Taylor, oceanographer and climatologist, from his book "CHILL" - chapter 2, p53; "There is accumulating evidence that the 11-year cycle of fluctuation in the solar wind causes a 3% variation in low-level reflective cloud cover.  If correct, this would lead to a pulse of warming sunlight (radiation of short wavelength) and we can test this assumption by perusal of satellite data on the amount of SW (short wave) radiation reaching the Earth's surface.  The data show clearly that such pulses exist.  When this evidence is coupled to evidence of a long-term rise in solar output from 1900 to 1995, which by inference would lessen cloud cover, then it is clear that these factors are powerful enough to account for the global warming signal in the twentieth century.  The final confirmation would be a downturn in global temperatures as solar output declined from its peak of 1900-95, cloud increased and more warming sunlight was reflected.  This is what has been observed, with a time-lag in peak temperatures at 1998, a reversal of cloud trends in 2001 and a sharp fall in surface temperatures in 2007."

As I said, there are numerous experiments underway at the moment attempting to verify this theory, and in particular the aerosol - cosmic ray link.  I await their results and conclusions with great interest.

There's a second solar factor which has also been largely ignored - our sun is a variable star!  Stars are a delicate balance between the gravitational forces trying to make it contract and the radiation pressure (caused by the nuclear reactions in the stars interior) which is trying to make it expand.  It is a fact that new stars actually "bounce" for several million years as an equilibrium is found between the two forces.  We have known for a very long time now that the sun goes through cycles, mostly linked to the number of sunspots, and we have recently shown that the solar wind and general solar activity varies on a regular cycle.  However, if we measure the visible output the variation is very small, and unlikely to have any significant effect on our climate.  However, when we measure the very short wave radiation output, the radiation which is responsible for warming the oceans, it has recently been shown that this varies by plus or minus 10%!  This is a huge difference, and more than likely is a big factor in driving some of the changes we are seeing.

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