Introduction

The arguments for and against Anthropogenic (human caused) Global Warming (AGW) are just too many to be covered here. However, four key arguments will be mounted against the idea that global warming is mostly caused by humans.

The first three arguments will be that the three major drivers of climate change are: the sun, cosmic rays and the earth's movements relative to the sun.

The final argument will be that the long term historical record of earth's climate shows clearly that the sun, cosmic rays and the earth are indeed the big drivers of climate change and global warming (and cooling). It will be also suggested that these three work cumulatively at times.

It's the sun

Many dismiss the role of the sun in climate change. It is a stance that would be laughable if it was not so asinine.

The Sun obviously must play a significant role in ongoing climate change. The sun has variability in terms of movement, size, and output over millions of years and this must effect the earth's climate. For example the sun's magnetic field goes through an eleven year cycle.

Sunspot activity waxes and wanes through cycles as a result. And these have a significant effect on the earth's climate. Rebbeca Lindsay (NASA) suggests that with so much effort being put into the role of AGW, the role of the sun has unfortunately been relegated to being uncontroversial.

While some groups try to play down the role of the sun, others see a much bigger role for the sun. They cite the contemporaneous warming of Mars with the Earth as solid proof of the sun's role.

An important figure in the role of the sun is one Habibullo Abdussamatov, who is the  head of space research at St. Petersburg's Pulkovo Astronomical Observatory in Russia.He suggests the real problem confronting humankind is a global temperature drop. Some astrophysicists point to this phenomenon because of the current quiet period of the sun.

Cosmic rays

Cosmic rays are another key driver of global warming. The suggestion here is that cosmic rays from far deep space play a much larger role in global warming than any man made effects. Of course the level of cosmic rays hitting the earth is supposedly related to the level of the sun's activity and is thus related to the previous point.

Gray reports on findings which suggests the role of cosmic rays in global warming and outlines the process by which this could happen. Scientists link the intensity of the cosmic rays to the level of the sun's magnetic field. When the sun's magnetic field is less active, there is an increase in amount of cosmic rays the penetrate the earth's atmosphere. There is a resultant decrease in earth's cloud cover and, as a result, global cooling would ensue.

It's the earth

The earth itself appears to play a key role in Global warming.

The Russian scientist, Milankovitch studied three aspects of the earths relationship to the sun. These are referred to as eccentricity, obliquity and precession.


In terms of eccentricity, it seems that there is a key oscillation that occurs every 100,000 years. These oscillations appear to correspond to the ice ages that the earth has experienced. The orbit of the earth is of course is elliptical and in mathematics this oscillation is referred to as eccentricity.

Another factor is the variation of the earth's obliquity or tilt of the earth's axis every 41,000 years. This tilt apparently varies between 22° and 24.5°.

Precession involves a change in the direction of earth axis with respect to various fixed stars.This has a period of roughly 26,000 years.

The long term historical record

One problem with the human caused global warming is the very narrow focus on extremely recent history. This site, however, gives a graph of climate change over the last 2 billion years - a rather longer period of time than the usual one or two hundred years discussed in the current literature.

Clearly this graph shows periods in Earth's climate history when things were a good deal hotter and a good deal cooler than they are now.

To conclude

One is confronted by the enormous impacts of the factors mentioned above in driving long term climate change borne out clearly by the historical record. As a result, it is hard not to feel that the current discourse by the IPCC might be somewhat myopic or nearsighted. There are host of other factors that also mitigate against a simplistic concept of Anthropogenic Global Warming (AGW). Not the least is the rising carbon dioxide levels appear to follow global warming rather than precede it.

However, suffice it to say that the big drivers - the sun, cosmic rays, and the earth (and their cumulative action borne out in the historical record) have been outline in this blog.

References

Abdussamatov, H. (2009). The sun defines the climate. Retrieved May 28, 2010, from http://climaterealists.com/index.php?id=4254

Cook, J. (2010).Skeptic arguments and what the science says. Retrieved May 28, 2010 from http://www.skepticalscience.com/argument.php

Global Greenhouse Warming.com. ( n.d.). Definition of global warming. Retrieved May 28, 2010, from http://www.global-greenhouse-warming.com/definition-for-global-warming.html

Gray, R. (2007). Cosmic rays blamed for global warming. Retrieved May 28, 2010 from http://www.telegraph.co.uk/news/worldnews/1542332/Cosmic-rays-blamed-for-global-warming.html

Lindsay, R. (2003). Under a variable sun. Retrieved May 28, 2010 from http://earthobservatory.nasa.gov/Features/VariableSun/

Mewaldt, R. A. (1996). Cosmic Rays. Retrieved May 28, 2010 from http://www.srl.caltech.edu/personnel/dick/cos_encyc.html

Ravilious, K (February 28, 2007). Mars melt hints at solar, not human, cause for warming, scientist says. Retrieved May 28, 2010 from http://news.nationalgeographic.com/news/2007/02/070228-mars-warming.html


Stanford SOLAR Center . (2008). Global warming:What is it? Retrieved May 28, 2010 from http://solar-center.stanford.edu/sun-on-earth/glob-warm.html