Global warming caused by Humans is referred to as Anthropomorphic Global Warming.

Although there is strong and increasing evidence that the world is warming up rapidly on average, proving that it is caused by us is much more difficult.

Natural Cycles

The temperature of the Earth certainly varies.  The variations are not just random; there are also world wide fluctuations with time.

Greenhouse Gases

There is little dispute about the physics of atmospheric warming because of greenhouse gases.  In fact if there were no greenhouse effect, our Earth would be about 30 degrees C colder than it is and life would be very difficult.  The Earth is not the only planet with a significant greenhouse effect.  The strongest one is on Venus where the temperature is hotter than the planet Mercury, despite being further from the Sun.  Titan (Saturn’s Moon) also has a strong greenhouse effect.

There is also not much dispute that our activities have increased the amount of several greenhouse gases in the air.

What there is much more doubt about is how much real difference this rise in greenhouse gases has.

Is the increase in global temperatures caused by the increase in greenhouse gases?  I and millions of other scientifically trained people have been examining the evidence.  The following is my interpretation.  Not everyone would agree.

Ice AgePrevented

Based on geological evidence, the carbon dioxide level of the atmosphere should have been about 240 Parts per Million (ppm).  We should also be at the start of an ice age.  The start of an ice age seems to be when the northern parts of Europe, Asia and North America stay covered in snow over one summer.  When this happens a much greater percentage of the sun’s heat and light is reflected back into space.

Human activities such as burning vegetation for farming and hunting, keeping ruminant animals, draining swamps and growing Rice raised the level of carbon dioxide to 280 ppm and maybe methane was increased as well, and prevented the first stage of a new ice age.  The snow melted each summer.  

Industrial Revolution

So by the start of the industrial revolution the carbon dioxide level was 280 ppm instead of 240 ppm.  Once much greater burning of coal and later other fossil fuels commenced the carbon dioxide level rose.  Now it is about 392 ppm (June 2010).  The methane level rose from about 700 Parts Per Billion (ppb) at the start of the industrial revolution to about 1788 ppb (2008).  Nitrous oxide also increased, and some basically man made greenhouse gases were released.  The total effect of these has been to increase the average temperature of the Earth.

The hottest decade ever recorded was the 1980’s.  Then this record was broken by the 1990’s.  Now this record has been broken again and the most recent decade was the hottest yet.

Prediction

I will make the obvious prediction for 2010-2019:

The next decade will be the hottest ever recorded.