Could the earth really turn into a scorching hot planet like Venus with surface temperatures around 460 degrees Celsius (860 degrees Fahrenheit)? Is it possible that our greedy burning of fossil fuels could be the trigger? Normally, such absurd questions are not worth the effort to answer, but this leads to the heart of current global warming alarmism; the runaway greenhouse effect.
So, is our fate the same as that of Venus? Before the Live Earth concert, climate crusader Al Gore wrote an article (or advertisement for his concert) for the New York Times in which he stated:
"Consider this tale of two planets. Earth and Venus are almost exactly the same size, and have almost exactly the same amount of carbon. The difference is that most of the carbon on Earth is in the ground ? having been deposited there by various forms of life over the last 600 million years ? and most of the carbon on Venus is in the atmosphere."
"As a result, while the average temperature on Earth is a pleasant 59 degrees, the average temperature on Venus is 867 degrees. True, Venus is closer to the Sun than we are, but the fault is not in our star; Venus is three times hotter on average than Mercury, which is right next to the Sun. It?s the carbon dioxide."
These two simple (minded) paragraphs are actually very interesting because of the logic flow used, but for the purposes of this article we will just look at the major thrust of Mr. Gore?s argument. The major difference between the earth and Venus is the carbon content in the atmosphere and that if we are not careful we could end up like Venus.
Let us start with some basic numbers. The carbon dioxide concentration in the Venusian atmosphere is around 96% . The level of carbon dioxide in the earth?s atmosphere before the industrial revolution was around 0.028% (280ppm) and currently is around 0.038% (380ppm). To drive home the point, Venus has a little over 2,500 times the concentration of carbon dioxide in the atmosphere then does the earth. This despite a 150 years of the industrial revolution.
You may be able to reason from the above information that we are not too close to having an atmosphere like that of Venus, and that no amount of fossil fuel burning will get us there. But here is the real kicker, the small changes in carbon dioxide, so the theory goes, will cause ?positive feedbacks? which will instigate a ?runaway greenhouse effect?, destroying life on earth and turning our delicate blue planet into a Venusian inferno.
So, could a doubling or even a tripling of carbon dioxide in our atmosphere actually cause a runaway greenhouse effect? I guess there is no better place to look than the ever popular United Nation?s Intergovernmental Panel on Climate Change (IPCC). One of the lead authors, David Karoly , pompously stated recently on a ?debate? about climate change that:
"55 million years ago? there was a massive injection of carbon into the atmosphere from geological processes and the temperature rose 20 degrees Celsius or more globally. Much more then we would expect from the increases we are seeing now." (clip starts at 4:50)
For good measure he stated later that 55 million years ago the concentration of carbon in the atmosphere was around 2000ppm and at another period it was around 10 times what it is today. (clip starts at 1:10)
Was there a runaway greenhouse effect then? Did the earth turn into Venus? Despite the best efforts and threats of Al Gore and the well funded environmental NGOs there is no danger of a runaway greenhouse effect.
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