Since I have recently been dragged into the climate debate I decided to do some of my own research on the subject. I came across this amazing website called www.scepticalscience.com. The site lists climate 172 “denier” statements like “climate’s changed before;” “It’s the sun;” and “Climategate CRU emails suggest conspiracy.” The neat thing about the site is that each “denier” comment has a rebuttal that links to the source of that rebuttal.
I clicked on “There’s no correlation between CO2 and temperature” and here’s some of the info that came up:
Water vapor constitutes about 95% of the earth’s greenhouse gases, 3% is CO2 and 2% is methane. The question is what percentage of that 3% is man-made and is that man-made portion really effecting climate change or is there a natural cycle at play here?
The amount of CO2 is increasing all the time – we just passed a landmark 400 parts per million concentration of atmospheric CO2, up from around 280ppm before the industrial revolution. That’s a 42.8% increase. Greenhouse gases keep the Earth’s surface 54°F warmer than it would be without them. We have added 42% more CO2 but that doesn’t mean the temperature will go up by 42% too?
There are several reasons why. Doubling the amount of CO2 does not double the greenhouse effect. The way the climate reacts is also complex, and it is difficult to separate the effects of natural changes from man-made ones over short periods of time. As the amount of man-made CO2 goes up, temperatures do not rise at the same rate. In fact, although estimates vary the last IPCC report (AR4) described the likely range as between 35.6 and 40.1°Fahrenheit, for double the amount of CO2 compared to pre-industrial levels.
“According to an ongoing temperature analysis conducted by scientists at NASA the average global temperature on Earth has increased by about 1.4°Fahrenheit since 1880. Two-thirds of the warming has occurred since 1975.”
Climate change is happening very quickly compared to changes that occurred in the past: “As the Earth moved out of ice ages over the past million years, the global temperature rose a total of 39.2 to 44.6°Fahrenheit over about 5,000 years. In the past century alone, the temperature climb of 1.4°Fahrenheit is roughly ten times faster than the average rate of ice-age-recovery warming.”
Much has been made of the fact that the rate of surface warming has slowed in the past decade. Yet the physical properties of CO2 and other greenhouse gases cannot change. But if that’s true, where is this heat going? The answer is into the deep oceans.
Before the industrial revolution, the CO2 content in the air remained quite steady for thousands of years. Natural CO2 is not static, however. It is generated by natural processes, and absorbed by others. Natural land and ocean carbon remains roughly in balance and have done so for a long time – and we know this because we can measure historic levels of CO2 in the atmosphere directly in ice cores.
Although our output of 29 gigatons of CO2 is tiny compared to the 750 gigatons moving through the carbon cycle each year, it adds up when more CO2 is released from outside of the natural carbon cycle by burning fossil fuels because the land and ocean cannot absorb the extra CO2. About 40% of this additional CO2 is absorbed. The rest remains in the atmosphere, and as a consequence, atmospheric CO2 is at its highest level in 15 to 20 million years (Tripati 2009). A natural change of 100ppm normally takes 5,000 to 20,000 years. The recent increase of 100ppm has taken just 120 years).
Human CO2 emissions upset the natural balance of the carbon cycle. Man-made CO2 in the atmosphere has increased by a third since the pre-industrial era, creating an artificial forcing of global temperatures which is warming the planet. While fossil-fuel derived CO2 is a very small component of the global carbon cycle, the extra CO2 is cumulative because the natural carbon exchange cannot absorb all the additional CO2.
The level of atmospheric CO2 is building up, the additional CO2 is being produced by burning fossil fuels, and that build up is accelerating.