There are a few succinct explanations of the nature of climate change around and I thought it might be nice to spread the word a little bit further. The waters have become so muddy on the issue that we’re getting beyond “the climate isn’t changing,” “it’s just part of a natural cycle” and “even if it’s getting hotter, it’s not a bad thing.”
It’s now strange conspiracy theories of grant money hungry scientists and a complicit media manipulated by huge green companies’ agendas. All of them chasing riches, and some attempting to bring about a new world order.
Sometimes it’s worthwhile to take a step back from the current debate and get back to some fundamentals. Here’s a condensed version of a fairly science-heavy article entitled “The CO2 problem in 6 easy steps” from realclimate.org. It aims to explain why increasing CO2 is a problem without using models:
- There is a natural greenhouse effect. This is illustrated through calculations based on the mean temperature of the earth, the amount of energy arriving at the earth and the fact that the planet is in radiative equilibrium.
- Trace gases contribute to the natural greenhouse effect. Remember high-school chemistry – spectrometry? IR spectra from space show absorption lines associated with CO2, H2O vapour, CH4 etc. The effect of CO2 in the mix has been calculated from these spectra, and it’s significant.
- The trace greenhouse gases have increased markedly due to human emissions. We know CO2 has increased by more than 30% and methane has more than doubled.
- Radiative forcing is a useful diagnostic and can easily be calculated. This one involves some scary maths for the layperson, but the conclusion is that a change in the radiation budget at the top of the atmosphere is a pretty good predictor of future surface temperature change. Read the original article for more detail.
- Climate sensitivity is around 3ºC for a doubling of CO2. By analysing the climate’s response to known forcing changes from the past, it is possible to derive a sensitivity figure of ~3ºC.
- Radiative forcing x climate sensitivity is a significant number. Current forcing from trace gasses implies an equilibrium of around 1.2ºC – since we aren’t there yet (~0.7ºC of warming to date), we’ve still got another 0.5ºC in the pipeline. Additional forcing from additional emissions as per BAU is calculated to result in 2ºC to 5ºC warming – significant, right?
And if you want more information about this stuff, check out “Is Global Warming Still Happening?” and “Empirical evidence that humans are causing global warming” from Skeptical Science.