Global Warming: Causality vs. Timeframes
The weather channel wetter-online pointed me to the latest global temperature anomalies which made me think about this post. Everybody knows that worldwide temperatures are rising. Rising as well does the concentration of CO2, which is literally fueled by burning fossil fuels. Ok, here goes the proof that rising CO2 levels correspond to rising temperatures:
As CO2 is the “most famous” greenhouse gas and thus causes temperatures to rise, the whole thing fits – at least for the timeframe we are looking at, which is 1970 to 2000. (OK, putting the two quantities on selected separate scales is a bit cheesy, but this is how media will sell these topics to us …)
Looking at the temperatures from 1880 to 2013 alone, gives rise to new questions when we look at the last decade:
Looking at the smoothing spline for the monthly data, we see that global warming has stalled for almost a decade now – temperatures even seem to fall slightly.
From the first plot we know that CO2 concentration rises steadily, even in the last decade. So let’s take a look at the correlation between global temperatures and CO2 concentration.
A simple linear regression for the years 1953 to 2003 (red dots) supports the causal relationship, and is supported with an R2 of 0,61. Temperatures rose roughly 0.01 degrees centigrade per 1 ppmv. This was an easy to use model, which leads to apocalyptic temperatures when being projected some decades to the future, as CO2 concentration rises roughly 2ppmv per year right now.
Looking at the timeframe of 2003 to 2013 (green dots), the linear trend is slightly negative with an R2 of 0,005, which leads to the conclusion that CO2 does not really have an influence on the global temperatures right now. Brushing over an arbitrary decade shows, that this change is really unique since the mid 60s:
But what is the conclusion now? Is the whole CO2 story bogus? The answer is a clear maybe. Doubtlessly, it is stupid to burn the very limited resources of fossil fuels at the rate we are doing right now – especially after fracking became the salvation for all global energy problems. There is no way around using regenerative energy sources which are CO2 neutral and thus are no threat to the climate.
Do we fully understand the changes in global climate? A clear “No”. The timeframes we are looking at for which we have reliable data is so small compared to the timeframe global climate changes occur, that it is hard to derive final conclusions from what happened in the last decades. Nonetheless, we can stop doing stupid thing, and e.g. sell our gas guzzling SUV tomorrow!