The Dark Horse podcast recently discussed a paper on climate change and possible causes. The paper suggests that urban heat islands and insufficient consideration of solar variability is interfering with our picture of global climate change. In short, it's quite difficult to say for sure what portion of observed warming may be caused by human activity.
The podcast discussion was great, and I'm planning to peruse the paper when I have time. I'm curious what others think on the subject.
Bigger picture:
- we have no idea what 'normal' climate variation is, on the scale of decades (which is the relevant scale). All data proxies (from before thermometers - eg tree rings and ice cores) are smoothed so that level of detail is lost. Plus they are absolutely awful data. (Plus thermometer data is awful for a ton of reasons...). So there is no basis whatsoever for saying that what's happening now is unnatural.
- what does "global temperature" even mean? It's not the average temp of the earth (which is a 3D sphere containing quite a lot of molten metal!). So it's some definition of "the surface".. ..but which bits? At what altitude? And do yo use a grid? But we don't have a grid of observations so you have to interpolate - and there are a ton of ways to do this. ..and what if you use a different grid? The more you think of it the more stupid and meaningless it is. The only remotely meaningful measure is total energy stored in the oceans - as any temp variation that could affect surface life is going to be driven by this. But nobody is interested in total ocean energy (it is increasing at a tiny rate and doesn't seem obviously to correlate to human activity).
The whole thing is a nonsense as soon as you start thinking critically about it.
Great addition.
Every so often I'll see alarmist graphs that show temperature variation over time, back into the ice age or what have you. Of course, the punchline to those graphs is that there is a sharp upwards curve starting right in the 20th century. That always seems disingenuous to me, because there's no way our temperature data from the ice age is anywhere near as granular as our temperature data today, so putting them on the same graph produces nonsense.
I don't think anyone is denying there is warming observed on a broad scale, at least in some form. There are just too many confounding factors to talk about a "scientific consensus" on what might be the cause of observed change.
Yep - grafting together series with different resolutions is a classic cheap trick, for CO2 as well as temp.
Climate has always changed - so if its warming now thats not odd. The only question is if its warming "unnaturally" and the only "proof" of this comes from these insane models. Its worth looking into that for amusement, they are literally extended weather forecasts.
