Have you done the same equation for 1998–2015?
Nope. An accurate estimate can’t be done over short timescales, partly because (if my understanding is correct — grain of salt here) it has been determined using experiments on models that natural internal variability can cause short-term temperature trends lasting at most 16 years. Thus, a temperature trend over a period of only 17 years might be unduly influenced by internal variability. And if you look over the temperature records of the past century you can clearly see several large short-term variations. That’s why I like to use a 15-year moving average to get an accurate impression of the long-term trend:
Also, since 2000, higher-than-average volcanic activity, lower solar irradiance, and more aerosols were released (e.g. remember how smoggy Beijing is) during the “hiatus” than models assumed. I say “assumed” since solar output and volcanic activity are not predictable, while human pollution is difficult to predict. All three of these factors had a (temporary) cooling effect, so failing to consider these factors would cause us to underestimate the effect of CO2.
A longer period of at least 30 years provides a better estimate. However, 40 years would probably give us an overestimate due to aerosol dissipation in the late 1970s. And then there’s the PDO cycle. PDO probably has a quite small effect on the global scale, but it had a 60-year observed period and therefore a 60-year time period such as 1950–2010 is ideal to largely eliminate any effect it might have.
And are you comforted by the fact that it took 60 years to go 25%, and the next 25% increase will likely take even longer?
What comforts me is the fact that — despite anti-sustainability efforts — solar energy dropped in price faster than anyone expected, and it’s now cheaper than coal in equatorial climates. Based on well-known economic principles I think its price is certain to drop significantly further. Also, I love these LFTR and SM-MSRs, which would make it easy to switch to clean energy in northern climates. Unfortunately liberals aren’t too keen on nuclear energy due to overblown fears, and conservatives tend not to support them because they don’t think AGW is a real problem (or maybe because they don’t love new technology like I do?).
But hypothetically, if we don’t switch to clean energy in a big way, I think another 25% increase will happen in a shorter, not longer time, since emissions have been rising exponentially (largely thanks to our new one-hump world) and, as I discussed, climate scientists believe natural carbon sinks will probably begin to slow down their absorption of CO2.
Also remember that if the ocean somehow speeds up its absorption, that would also be a bad thing — some would argue even worse.
Btw I’m not sure if you saw the original replies that this “addendum” is based on, and since the guy I was responding to basically seems to have ignored what I said, it would be nice if you had a look instead :)
You’ve raised numerous points which we can talk about later. But first let’s talk temperature data, because once again…medium.com
1) You have to be able to predict CO2 levels as huge — which means making gross assumptions about technology that is…medium.com
This guy John seems unable to separate different issues — scientists must be able to reason about single issues in isolation, but John can’t or won’t. Everything he writes involves conflating different issues and it usually comes out as a Gish Gallop. Also, he seems to do everything with qualitative rough estimates instead of quantitatively, which can be misleading if abused. For instance if you round off and multiply the numbers 33, 22, 14, you get a much different result than if you multiplied them properly, and a similar sort of systematic “rounding” effect pervades his analysis (he consistently underestimates observations while consistently overstating climatologists’ predictions).