Watts Up With That (WUWT) has a new post by Bob Tisdale called Part 1 – Comments on the UKMO Report about “The Recent Pause in Global Warming”. This post is a comment on one of the new reports released by the UK Met Office. The reports can are described here and the first one is titled Observing changes in the climate system.
Now, I haven’t read the reports in detail, but what I have read seems good – I would say that though, wouldn’t I? Bob’s post is also rather long, so wasn’t going to comment on much. There were two things that caught my eye though. He includes the figure below, which is from the IPCC’s 4th Assessment Report. The top figure is a comparison between the observed global surface temperature anomaly and an ensemble of model means that include anthropogenic and natural forcings. The lower figure is one in which the models only include natural forcings.
Bob then goes on to say
The IPCC wanted the people of the world—and, more importantly, lawmakers—to believe that only manmade greenhouse gases could have explained the warming since the mid-1970s.
This isn’t really a fair representation of what the IPCC concluded on the basis of this figure. What they conclude is that including anthropogenic and natural forcings provide(s) a consistent explanation of the observed temperature record. Models with only natural forcings do not simulate the warming observed over the last three decades. This doesn’t say it has to be anthropogenic, simply that including anthropogenic forcings produces results that are consistent with observations. Leaving out the anthropogenic forcings produces results that – in the last 3 decades – are not. So, it could be something else, but what is it? Also, as I tried to explain in an earlier post today, trying to explain what we’re currently experiencing through natural variability alone is difficult.
The other thing I noticed was that Bob is repeating his normal it’s all because of ENSO events idea. He includes the following figure which shows the global surface temperature anomaly since 1950 and also indicates the time of some kind of climate shift and the times of major El Nino events.
Bob’s interpretation is that the global surface temperature is simply responding to El Nino heating events. I’m sure it does, but as I try to explain in this post, El Nino events cannot really change the equilibrium surface temperature. Consequently any energy released by El Nino events should be lost in a reasonably short time period. The temperature cannot remain enhanced if the equilibrium temperature is unchanged and ENSO events can’t change the equilibrium surface temperature.
Furthermore, what I try to explain in this post is that it’s not unreasonable that the oceans absorb a large fraction of the excess energy. The amount of energy that a particular patch of the surface absorbs will be determined (approximately) by the difference between the incoming flux (from the Sun) and the outgoing flux (based on the surface temperature). On average, I believe, the oceans are likely to have a larger difference than the land and hence typically absorb a bigger fraction of the excess than the land. If so, it seems reasonable, that there might be periods where the surface warming is slow (most of the energy going into the oceans) followed by a sudden jump at a large El Nino event where energy in the oceans is brought to the surface to heat the land and atmosphere. The ENSO events are, therefore, simply providing a mechanism for transferring some of the excess energy through the climate system to eventually heat the atmosphere and land. They, alone, can’t explain the long-term warming trend that is clearly evident in the figure above.
Anyway, that’s my “brief” comment on Bob Tisdale’s review of the first of the Met Office’s recent reports. Sadly, more of the same from Bob and, unless someone can convince me otherwise, another indication that he doesn’t really understand the basics of global warming and the concept of energy conservation.