David Rose has been talking to David Whitehouse of the GWPF about the reaction to his Mail on Sunday article in which he criticised the global warming hype which we saw at the peak of El Nino warming earlier this year. He seems genuinely astounded by the reaction and one can hardly blame him. We are used to members of the global warming establishment slapping down as ‘unscientific’ any criticism in the popular press of accepted climate change wisdom, but this went a stage further. Not only was the ‘rebuttal’ of Rose’s article impolite and unprofessional, it went so far wide of the mark as to accuse him of stating things he did not say.
The vexed question of how much (or how little) El Nino has contributed to the significant warming which we saw in 2015/16 rumbles on across social media and blogs. Tamino in particular gets seriously stupid about this:
David Rose insists that he doesn’t deny the trend. But he keeps on saying stuff like this:
“Our story showed that these record high temperatures were triggered by naturally occurring but freak conditions caused by El Nino — and not, as had been previously suggested, by the cumulative effects of man-made global warming.”
The record high was due to man-made global warming: it made the latest el Niño peak hotter than it ever got before. But David Rose just denied that the record high was due to man-made global warming. That’s why I call him a denier.
Which brings me to something which I think needs pointing out, and which has not been made very clear, especially by scientists. To state the bleedin’ obvious, in comparison to the aggregate rise in global mean surface temperatures which we have seen since 1850, the contribution from the latest El Nino is modest. Hence Peter Stott tells Carbon Brief:
An estimate of less than 0.1C due to El Niño on 2015 global mean annual mean temperatures is less than 10% of the approximately 1C warming of 2015 relative to pre-industrial levels.
In other words, El Niño contributed “a small amount on top” of the warming greenhouse gases are already causing, says Stott.
Thus we see the origin of the ‘small amount on top’ quote. But when reported in much of the media, this vital context was either left out or blurred, giving the impression that the contribution from ENSO to the short term warming we saw in 2015 (which arguably was singly responsible for pushing that year into significant record territory) was just a small amount on top of the contribution from AGW. The real and significant contribution from El Nino was subtly downplayed as just the icing on the cake. Also, not even the IPCC attributes all post industrial warming to emissions, just most of that from 1950 on. But even accepting this distinction, scientists still maintain that the actual contribution to the record warmth in 2015 was of the order of 0.07C (Gavin’s estimate) to 0.09C. As the 2015 annual mean global temperature was almost 0.2C warmer than the previous ‘warmest year’ (2014), this leaves scientists having to explain how man-made global warming contributed 0.13C to 0.11C to the sudden spike in annual mean global temperatures after 2014; because that is basically what they are implying using the estimates quoted above.
Scientists estimate that the contribution to the annual mean global temperature in 2016 due to El Nino will be 0.2C (roughly the same as it was in 1998). So depending on what the global mean for 2016 comes out at, we may or may not be looking at a similar implied contribution from AGW in 2016.
I’ve tried on Twitter to get answers to this vexed question of how, seemingly, we saw a huge acceleration in the underlying global warming trend in 2015 (and 2016 too probably) over the trend from about 2001 to 2014. It’s clearly nonsense and I did at least get Ken Rice to concede that fact, but no scientist as far as I am aware has explained how the low estimate of El Nino’s contribution to record warmth in 2015 can be reconciled with the huge amount of global warming we saw that year. I get the impression that scientists would rather the question was not asked and that we all just carried on assuming that ‘global warming’ played a ‘big part’ (or will eventually be seen to have played a big part – via the magic of statistical long term trends) in the record warmth of 2015/16, whilst ENSO was just a bit player.
In this respect, if annual mean global temperatures in the next decade or so average out 0.2C or more above 2014, then we can definitely say that global temperatures have ‘stepped up’ and the long term warming trend may be reasserting itself in the data. But AGW science is in more difficulties if that doesn’t happen. As things stand, global temperatures have dropped sharply and 2017 looks like it may be a cool year. How cool is anybody’s guess. All we have at the moment are two very warm years standing head and shoulders above a decade plus series of other less warm years which marked a Pause or slowdown in global warming, and those two very warm years have just happened to coincide with the longest and probably most intense El Nino since NOAA started recording in 1950.