It does seem like going over old ground again and again and again. Science deniers keep repeating the same tired denialisms again and again and again. It's happened on two anti-science blogs today, at Judith Curry's blog and at Anthony Watts' blog. Anthony Watts is, I think, trying to argue that because New Orleans is still on the map, then climate science is a hoax. Judith appears to be trying to argue that most (75%) of the warming since 1950 was caused by magic. Okay - I exaggerate a tad, but not much. See if you agree.
The hurricane strawman
The first one is easy to counter, because Anthony Watts does it himself. He builds the strawman that someone said there were going to be more hurricanes so he can knock it down (archived here). Science doesn't say unequivocally whether there are going to be more or less hurricanes and tropical cyclones. It's not been resolved what will happen as global warming kicks in.
There was a paper in PNAS a couple of years ago by Kerry Emanuel, in which he wrote:
An increase in global mean frequency during roughly the first three quarters of the 21st century is indicated, with a total increase in the range of 10-40%. ... most of the increase in frequency is in the North Pacific, but with substantial increases in the North Atlantic and South Indian oceans as well. The only coastal region that experiences a substantial decline in track crossings is the southeast coast of Australia.
In that same paper, he also wrote that it will take some time to be more definitive about what is going to happen:
The differences between our results, those arrived at by applying the same technique to CMIP3 models, and the conclusions of other groups using different models and/or using different methods suggest that projections of the response of tropical cyclones to projected climate change will remain uncertain for some time to come.
In any case, Anthony Watts didn't bother with scientific papers. He cites news reporters as making any sort of claim with regard to frequency. And even then he restricts himself to hurricanes that make landfall in the USA. And even then at least one quote is about "more severe storms through the end of the century", which Anthony Watts seems to think is now - getting ahead of himself by 85 years. (Not to mention Haiyan, Yasi, Sandy etc and the fact that just because conditions don't favour hurricanes in the Atlantic right now, notwithstanding tropical storm Erika, the "Western Pacific Tropical Cyclone Activity Sees Record Year to Date".)
Deniers do have a tendency to make up stuff about "what the science says" so that they can knock it down. It's a logical fallacy of the strawman type, and is Telltale Technique No. 2 of climate science denial. Anthony doesn't even bother saying what more or less hurricanes mean in regard to global warming. Nor does he discuss severity vs frequency. One can speculate that the message he is trying to convey is that there has only been Hurricane Sandy to rival Katrina in the past ten years in terms of damage in the USA, therefore climate science is a hoax. Pretty dumb, hey?
Update: I just noticed this in the news bits at the bottom of the page. An article in Time, explaining why global warming will make hurricanes worse - even if they don't get any fiercer (which they probably will). It's because of rising sea levels. (Added 1:50 am 29/08/15.)
Humans are causing global warming
Next comes denier Judith Curry (archived here). She is disputing the cause of global warming, (as well as trying to play down the fact that almost all scientific papers that attribute a cause to warming, say its because of human activities). She's turning (or turned) into an utter nutter denier.
To see how much the earth has warmed since surface temperature records were widespread enough for estimations, here is a chart showing GISTemp, and how the global mean surface temperature has risen by more than 0.8 °C over the average for the entirety of last century:
|Data source: GISS NASA|
The IPCC AR5 Summary for Policy Makers states that it is likely that all the warming since 1950 can be attributed to human activity, stating of the period since 1950 that:
The best estimate of the human induced contribution to warming is similar to the observed warming over this period.And more specifically, in Chapter 10 of the IPCC AR5 WG1 report:
Based on the well constrained attributable anthropogenic trends shown in Figure 10.4 we assess that anthropogenic forcings likely contributed 0.6°C–0.8°C to the observed warming over the 1951–2010 period (Figure 10.5).
|Figure 10.5: Assessed likely ranges (whiskers) and their mid-points (bars) for attributable warming trends over the 1951–2010 period due to well-mixed greenhouse gases (GHG), other anthropogenic forings (OA), natural forcings (NAT), combined anthropogenic forcings (ANT), and internal variability. The HadCRUT4 observations are shown in black with the 5–95% uncertainty range due to observational uncertainty in this record (Morice et al., 2012). Source: IPCC AR5 WG1|
The uncertainty around the contribution of greenhouse gases and "other anthropogenic forcings" are the largest. But the greenhouse gas forcing is far from negative. None of this is new. Climate scientists know that the world is warming because of human activity. Well most of them do. It's only deniers that dispute that, but they have nothing to replace it with.
Judith Curry: "magic" caused global warming?
Judith Curry in a comment to her latest blog article, said that she thinks that only 50% +/- 25% of the rise in global mean surface temperature since the mid-twentieth century can be attributed to human activity.
Look at that.
I've looked at Judith's low end estimate of 25% and tried to work out what she thinks could have caused the other 75% of warming. She hasn't said. In the shaded rectangle is what Judith thinks might not have been caused by human activity:
|Data source: GISS NASA|
Even the highest temperatures of the Holocene took a heck of a lot longer than six decades to reach the maximum. There's nothing that could explain the sudden dramatic increase in global surface temperature other than the rapid increase in greenhouse gases.
Judith doesn't say what she thinks caused the other 75% to 25%, nor where she got her numbers from. Nor does she explain why she's got that huge, gigantic margin around her wild guess. In other words, we can take it that what she wrote wasn't based on any understanding of science. It was a wild guess. A flailing about. No research required. She might as well claim it's between -100% and +100%. Or between none and all.
Do you think perhaps Judith thought for half a second to settle on what she figured might give her an "out" with both scientists and fake sceptics? If so, I'd say she lost. She lost with the scientists because it shows that she doesn't read science. She lost with the fake sceptics because they don't believe that the earth has warmed, let alone that humans had any hand in it.
Since Judith isn't inclined to offer any evidence or even a hypothesis for the number, which I'll make my own wild guess was plucked out of thin air, I figure I'll try some myself.
- Little ice age bounce = magic
- Stadium wave bounce = magic
- The sun - except that there's been no increase in solar irradiance
- The moon - except that it's never affected surface temperature before
- Cosmic rays - except that nothing's changed to make them cause any change in surface temperature
- Volcanoes - if anything they cause a short term cooling. And there's been no known increase in CO2 from volcanoes. (This can be measured.)
- Warmth coming out of the ocean by magic or internal variability, such as the Atlantic multidecadal oscillation or the Pacific decadal oscillation. See below:
Think about it for a moment. If 75% of the warming was from some sort of oceanic oscillation, then how is it that the temperature has risen so much so quickly? It doesn't make sense. If it was from the Atlantic or the Pacific sending warmer water to the surface, then
- where is that warm water supposed to have come from and how did it get so hot?
- why is it so much hotter than it was the last time the AMO was positive?
- how did the world stay so warm when the PDO was in its cool phase recently?
I've written before about work that shows that the AMO doesn't contribute a lot to global surface temperature fluctuations - here and here. And the PDO is probably just coming out of a cool phase. If warming was caused by "natural" oscillations in the Pacific ocean, then it should have cooled the world recently. Instead it continues to get warmer.
Deniers don't have a coherent message
I'd have thought that deniers might have tried to come up with some consistent "denial" message in preparation for the Paris talks later this year. You know, like tossing snowballs on the floor of the UN building and claiming that it's proof that an ice age is coming. Instead they are just re-hashing inconsistent old denier memes that don't make any sense. And showing how they don't read science.
They've still got time, I suppose, to steal some more emails and distort them in a re-hash of the CRU theft. Or maybe they've given up and have decided to drop any pretence at being rational human beings. When you've got Judith Curry favouring a denier blogger over thousands of scientific papers, it's a fairly good sign that she's given up. Anthony Watts is not showing any creativity either. He never has.
References and further reading
Emanuel, Kerry A. "Downscaling CMIP5 climate models shows increased tropical cyclone activity over the 21st century." Proceedings of the National Academy of Sciences 110, no. 30 (2013): 12219-12224. doi: 10.1073/pnas.1301293110 (open access)
- Tropical Cyclones - More and More Often - HotWhopper article about the above
- Why Climate Change Could Make Hurricane Impact Worse - article by Justin Worland in Time
From the HotWhopper archives