Another response to a recent blog article here. This one is by Roger Helmer, a member of European Parliament since 1999 and leader of a UKIP delegation. Kudos to Mr. Helmer for taking the time to explain his views in a public forum. He is taking issue with a Guardian article that talks about how “climate science deniers can accept so many ‘impossible things’ all at once”. Mr. Helmer’s article mainly lays out a summary of how he sees the world, with centerpiece claim:
I’m not aware of anyone who rejects the science. But we (clearly I am someone whom the Guardian regards as a “climate denier”) do reject dogmatic interpretations of the science that lead to improbable conclusions.
Helmer starts with some common philosophical musing about how science is never settled. This is naturally correct in the abstract – science is always open to new data, new theory and interpretations – however in the modern contrarian repetition it seems essentially to be used to mean “there aren’t really any such things as scientific facts.” That much leans heavily into an explicitly solipsistic (postmodern?) anti-science and anti-Enlightenment position.
From the point of view of skeptical/rational reasoning, the nuance is captured in biologist Stephen Jay Gould’s comment that
In science, ‘fact’ can only mean ‘confirmed to such a degree that it would be perverse to withhold provisional assent.’
And with respect to rational policy action, arch-skeptical philosopher Bertrand Russell offers:
I am prepared to admit any well-established result of science, not as certainly true, but as sufficiently probable to afford a basis for rational action.
Philosophy aside, it is certainly true that the science of anthropogenic climate change is a mix of highly “settled” topics (e.g. experts are very, very confident in the existence of the radiative greenhouse effect, in the 40% human-caused global increase in the concentration of CO2 in our atmosphere, in observations of total warming of the system, in the fact that there is increased specific humidity as temperature rises which further amplifies the greenhouse effect, and so on) but there are also much more open topics of interest such as the true extent of anthropogenic aerosol cooling (to exactly what degree is our slight net browning/shading of the air acting against greenhouse warming?), the full dynamics of polar ice sheets and the speed with which they will melt, the full extent of ‘feedback’ effects such as whether cloud response to temperature & humidity changes will accelerate or slow warming, and so forth. So the proper question is, which type of scientific question/evidence are climate contrarians such as Mr. Helmer rejecting, when speaking of “improbable conclusions”?
Helmer presses forward with more references to the philosophy of scientific method:
“indeed if a proposition is not falsifiable, it is not science”
Fair enough. Where does he go with this?
We “deniers” note that the world’s average temperature has followed a 1000-year cyclical pattern for at least 10,000 years, and arguably for much longer
(Apologies to the readers who are groaning at this point. I hope from the title it was clear that I was not promising a fascinating scientific dispute.)
So, “1000-year cyclical pattern”. On the face of it, we should be able to test/falsify this claim. We can see if this 1,000 year cyclical pattern shows up in reproductions of past global temperature, which scientists construct by carefully combining different proxy reconstructions, as in the very large Pages 2K effort:
78 researchers from 24 countries, together with many other colleagues, worked for seven years in the PAGES 2k project on the new climate reconstruction … based on 511 climate archives from around the world, from sediments, ice cores, tree rings, corals, stalagmites, pollen or historical documents and measurements (Fig. 1). All data are freely available
Here is a chart with Pages 2K data superimposed with another global reconstruction (Marcott 2013), with the instrumented record tacked on in red.
(You can ignore the modern red spike for our purposes here. Critics complain bitterly about such comparisons, because the modern data has higher resolution than the reconstructions, so they hope modern spikes as we are currently seeing are common and hidden in the past data, though Pages 2K has pretty good resolution on order of a few decades. That argument is generally debunked here and in the referenced/linked statistical tests, but it’s a side topic relative to our subject.)
From the Pages 2K abstract, “The most coherent feature in nearly all of the regional temperature reconstructions is a long-term cooling trend, which ended late in the nineteenth century”.
So, clearly no signs of a 1,000 year cycle in that long-term cooling trend. Nor are there any in the data going further back. The only cycles we see on (much) larger timeframes are the ‘ice age’ glaciation cycles themselves, which line up with the long, slow changes in earth’s orbital tilt – changes which are much too slow to explain the rapid global warming of the past ~150 years.
We can therefore say that Helmer’s claim is falsified. If someone disagrees, perhaps they can rephrase the claim in a way which is falsifiable, to meet the criteria for science that Helmer himself has laid out for us.
No one denies that CO2 is a greenhouse gas. But we do question the dogmatic assumption that the world’s complex and chaotic climate system can be reduced to a single variable. Even the IPCC identifies many factors that impact on the global climate (like solar changes and volcanoes), before deciding that perhaps CO2 is the only one that merits its attention.
More commonplace fallacious shenanigans here. First Helmer cues up a straw man – “we question the assumption that the world’s complex and chaotic climate system can be reduced to a single variable”. Who, pray tell, assumes this? Helmer immediately concedes that “even” the IPCC summary of climate science discusses lots of factors. But apparently they “decide” that CO2 merits special attention. So why do they “decide” that?
Well, here’s the IPCC’s latest “radiative forcing” chart. This is a chart which shows current estimates of the influence of different factors on earth’s energy budget – the balance between incoming and outgoing energy (radiation) which determines the total energy in the system and therefore global temperature – based on applied physics and measurements, in watts per square meter of energy influence (bars to the right are adding that much energy to the amount retained in the system).
Notice the tiny bar at the bottom representing “changes in solar irradiance”. The key question is not whether a natural factor like the sun is important – of course it is, as it essentially supplies all the heat we experience on earth. But for climate change the question is which factors are currently changing aggressively, so as to explain the similarly aggressive change in global temperatures. It happens natural factors like volcanos and the sun have not undergone particularly major changes in the last 150 years, compared to the large changes in greenhouse gases.
Looking at this chart, does it seem like the IPCC (and climate science generally) has arbitrarily decided to look at the role of CO2? (Note that the chart also shows significant warming factors in the anthropogenic increase in methane and other gases as well.)
So, if we charitably interpret Helmer’s comments, the best we can say is that he disputes the sources of these estimates for physical energy influences (though he offers no argument why.) On what foundation of physical theory are these sorts of estimates for, say, CO2 based? It happens that the changes to outgoing longwave radiation (“earth’s body heat”) that result from a change in concentration of a greenhouse gas like CO2 are essentially exactly accurately predicted by the calculations of infrared radiative transfer theory and modern atmospheric physics, worked out more than half a century ago by such wild-eyed activists as the US Office of Naval Research in 1945. Consider Figure 3 in this paper, for example. Note how real science actually passes exactly the sort of falsifiability tests Helmer claims to value.
Alright. So far, Helmer has not had much luck highlighting errors in the mainstream view in defense of his “questioning”. He turns to another popular internet contrarian claim:
We note also that the standard IPCC position involves large numbers of computer models of global temperature which have persistently and grossly over-estimated future temperatures
While inaccurate, this is probably the most successful talking point (in political terms) circulated by climate contrarians. It is usually backed by an infamous, misleadingly constructed chart, and the spin is rooted in the fact that surface temperatures are highly influenced by multi-year weather patterns, chiefly El Nino (ENSO), which (for our purposes here) temporarily varies the amount of heat that is circulating on the surface vs. that which is buried more deeply in the ocean. ENSO-type circulation patterns cannot be predicted very far in advance, so unfortunately scientists are only able to evaluate surface warming projections on multi-decade timeframes. This creates space for contrarians to exploit this complexity – to look at shorter periods and claim disagreement between observations and projections.
To start, the first test of physical climate theory is to look at the total energy budget and therefore the big dog, the ocean, where something like 93% of heat accumulation is expected to happen under global warming. As discussed some in this post, according to the data we have (enhanced in particular by the worldwide network of diving ARGO buoys deployed starting in 2000), the ocean is warming rather consistently with theory. Here’s one comparison, from Cheng et al 2015 published last year:
Helmer’s claim that models of global temperature have “persistently and grossly over-estimated future temperatures” is not accurate when looking at the very largest picture of total energy accumulation. So we’re not plausibly in the neighborhood of questioning the fundamentals of global warming. But is his claim true when looking at the surface record?
The IPCC summary is that:
Over the 62-year period 1951–2012, observed and CMIP5 ensemble-mean trends agree to within 0.02°C per decade (Box 9.2 Figure 1c; CMIP5 ensemble-mean trend 0.13°C per decade). There is hence very high confidence that the CMIP5 models show long-term GMST trends consistent with observations, despite the disagreement over the most recent 15-year period
So, no – 0.02°C per decade agreement seems pretty good, when we are worried about 2-3°C total warming getting added on in this century to the ~1° we’ve already warmed. Here is how the projections made from simulations done around 2003 look like they are playing out, courtesy NASA:
Observations are currently running above the mean of projections, and have remained within the 95% confidence range. (The contrarian argument is based on artfully looking at periods of flatter trends, like the unexpectedly pronounced one seen from 1998 to 2013, which mostly ran below the projected mean. This was due in part to a longer run with lower frequency/strength El Nino events relative to the giant 1998 El Nino. Note that the big El Nino events in 1998 and 2015 are measured (by all indices) to be pretty comparable in terms of scale, yet the peak global temperature in the 2016 event was around 0.4°C warmer according to GISTEMP – a fun point to ask “no surface warming” contrarians to try to explain – they won’t.)
What do published, peer-reviewed scientific assessments of climate models say about their skill?
models have skillfully simulated many large-scale aspects of observed climate changes, including but not limited to the evolution of the global mean surface air temperature in the 20th century
coupled models have been steadily improving over time and that the best models are converging toward a level of accuracy that is similar to observation-based analyses of the atmosphere
global temperature continues to increase in good agreement with the best estimates of the IPCC
The claim that climate models systematically overestimate the response to radiative forcing from increasing greenhouse gas concentrations therefore seems to be unfounded
A pretty different picture from that assumed on political and contrarian blogs.
Helmer rushes through some additional common internet myths:
Warmists cheerfully assume that rising CO2 levels over the last century are solely the result of anthropogenic emissions. They could equally be the result of cyclical warming and out-gassing from the oceans.
Here, he is rejecting very well-established evidence of the human source of the CO2 increase via multiple lines of evidence, some of them technical including isotope analysis (decreasing atmospheric C13/C12 carbon isotope indicates burning of sequestered fossilized carbon vs. that from the oceans) and including some common sense arguments. First, simply look at when atmospheric CO2 levels rose compared to when human CO2 emissions started to rise, and try to convince yourself the parallel is a coincidence:
Secondly, you can do the math and show that estimates of total CO2 burned so far by humans (fossil fuels being a well-tracked economic commodity) exceed the total increase found in the atmosphere. So if you think there is another source besides humans, you also get to try to explain where all of the CO2 emitted by humans went.
We recall that in geo-historical terms, the current level of atmospheric CO2 at around 400 ppm is very low – the level has been at least ten times higher, maybe fifteen times, in the remote past, and those periods were not associated with “runaway global warming”
Arbitrary subjective comments (“400 ppm is very low” – for what? the core source of impact is the rate of climate change compared to what our geologically young civilization is used to) plus another straw man – “runaway” warming is not the concern being raised by scientists, except in the sense that the warming and sea level rise has enormous inertia and will not stop for decades/centuries even after we are able to flatten or reduce emissions.
We “deniers” even know enough about climate science to be aware that the warming effect of atmospheric CO2 is non-linear — it follows a law of diminishing returns. It takes a doubling of CO2 to produce a given temperature impact
Congratulations on what you “even know”, but this is a case of taking a known fact and implying it fits some contrarian narrative about why things aren’t as bad as they say. It happens that this fact is fully incorporated into all of the mainstream/IPCC projections and mitigation analyses (as Helmer seems actually to be aware). So far human emission increases have been quite a bit faster than linear.
The IPCC offers a range of estimates [for degrees warming per doubling of CO2] from 1.5oC to 4.5oC – an enormous variation. A factor of three.
Also true – this is the total uncertainty around feedbacks that I mentioned above, i.e. the ways in which a warming climate results in effects which can cause additional warming and compound the problem (“positive” feedback means enhanced warming, like the loss of arctic sea ice allowing more sunlight to be absorbed by the ocean vs. reflected).
The wide spread here results from a range of estimates derived from three main lines of inquiry (paleoclimate-based estimates, modern observation-based estimates, and model-based estimates, all with pros and cons.) Note that this entire range indicates that the total feedback effects in the system are almost certainly positive (enhancing warming), as CO2 on its own only drives about 1.2°C warming per doubling.
Some climate scientists believe that the actual value may be even lower, and the gross over-estimates of computer-based temperature projections lend credence to that view.
Well we know this much is not true, per above, as the “gross over-estimates” are invented.
It is simply absurd that the Paris Climate Conference proposes “a limit of 2oC on global warming”, and argues between 2o and 1.5o, when the official climate science body, the IPCC, offers such a huge range of uncertainty on climate sensitivity. Its forecasts become virtually meaningless.
Helmer could try to support this, by showing the difference in timeframe between when thresholds like 2°C are reached under different feedback scenarios. In practice, he’d find that it is a matter of decades. In other words, it is not absurd to look at a range of scenarios in making rational policy decisions. As we are politically challenged to address emission growth at all, what the feedback range means in practice is that we must hope it is on the low end, as we have a chance of significantly limiting costly impact there. If the reality is very high in the spread, we likely do not (i.e. we’re probably just f’d). As the American Geophysical Union says in their statement on the subject (below), “no uncertainties are known that could make the impacts of climate change inconsequential.”
Add to this the effect of both positive and negative feed-back effects, which are not at all well-understood, and the uncertainty becomes overwhelming
Here Helmer is just confused on the basic concept – the uncertainty around “degrees warming per doubling of CO2” discussed above is the uncertainty around total positive and negative feedback effects. So he is “adding” the same uncertainty twice, to make it sound worse.
How does this all tally up? While in some cases Helmer is just trying to spin things with smoke and hand-waving, in many cases he clearly makes assertions that directly contradict well-established and validated scientific evidence and theory. So, the response to Helmer’s claim that “I’m not aware of anyone who rejects the science” must be that in fact, he does, namely himself. In other words
Yes, Mr. Helmer, you do reject the science of anthropogenic warming.
He concludes with an appeal to authority:
I personally lean to the view of distinguished American atmospheric physicist Fred Singer that “if there is a signal from anthropogenic CO2 emissions, it is lost in the noise of other factors”
… to a well-known climate contrarian. If you believe grumpy physicists with outlier opinions must have well-informed criticisms of climate science, I have a longer post here on that particular topic, and a similar one could be written for Fred Singer. And if you want to know what atmospheric physicists think, you could of course listen to a very long list of experts with stronger reputations as well as mainstream organizations such as the National Center for Atmospheric Research (NCAR), the National Oceanic and Atmospheric Administration (NOAA), or the American Physical Society.
At this point, everyone is probably aware that contrarians bristle mightily at such mentions of the overwhelming consensus among the world’s top experts in the field and among top scientists globally. Helmer gets into this with some hand-wringing about “97% of publishing climate experts” type references:
Yet the Guardian is still repeating the “97% consensus” myth which has been comprehensively debunked
The core finding that high numbers of highly-published experts (or papers) on climate science support the claim of anthropogenic warming has been reproduced in a long series of surveys, but contrarians love to argue about this (generally much more than they like to talk about physical evidence – watch for that in comments sections), usually claiming that papers that don’t address the topic one way or another must be counted as a vote for “uncertain”, which ends up being not a particularly productive discussion.
I personally think it is simpler to just point out that literally every national academy of science, every national science agency, and every private association of physical scientists across a range of disciplines (physics, geophysics, geology, oceanography, statistics, meteorology, biology etc.), all over the world, endorse the mainstream view on anthropogenic warming. Just to cite a few representative examples:
Humanity is the major influence on the global climate change observed over the past 50 years. Rapid societal responses can significantly lessen negative outcomes… While important scientific uncertainties remain as to which particular impacts will be experienced where, no uncertainties are known that could make the impacts of climate change inconsequential. Furthermore, surprise outcomes, such as the unexpectedly rapid loss of Arctic summer sea ice, may entail even more dramatic changes than anticipated.
There is unequivocal evidence that Earth’s lower atmosphere, ocean, and land surface are warming… The dominant cause of the warming since the 1950s is human activities. … Avoiding this future warming will require a large and rapid reduction in global greenhouse gas emissions.
The EFG recognizes the work of the IPCC and other organizations, and subscribes to the major findings that climate change is happening, is predominantly caused by anthropogenic emissions of CO2, and poses a significant threat to human civilization.
The American Institute of Biological Sciences (AIBS) and other leading scientific organizations have reaffirmed the scientific consensus that climate change is occurring and is primarily caused by human activities… The impact of climate change on natural resources and biological systems will be profound.
The scientific understanding of climate change is now sufficiently clear to justify nations taking prompt action. It is vital that all nations identify cost-effective steps that they can take now, to contribute to substantial and long-term reduction in net global greenhouse gas emissions.
– Joint science academies’ statement from the National Academy of Sciences, United States of America, Royal Society, United Kingdom, Academié des Sciences, France, Russian Academy of Sciences, Russia, Chinese Academy of Sciences, China, Indian National Science Academy, India, Science Council of Japan, Japan, Royal Society of Canada, Canada, Deutsche Akademie der Naturforscher Leopoldina, Germany, Academia Brasiliera de Ciências Brazil and Accademia dei Lincei, Italy
It is not surprising, naturally, that contrarians do not like to be reminded of all this. Of course, such overwhelming consensus is not “proof” on its own, nor is it claimed to be. But pretending there is no consensus on important core points regarding anthropogenic warming is sheer emotional, willful denial of reality.
This actual, widespread rejection of mainstream scientific views is a rather significant development for our respective nations, both with rich traditions of scientifically enlightened governance and deep roots in the Enlightenment tradition.
In the U.S., the National Academy of Sciences is a private, autonomous organization set up by Abraham Lincoln in 1863 to advise the nation on critical questions of scientific policy, consistent with the founders’ vision of a nation where “A people who mean to be their own governors, must arm themselves with the power knowledge gives” (Madison). Members are elected in recognition of distinguished and continuing achievements in original research, still considered one of the highest honors in science. The UK Royal Society plays a similar role, founded in 1660, once chaired by Isaac Newton, and is possibly the oldest scientific society in existence.
That the major conservative political parties in both countries now roundly reject the opinions of both NAS and the Royal Society respectively – and the scientific evidence which supports the consensus view they endorse (see their joint report here) – marks a major fork in the road for both countries.
What is at stake? Helmer waves his hands briefly at the question of impact, referring placidly to CO2 greening:
In fact the current increase in atmospheric CO2 is greening the planet, promoting plant growth, bio-mass formation and crop yields
which while much overhyped is in fact one of the (few) positive impacts we can hope to see, but conveniently ignores the actual complexity of total climate change impacts to agriculture and ecosystems. The IPCC summary on impacts notes, for example:
Based on many studies covering a wide range of regions and crops, negative impacts of climate change on crop yields have been more common than positive impacts (high confidence)
Besides the obvious larger threats such as losing large portions of the world’s major coastal cities to storm surge and inundation over time, and all of the other uncertainties in terms of drought and storms as the planet’s climate transforms, it is not hard to note more serious negative impacts right in front of our eyes today. Here in 2016 alone we’re observing mass die-offs in the world’s coral reefs due to thermal-stress – 22% or more mortality of the entire Great Barrier Reef in one season, part of an ongoing decline of more than half of total reef cover there since 1985, with the IPCC summary view concluding:
Coral reefs within CBS, SES, and STG are rapidly declining as a result of local stressors (i.e. coastal pollution, overexploitation) and climate change (high confidence). Elevated sea temperatures drive impacts such as mass coral bleaching and mortality (very high confidence), with an analysis of the Coupled Model Intercomparison Project Phase 5 (CMIP5) ensemble projecting the loss of coral reefs from most sites globally by 2050 under mid to high rates of ocean warming (very likely)
Not everyone gets the chance to live in times where changes of this magnitude are under way, and decisions of such impact face our fractious civilization as a whole. In contradiction to Mr. Helmer, I’m afraid one of the most fundamental questions before us does in fact appear to be the simple question of whether our nations accept – or reject – scientific evidence and understanding as a sound basis for informing such decisions.