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What lies beneath? The scientific understatement of climate risks

Brad H

Hi David (Klein),

I'm hoping you might respond to a couple of issues while reading the article and the report it refers to below? There has been much discussion of the "conservative" nature of the maintream scientific bodies in accurately portraying the urgency of the climate situation, particularly, in regards to non-linear, abrupt climate change. David Spratt and Ian Dunlop argue that there is a historic reticence on the part of the IPCC "to spell out the full risk implications of climate science in the absence of perfect information." The Report, they say "seeks to alert the wider community and leaders to these limitations and urges change to the IPCC approach, and to the wider UNFCCC negotiations." David, you have defended the IPCC in its approaches in the past while enlightening readers on the inside processes of the IPCC. Could you respond to Spratt and Dunlop's claims and recommendations? Thanks! Brad

What lies beneath? The scientific understatement of climate risks

By David Spratt and Ian Dunlop
This blog is the Introduction to What Lies Beneath: The scientific understatement of climate risks, published today by Breakthrough, the National Centre for Climate Restoration.

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Three decades ago, when serious debate on human-induced climate change began at the global level, a great deal of statesmanship was on display. There was a preparedness to recognise that this was an issue transcending nation states, ideologies and political parties which had to be addressed proactively in the long-term interests of humanity as a whole, even if the existential nature of the risk it posed was far less clear cut than it is today.

As global institutions were established to take up this challenge, such as the UN Framework Convention on Climate Change (UNFCCC) at the Rio Earth Summit in 1992, and the extent of change this would demand of the fossil-fuel-dominated world order became clearer, the forces of resistance began to mobilise. Today, as a consequence, and despite the diplomatic triumph of the 2015 Paris Agreement, the debate around climate change policy has never been more dysfunctional, indeed Orwellian.
In his book 1984, George Orwell describes a double-speak totalitarian state where most of the population accepts “the most flagrant violations of reality, because they never fully grasped the enormity of what was demanded of them, and were not sufficiently interested in public events to notice what was happening. By lack of understanding they remained sane.”

Orwell could have been writing about climate change and policymaking. International agreements talk of limiting global warming to 1.5–2°C, but in reality they set the world on a path of 3–5°C. Goals are reaffirmed, only to be abandoned. Coal is “clean”. Just 1°C of warming is already dangerous, but this cannot be said. The planetary future is hostage to myopic national self-interest. Action is delayed on the assumption that as yet unproven technologies will save the day, decades hence. The risks are existential, but it is “alarmist” to say so. A one-in-two chance of missing a goal is normalised as reasonable.

Climate policymaking for years has been cognitively dissonant, “a flagrant violation of reality”. So it is unsurprising that there is a lack of a understanding amongst the public and elites of the full measure of the climate challenge. Yet most Australians sense where we are heading: three-quarters of Australians see climate change as catastrophic risk, and half see our way of life ending within the next 100 years.

Politics and policymaking have norms: rules and practices, assumptions and boundaries, that constrain and shape them. In recent years, the previous norms of statesmanship and long-term thinking have disappeared, replaced by an obsession with short-term political and commercial advantage Climate policymaking is no exception.

Since 1992, short-term economic interest has trumped environmental and future human needs. The world today emits 48% more carbon dioxide (CO2) from the consumption of energy than it did 25 years ago, and the global economy has more than doubled in size. The UNFCCC strives "to enable economic development to proceed in a sustainable manner”, but every year humanity’s ecological footprint becomes larger and less sustainable. Humanity now requires the biophysical capacity of 1.7 planets annually to survive as it rapidly chews up the natural capital.

A fast, emergency-scale transition to a post-fossil fuel world is absolutely necessary to address climate change. But this is excluded from consideration by policymakers because it is considered to be too disruptive. The orthodoxy is that there is time for an orderly economic transition within the current short-termist political paradigm. Discussion of what would be safe –– less warming that we presently experience –– is non-existent. And so we have a policy failure of epic proportions.

Policymakers, in their magical thinking, imagine a mitigation path of gradual change, to be constructed over many decades in a growing, prosperous world. The world not imagined is the one that now exists: of looming financial instability; of a global crisis of political legitimacy; of a sustainability crisis that extends far beyond climate change to include all the fundamentals of human existence and most significant planetary boundaries (soils, potable water, oceans, the atmosphere, biodiversity, and so on); and of severe global energy sector dislocation.

In anticipation of the upheaval that climate change would impose upon the global order, the Intergovernmental Panel on Climate Change (IPCC), was established by the UN in 1988, charged with regularly assessing the global consensus on climate science as a basis for policymaking. The IPCC Assessment Reports (AR), produced every 5–6 years, play a large part in the public framing of the climate narrative: new reports are a global media event. AR5 was produced in 2013-14, with AR6 due in 2022. The IPCC has done critical, indispensable work of the highest standard in pulling together a periodic consensus of what must be the most exhaustive scientific investigation in world history. It does not carry out its own research, but reviews and collates peer-reviewed material from across the spectrum of this incredibly complex area, identifying key issues and trends for policymaker consideration.

Observed sea-level rise 1970-2010 from tide gauge data (red) and satellite measurements (blue) compared to model projections for 1990-2010 from the IPCC Third Assessment Report (grey band). (Source: The Copenhagen Diagnosis , 2009)
However, the IPCC process suffers from all the dangers of consensus-building in such a wide-ranging and complex arena. For example, IPCC reports, of necessity, do not always contain the latest available information. Consensus-building can lead to “least drama”, lowest-common-denominator outcomes which overlook critical issues. This is particularly the case with the “fat-tails” of probability distributions, that is, the high-impact but relatively low-probability events where scientific knowledge is more limited. Vested interest pressure is acute in all directions; climate denialists accuse the IPCC of alarmism, whereas climate action proponents consider the IPCC to be far too conservative. To cap it all, the IPCC conclusions are subject to intense political oversight before being released, which historically has had the effect of substantially watering-down sound scientific findings.

These limitations are understandable, and arguably were not of overriding importance in the early period of the IPCC. However, as time has progressed, it is now clear that the risks posed by climate change are far greater than previously anticipated. We have moved out of the twilight period of much talk but relatively limited climate impacts. Climate change is now turning nasty, as we have witnessed in 2017 in the USA, South Asia, the Middle East and Europe, with record-breaking heatwaves and wildfires, more intense flooding and more damaging hurricanes.

The distinction between climate science and risk is now the critical issue, for the two are not the same. Scientific reticence — a reluctance to spell out the full risk implications of climate science in the absence of perfect information — has become a major problem. Whilst this is understandable, particularly when scientists are continually criticised by denialists and political apparatchiks for speaking out, it is extremely dangerous given the “fat tail” risks of climate change. Waiting for perfect information, as we are continually urged to do by political and economic elites, means it will be too late to act.

Irreversible, adverse climate change on the global scale now occurring is an existential risk to human civilisation. Many of the world’s top climate scientists quoted in this report well understand these implications — James Hansen, Michael E. Mann, John Schellnhuber, Kevin Anderson, Eric Rignot, Naomi Oreskes, Kevin Trenberth, Michael Oppenheimer, Stefan Rahmstorf and others — and are forthright about their findings, where we are heading, and the limitations of IPCC reports.

This report seeks to alert the wider community and leaders to these limitations and urges change to the IPCC approach, and to the wider UNFCCC negotiations. It is clear that existing processes will not deliver the transformation to a low-carbon world in the limited time now available.

We urgently require a reframing of scientific research within an existential risk-management framework. This requires special precautions that go well beyond conventional risk management. Like an iceberg, there is great danger “In what lies beneath”.
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David Klein

Hi Brad,

Thanks for this important post. Let me make a correction. I have cited research from the IPCC as well as more path breaking research from many of its critics and I've corrected some misinformation about mathematical climate models, but I've never defended the IPCC as you assert (except in other venues from climate deniers). In fact I gave references to forceful criticisms of the IPCC in my book that go back to 2012. Both the political and scientific conservativism of the IPCC were well known before this recent report came out. It is worth pointing out, however, that the IPCC reports, as conservative as they are, do acknowledge predictions of the worst possible threats to human life and the biosphere up to the level of conditions that would result in mass extinction.

In some respects this Breakthrough report does not go far enough. For example it highlights Michael Mann as a critic of IPCC conservativism, but it was Mann who led the charge against Wallace-Wells for his penetrating New York Magazine article, The Uninhabital Earth, which seems to be accurate except for some very minor details (and I said so at the time) .

While Spratt and Dunlop raise some important and valid scientific issues and focus appropriately on risk (rather than solely on probabilities), like most mainstream reporters, they completely omit any discussion of the primary driving force behind ecocide, namely capitalism.

If one wants to resist global warming, there is no more important way than to militate openly against capitalism. The IPCC fails to do this because it serves at the behest of the global ruling class. The world's leading climate scientists, including critics of the IPCC, won't even say the word "capitalism" aloud even though some of them, like Anderson, are starting to recognize that economic growth --- an inexorable feature of capitalism --- is the driver of climate change.

All of this underscores the importance of SCNCC. No other grassroots collection that I know of has been as effective and diligent in publicly identifying capitalism as a failed economic system and as the fundamental source of the climate crisis, and in proposing ecosocialism as an alternative.


Brad H

- FYI article referencing readjustments/correction of bias in models
- important, but one also gets a sense of 'quibbling' in the face of dire urgency to act....

NASA study fixes error in low contrarian climate sensitivity estimates

Some previous studies claiming that the climate is insensitive to carbon pollution missed a key factor

Earth seen from the International Space Station, taken by NASA astronaut Gregory Reid Wiseman from the International Space Station on, 02 September 2014. Photograph: NASA/Reid Wiseman/EPA

Dana Nuccitelli

Tuesday 12 January 2016 11.00 GMT Last modified on Wednesday 22 February 2017 17.58 GMT

Climate sensitivity – the amount of global surface warming we’ll see as a result of rising atmospheric carbon dioxide levels – has become contrarians’ favorite basis to argue against cutting carbon pollution. If the Earth’s climate is relatively insensitive to rising carbon levels, then it’s somewhat less urgent that we stop burning massive quantities of fossil fuels. However, a new NASA study indicates that’s not the case.

There are a few different ways that climate scientists estimate the Earth’s sensitivity to rising carbon. When they look at climate changes in the distant past (paleoclimate), and at simulations from complex climate models, they get about the same result: if the amount of carbon dioxide in the atmosphere doubles, temperatures will rise between 2°C and 4.5°C, most likely 3°C.

However, a few studies in recent years using a third method have yielded somewhat lower results. This method uses recent measurements of temperature and heat changes, combined with estimates of how “forcings” like the increased greenhouse effect have caused the Earth’s energy balance to change, all input into somewhat simpler climate models.

These results caused the latest IPCC report to drop its lower estimate of the likely climate sensitivity to double carbon dioxide from 2°C to 1.5°C. Climate scientists were faced with the question, why did this third approach (known as the “energy budget approach”) yield somewhat lower results than others, and which estimate is right?

A new study by Kate Marvel, Gavin Schmidt, Ron Miller, and Larissa Nazarenko at the NASA Goddard Institute for Space Studies appears to have found the answer. They drew upon previous research by Drew Shindell and Kummer & Dessler, who identified a flaw in studies taking the energy budget approach. Those studies had assumed that the Earth’s climate is equally sensitive to all forcings.

In reality, as world-renowned climate scientist James Hansen noted in a 1997 paper, some forcings are more efficient at causing the Earth’s surface temperature to change than others. Those in which the effects are focused in the northern hemisphere tend to be more efficient, for example. Andrew Dessler explains in the video below.

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Andrew Dessler explains the flaw in studies suggesting climate sensitivity is low.
Drew Shindell first identified this deficiency with these low sensitivity studies in a 2014 paper. Shortly thereafter, Kummer & Dessler published a paper noting that this issue could potentially bring the climate sensitivity estimates from the energy budget method in line with estimates from climate models and paleoclimate studies. This new NASA paper builds upon those previous studies by better quantifying the efficiencies of different forcings over the historical period and the effect this has on energy budget approach climate sensitivity estimates.

The NASA scientists ran climate models using just one forcing at a time – changes in greenhouse gases, aerosol pollution, land use changes, etc. – to see how efficient each is at changing the global surface temperature. As it turns out, forcings that have tended to cause cooling, like increased aerosol pollution, are particularly efficient.

The scientists then repeated the energy budget study approaches incorporating what they learned about the various forcing efficiencies, and found that the previous climate sensitivity estimates were indeed biased low. As the NASA study authors wrote,

Climate sensitivities estimated from recent observations will therefore be biased low in comparison with CO2-only simulations owing to an accident of history

The “accident of history” is that the more efficient forcings happen to be those that have had a cooling effect on temperatures in recent decades, while the less efficient forcings happen to be those that have caused warming. By assuming they were all equally efficient, the previous energy budget studies, for example by Nic Lewis and Judith Curry, biased their climate sensitivity estimates low. The new best estimate puts climate sensitivity right around 3°C warming in response to doubled carbon dioxide levels, in line with estimates from climate models and paleoclimate studies.

Gavin Schmidt provides more detail at RealClimate. He also notes that conservative media outlets like the Daily Express and Daily Mail, and science denial blogs badly misrepresented their study results, as happens all too often.

It’s also important to note that relying solely on the previous energy budget model results is a clear-cut case of cherry picking. That method was the outlier, yielding lower climate sensitivity estimates than other approaches. In fact, there have been a number of recent studies using observed changes in cloud cover, finding that the climate models with the higher sensitivities are those that reproduce the cloud changes most accurately.

Moreover, it’s worth pointing out that even ‘low’ estimates are not that low. As climate scientist Chris Forest noted, if they were correct, “It might buy us five or ten years” to solve the problem. We’re so far behind the carbon pollution cuts needed to avoid dangerous climate change, that extra decade wouldn’t even be enough. Even if the contrarians were right, we would still need to cut carbon pollution rapidly.

However, the NASA study shows that the previous estimates were indeed biased low, and correcting for that bias brings them into agreement with estimates using other approaches. This result makes it all the more urgent that we ratchet down carbon pollution emissions as quickly as possible to curb the risks associated with rapid climate change.