A demo showing our broken climate policy debate

Summary: Progress in the climate policy debate comes too slowly. The use and misuse of RCP8.5 shows why. At this pace, the climate will give final answers before we get a consensus. We can’t afford this.

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In 2015 I gave one of the early critiques of the RCP8.5 scenario. Is our certain fate a coal-burning climate apocalypse? No! And then Manufacturing climate nightmares: misusing science to create horrific predictions (it was the first Dr. Curry saw about the issue). I – and the many who followed – said two easily proven things.

  • The RCP8.5 scenario was a good worst-case scenario, showing what might happen if many things go wrong. It is either unlikely or impossible.
  • The RCP8.5 has been described as the “business as usual” (BAU) scenario and so become the central scenario for both researchers and policy-makers. It is not BAU (see below for details), and should not be the main case for either group.

In most other fields, there would have been debate and then RCP8.5 would have been used only in an appropriate way – as a worst-case scenario. But this is climate science, and five years later the debate continues to chase its tail. But this might be changing.

For an introduction to the RCPs, see “Understanding The Great Climate Science Scenario Debate” by Roger Pielke Jr. (Professor, U CO-Boulder) at Forbes. That these kinds of articles appear the major journals show that climate scientists might be seeing the obvious: “Emissions – the ‘business as usual’ story is misleading” by Zeke Hausfather and Glen P. Peters in Nature – “Stop using the worst-case scenario for climate warming as the most likely outcome; more-realistic baselines make for better policy.” I recommend reading it in full, especially their conclusions.

“A sizeable portion of the literature on climate impacts refers to RCP8.5 as business as usual, implying that it is probable in the absence of stringent climate mitigation. The media then often amplifies this message, sometimes without communicating the nuances. This results in further confusion regarding probable emissions outcomes, because many climate researchers are not familiar with the details of these scenarios in the energy-modelling literature. …

“Happily – and that’s a word we climatologists rarely get to use – the world imagined in RCP8.5 is one that, in our view, becomes increasingly implausible with every passing year. …

“We must all – from physical scientists and climate-impact modellers to communicators and policymakers – stop presenting the worst-case scenario as the most likely one. Overstating the likelihood of extreme climate impacts can make mitigation seem harder than it actually is. This could lead to defeatism, because the problem is perceived as being out of control and unsolvable. Pressingly, it might result in poor planning, whereas a more realistic range of baseline scenarios will strengthen the assessment of climate risk.”

The fun for activists is over when even the BBC runs the headline “Climate change: Worst emissions scenario ‘exceedingly unlikely’.” It took a decade to make this simple point.

The skeptics contribute to the confusion

Many skeptics – both scientists and laypeople – say that RCP8.5 is “bad science” or “impossible.” Both are absurd. The first is easy to dismiss. The RCP’s are well-constructed and part of a decade-long research program. These papers clearly describe some of the many paths by we might get to RCP8.5. They often describe it as a “business as usual” scenario – which it is not.

The second objection is more complex. If it is impossible, then RCP8.5 is not a useful worst-case scenario for researchers and policy-making. It is not impossible. There are many ways to get to a given concentration pathway. We might get to RCP8.5 via inflection points in some long-standing trends (e.g., energy efficiency, population). We might get there by a poorly understood event (i.e., a massive release of methane from melting permafrost) whose probability cannot be estimated at present. We might thereby large emissions of greenhouse gases from burning fossil fuels. We might get there because the strength of carbon cycle feedbacks or a dozen other climate dynamics are worse than currently estimated.

Each of those, in turn, can occur for several reasons. Technological progress could slow. Population growth might be faster than predicted, perhaps because fertility in Africa slowed less than expected. Petroleum might be less than estimated; coal deposits might be less than estimated (they probably are). Either of these would force tapping lower-quality deposits – which would release more CO2.

The worst-case scenario reminds us that bad things happen. Sometimes our luck goes bad and many bad things happen. These rare events make history. Let’s not become history like that.

Many things went wrong to make the Titanic famous

At 11:40 pm on 14 April 1912 the RMS Titanic was on its last voyage. The captain disregarded warnings of icebergs, and ordered steaming at high speed (22 knots) under a dark sky (no moon, no Venus) with no wind (so no waves breaking on the ice).

The lookouts peer ahead, but without binoculars. Second officer David Blair had the key to the locker holding the binoculars. He was transferred off the ship before it left on its maiden voyage from Southampton and accidentally took the key with him.

The lookouts sounded three bells for an object dead ahead. First Officer William Murdoch ordered the rudder “hard astarboard” and the engines “full astern” – intending to steer around the iceberg. That was not the “book” response, and it did not work well. Reversing the engines reduced the flow over the rudder and its effectiveness. Even so, the Titanic almost made it. The hull gently brushed against the ice.  Water entered through 230′ rips where plates buckled and seams opened.

The Californian was close and could have rescued its passengers. Through incredible negligence, it did not do so (its captain was broken for negligence).

The rest is history. All of these things were necessary for the disaster. What were the odds of all these things happening on one voyage?


Well-designed worst-case scenarios are unlikely or impossible. And sometimes they happen. We need to prepare for those. But it is imprudent to bankrupt ourselves to prevent them – or become obsessed with one risk ignore other high-priority needs.

How should we use all these scenarios? There is a large body of knowledge and experience in the field of risk management. Of course they have little role in climate science and climate policy. This is a madness that we can fix by forcing climate science institutions to behave better. That means more science, less politics – as I propose here and here.

Second, we need to understand that we face many serious risks. Allowing activists to focus us on one that find politically useful could be disasterous. We need to allocate our limited funds with a rational awareness of the full spectrum of risks – as I propose here.

Simple and sensible steps can help us steer to a safe and prosperous future. Getting there requires our involvement to make it happen.

For More Information

Ideas! For some shopping ideas see my recommended books and films at Amazon. Also, see a story about our future: Ultra Violence: Tales from Venus.

If you liked this post, like us on Facebook and follow us on Twitter. For more information see The keys to understanding climate change, all posts about coalabout the RCPs, and especially these …

  1. Climate scientists can restart the climate policy debate & win: test the models!
  2. We can end the climate policy wars: demand a test of the models.
  3. Focusing on worst-case climate futures doesn’t work. It shouldn’t work.
  4. Roger Pielke Jr.: the politics of unlikely climate scenarios.
  5. Is climate change an existential threat to humanity?
  6. After 30 years of failed climate politics, let’s try science! – A proposal to break the policy gridlock.
  7. The biggest question: how much will the world warm?
  8. An obvious solution to the climate policy crisis.

Activists don’t want you to read these

Some unexpected good news about polar bears: The Polar Bear Catastrophe That Never Happened by Susan Crockford (2019).

To learn more about the state of climate change see The Rightful Place of Science: Disasters & Climate Change by Roger Pielke Jr., professor for the Center for Science and Policy Research at U of CO – Boulder (2018).

The Rightful Place of Science: Disasters and Climate Change
Available at Amazon.


12 thoughts on “A demo showing our broken climate policy debate”

  1. From the Nature article:

    “Those who are tasked with taking climate action on the basis of information from model scenarios are increasingly calling for a more risk-based approach to help with adaptation and mitigation 14. This approach accounts for the relative likelihood of different outcomes. Controversially, it requires researchers to assign probabilities to scenarios 16. Critics don’t want to do this, because many see it as an arbitrary process. But when specialists refuse to assign probabilities, users often do so themselves. Most do so poorly because they do not have a deep understanding of the assumptions that underpin these scenarios.”

    A better risk approach is something I have pointed out for years. It does have a sociological problem: In the face of unknown risk, because costs are unknown, mitigation is conserving or expanding what you do know. This often translates to saving money. The problem is that, to date, capitalism works best. The uncomfortable knowledge is that we should be encouraging the growth of world wealth, especially in poor countries, now. At this point that means fossil fuel energy since renewable energies, at present, are neither cheap nor dependable.

    I am not optimistic such conclusions will be promulgated by the climate political units, which includes the IPCC.

    1. John,

      As I said in the post, there is no need to re-invent the wheel. There is a large and well-proven body of knowledge about risk management methods. We just don’t use it – or even consult these experts – in the cafeteria food fight over climate policy. the participants are having too much fun!

      More than anything else, it needs adult intervention.

  2. Exactly what is our “climate policy”? Seems to me it changed three years ago (that makes it political).

    The quibble goes on over 200 ppm CO2, or something of that nature (the scientific end, or so I’ve read).

    1. Ron,

      How did it change three years ago? Trump has done nothing but his usual symbolic acts.

      “The quibble goes on over 200 ppm CO2, or something of that nature …”

      That’s quite bonkers.

    1. Ron,

      Total nonsense. Most of these are straight-forward bonuses to the auto and oil industries, repealing anti-pollution regulations as Republicans have been doing for generations. Long before anyone in the public heard of Global Warming.

      The Paris repeal was drama. It had no legal effect. Without Senate approval, taking actions on it would not have survived court review.

      1. Larry,

        You may be right but the Clean Air Act of 1970 was under Nixon. That changed many things automotive, I made a living fixing emission controls on Ford L/M vehicles due to that Act and others.

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