Tag Archives: climate science

Climate scientists can restart the climate change debate & win: test the models!

Summary; Public policy about climate change has become politicized and gridlocked after 26 years of large-scale advocacy. We cannot even prepare for a repeat of past extreme weather. We can whine and bicker about who to blame. Or we can find ways to restart the debate. Here is the next of a series about the latter path, for anyone interested in walking it. Climate scientists can take an easy and potentially powerful step to build public confidence: re-run the climate models from the first 3 IPCC reports with actual data (from their future): how well did they predict global temperatures?

Trust can trump Uncertainty.”
Presentation by Leonard A Smith (Prof of Statistics, LSE), 6 February 2014.

The most important graph from the IPCC’s AR5

Figure 1.4 from the IPCC's AR5

Figure 1.4 from p131 of AR5: the observed global surface temperature anomaly relative to 1961–1990 in °C compared with the range of projections from the previous IPCC assessments. Click to enlarge.


Why the most important graph doesn’t convince the public

Last week I posted What climate scientists did wrong and why the massive climate change campaign has failed. After 26 years, one of the largest longest campaigns to influence public policy has failed to gain the support of Americans, with climate change ranking near the bottom of people’s concerns. It described the obvious reason: they failed to meet the public’s expectations for behavior of scientists warning about a global threat (i.e., a basic public relations mistake).

Let’s discuss what scientists can do to restart the debate. Let’s start with the big step: show that climate models have successfully predicted future global temperatures with reasonable accuracy.

This spaghetti graph — probably the most-cited data from the IPCC’s reports — illustrates one reason for lack of sufficient public support in America. It shows the forecasts of models run in previous IPCC reports vs. actual subsequent temperatures, with the forecasts run under various scenarios of emissions and their baselines updated. First, Edward Tufte probably would laugh at this The Visual Display of Quantitative Information — too much packed into one graph, the equivalent of a Powerpoint slide with 15 bullet points.

But there’s a more important weakness. We want to know how well the models work. That is, how well each forecast if run with a correct scenario (i.e., actual future emissions, since we’re uninterested here in predicting emissions, just temperatures). Let’s prune away all those extra lines on the spagetti graph, leaving forecasts from 1990 to now that match the actual course of emissions.

The big step: prove climate models have made successful predictions

“A genuine expert can always foretell a thing that is 500 years away easier than he can a thing that’s only 500 seconds off.”
— From Mark Twain’s A Connecticut Yankee in King Arthur’s Court.

A massive body of research describes how to validate climate models (see below), most stating that they must use “hindcasts” (predicting the past) because we do not know the temperature of future decades. Few sensible people trust hindcasts, with their ability to be (even inadvertently) tuned to work (that’s why scientists use double-blind testing for drugs where possible).

But now we know the future — the future of models run in past IPCC reports — and can test their predictive ability.

Karl Popper believed that predictions were the gold standard for testing scientific theories. The public also believes this. Countless films and TV shows focus on the moment in which scientists test their theory to see if the result matches their prediction. Climate scientists can run such tests today for global surface temperatures. This could be evidence on a scale greater than anything else they’ve done.

Model of a hurricane.

A hurricane in the Weather Research & Forecasting (WRF) Model. From NCAR/UCAR.

Testing the climate models used by the IPCC

“Probably {scientists’} most deeply held values concern predictions: they should be accurate; quantitative predictions are preferable to qualitative ones; whatever the margin of permissible error, it should be consistently satisfied in a given field; and so on.”
— Thomas Kuhn in The Structure of Scientific Revolutions (1962).

The IPCC’s scientists run projections. AR5 describes these as “the simulated response of the climate system to a scenario of future emission or concentration of greenhouse gases and aerosols … distinguished from climate predictions by their dependence on the emission/concentration/radiative forcing scenario used…”. The models don’t predict CO2 emissions, which are an input to the models.

So they should run the models as they were when originally run for the IPCC in the First Assessment Report (FAR, 1990), in the Second (SAR, 1995), and the Third (TAR, 2001). Run them using actual emissions as inputs and with no changes of the algorithms, baselines, etc. How accurately will the models’ output match the actual global average surface temperatures? This was proposed by Roger Pielke Jr (Prof Environmental Studies, U CO-Boulder) in “Climate predictions and observations“, Nature Geoscience, April 2008.

Of course, the results would not be a simple pass/fail. Such a test would provide the basis for more sophisticated tests. Judith Curry (Prof Atmospheric Science, GA Inst Tech) explains here:

“Comparing the model temperature anomalies with observed temperature anomalies, particularly over relatively short periods, is complicated by the acknowledgement that climate models do not simulate the timing of ENSO and other modes of natural internal variability; further the underlying trends might be different. Hence, it is difficult to make an objective choice for matching up the observations and model simulations. Different strategies have been tried… matching the models and observations in different ways can give different spins on the comparison.”

On the other hand, we now have respectably long histories since publication of the early IPCC reports: 25, 20, and 15 years. These are not short periods, even for climate change. Models that cannot successfully predict over such periods require more trust than many people have when it comes to spending trillions of dollars — or even making drastic revisions to our economic system (as urged by Naomi Klein and Pope Francis).


Re-run the models. Post the results. More recent models presumably will do better, but firm knowledge about performance of the older models will give us useful information for the public policy debate. No matter what the results.

As the Romans might have said when faced with a problem like climate change: “Fiat scientia, ruat caelum.” (Let science be done though the heavens may fall.)

“In an age of spreading pseudoscience and anti-rationalism, it behooves those of us who
believe in the good of science and engineering to be above reproach whenever possible.“
P. J. Roach, Computing in Science and Engineering, Sept-Oct 2004 — Gated.

World Models

Other posts in this series

These posts sum up my 330 posts about climate change.

  1. How we broke the climate change debates. Lessons learned for the future.
  2. A new response to climate change that can help the GOP win in 2016.
  3. The big step climate scientists can make to restart the climate change debate – & win.

For More Information

(a)  Please like us on Facebook, follow us on Twitter, and post your comments — because we value your participation. For more information see The keys to understanding climate change and My posts about climate change. Also see these about models…

(b)  This is an obvious idea. I saw one mention of this on the web (e.g., by Carrick in this Sept 2013 thread at Climate Audit) — there are probably others — but nothing by a climate scientist — formally or informally made. We can only guess why.

The odds that no scientist thought of this are IMO zero. Why has this not been done? We can only guess.

(c)  I learned much, and got several of these quotes, from a 2014 presentations by Leonard A Smith (Prof of Statistics, LSE): the abridged version “The User Made Me Do It” and the full version “Distinguishing Uncertainty, Diversity and Insight“. Also see “Uncertainty in science and its role in climate policy“, Leonard A. Smith and Nicholas Stern, Phil Trans A, 31 October 2011.

(d)  Introductions to climate modeling

These provide an introduction to the subject, and a deeper review of this frontier in climate science.

Judith Curry (Prof Atmospheric Science, GA Inst Tech) reviews the literature about the uses and limitation of climate models…

  1. What can we learn from climate models?
  2. Philosophical reflections on climate model projections.
  3. Spinning the climate model – observation comparison — Part I.
  4. Spinning the climate model – observation comparison: Part II.

(d)  Selections from the large literature about validation of climate models

What are your recommendations: how to re-start the climate change debate?

Summary:  Today’s post gives a challenge and two useful presentations about climate change. How can climate scientists restart the debate — and gain majority support for large-scale public policy measures for mitigation of and adaptation to climate change? Plus a presentation overflowing with insights about climate science (not what you might expect from a Professor of Statistics), and a presentation by Roger Pielke Sr. about the state of the art in climate science.

“The climate is what you expect; the weather is what you get.”
— From Robert Heinlein’s Time Enough for Love.

Your ideas

A challenge for you

Last week I posted What climate scientists did wrong and while the massive climate change campaign has failed. After 26 years, one of the largest longest campaigns to influence public policy has failed to gain the support of Americans, with climate change ranking near the bottom of people’s concerns. It described the obvious reason: they failed to meet the public’s expectations for behavior of scientists warning about a global threat (i.e., a basic public relations mistake).

The next few posts explain how climate scientists can re-start the public policy debate about climate change and win — gaining approval of large-scale public policy measures for mitigation and adaptation). It’s taken longer than I planned to research; the first goes up tomorrow. So for today I pass the ball to you. Post your recommendations for climate scientists in the comments!

Recommendation #1, a brilliant presentation overflowing with ideas

Here are the slide decks to two interesting presentations. The first is by Leonard A Smith (Prof of Statistics, London School of Economics): “Distinguishing Uncertainty, Diversity and Insight“.  It’s long, dense, and difficult to follow without the speech — but brilliant and over-flowing with insights. I especially recommend slides 76-86 describing the constraints limiting climate models. He does it unusually clearly using simple graphs of model complexity (run time) vs. forecast lead time (how far in the future it can see).

Presentation by Leonard Smith

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How climate change can help the GOP win in 2016

Summary: Republicans have adopted a purely negative platform for dealing with climate change, a difficult to explain policy that puts them in opposition to most scientists. This post describes an alternative platform, one that is consistent with their principles, easy to explain, appealing to undecided voters, and cuts through the chaff of factional bickering. It’s the kind of policy that helps create coalitions that win elections.

“… a genuine leader is not a searcher for consensus, but a molder of consensus.”
— Martin Luther King’s speech “Remaining Awake Through a Great Revolution“, at the Episcopal National Cathedral in Washington on 31 March 1968.

Republicans Flag


  1. GOP weakness on climate change
  2. An agenda for the 21st century.
  3. Conclusions.
  4. Other posts in this series.
  5. For more information.

(1) The Republicans’ weak stance on climate change

The Republicans have ceded the politics of climate change to the Democrats. The only mention of it in the 2012 Republican platform is trivial…

“Finally, the strategy subordinates our national security interests to environmental, energy, and international health issues, and elevates “climate change” to the level of a “severe threat” equivalent to foreign aggression.”

So far the GOP’s 2016 presidential candidates have little to say about it. I see no policy statements about climate change on the issues pages of campaign websites for Rick Santorum, Jeb Bush, Ben Carson, Mike Huckabee, Marco Rubio, Ted Cruz, and Rand Paul.

Carly Fiorina says that the solution to climate change is “innovation not regulation”, without many details (her website points to video clip here, and here). She also says — logically — that California should have prepared better for the drought — although her specific recommendations are illogical: more dams and water infrastructure (ineffective and too expensive to cope with multi-year droughts) and massive destruction of California’s ecology (e.g., damage to key species such as the delta smelt — calling it unimportant because it’s a “small fish”).

When questioned, Republican candidates tend to respond with evasions and half-understood techno-babble (even if they understood it, the public would not) — or just deny the problem (see responses at the CNN debate). There is a better way, one consistent with their commitment to a strong defense and a sound infrastructure for America.

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Alaska’s climate scientists tell us the rest of the news, what Obama forgot to mention

Summary: Obama journeys to Alaska and says things. Our journalist-stenographers reprint this as news. They do not consult local experts, and so miss an important part of the story. This post gives you the rest of the news.  {2nd of 2 posts today.}

Alaska temperatures 1949-2014

From the Alaska Climate Research Center. Click to enlarge.

The great oddity of the climate change campaign is the disinterest of journalists in reporting it well. Stories about our certain doom often omit vital context (e.g., burning off the world’s fossil fuels means the 21st century relies on coal for energy, like the 19thC), forget to mention the IPCC when it disagrees with alarmists (e.g., about the danger of a methane apocalypse), and ignore the host of research facilities studying relevant aspects of our changing world.

We see that last factor at work in journalists’ reporting about Obama’s climate campaign tour of Alaska. Google News shows no stories in the mainstream news mentioning the findings of the Alaska Climate Research Center. I have posted their work in response to previous panicky stories about Alaska melting in 2009, in 2013, and again here.

Here is their Temperature Changes in Alaska page (updated annually; red emphasis added). It’s quite clear.

“This page features the trends in mean annual and seasonal temperatures for Alaska’s first-order observing stations since 1949, the time period for which the most reliable meteorological data are available. The temperature change varies from one climatic zone to another as well as for different seasons. If a linear trend is taken through mean annual temperatures, the average change over the last 6 decades is 3.0°F.

“… Considering just a linear trend can mask some important variability characteristics in the time series. The figure at right shows clearly that this trend is non-linear: a linear trend might have been expected from the fairly steady observed increase of CO2 during this time period. The figure shows the temperature departure from the long-term mean (1949-2009) for all stations. It can be seen that there are large variations from year to year and the 5-year moving average demonstrates large increase in 1976.

“The period 1949 to 1975 was substantially colder than the period from 1977 to 2009, however since 1977 little additional warming has occurred in Alaska with the exception of Barrow and a few other locations. The stepwise shift appearing in the temperature data in 1976 corresponds to a phase shift of the Pacific Decadal Oscillation from a negative phase to a positive phase. Synoptic conditions with the positive phase tend to consist of increased southerly flow and warm air advection into Alaska during the winter, resulting in positive temperature anomalies.”

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What’s the consensus of climate scientists? Why do we care?

Summary: Here’s a briefing about climate change, prepared for Politifact at their request. Unused, of course, since the reporter was just fishing for smears (here’s an analysis of what they published). However, it’s a useful introduction to this complex subject. What do we know about the consensus of climate scientists, and why does it matter? These are unedited emails, and so roughly written and unproofed.   {2nd of 2 posts today.}

Stories, better than science

Initial Inquiry by Linda Qiu of Politifact, and my response

I’m a reporter with PolitiFact, the fact-checking website of the Tampa Bay Times. I’m currently looking into something Rick Santorum said: 57% of scientists “don’t buy into the idea that CO2 is the knob that’s turning the climate.” His campaign hasn’t gotten back to me on his source but one of your posts also has the figure, but it’s not quite what Santorum said. So I was hoping for your take on Santorum’s reading on your analysis — how accurate is it?

I have a lot of data about this. Here’s a quick data dump. I’m in the middle of something about this very subject, so don’t have time to compose. Tell me what more you’d like. I can provide links and cites for all of this. I work late, so deadlines are not a problem.

There have been many surveys seeking to determine the consensus of scientists and the subgroup of climate scientists (neither group having a clear definition) about the headline attribution statements of the IPCC. That is, how much of the warming since 1950 is attributed to us.  The IPCC states its findings in two parts: the finding, and the IPCC’s confidence in that finding. The latter is off little relevance to science, but obviously of great importance when taking public policy action. For example, it’s nice to know that all scientists believe “X”, but what if they have little confidence in that belief?

The standard measure of confidence is 95% (defining what this means is both complex and controversial, especially now with the replication crisis). The IPCC defines 90%+ as “very likely” and 95%+ as “extremely likely”.

The first round of surveys concerned only the first part: how much of the warming is from us. Almost all scientists agree that there has been warming during the past 2 centuries; only the amount and cause is debated.  They found strong agreement with the IPCC finding (what that finding is I’ll discuss below).

In March – April 2012 the PBL Netherlands Climate Assessment Agency, with several other scientists, conducted a survey of approximately 6,550 scientists studying climate change. This was imo excellent — the best survey on the subject done so far, by far. It was published as “Scientists’ Views about Attribution of Global Warming” by Bart Verheggen et al in the 19 Aug 2014 issue of Environmental Science and Technology (peer-reviewed). In April 2015 they published a more detailed report.  The first questions asked about the finding of the IPCC’s Fourth Assessment Report (AR4) in their Summary for Policy-makers:

“Most of the observed increase is global average temperature since the mid-20th century is very likely due to the observed increase in anthropogenic greenhouse gas concentrations.”  {The subject is important since proposed measures to reduce climate change {Obama’s Clean Power Plan} focus almost exclusively on reducing emissions of greenhouse gases.

The PBL survey found that only 64% of climate scientists responding agreed that over half of the warming since 1950 was from anthropogenic greenhouse gases (GHG) — a majority, but less than I (and others) expected).

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Politifact tells us about American politics and science. We should listen.

Summary: This vignette illustrates important aspects of the climate change debate, and why it has failed to gain sufficient support from Americans to pass large-scale public policy measures. For two decades journalists and scientists have cooperated to produce political propaganda, exaggerating and misrepresenting the work of the IPCC. Their failure should inspire us, showing a resistance to manipulation greater than many people expected (it surprises me).

Orwell: truth as revolutionary act

My post, which started this kerfuffle

In July I published The 97% consensus of climate scientists is only 47%, which showed the hidden results of an excellent survey of scientists’ agreement with the IPPC’s attribution statements about the role of anthropogenic greenhouse gases in global warming. It was high, but lower than usually described — and below the standard for significance. The question has important implications; Obama’s sweeping Clean Power Plan rests on this finding (details here).

it attracted some attention on skeptics’ websites, and pushback from climate activists (both laypeople and scientists). Then GOP presidential candidate Rich Santorum cited this information, and the activists began their usual smear campaign. The facts are quite simple, for those who want to know.

The article at Politifact

Politifact started the cover-up with “Santorum cites flawed climate change figure, and misquotes it” by Linda Qui. She asked me for information. I gave her several thousand words (which I’ll publish next week). She didn’t find anything useful for smearing me, so she ignored it.

Below are the relevant parts of her hit job. My responses follow each quote. Qui tells me she consulted Verheggen and “6 other climate scientists/people who study the consensus issue” “and they all agreed with the survey author”. As you will see below, all that work produced only the weakest of rebuttals. But we can learn much from their attempt.

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Are 30 thousand species going extinct every year?

Summary: The warnings become increasingly dire and shrill as we approach November’s United Nations Climate Change Conference in Paris. One theme warns about the increasing rate of extinctions, described with astonishing numbers — and projected to add humanity to the endangered species list. As usual, these claims distract attention from serious and imminent threats, such as our dying oceans. Let’s look beyond the hysteria to the science.

Extinction Poster



  1. Our certain doom from the great extinction.
  2. How many species are there?
  3. How many species have gone extinct?
  4. Should we fear forecasts of mass extinction?
  5. Conclusion.
  6. For More Information.
  7. For a useful perspective on these matters.


(1)  Our certain doom, chapter XXI: the great extinction

Exaggeration is the primary tool of activists in the publicity campaign to force public policy changes to fight climate change. “Anything goes” became their watchword once they broke free from the peer-reviewed literature.

It starts with science at the website Endangered Species International — “More than 16,000 species are threatened to become extinct in the near future.” “Of the 44,838 species assessed worldwide using the IUCN Red List criteria, 905 are extinct {was 784 in 2006} and 16,928 are listed as threatened to be extinct.”

Next politics goes wild: The Convention on Biological Diversity went into force in December 1993. Among its best known results are these words by Executive Secretary Ahmed Djoghlaf on 21 May 2007 — about extinctions happening now (not just threatened for the future).

“Every hour, three species disappear. Every day, up to 150 species are lost. Every year, between 18,000 and 55,000 species become extinct.  The cause: human activities. … Climate change is one of the major driving forces behind the unprecedented loss of biodiversity. “

This has frequently been debunked. But even after 8 years of rebuttals to this and similar exaggerations, Real News Network repeats this claim in Climate Change: Have We Reached the Point of No Return? (Climate change zombie myths live on the Left, much as Zombie Economics does on the Right.) The RNN story has the typical climate activists’ mix of unbalanced facts, assertions far outside the climate science consensus (and the IPCC), plus exaggerations. They used the poster at the top if this post as their headline graphic.

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