Tag Archives: global warming

The core of the climate debate: how much of the past warming did we cause?

Summary:  Today we have a post by Judith Curry, a leading climate scientist, going to the very heart of the debate: how much of the warming since 1950 results from us? Before making predictions, how confidently can we see our past?

Climate change presents one of the greatest challenges in humanity’s history. To accurately assess long slow changes in Earth’s biosphere, discerning the effects of our effects from natural cycles. Equally difficult, our political machinery must accurately see the conclusions of climate scientists, and take appropriate steps. These are largely sociological processes, called upon to work on a level seldom seen in our past.

Voltaire: Doubt & Certainty



  1. The 50-50 argument
  2. About Judith Curry
  3. Vital info about climate change
  4. For More Information
  5. Advice from Bertrand Russell


The 50-50 argument

by Judith Curry, at her website Climate Etc
24 August 2014
Posted here under her Creative Commons license

(a)  Choose which hypothesis you prefer

Pick one:

  1. Warming since 1950 is predominantly (more than 50%)  caused by humans.
  2. Warming since 1950 is predominantly caused by natural processes.

When faced with a choice between 1 and 2,  I respond:  ‘I can’t choose, since i think the most likely split between natural and anthropogenic causes to recent global warming is about 50-50′.  Gavin thinks I’m ‘making things up’ {see the discussion in comments here}, so I promised yet another post on this topic.

For background and context, see my previous 4 part series Overconfidence in the IPCC’s detection and attribution.

(b)  Framing

The IPCC’s AR5 (2014) attribution statement:

It is extremely likely that more than half of the observed increase in global average surface temperature from 1951 to 2010 was caused by the anthropogenic increase in greenhouse gas concentrations and other anthropogenic forcings together. The best estimate of the human induced contribution to warming is similar to the observed warming over this period.

I’ve remarked on the ‘most’ (previous incarnation of ‘more than half’, equivalent in meaning) in my Uncertainty Monster paper: “Further, the attribution statement itself is at best imprecise and at worst ambiguous: what does “most” mean – 51% or 99%?” Whether it is 51% or 99% would seem to make a rather big difference regarding the policy response.  It’s time for climate scientists to refine this range.

I am arguing here that the ‘choice’ regarding attribution shouldn’t be binary, and there should not be a break at 50%; rather we should consider the following terciles for the net anthropogenic contribution to warming since 1950: >66%, 33% – 66%, <33%.  Hence 50-50 refers to the tercile 33-66% (as the midpoint)

Note:   I am referring only to a period of overall warming, so by definition the cooling argument is eliminated.  Further, I am referring to the NET anthropogenic effect (greenhouse gases + aerosols + etc).   I am looking to compare the relative magnitudes of net anthropogenic contribution with net natural contributions.

Further, by global warming I refer explicitly to the historical record of global average surface temperatures.  Other data sets such as ocean heat content, sea ice extent, whatever, are not sufficiently mature or long-range (see Climate data records: maturity matrix).   Further, the surface temperature is most relevant to climate change impacts, since humans and land ecosystems live on the surface.  I acknowledge that temperature variations can vary over the earth’s surface, and that heat can be stored/released by vertical processes in the atmosphere and ocean.  But the key issue of societal relevance (not to mention the focus of IPCC detection and attribution arguments) is the realization of this heat on the Earth’s surface.

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Have the climate skeptics jumped the shark, taking the path to irrelevance?

Summary: How do myths get entrenched in conservatives’ minds, exerting a pull to the right on American politics? We can understand the process — and perhaps fight it — by studying specific cases. Like the one happening right now, about the secret conspiracy of government scientists manipulating the US climate data to exaggerate global warming. These myths take hold in part because most people, including journalists, consider them too daft to bother with. Like a small infection. In the coming months we’ll see how well the skeptics — and America — fight this off.

Altered version of Newsweek Aug 2007 cover

Altered version of Newsweek Aug 2007 cover


BENGHAZI: the model for debates in our mad age

I saw the first sparks of the Benghazi BENGHAZI myth as they flew through the right-wing blogosphere. I remember a Sergeant (having an impressive bio) explain how the decisions that night could only have been made by the President as he watched events in real-time on the giant monitors in the War Room. I laughed at this fantasy by someone who probably spent too much time watching TV, and too little studying the vast-beyond-imagining but slow-moving US government apparatus. Many Congressional investigations — and thousands of articles and Fox TV shows — later, it’s not so funny.

Right now a similar social virus spreads through the political right of America. This post briefly describes it, puts it in a broader context, and discusses the possible effects. For details about the story see:

  1. Did NASA and NOAA dramatically alter US climate history to exaggerate global warming?
  2. Comment threads about global warming show the American mind at work, like a reality-TV horror show., 29 June 2014
  3. The climate wars get exciting. Government conspiracy! Shattered warming records! Global cooling!

This story has a second dimension. Movements have life cycles, and are subject to “illnesses”. One of these is “jumping the shark“, a decline in quality following an over-the-top moment in the plot. I saw this happen in the Peak Oil Movement at the 2008 US Conference of the Assn for the Study of Peak Oil and Gas (also see posts at The Oil Drum from that period). People competed to have the most dire forecasts, the most authoritative conspiracy theory — with a complete collapse of intellectual integrity by the group, and failure of its leaders to maintain discipline. (As with Benghazi, I saw this but did not appreciate its significance)

The result: growing irrelevance, and loss of members and influence. This is unrelated to the issue of peak oil, which not only remains serious but also intersects with the potentially equally serious challenge of climate change. It’s also unrelated to the work of scientists, which mostly works on a separate plane.

“There go the people. I must follow them, for I am their leader.”
— attributed to French politician Alexandre Auguste Ledru-Rollin (1807-1874)

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The climate wars get exciting. Government conspiracy! Shattered warming records! Global cooling!

Summary: Today’s post shows how the climate wars about the public policy response to global warming, grow more interesting as both sides abandon science. Unfortunately the public remains apathetic. For good reason, after a decade of constant barrages of misinformation by Left and Right. Especially considering our history, with so much that we knew eventually proven to be false. The climate wars a powerful example of our broken observation-orientation-decision-action (OODA) loop. Let’s hope that the challenges of the 21st century don’t require America to act in a smart or effective way.
Choose to Know


  1. May’s temperature shattered the records!
  2. Government scientists conspire to fake climate data!
  3. About global cooling
  4. For More Information

(1)  May’s temperature shattered the records!

NASA Shows May Global High Temperature Record Shattered as Climate Policy Staggers Forward“, Robert Marston Fanney (fantasy writer; bio here), at his blog RobertScribbler, 18 June 2014.  The facts disagree with “shattered”. The datasets differ about the highest May. On the two that show May as a record, the differences are not statistically significant (the opposite of “shattered”).

  1. NASA GISS dataset: the highest May on record. The anomaly was 0.76°C (1.37°F) above the 1951-1980 average, and 0.06°C (0.11°F) higher than May 2012 and May 2010 (tied)
  2. NOAA’s NCDC: the warmest May on record. The anomaly was 0.74°C (1.33°F) higher than the 20th century average, and 0.02°C (0.03°F) higher than May 2010 (the second highest).
  3. HADCRUT4 — “Taking central estimates, May 2014 was globally the warmest May on record. Factoring in uncertainty, we can say it was a top 10 May.” (per Tweet by John Kennedy, UK Met Office)
  4. RSS satellite record: 6th warmest May
  5. UAH satellite: 3rd warmest May (details here)

But who cares about the facts when a fantasy writer spins an alarmist story! It has truthiness. Those who believe the alarmist accept each new story. Skeptics don’t believe the alarmists (even when they’re right), but too often believe equally exaggerated stories from activists on their side. For example …

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Comment threads about global warming show the American mind at work, like a reality-TV horror show

Summary:  Belief in a secret conspiracy of government scientists manipulating US climate data to exaggerate global warming might join Benghazi BENGHAZI in the right-wing canon. See this happen in real time in the comment threads at Prof Curry’s website, showing the American mind at work on one of our most important public policy issues. It’s a sad spectacle, deserving your attention. We can do better, if only we would try. (updated July 2)

This is second in a series about this fascinating story. It is one of a series of posts using popular media as a mirror in which we can more clearly see who we are, and what we’re becoming.

All Seeing Eye


I strongly recommend reading the comments to “Skeptical of skeptics: is Steve Goddard right?“ by Judith Curry (Prof, GA Inst Tech) at her website, Climate Etc.  (update: and to her follow-up post here). It’s a typical discussion about politicized science in America, with comments by scientists, talented amateurs, and extremist partisans. The latter dominate, with anti-science their primary theme.

If you step back from the specific issue, this thread reads like countless others in recent years by the Right (e.g. about evolution, the extreme example) — and by the Left  (e.g., genetically-modified food and nuclear power).  And by both the Left and Right about climate and economics. A common element is people who have little or no understanding of the subject, but confidently proclaim the relevant scientists to be fools, crooks, or charlatans (this is a defining characteristic of the public climate wars, with activists on both sides so condemning scientists on the “other side”).

Political leaders cherish such followers, their vanguard of high-energy “useful idiots” (an essential concept for political engineers, origin unknown). They’re easily directed and immune to rebuttal by fact or logic (they don’t listen to their opponents, who are misguided if not evil). As a chorus they entertain the faithful and can often shout down saner voices.

“Then the sheep broke out into a tremendous bleating of `Four legs good, two legs bad!’ which went on for nearly a quarter of an hour and put an end to any chance of discussion.”

This is a manifestation of an deeper ill in American life, anti-intellectualism. The best-known descriptions of this are two works by Richard Hofstadter. The comment thread at Climate Etc shows both of these traits proudly displayed.

(1)  Anti-intellectualism in American Life (1963).  It includes the belief that everyman can understand technical matters as well as experts, without bothering with years of study. It’s as or more serious now than in 1963.

Twenty-first century philistines, suffering from a lack of imagination and curiosity, have seized upon understandable economic anxieties since the financial crash of 2008, to shepherd an increasingly large flock of American sheep into the livestock freight carrier Pulitzer prize winning historian, Richard Hofstadter, called “anti-intellectualism.” … The American mind is swimming in icy waters …

— “America’s New Wave of Anti-Intellectualism“, David Masciotra (journalist), The Daily Beast, 9 March 2014

(2) The Paranoid Style in American Politics“, Harpers Magazine, November 1964 — To the Right-wing climate scientists are not just wrong, but in an active conspiracy to deceive us — they “fake”, fiddle”, and “rig” the data. Excerpt:

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Learn what few know: how much did we warm in May? how much has the world warmed since 1979?

Summary: The world has been warming. Seldom mentioned is how much it has warmed, which allows alarmists to more easily sow fear. For the answer we turn to the NASA-funded global temperature data from satellites.  They show the warming since 1979 is small (so far; the future might be quite different). The truth is out there for people willing to see it. Only with it can we prepare for our future.

“It is extremely likely (95 – 100% certain) that human activities caused more than half of the observed increase in global mean surface temperature from 1951 to 2010.”
— conclusion of the IPCC’s AR5 Working Group I

Pure alarmist propaganda



  1. Status report: what do satellites tell us about global warming?
  2. The long-term history of warming
  3. Who produces this satellite data & analysis?
  4. About The Elusive Absolute Surface Air Temperature (SAT)
  5. For More Information

To the right is a typical over-the-top image to arouse fear, about a world now less than one °F warmer than the 30-year average.

(1) Status report: what do satellites tell us about global warming in May 2014?

Satellites provide the most comprehensive and reliable record of the atmosphere’s warming since 1979.

The May 2014 Global Temperature Report
by the Earth System Science Center of the University of Alabama in Huntsville
(Blue is cold; red warm}. Click to enlarge.

May 2014 Global Temperature Report

Earth System Science Center of the University of Alabama in Huntsville


See the equivalent graph from the surface temperature stations of the Climate Anomaly Monitoring System (CAMS) of the Climate Prediction Center (CPC) at the U.S. National Centers for Environmental Prediction (NCEP).

Key points from the UAH report (prepared under contract for NASA), which show a world that has warmed since 1979, but only slightly (few alarmists know this; even fewer admit it):

  1. It was the 3rd warmest May in the satellite record (since 1979). The global composite temperature in May was +0.33°C (0.59°F) above the average for May during 1981-2010.  {the other satellite record, RSS, has it the 6th warmest}
  2. The warmest May was in 1998, during the “El Niño of the century”, at +0.56°C (about 1.0°F) warmer than average.
  3. May 2010 — also an El Niño month — was 2nd warmest at +0.45°C (0.81°F).

More about the world’s atmosphere temperatures in May:

  1. Global climate trend of temperature starting in 16 November 1978: +0.14°C  (0.3°F) per decade.
  2. Compared to seasonal norms, in May the coolest area on the globe was over the northern Pacific Ocean,
    where temperatures were as much as -2.8°C  (3.7°F) cooler than seasonal norms.
  3. The warmest area was along the western border of Kazakhstan, where tropospheric temperatures were +4.2°C  (7.5°F) warmer than seasonal norms.
  4. Anomalies are computed per the World Meteorological Organization (WMO) recommended method, comparing the current temperatures vs. a 30 year base period ending with the latest decade.

For more detail see Global Temperature Update Through 2013, James Hansen, Makiko Sato and Reto Ruedy, 21 January 2014.

(2)  The vital context: a longer-term temperature history

Two decades of cool weather, followed by 15 years of warm weather. Wide swings in temperature; a relatively flat trend since 1998 – 2000. For more about the pause see links to climate research in Section 5.

(a)  From the UAH monthly report,  a graph of the full record of UAH satellite data (started in 1979). Click to enlarge.

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Is the Tea Party wrong about global warming? Yes! And no.

Summary: Climate change might pose one of the greatest threats to humanity in its history since the supervolcano Toba exploded 70 thousand years ago, almost exterminating our species. Or not. Managing this complex issue profoundly challenges our social and political institutions. We’re failing so far, with no signs of improvement. Here is post #50 in a series documenting this. There’s still time to do better. The stakes are high.

An hourglass for the world

By LucAleria; Wikimedia Commons image



  1. A vital issue reduced to a cacophony
  2. Conservatives are right about global warming
  3. Conservatives are wrong about global warming
  4. Conclusions
  5. For More Information


(1)  A vital issue reduced to a cacophony

Climate change powerfully illustrates America’s broken observation-orientation-action (OODA) loop, and how this cripples our ability to craft effective public policy responses to our changing world. It’s become politicized, with both sides focused on the success of their side — the truth a secondary consideration.

Comments frequently remind me of this. I posted a comment the skeptics at Jeff Condon’s The Air Vent about the benefits of properly citing the source of graphics. Amazingly, the folks there disagreed. “I don’t think references add much credibility to correlation sorted paleoclimatology..” After all, “climate scientists make plenty of errors on blogs just like the rest of us.” Worth a read of their tribal reactions.

I cited “In the Eye of the Storm“ by James Hanley (Assoc Prof of Political Science, Adrian College). His reply:

“Oh, lord, why did you have to reference me. I’m not on your side.”

This is a mild comment, not serious in itself, but typical of the public debate about climate. The tribe, the side, the team is what matters. Are you with the Kool Kids or against them? Articles are read to determine which side the author belongs to; all reactions follow from that. I doubt Prof Hanley knows anything about my views about climate change, but confidently guesses. That’s the rule seen in the thousands of comments to the 185 posts about climate change on the FM website.(summarized here)

After years of this the public debate about climate change has become a cacophony, leaving a large fraction of Americans with strongly-held but often factually incorrect opinions. For evidence today let’s look at conservative’s opinions about global warming (see links at the end for examination of the Left’s views). Here are two polls which, unlike most, ask fairly scientifically precise questions about global warming.

(2)  Conservatives are right about global warming

From a Pew Research poll conducted 9 – 13 October 2013. Red emphasis added.

From what you’ve read and heard, is there solid evidence that the average temperature on earth has been getting warmer over the past few decades, or not? Do you believe that the earth is getting warmer mostly because of human activity such as burning fossil fuels, or mostly because of natural patterms {sic} in the earth’s environment?

Bloomberg plots the results:

Bloomberg graph of Global Warming

Bloomberg, 9 May 2014

The detailed numbers from the Pew Poll:

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Cutting to the heart of the public policy debate about climate change

Summary:  After a quarter-century of the climate wars, the chaff thrown up by political activists on both sides has largely obscured the key questions which we must answer in order to deal with this, perhaps the most important of the many shockwaves facing us. Today we look at the most important question of logic in the decision-making process.

“This impatience with ambiguity can be criticized in the phase: the absence of evidence is not the evidence of absence.”
— Carl Sagan in The Demon-haunted World – Science as a Candle in the Dark (1995), using the phrase attributed to British astrophysicist Martin Rees

Globe Aflame



  1. The very heart of the climate debate
  2. Absence of evidence is not evidence of absence
  3. Isn’t the climate signal from humanity obvious?
  4. For More Information


(1)  The very heart of the climate debate

Judith Curry (Prof Atmospheric Science, GA Inst Tech) carved to the heart of the climate wars — the debate over the public policy response to climate change (running on a different track than the policy debate in the pubic arena) comes down to questions of epistemology and logic. How do we leap from a body of evidence to knowing enough to rely on theories? Especially when the theories are compelling, but there is as yet minimal evidence to validate or prove them.

Curry starts with the basics of scientific reasoning, with two methodologies — both equally legitimate. Which to use depends on one’s professional judgement.

Recall the dueling papers on Climate Null Hypotheses by myself and Kevin Trenberth.   Depending on which null hypothesis you select as a default position when conducting research you approach the problem in a different way.

  1. Humans have no influence on extreme weather events
  2. Humans are influencing extreme weather events

For #1, the null would be rejected if you find evidence of a human influence. In the absence of such evidence, #1 is not rejected. This is what Roger Pielke Jr argued.

For #2, the null would be rejected if there is evidence of no influence. RealClimate and Kerry Emanuel  {Prof Meteorology, MIT} essentially conclude that the data is insufficient, so they argue from ‘physics’ and state that there is no evidence of absence.

To me, the ‘no evidence of absence’ argument is rather fatuous given that simple thermodynamical reasoning is not really useful in elucidating the impacts of AGW on extreme weather events.

This grounds the debate in science and logic, not a matter of certainty as implied by activists.  For those of us who are not scientists, let’s look at this logical tool: “Absence of evidence is not evidence of absence.” What does it mean?

(2)  Absence of evidence is not evidence of absence

Its first known use is by the British astrophysicist Martin Rees, discussing the search for extraterrestrial intelligence (SETI):

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