What the Climate Models have Taught Us

February 5, 2015

We’ve heard a lot about the so called “pause” in global temperatures over the recent decade – a misnomer, since temperatures have continued to rise, just not as rapidly as during, say, 1991 to 2006, to cherry pick an era of faster-than-projected rise.

Scientists were pretty sure that those rapid rises were part of natural variability, and would not be sustained, and that’s what’s happened. So not a big revelation in what we are seeing today.

Stefan Rahmstorf at Real Climate:

And a reminder:  The warming trend of the 15-year period up to 2006 was almost twice as fast as expected (0.3°C per decade, see Fig. 4 here), and (rightly) nobody cared. We published a paper in Science in 2007 where we noted this large trend, and as the first explanation for it we named “intrinsic variability within the climate system”. Which it turned out to be.

The notion that climate science is “based on computer models” is a false one, but comes up a lot, recently on the Senate floor in a rant by denialist Senator Jeff Sessions.  No experienced scientist is surprised when the planet doesn’t conform exactly to what a particular model run shows – and moreover, many indicators of planetary change are moving well ahead of projections made not too long ago – notably arctic sea ice loss, melting ice sheets, and subsequent sea level rise.
Above, in a recent interview, Atmospheric scientist Ken Caldeira, talks about key areas where climate models have been very much spot-on – and helped confirm the “fingerprints” of human caused global change.(this interview ties in with John Cook’s MOOC – Massive Online Open Course, “Making Sense of Climate Denial”)
At the bottom, I’ve also embedded my interview with Mike MacCracken, and clips from his 1982 talk at Sandia Labs, where he outlined the changes that scientists, using models, expected to see decades ago, all of which are now part of our emerging reality.

Now a new study of the Pliocene, a period of the not too distant geological past that many scientists compare to our own, shows that climate sensitivity, the response of the planet to carbon dioxide levels during that era, was very much like what our current best estimates tell us.

Phys.org:

New evidence showing the level of atmospheric CO2 millions of years ago supports recent climate change predications from the Intergovernmental Panel on Climate Change (IPCC).

A multinational research team, led by scientists at the University of Southampton, has analysed new records showing the CO2 content of the Earth’s atmosphere between 2.3 to 3.3 million years ago, over the Pliocene.

During the Pliocene, the Earth was around 2ºC warmer than it is today and atmospheric CO2 levels were around 350-400 parts per million (ppm), similar to the levels reached in recent years.

By studying the relationship between CO2 levels and during a warmer period in Earth’s history, the scientists have been able to estimate how the climate will respond to increasing levels of carbon dioxide, a parameter known as ‘climate sensitivity’.

The findings, which have been published in Nature, also show how climate sensitivity can vary over the long term.

“Today the Earth is still adjusting to the recent rapid rise of CO2 caused by human activities, whereas the longer-term Pliocene records document the full response of CO2-related warming,” says Southampton’s Dr Gavin Foster, co-author of the study.

“Our estimates of climate sensitivity lie well within the range of 1.5 to 4.5ºC increase per CO2 doubling summarised in the latest IPCC report. This suggests that the research community has a sound understanding of what the climate will be like as we move toward a Pliocene-like warmer future caused by human greenhouse gas emissions.”

More here on the Pliocene, and its warning for our world today.

Lead author of the study, Dr Miguel Martínez-Botí, also from Southampton said: “Our new records also reveal an important change at around 2.8 million years ago, when levels rapidly dropped to values of about 280 ppm, similar to those seen before the industrial revolution. This caused a dramatic global cooling that initiated the ice-age cycles that have dominated Earth’s climate ever since.”

The research team also assessed whether was different in warmer times, like the Pliocene, than in colder times, like the glacial cycles of the last 800,000 years.

Professor Eelco Rohling of The Australian National University in Canberra says: “We find that climate change in response to CO2 change in the warmer period was around half that of the colder period. We determine that this difference is driven by the growth and retreat of large continental ice sheets that are present in the cold ice-age climates; these ice sheets reflect a lot of sunlight and their growth consequently amplifies the impact of CO2 changes.”

Professor Richard Pancost from the University of Bristol Cabot Institute, added: “When we account for the influence of the ice sheets, we confirm that the Earth’s climate changed with a similar sensitivity to overall forcing during both warmer and colder climates.”
Here, Mike MacCracken, one of climate science’s living arch-druids, talks about the projections he was looking at in the late 70s and early 80s.  His talk from Sandia Labs in 1982 could have been given last week.

 

 

26 Responses to “What the Climate Models have Taught Us”

  1. omnologos Says:

    Very good. We have a workable definition for the “pause” (as in, the period when temperatures have risen just not as rapidly as between 1991 and 2006).

    We also haven confirmation sensitivity is between 1.5 and 4.5C, and it’ll get lower as temperatures get warmer.

    finally we’re told ice age cycles are linked to low co2 concentration. IOW our emissions are taking us away from the risk of ice ages.

    I’m fine with that all.

    • redskylite Says:

      I’m not fine with it, the 1.5ºC – 4.5ºC temperature increase is per doubling of atmospheric CO2 concentrations, who knows what density we will end up with (x2?, x3?,x4?), especially if Tundra and other buried natural carbon stores are released/rainforests die etc . Humans and their ancestors have gotten through previous glacial/ice age cycles in the past, but we have never been challenged by the increasing warming that is coming our way now.

      More and more science reports are being released on species extinctions, both land and marine, like mankind these species have also not been challenged by pliocene temperatures before, but what is most truly alarming to me is the incredible relative speed at which we are approaching it, compared to previous natural geological/Milankovitch cycles.

      There are a few climate scientists, predicting luke-warm increases and downplaying the effects, then the majority in the middle who are saying we can bring it under control (but need to hurry), then there are those who say it is far too late.

      I hope the last group are proved wrong for my children’s, children’s sake.


    • Omno, remember the quote from Emerson? “A foolish consistency is the hobgoblin of little minds.” How is that period of low rising temperatures between 1991 and 2006? The regression line doesn’t appear to have changed any in that period. You do know what a regression line is, don’t you?

    • Gingerbaker Says:

      That would be the definition of the “so-called” “pause”. I’m sure that was an unintended deletion on your part.

      • omnologos Says:

        I was under the impression that around here the “pause” is called anything apart from “the pause” 🙂

        • Gingerbaker Says:

          Sorry. You claimed that you ” copied the words used by Peter in the post”. But you didn’t.

          And since you used your interpretation of Peter’s words – and not his actual words – to continue your snide quixotic campaign about who said what about ‘pauses’, I wanted to point out your error.

          So you could apologize for it.

          • omnologos Says:

            We’ve been here before. In a past thread we all agreed the “pause” cannot just be called a pause. That’s why I put the “scary quotes”. And rather than interpreting I simply remarked that we’ve got now a definition for it written by Peter himself, and I happen to be perfectly comfortable with it – incidentally also because it’s consistent with the efforts being put by many scientists to investigate it.

          • Gingerbaker Says:

            If you are going to claim that you merely quoted somebody, then quote them, otherwise, you see, ‘splaining why you added scary quotes comes off as you rationalizing your lying about your quotation.

            Also, nobody here gives a shit about your mission to play “Gotcha!” with the word “pause”. Just you.

            And the rest of us are bored. Bored. B.O.R.E.D.

            B-O-R-E-D.

            With you.

          • dumboldguy Says:

            A-M-E-N

          • omnologos Says:

            you will be bored for real the day you will stop trying to split hair on my comments. Methinks more than one person here only exists in terms of splitting hair on my comments so the story will continue.

          • dumboldguy Says:

            You flatter yourself (and demonstrate the depth of your delusion and self-absorption) when you state “more than one person here only exists in terms of splitting hair on my comments”.

            What we do with your “comments” is akin to shoveling shit in the barnyard. We are trying to avoid tracking it into the house of Crock and getting it on the carpet of rationality found therein.

            Get a brain or go away!

  2. redskylite Says:

    I appreciated that video from Ken Caldeira, computer modelling is used extensively in other scientific and engineering fields for many decades now, so why should it not be an equally reliable and valuable tool/aid in climate science ?

    I read a unusual study this week from Monash university, that divided people into skeptics and believers.

    Basically tells us to be nice to each other, I’m game but tell Watts and those fire belching Curry munchers (Judith).

    http://theconversation.com/overcoming-the-social-barriers-to-climate-consensus-36889

  3. Gingerbaker Says:

    Peter

    The graphic showing Florida coastline before/after SLR is OK, but…. what would be more expressive would be an artist’s rendering of Manhattan landmark streets under 3 – 15 meters of SLR?

    Something like this:

    http://oneclimateonechallenge.blogspot.com/2012/02/glaciers-at-your-feet.html

    You can generate whatever you want, supposedly, with Google Earth graphics, follow this:

    http://www.gearthblog.com/blog/archives/2007/05/rising_water_effects.html


  4. [Stupid wordpress.com! One more & last try of potential duplicate.]

    “a misnomer, since temperatures have continued to rise, just not as rapidly as during, say, 1991 to 2006, to cherry pick an era of faster-than-projected rise.”

    More than a misnomer. Please don’t tell statistical nonsense (nay, a crock of idiotic bullshit) like this. Lest you want the pause zombie to walk on. Actually, on first reading I had the impression that Peter himself is still not getting it.

    One last time, for everybody mouthing about a “pause”, here’s essential HOMEWORK to do: Get your eyeballs to examine a surface temp graph starting 1970. Draw in the trend line. Repeat with graph turned 180°. Compare. Examine the wiggles around the trend line. (Now you know all you need about global warming. KEEP A PRINTOUT: So next time you meet a pause zombie you can stick it in his face.)

  5. omnologos Says:

    Two pauses, eleven hiatuses and one lull in a single NS article

    http://www.newscientist.com/article/dn27012-burst-of-warming-may-end-lull-in-rising-temperatures.html

    Deniers everywhere!!

    • dumboldguy Says:

      Omnomoron spends two full weeks looking for some sort of “proof” of something and comes up with an article that he doesn’t even understand (or he wouldn’t have linked it). Perhaps someone will attempt to explain it to him—-not me, I don’t have the patience, or not since I last spent weeks trying to get a developmentally challenged toad to do calculus, and that’s about how difficult it would to be to get Omno to understand science.

      • omnologos Says:

        it’s not a matter of patience but of understanding, in fact, science. And the scientists who have been working on the pause/lull/hiatus that you and others keep trying to argue against.

        You do not even understand that I have not spent two weeks looking for anything. The article is from eight hours ago and it made a round of twitter accounts – that’s how it came to my attention.

        But I know all of this will not even light up a single brain cell in your brain.

        We can now add NS to the list. I do not think there is any reputable or even disreputable scientific publication that has denied the existence of the phenomenon otherwise known as pause/hiatus/slowdown/lull/temperatures-rising-not-as-rapidly – a phenomenon that might have ended already for all we know, but still it has been no figment of nobody’s imagination.

        To argue the contrary is a form of denial strictly confined to sad commenters, especially those who cannot contribute anything apart from bilious remote telepsychologizing.

        Could the aforementioned losers now please avoid vomiting the usual “the pause doesn’t matter wrt long-term global warming”. We’ve been here before – of course 15 years don’t matter compared to 150. This does not mean that 15 years do not even exist.


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