Good news from the IPCC

I haven’t seen this reported elsewhere (so perhaps I am way off base) but I think the new statement of climate sensitivity in the IPCC AR5 represents some real good news compared with the statement in AR4

Here is the statement from AR5:

Climate sensitivity is likely in the range 1.5°C to 4.5°C, extremely unlikely less than 1°C, and very unlikely greater than 6°C

And here is the statement from AR4:

Climate sensitivity is likely to be in the range of 2 to 4.5°C with a best estimate of about 3°C, and is very unlikely to be less than 1.5°C. Values substantially higher than 4.5°C cannot be excluded, but agreement of models with observations is not as good for those values

The part I put in bold represents the terrifying possibility that climate sensitivity is much higher than we thought. Thankfully research published since the 2007 IPCC AR4 indicates that this terrifying scenario is not likely to be accurate.

Of course this doesn’t mean we are out of the woods. The estimates of climate sensitivity in AR5 are plenty worrisome and even the low-end estimate of 1.5°C is reason for real concern . To stretch the ‘out of the woods’ metaphor in the 2007 AR4 report we were lost in the woods and in real danger (the estimate of climate sensitivity). On top of it all there was a distant howl of hungry wolves (the possibility of climate sensitivity being substantially higher) . Now in 2013 with AR5 we are still lost in the woods, and in real danger but the wolves are gone.

In a field like climate change, where dire news in the norm, I think this qualifies as very good news.

15 thoughts on “Good news from the IPCC

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  1. Well, there’s this too.

    This is sorta good news, kinda, but it’s definitely not good enough news to outweigh the six more years of inaction since AR4.

  2. Don’t really get how anywhere between 1 and 6 degrees of warming is a cheery prospect given, for example, rapid Arctic ice melt at global average of 0.8 degrees.

  3. My impression is that this ‘good’ news (‘not so terrible’ is perhaps better) has been reported in most articles with any reasonable level of detail in it. The problem is that so much time and space is dedicated to countering the ridiculously overblown claims about the report from those in denial that reasonable discussion gets swamped.

    As an attempt at that reasonable discussion, to what extent are the marginally lower estimates for sensitivity cancelled out by evidence of more severe impacts from a given level of warming? Sea level rise and Arctic sea ice are two obvious examples – are there others? Are there examples of impacts that are projected to be less severe than previously expected?

    1. The big picture is still very dire. as mt pointed out this is definitely not good enough news to outweigh the six more years of inaction since AR4.

  4. Interesting that anyone would regard things as optimistic. I’m not very interested in the sensitivity fights, which seem a rather technical way of saying we will get what we get, which as far as I can see, is a cascade of worsening effects (and time does *not* stop at 2100). In support of which I include a few links that seemed to relate to the topic in general.

    “Is the IPCC right on climate change? Just ask the world’s farmers
    “Observations by farmers in Africa, Asia and Latin America confirm reports of rising temperatures and extreme weather”

    from Time, a couple:
    “Shifting Baselines: Why the Environment Is Even Worse Off Than You Think
    “When it comes to the ocean, we don’t know how good we used to have it.

    “Antarctica Melted in the Past, and As the Climate Warms, It’s Poised to Melt Again
    “The South Pole has been the stable one in the climate change era—relatively speaking. But a pair of studies about Antarctica’s past and its present point towards a very different future.”

    And, slightly OT, about all that misinformation and distraction weeks before the report (unfortunately, this is working better for them, not worse):
    “Greedy Lying Bastards”

    Then there’s this:
    “Meteorologist Breaks Down In Tears After Climate Change Report, Say He Will Never Fly Again” (IMNHSO, a true mensch)

    1. Optimism and good news are relative I suppose. Its good news in the sense that we would be in a worse position were climate sensitivity significantly higher than it appears to be.

      The overall picture is still quite grim as you rightly point out.

    2. Thanks Dan. I’ve been thinking a bit about this “good news/bad news” nexus and the many ways we have tried over the decades to find ways to work with it. We are also beleaguered by social scientists and other theorists telling us how to communicate. I still think a solid disaster is the only thing that seems to get stubborn people’s attention, though not for long. However, since we are talking about the whole future of the community of humankind it is a desperate conundrum.

      A large part of my participation in climate discussions began at AccuWeather, where Brett Anderson has labored patiently with a posse of deniers over the years, and then a flight to DotEarth, which at the time was hospitable enough to real climate science but not choirish. It seemed like a good place for somebody who likes to write and is interested in climate and science to beaver away. I have come to the conclusion that sticking up for reality over there is a losing proposition, which is depressing for the only long-running discussion. Andy himself has moved to the right and only rarely mentions any “solution” but “bridge fuels”, along with bringing in “moderates” (Pielke, forsooth, and Hoerling et al.) but does do a good job of collecting and presenting a variety of source material. It was when I realized that I was being used as a kind of hockey (stick) puck that I reluctantly came to the conclusion that the truth has no chance with a longstanding and dedicated political bunch. In fact, promoting that truth just provides a target for climate bullies and lots of practice for PR argumentators.

      Well, this is OT to sensitivity, but if there is a proper way to get out of the scientific insiders’ group, which is opaque to a large majority of the population and tends to be too strict about ways of presenting real information, I’d like to know what it is. In my personal life, I do sometimes come across an opportunity, and am well armed with the proper caveats about climate being weather over space and time, extreme weather being complex, etc. etc., but that’s not good enough.

      We need almost the whole population, and soon …

      That’s why I find present weather and what we know about it the best tool, difficult as it is, and hedged about with exceptions on both sides. I find the fierceness and frequency of weather history in the making sufficient to get people’s attention.

    3. correction, aargh: only long running discussion at the New York Times (supposedly a leftish though greyish (ish) lady).

  5. I will just point out that confidence in ECS ~3C is difficult so long as the GCMs remain unable to manage a transition from current to Pliocene-like conditions. *Maybe* the slow feedbacks will do us the favor of waiting a few centuries to kick in substantially, but most of the evidence seems to point in the other direction.

  6. Money for nothin’
    — Horatio Algeranon’s interpretation of Dire Straights (which the money grubbing scientists claim we are in)

    Now look at them scientists that’s the way you do it
    You play the public with the IPCC
    That ain’t workin’ that’s the way you do it
    Money for nothin’, and trips for free
    Now that ain’t workin’ that’s the way you do it
    Lemme tell ya them guys ain’t dumb
    Maybe get a blister on your mousing finger
    Maybe get a blister on your bum

    We gotta install scientist covins
    Custom funding deliveries
    We gotta move these alarmist papers
    We gotta move these levels of seas

    The UN envoy with the earring and the makeup
    Yeah buddy that’s her au pair
    The UN envoy got her own jet airplane
    The UN envoy she’s a millionaire

    We gotta install scientist covins
    Custom funding deliveries
    We gotta move these alarmist papers
    We gotta move these levels of seas

    I shoulda learned to play the public
    I shoulda learned to play them ducks
    Look at that drama, he sounds so slick up on the camera
    Mann will he make some bucks
    And he’s up there, what’s that? Hill lyin’ noises?
    Bangin’ on the public for a carbon fee
    That ain’t workin’ that’s the way you do it
    Get your money for nothin’, get your perks for free

    We gotta install scientist covins
    Custom funding deliveries
    We gotta move these alarmist papers
    We gotta move these levels of seas

    Now that ain’t workin’ that’s the way you do it
    You play the public with the IPCC
    That ain’t workin* that’s the way you do it
    Money for nothin’, and trips for free
    Money for nothin’ and perks for free

    * ‘taint “workin group” neither

  7. Very good news indeed: The Sea level rise estimate is still ridiculously non-alarming. And,

    This is perhaps the biggest change over the 4th IPCC report: a much more rapid sea-level rise is now projected (28-98 cm by 2100). This is more than 50% higher than the old projections (18-59 cm) when comparing the same emission scenarios and time periods.

    Greenland melt negligible. Antarctic melt negligible. We are safe. Rejoice!

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