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Bending low with Bated breath

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“Shall I bend low and in a bondman’s key,
With bated breath and whisp’ring humbleness…?”

Shylock (Merchant of Venice, Act 1, Scene 3)

As dark nights draw in, the venerable contrarians at the GWPF are still up late commissioning silly pseudo-rebuttals to mainstream science. The latest, [but see update below] which no-one was awaiting with any kind of breath, is by Dr. Ray Bates (rtd.) which purports to be a take-down of the recent #SR15 report. As Peter Thorne (an IPCC author) correctly noted, this report is a “cut-and-paste of long-debunked arguments”. I’ve grown a little weary of diving down to rebut every repetitive piece of nonsense, but this one has a few funny aspects that make it worthwhile to do so.

When they go low, we go “sigh…”.

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Model Independence Day

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We hold these truths to be self-evident, that all models are created equal, that they are endowed by their Creators with certain unalienable Rights, that among these are a DOI, Runability and Inclusion in the CMIP ensemble mean.

Well, not quite. But it is Independence Day in the US, and coincidentally there is a new discussion paper (Abramowitz et al) (direct link) posted on model independence just posted at Earth System Dynamics.

[Read more…] about Model Independence Day

References

  1. G. Abramowitz, N. Herger, E. Gutmann, D. Hammerling, R. Knutti, M. Leduc, R. Lorenz, R. Pincus, and G.A. Schmidt, "Model dependence in multi-model climate ensembles: weighting, sub-selection and out-of-sample testing", 2018. http://dx.doi.org/10.5194/esd-2018-51

If you doubt that the AMOC has weakened, read this

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A few weeks ago, we’ve argued in a paper in Nature that the Atlantic overturning circulation (sometimes popularly dubbed the Gulf Stream System) has weakened significantly since the late 19th Century, with most of the decline happening since the mid-20th Century. We have since received much praise for our study from colleagues around the world (thanks for that). But there were also some questions and criticisms in the media, so I’d like to present a forum here for discussing these questions and hope that others (particularly those with a different view) will weigh in in the comments section below. [Read more…] about If you doubt that the AMOC has weakened, read this

IPCC Communication handbook

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A new handbook on science communication came out from IPCC this week. Nominally it’s for climate science related communications, but it has a wider application as well. This arose mainly out of an “Expert meeting on Communication” that IPCC held in 2016.

6 principles to help IPCC scientists better communicate their work

There was a Guardian article on it as well.

The six principles are pretty straightforward:

  1. Be a confident communicator
  2. Talk about the real world, not abstract ideas
  3. Connect with what matters to your audience
  4. Tell a human story
  5. Lead with what you know
  6. Use the most effective visual communication

Each is supported with references to the relevant literature and with climate-related (“real world”) examples that are themselves confidently communicated with effective visuals.

But what do people think? Is this a useful addition to the literature on communication? Anything you think doesn’t work? or that perhaps surprises you?

PS. I’m perhaps a little biased because they use a Peter Essick photo for their cover art that was also in my book.

1.5ºC: Geophysically impossible or not?

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Guest commentary by Ben Sanderson

Millar et al’s recent paper in Nature Geoscience has provoked a lot of lively discussion, with the authors of the original paper releasing a statement to clarify that their paper did not suggest that “action to reduce greenhouse gas emissions is no longer urgent“, rather that 1.5ºC (above the pre-industrial) is not “geophysically impossible”.

The range of post-2014 allowable emissions for a 66% chance of not passing 1.5ºC in Millar et al of 200-240GtC implies that the planet would exceed the threshold after 2030 at current emissions levels, compared with the AR5 analysis which would imply most likely exceedance before 2020. Assuming the Millar numbers are correct changes 1.5ºC from fantasy to merely very difficult.

But is this statement overconfident? Last week’s post on Realclimate raised a couple of issues which imply that both the choice of observational dataset and the chosen pre-industrial baseline period can influence the conclusion of how much warming the Earth has experienced to date. Here, I consider three aspects of the analysis – and assess how they influence the conclusions of the study.
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Why extremes are expected to change with a global warming

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Joanna Walters links extreme weather events with climate change in a recent article in the Guardian, however, some  reservations have been expressed about such links in past discussions.

For example, we discussed the connection between single storms and global warming in the post Hurricanes and Global Warming – Is there a connection?, the World Meteorological Organization (WMO) has issued a statement, and Mike has recently explained the connection in the Guardian.

[Read more…] about Why extremes are expected to change with a global warming

Something Harde to believe…

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A commenter brings news of an obviously wrong paper that has just appeared in Global and Planetary Change. The paper purports to be a radical revision of our understanding of the carbon cycle by Hermann Harde. The key conclusions are (and reality in green):

  • The average residence time of CO2 in the atmosphere is found to be 4 years.

    [The residence time for an individual molecule is not the same as the perturbation response time of the carbon cycle which has timescales of decades to thousands of years.]

  • The anthropogenic fraction of CO2 in the atmosphere is only 4.3%.

    [Actually, it’s 30%.]

  • Human emissions only contribute 15% to the CO2 increase over the Industrial Era.

    [It’s all of it.]

Since these points contradict multiple independent sources of evidence, I can, without hesitation, predict that there are fundament flaws in this paper that will raise serious questions about the quality of the peer-review that this paper went through. Oddly, this paper is labeled as an “Invited Research Article” and so maybe some questions might be asked of the editor responsible too.

Notwithstanding our last post on the difficulty in getting comments published, this paper is crying out for one.

But this kind of thing has been done before, does not require any great sophistication or computer modeling to rebut, and has come up so many times before (Salby (also here), Beck, Segalstad, Jaworowski etc.), that perhaps a crowd-sourced rebuttal would be useful.

So, we’ll set up an overleaf.com page for this (a site for collaborative LaTeX projects), and anyone who wants to contribute should put the gist of their point in the comments and we’ll send the link so you can add it to the draft. Maybe the citizen scientists among you can pull together a rebuttal faster than the professionals?

Update: The crowd-sourced comment has appeared Köhler et al (2018).

References

  1. H. Harde, "Scrutinizing the carbon cycle and CO2 residence time in the atmosphere", Global and Planetary Change, vol. 152, pp. 19-26, 2017. http://dx.doi.org/10.1016/j.gloplacha.2017.02.009
  2. P. Köhler, J. Hauck, C. Völker, D.A. Wolf-Gladrow, M. Butzin, J.B. Halpern, K. Rice, and R.E. Zeebe, "Comment on “ Scrutinizing the carbon cycle and CO 2 residence time in the atmosphere ” by H. Harde", Global and Planetary Change, vol. 164, pp. 67-71, 2018. http://dx.doi.org/10.1016/j.gloplacha.2017.09.015

Comparing models to the satellite datasets

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How should one make graphics that appropriately compare models and observations? There are basically two key points (explored in more depth here) – comparisons should be ‘like with like’, and different sources of uncertainty should be clear, whether uncertainties are related to ‘weather’ and/or structural uncertainty in either the observations or the models. There are unfortunately many graphics going around that fail to do this properly, and some prominent ones are associated with satellite temperatures made by John Christy. This post explains exactly why these graphs are misleading and how more honest presentations of the comparison allow for more informed discussions of why and how these records are changing and differ from models.
[Read more…] about Comparing models to the satellite datasets