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Model Independence Day

Filed under: — gavin @ 4 July 2018

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.

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  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", Earth System Dynamics Discussions, pp. 1-20, 2018.

If you doubt that the AMOC has weakened, read this

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. More »

The Alsup Aftermath

The presentations from the Climate Science tutorial last month have all been posted (links below), and Myles Allen (the first presenter for the plaintiffs) gives his impression of the events.
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IPCC Communication handbook

Filed under: — gavin @ 31 January 2018

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?

Filed under: — group @ 4 October 2017

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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