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The claim of reduced uncertainty for equilibrium climate sensitivity is premature

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A recent story in the Guardian claims that new calculations reduce the uncertainty associated with a global warming:

A revised calculation of how greenhouse gases drive up the planet’s temperature reduces the range of possible end-of-century outcomes by more than half, …

It was based on a study recently published in Nature (Cox et al. 2018), however, I think its conclusions are premature.

[Read more…] about The claim of reduced uncertainty for equilibrium climate sensitivity is premature

References

  1. P.M. Cox, C. Huntingford, and M.S. Williamson, "Emergent constraint on equilibrium climate sensitivity from global temperature variability", Nature, vol. 553, pp. 319-322, 2018. http://dx.doi.org/10.1038/nature25450

Unforced Variations: Jan 2018

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Happy new year, and a happy new open thread.

In response to some the comments we’ve been getting about previous open threads, we are going to try separating out OT comments on mitigation/saving the planet/theories of political action from ones related to the physical climate system. This thread remains a place for climate science issues, questions, & news, but we have started a new Forced Responses thread where people can more clearly discuss mitigation issues. We realise that sometimes it can be hard to cleanly separate these conversations, but hopefully folk can try that out as a new year’s resolution!

Note we will be updating the Model/Data comparisons over the next few weeks as the various observational data sets get updated for calendar year 2017. The main surface temperature datasets will be released around Jan 18.

What did NASA know? and when did they know it?

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If you think you know why NASA did not report the discovery of the Antarctic polar ozone hole in 1984 before the publication of Farman et al in May 1985, you might well be wrong.

One of the most fun things in research is what happens when you try and find a reference to a commonly-known fact and slowly discover that your “fact” is not actually that factual, and that the real story is more interesting than you imagined…

[Read more…] about What did NASA know? and when did they know it?

References

  1. J.C. Farman, B.G. Gardiner, and J.D. Shanklin, "Large losses of total ozone in Antarctica reveal seasonal ClOx/NOx interaction", Nature, vol. 315, pp. 207-210, 1985. http://dx.doi.org/10.1038/315207a0

Fall AGU 2017

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It’s that time of year again. #AGU17 is from Dec 11 to Dec 16 in New Orleans (the traditional venue in San Francisco is undergoing renovations).

As in previous years, there will be extensive live streams from “AGU On Demand” (free, but an online registration is required) of interesting sessions and the keynote lectures from prize-winners and awardees.

Some potential highlights will be Dan Rather, Baba Brinkman, and Joanna Morgan. The E-lightning sessions are already filled with posters covering many aspects of AGU science. Clara Deser, Bjorn Stevens, David Neelin, Linda Mearns and Thomas Stocker are giving some the key climate-related named lectures. The Tyndall Lecture by Jim Fleming might also be of interest.

As usual there are plenty of sessions devoted to public affairs and science communication, including one focused on the use of humour in #scicomm (on Friday at 4pm to encourage people to stay to the end I imagine), and a workshop on Tuesday (joint with the ACLU and CSLDF) on legal issues for scientist activists and advocates.

AGU is also a great place to apply for jobs, get free legal advice, mingle, and network.

A couple of us will be there – and we might find time to post on anything interesting we see. If any readers spot us, say hi!

A brief review of rainfall statistics

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There have been a number of studies which show that we can expect more extreme rainfall with a global warming (e.g. Donat et al., 2016). Hence, there is a need to increase our resilience to more rainfall in the future.

We can say something about how the rainfall statistics will be affected by a global warming, even when the weather itself is unpredictable beyond a few days.

Statistics is remarkably predictable for a large number of events where each of them is completely random (welcome to thermodynamics and quantum physics).

The normal distribution has often been used to describe the statistical character of daily temperature, but it is completely unsuitable for 24-hr precipitation. Instead, the gamma distribution has been a popular choice for describing rainfall.

I wonder, however, if there is an even better way to quantify rainfall statistics.

[Read more…] about A brief review of rainfall statistics

References

  1. M.G. Donat, A.L. Lowry, L.V. Alexander, P.A. O’Gorman, and N. Maher, "More extreme precipitation in the world’s dry and wet regions", Nature Climate Change, vol. 6, pp. 508-513, 2016. http://dx.doi.org/10.1038/nclimate2941

El Niño and the record years 1998 and 2016

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2017 is set to be one of warmest years on record. Gavin has been making regular forecasts of where 2017 will end up, and it is now set to be #2 or #3 in the list of hottest years:

In either case it will be the warmest year on record that was not boosted by El Niño. I’ve been asked several times whether that is surprising. After all, the El Niño event, which pushed up the 2016 temperature, is well behind us. El Niño conditions prevailed in the tropical Pacific from October 2014 throughout 2015 and in the first half of 2016, giving way to a cold La Niña event in the latter half of 2016. (Note that global temperature lags El Niño variations by several months so this La Niña should have cooled 2017.) [Read more…] about El Niño and the record years 1998 and 2016