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The claim of reduced uncertainty for equilibrium climate sensitivity is premature

Filed under: — rasmus @ 21 January 2018

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.

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  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.

A brief review of rainfall statistics

Filed under: — rasmus @ 21 November 2017

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.

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  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.

Impressions from the European Meteorological Society’s annual meeting in Dublin 

Filed under: — rasmus @ 14 September 2017

The 2017 annual assembly of the European Meteorological Society (EMS) had a new set-up with a plenary keynote each morning. I though some of these keynotes were very interesting. There was a talk by Florence Rabier from the European Centre for Medium-range Weather Forecasts (ECMWF), who presented the story of ensemble forecasting. Keith Seitter, the executive director of the American Meteorological Society (AMS), talked about the engagement with the society on the Wednesday.

The Helix at DCU was the main venue of #EMS2017

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Why extremes are expected to change with a global warming

Filed under: — rasmus @ 5 September 2017

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.

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What do you need to know about climate?

What do you need to know about climate in order to be in the best position to adapt to future change? This question was discussed in a European workshop on Copernicus climate services during a heatwave in Barcelona, Spain (June 12-14).

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