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Climate indicators

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The climate system is complex, and a complete description of its state would require huge amounts of data. However, it is possible to keep track of its conditions through summary statistics.

There are some nice resources which give an overview of a number for climate indicators. Some examples include NASA and The Climate Reality Project.

The most common indicator is the atmospheric background CO2 concentration, the global mean temperature, the global mean sea level, and the area with snow or Arctic sea ice. Other indicators include rainfall statistics, drought indices, or other hydrological aspects. The EPA provides some examples.   

One challenge has been that the state of the hydrological cycle is not as easily summarised by one single index in the same way as the global mean temperature or the global mean sea level height. However, Giorgi et al. (2011) suggested a measure of hydro-climatic intensity (HY-INT) which is an integrated metric that captures the precipitation intensity as well as dry spell length.  

There are also global datasets of indices representing the more extreme aspects of climate called CLIMDEX, providing a list of 27 core climate extremes indices (so-called the ‘ETCCDI’ indices, referring to the ‘CCl/CLIVAR/JCOMM Expert Team on Climate Change Detection and Indices’).

In addition, there is a website hosted by the NOAA that presents various U.S. Climate Extremes Index (CEI) in an interactive way.

So there are quite a few indicators for various aspects of the climate. One question we should ask, however, is whether they capture all the important and relevant aspects of the climate. I think that they don’t, and that there are still some gaps.

[Read more…] about Climate indicators

References

  1. F. Giorgi, E. Im, E. Coppola, N.S. Diffenbaugh, X.J. Gao, L. Mariotti, and Y. Shi, "Higher Hydroclimatic Intensity with Global Warming", Journal of Climate, vol. 24, pp. 5309-5324, 2011. http://dx.doi.org/10.1175/2011JCLI3979.1

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

Fake news, hacked mail, alternative facts – that’s old hat for climate scientists

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Distortion? False information? Conspiracy theories? Hacked email? Climate scientists have known all this for decades. What can be learned from their rich experience with climate propaganda.

The world is slowly waking up. “Post-truth” was declared the word of the year 2016 by the Oxford Dictionaries. Finally, people start to widely appreciate how dangerous the epidemic of fake news is for democracy.

Stir up hate, destroy discourse, make insane claims until no one can distinguish the most bizarre absurdity from the truth any more.

Thus the Austrian author Robert Misik aptly describes the strategy of right-wing populists.

Some call it “alternative facts”. (Those are the convenient alternative to true facts.) Let’s simply call it propaganda. [Read more…] about Fake news, hacked mail, alternative facts – that’s old hat for climate scientists

Blizzard Jonas and the slowdown of the Gulf Stream System

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Blizzard Jonas on the US east coast has just shattered snowfall records. Both weather forecasters and climate experts have linked the high snowfall amounts to the exceptionally warm sea surface temperatures off the east coast. In this post I will examine a related question: why are sea surface temperatures so high there, as shown in the snapshot from Climate Reanalyzer below?

 

GFS-025deg_NH-SAT1_SST_anom_24_Jan_2016

I will argue that this warmth (as well as the cold blob in the subpolar Atlantic) is partly due to a slowdown of the Atlantic Meridional Overturning Circulation (AMOC), sometimes referred to as the Gulf Stream System, in response to global warming. There are two points to this argument:

[Read more…] about Blizzard Jonas and the slowdown of the Gulf Stream System

Labels for climate data

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metadata-fig “These results are quite strange”, my colleague told me. He analysed some of the recent climate model results from an experiment known by the cryptic name ‘CMIP5‘. It turned out that the results were ok, but we had made an error when reading and processing the model output. The particular climate model that initially gave the strange results had used a different calendar set-up to the previous models we had examined.

[Read more…] about Labels for climate data

A new European report on climate extremes is out

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A new report on extreme climate events in Europe is just published: ‘Extreme Weather Events in Europe: preparing for climate change adaptation‘. It was launched in Oslo on October 24th by the Norwegian Academy of Science and Letters, and the report is now available online.

Front cover of 'Extreme Weather Events in Europe: preparing for climate change adaptation'
Front cover of ‘Extreme Weather Events in Europe:
preparing for climate change adaptation’

What’s new? The new report provides information that is more specific to Europe than the SREX report from the Intergovernmental Panel on Climate Change (IPCC), and incorporate phenomena that have not been widely covered.

It provides some compelling information drawn from the insurance industry, and indeed, a representative from Munich Re participated in writing this report. There is also material on convective storms, hail, lightening, and cold snaps, and the report provides a background on extreme value statistics, risk analysis, impacts, and adaptation.

[Read more…] about A new European report on climate extremes is out

A new experiment with science publication

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A while ago, I received a request to publish a paper on a post that I had written here on RealClimate, exposing the flaws in the analysis of Humlum et al., (2011).

Instead of writing a comment to one paper, however, I thought it might be useful to collect a sample of papers that I found unconvincing (usual suspects), and that have had a fairly high public profile.

[Read more…] about A new experiment with science publication

References

  1. O. Humlum, J. Solheim, and K. Stordahl, "Identifying natural contributions to late Holocene climate change", Global and Planetary Change, vol. 79, pp. 145-156, 2011. http://dx.doi.org/10.1016/j.gloplacha.2011.09.005