Much evidence has accumulated that temperature extremes and variability are changing. Accurately diagnosing such changes is of vital societal interest, not least because human induced climate change is often expected to materialise primarily through changes in the extreme tails.
Quantifying these features of climate time series statistically in climate models and observations is not straightforward. To a large extent, that is because extreme events are rare by definition, a fact that seems hardly surprising. This fact implies, however, that conventional methods quickly break down when it comes to the tails. This blog post serves s a cautionary note, in which we discuss how apparently very simple methods can result in severely biased estimates, and how this can be avoided1,2.
Guest post by Sebastian Sippel, MPIB, based on Sippel et al. (2015) Continue reading How to quantify changes in climate extremes without inducing artefacts?
Was last year really the warmest on record? As soon as NOAA published its official announcement in January, this question invaded the web feeding blogs, online newspapers and forums with passionate discussions. Relevant or pointless? The question is not so much knowing whether or not a new record was broken. Should 2014 rank second or third, this wouldn’t change the big picture: last year, temperatures on our planet continued the existing long-term positive trend. On top of that, the story is a bit thicker than the one single number obtained when averaging near-surface air temperatures in time and space. So, 2014: year of extremes or warm year in a changing climate?
Guest post by François Massonnet, Université Catholique de Louvain, Belgium / Catalan Institute of Climate Sciences, Spain Continue reading Extremes of 2014 in review
Model projections of heavy precipitation and temperature extremes include large uncertainties. However, disagreement between individual simulations primarily arises from internal variability, whereas models agree remarkably well on the forced signal.
Post based on Fischer et al., 2014, Geophys. Res. Lett.
Continue reading Projected changes of precipitation and temperature extremes