The hottest 3-day average of Tmax in 2018 (ECMWF analyses up to 24 July 2018, forecasts up to 31 July 2018) compared to the highest 3-day maximum temperature in the period 1981-2010 that is currently the “normal” period (ERA-interim). Along coasts there are artefacts from comparing the high-resolution analyses with the lower-resolution ERA-interim reanalysis. Graphic: World Weather Attribution

Dr. Jeff Masters
27 July 2018
(Weather Underground) – The intense, unrelenting heat wave that has gripped northern Europe during the summer of 2018 was made at least 2 – 5 times more likely at some locations by climate change, according to a preliminary analysis released on Friday by the World Weather Attribution network. This network, staffed by a team of scientists from six institutions, was established to provide near-real time analysis of how climate change might be affecting extreme weather events. The scientists used data from seven weather stations in Ireland, the Netherlands, Denmark, Sweden, Norway, and Finland; a UK station was not included, due to time constraints.The study found that rising global temperatures have increased the likelihood of the summer 2018 heat wave by five times in Denmark, three times in the Netherlands and two times in Ireland. The data for Scandinavia was too noisy to determine a specific number, with the report concluding “climate change increased the odds of a heat wave as observed in 2018 in Scandinavia but we cannot quantify by how much.”The study focused on individual stations, not on larger areas like previous attribution studies have. A climate change signal is harder to distinguish from the noise in observations taken at individual places, meaning that the numbers quoted are likely to be low. This underestimate may be as much as a factor of two, since a study the same group did of the 2017 southern Europe heat wave found “an increase in the occurrence likelihood of a heat wave like the one observed was at least a factor two larger in the area average than at individual stations.” CarbonBrief has a more in-depth look at the study.The results of the attribution study are not a surprise, since the increasing frequency and intensity of heat waves are among the most obvious and well-documented effects of climate change. If we continue to avoid making a concerted effort to reduce our emissions of heat-trapping greenhouse gases, heat waves as extreme as this one will simply be ordinary summer weather a few decades from now.The great northern European heat wave of 2018 continued to set all-time records on Friday, July 27, with Norway bearing the brunt of the record heat. According to weather records expert Maximilliano Herrera, dozens of all-time heat records fell at stations with a long period of record (POR) in Norway, some falling by a remarkable 4°C (7°F)—a very rare margin to break an all-time heat record by. Mr. Herrera, along with weather records experts Etienne Kapikian and Michael Theusner, have put together the following list of stations that set notable all-time heat records July 25 – 27. These stations had at least a 40-year period of record (POR). [more]

2018 European Heat Wave Up to 5 Times More Likely Due to Climate Change