In common with several other parts of the earth, the UK has experienced an increasing frequency of extreme weather events such as this year's hot, dry summer. Droughts, wildfires and floods have also been occurring with greater frequency in other parts of the world. According to an analysis published in Nature Communications, rising temperatures in the Arctic - linked to climate change - have slowed the circulation of the jet stream and other giant planetary winds, which has led to pressure fronts getting 'stuck' and to greater weather extremes.
The article in Nature Communications explains that accelerated warming in the Arctic, as compared to the rest of the globe, might be having profound impacts on mid-latitude weather.
The paper reviews the scientific evidence behind three leading hypotheses on the influence of Arctic changes on mid-latitude summer weather and shows that interactions between Arctic temperatures and other parts of the earth could lead to more persistent hot-dry extremes in the mid-latitudes, which include the EU countries, US, Russia and China.
The researchers, who come from leading institutions in Europe and the US, say: "The exact nature of these non-linear interactions is not well quantified but they provide potential high-impact risks for society."
Their paper explains that there has been an observed increase in the frequency and intensity of extreme heat and heavy rainfall events since the late 1980s, especially in mid-latitude regions, and that these have been linked to man-made global warming.
Near-surface temperatures in the Arctic have been rising at a pace that is two to four times faster than the rest of the globe; and effect known as 'Arctic amplification'. The extent to which AA affects the mid-latitude circulation and possibly contribute to the observed increases in weather extremes has been a subject of active debate.
The authors warn that this situation could lead to “very extreme extremes”, which occur when abnormally high temperatures linger for unusually prolonged periods producing heatwaves, wildfires and floods.
Recent records from the UK Met Office National Climate Information Centre show that the UK is hotter and wetter than at any other time in the last 100 years. 2017 was the fifth warmest on record and the UK has experienced nine of the 10 hottest years on record since 2002.
Though the summer of 2018 has been dry, in many parts of the UK, the amount of rainfall has actually gone up. Average annual rainfall has been 20% higher in the years between 2008 and 2017 than those between 1961 and 1990.
Chris Rapley, professor of climate science at University College London (quoted in The Guardian) said: “What happens in the Arctic doesn’t stay in the Arctic.
"By upsetting the energy balance of the planet we are changing the temperature gradient between the equator and the pole. This in turn sets in motion major reorganisations of the flow patterns of the atmosphere and ocean.
“The consequences are emerging and they are disruptive, and likely to become even more profoundly so. We are on a journey and the destination doesn’t look good.”