Hannah Bloomfield – Cabot Institute for the Environment blog

Temperature anomaly in Europe, Jan 1. Much of the continent was 10°C or more (dark red and grey) above the long-term average.
WX Charts, CC BY-NC

An extreme winter heatwave meant countries across Europe experienced a record-breaking New Year’s Day. New daily temperature records for the month of January were set in at least eight countries: Belarus, Czechia, Denmark, Latvia, Liechtenstein, Lithuania, Netherlands and Poland.

In many cases the temperatures were not just breaking the old highs, but smashing them by massive margins. On a typical January day in Warsaw, Poland, temperatures would barely go above freezing, yet the city recently experienced 19℃, breaking the previous January high by 5.1℃.

New January records were set at thousands of individual stations in many other countries such as 25.1℃ at Bilbao airport in Spain, 0.7℃ hotter than the previous record set only last year. Large areas of central and Eastern Europe experienced temperatures 10℃ to 15℃ warmer than average for this time of year – and that has persisted through the week.

When Europe experienced extreme heat in July of last year, more than 20,000 died. Fortunately winter heatwaves are much less deadly, but they can still affect both human society and natural ecosystems in many ways.

1. Less energy is needed

In Europe deaths due to cold weather vastly outweigh those caused by extreme high temperatures – in the UK there are ten times more. Warmer winters will reduce this excess mortality and, with the current cost-of-living crisis, many will have been relieved that a heatwave meant less energy was needed to heat their homes.

Electricity demand is influenced by things like the time of day, the day of the week and socio-economic factors like the COVID pandemic or the war in Ukraine. The weather also makes a difference. For example, in Poland and the Netherlands demand was noticeably lower than average, especially since January 1 was a Sunday. The extent of the heatwave also meant countries could refill some of their winter gas reserves, or large batteries.

Energy consumption in Poland December 28 to January 5. The red line shows the 2022-2023 heatwave period, and the grey lines show available data from 2015-2022.
Hannah Bloomfield / data: transparency.entsoe.eu, Author provided

2. Reduced yields for some crops

Winter warm spells don’t always have such a positive impact though. For instance a lack of snow in the mountains affects agriculture and can reduce crop yield, since snow creates an insulating blanket that prevents frost from penetrating into the soil. This means snow can actually increase soil moisture more than rainfall, thus improving growing conditions later in the season.

The big snow melt in spring time replenishes reservoirs and allows hydroelectricity generation, but unexpected snow melt can lead to flooding. Changes to the timings of these events will require preparation and adaptation to enable a steady supply of water to where we need it.

Warmer temperatures will create longer growing seasons in many regions. This is not always the case though. A recent study showed that for alpine grasslands an earlier growing season (the point when snow has melted entirely) leads to ageing and browning of the grasses in the later part of the summer.

3. The snow economy is in trouble

The heatwave caused ski resorts across the Alps to close in what should be their busiest time of year. In January the slopes would be expected to have a good covering of snow – but instead we saw green grassy fields.

This hits the local economy where many people rely on winter sports tourism. Events such as the Adelboden alpine ski World Cup are relying on artificial snow, which comes with a further environmental cost increasing the carbon footprint of ski resorts and requiring a large water supply. Indeed, the Beijing winter Olympics used the equivalent of daily drinking water for 900 million people to generate the artificial snow it required.

4. Animals out of sync with the climate

We humans are perhaps fortunate, as we are able to adapt. Some ski resorts have already opened mountain bike trails in winter to offer alternative tourism, but wildlife and ecosystems cannot adjust so rapidly.

In the mountains many species, such as ptarmigan and mountain hares, change their colouring for winter to camouflage in the white snow. The timing of this change is determined by length of day – not the temperature or amount of snow. These creatures are at greater risk of being preyed on when it is warmer.

White rabbit, brown background — Mountain hares are dressed for a climate that has changed.
Mark Medcalf / shutterstock

Over the past century heat extremes in Europe have increased in intensity and frequency. Both the general warming and heatwave events have been firmly attributed to humans.

Future projections suggest these trends will continue and heatwaves in both summer and winter will get hotter, last longer, and occur more often. We need to learn to adapt for these changes in all seasons and think about the impacts on everyone – and everything – on our planet.

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This blog is written by Cabot Institute for the Environment members Dr Vikki Thompson, Senior Research Associate in Geographical Sciences, University of Bristol and Dr Hannah Bloomfield, Postdoctoral Researcher in Climate Risk Analytics, University of Bristol. This article is republished from The Conversation under a Creative Commons license. Read the original article.

A new type of extreme weather

So should we be worried about this period of low wind? In short, no. The key thing here is that we’re experiencing an extreme event. It may not be the traditional definition of extreme weather (like a large flood or a hurricane) but these periods, known in energy-meteorology as “wind-droughts”, are becoming critical to understand in order to operate power systems reliably.

Recent research I published with colleagues at the University of Reading highlighted the importance of accounting for the year-to-year variability in wind generation as we continue to invest in it, to make sure we are ready for these events when they do occur. Our team has also shown that periods of stagnant high atmospheric pressure over central Europe, which lead to prolonged low wind conditions, could become the most difficult for power systems in future.

Climate change could play a role

When we think about climate change we tend to focus much more on changes in temperature and rainfall than on possible variations in near-surface wind speed. But it is an important consideration in a power system that will rely more heavily on wind generation.

The latest IPCC report suggests that average wind speeds over Europe will reduce by 8%-10% as a result of climate change. It is important to note that wind speed projections are quite uncertain in climate models compared with those for near-surface temperatures, and it is common for different model simulations to show quite contrasting behaviour.

Colleagues and I recently analysed how wind speeds over Europe would change according to six different climate models. Some showed wind speeds increasing as temperatures warm, and others showed decreases. Understanding this in more detail is an ongoing topic of scientific research. It is important to remember that small changes in wind speed could lead to larger changes in power generation, as the power output by a turbine is related to the cube of the wind speed (a cubic number is a number multiplied by itself three times. They increase very fast: 1, 8, 27, 64 and so on).

World map with dark blue (less wind) in Europe, North America and China

Change in wind speed compared to 1986-2005 if we were to limit global warming to 1.5C. Areas in blue will have less wind; areas in green, more wind.
IPCC Interactive Atlas, CC BY-SA

The reductions in near-surface wind speeds seen in the above map could be due to a phenomenon called “global stilling”. This can be explained by the cold Arctic warming at a faster rate than equatorial regions, which means there is less difference in temperature between hot and cold areas. This temperature difference is what drives large-scale winds around the globe through a phenomenon called thermal wind balance.

With all the talk of wind power being the answer to our energy needs, amid spiralling gas prices and the countdown to COP26, the recent wind drought is a clear reminder of how variable this form of generation can be and that it cannot be the sole investment for a reliable future energy grid. Combining wind with other renewable resources such as solar, hydropower and the ability to smartly manage our electricity demand will be critical at times like this summer when the wind is not blowing.

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This blog was written the Cabot Institute for the Environment member Dr Hannah Bloomfield, Postdoctoral Researcher in Climate Risk Analytics, University of Bristol. This article is republished from The Conversation under a Creative Commons license. Read the original article.

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