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Global warming on the rise

Global warming on the rise

An alarming weather anomaly has recently been observed in Antarctica. At certain moments, the temperatures in the second half of March were more than 40 Celsius degrees above normal. How to interpret these data? Was it a one-time event or part of a long-term trend? Prof. Robert Twardosz from the Department of Climatology at the JU Institute of Geography and Spatial Management will shed more light on this issue.

The ongoing climate warming is one of the most serious problems faced by scientists and ordinary people alike, because, as experience from recent years has shown, it brings about numerous dangerous environmental, economic, and biometeorological effects, some of which pose a direct threat to human health and life. These include the abnormally hot summers of 2003 in Western Europe and of 2010 in Eastern Europe, with a number of dire consequences, such as numerous excess deaths in France or extensive wildfires in Russia. The memories of these extreme weather conditions were still fresh when similar situations occurred in South Europe in 2012 and in Central Europe in 2015. The drought accompanying the heatwave of August 2015 led to electric power shortages in Poland due to low water levels in rivers and the resultant shortage of water for cooling power plants. In 2018 large parts of Europe were affected by very hot weather in April and May. Such an early heatwave can be harmful from the biometeorological point of view since the human body has not yet managed to adapt to hot temperatures after winter. The fast onset of hot and usually dry weather after a mild and almost snowless winter worsens the problem of drought. In 2019 another month – June – could be classified as exceptionally warm. It turned out to be the hottest month in Kraków since the start of temperature recording in 1792. It should be stressed that the observed significant rises in temperature concerned different time periods – from several days to entire seasons. Obviously, the longer periods of hot weather (lasting one month or longer) tend to be much more harmful to human beings.

Number of large-area temperature anomalies in Europe

Figure 1. Number of large-area temperature anomalies in Europe (negative LATA- and positive LATA+) from 1951 to 2020 (Twardosz and Kossowska-Cezak, 2021); Article.

The observed rise in the frequency of such long-term thermal anomalies, especially those covering large areas (Figure 1), as well as heatwaves, contributes to a sharp rise in the average air temperature. This is especially evident in Europe, where the warming has been the most severe as compared to other areas. The analysis of temperature during the 70-year period between 1951 and 2020 has indicated that the linear rise of air temperature in Europe has continued since 1985 (Figure 2) at a pace of 0.051 °C/year. It’s possible that this has been the greatest climate warming for the last 2 thousand years. Generally speaking, the further to the north and east of the continent the stronger the trend becomes. The temperature rise has been the sharpest in the European Arctic – 0.06-0.08 °C/year during the last 35 years. The changes in average yearly temperature at Hopen station (Figure 3) illustrate this trend very well.

Maps of average yearly air temperature

Figure 2. Maps of average yearly air temperature (regression coefficient; slope; unit: °C/year) in the period 1951-2020 (left) and 1985-2020 (right) (Twardosz et al.); Article.   

The expected consequences of such a severe warming in the Arctic are wide-ranging. The most evident ones include the reduction of the area of mountain glaciers and sea ice as well as changes in permafrost and snow cover. They are quickly followed by changes in the composition (e.g. the encroachment of shrub vegetation). Some of the observed effects, such as those related to less severe weather conditions can be considered as beneficial to humans.

The media have recently informed about extremely high temperatures observed in Antarctica. This continent is very specific because of the occurrence of the lowest temperatures on earth. In 1983, -89.2°C, the lowest air temperature at the surface of the earth, was recorded at Vostok station. Such extremely low temperatures result from a number of factors, including lack of sunlight during the polar night. The presence of snow-ice surface and large heights above sea level (surpassing 4,000 metres in the eastern part) also play a major role in this context. Studies into climate change in Antarctica are very difficult, as researchers have access to weather measurements from only a few stations and the data has been recorded for a relatively short period of time. It has been stressed that when compared to other regions, Antarctica has been characterised by greater ‘resilience’ to the current global warming. A drop in temperature has even been observed in some of its parts, e.g. in East Antarctica.

Long-term changes in average yearly air temperature in the European Arctic (Hopen Station)

Figure 3. Long-term changes in average yearly air temperature in the European Arctic (Hopen Station)

At the end of the second decade of March 2022, that is during early autumn on the southern hemisphere, record maximum temperatures were observed at two inland stations on the continent, Concordia and Vostok – 12.0 and 17.7 °C, respectively. The abnormally warm weather (in relative terms) continued for 5 straight days, that is from 17 to 21 March. This phenomenon was even described as a ‘heatwave’. This short episode happened in a month when an upward trend in temperature is not observed, as confirmed by Vostok station records (Figure 4). This exceptional warming was caused by circulation factors, specifically by an influx of warm air into the continent’s interior.

Long-term changes in average temperature in March at Vostok station (Antarctica)

Figure 4. Long-term changes in average temperature in March at Vostok station (Antarctica)

All in all, it should be stressed that the current global warming is a complex and spatially diverse process, requiring constant monitoring in order to better asses its possible social, economic and environmental impact.

Original text by Prof. Robert Twardosz from the Department of Climatology at the JU Institute of Geography and Spatial Management: www.nauka.uj.edu.pl

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