Increasing Tropical Nights in Europe Pose Health Risks

A recent report from the EU's climate monitoring program, Copernicus, along with the World Meteorological Organization (WMO), reveals a concerning rise in tropical nights across Europe. Defined as nights when temperatures do not drop below 20 degrees Celsius, these occurrences are becoming more frequent, particularly in Southeast Europe.

During the summer of 2024, Southeast Europe recorded an unprecedented 23 tropical nights, significantly higher than the average of 8 and surpassing the previous record of 16 nights set in 2012. This trend is alarming as elevated nighttime temperatures hinder the body's ability to recuperate from daytime heat stress.

Florence Rabier, the director-general of the European Centre for Medium-Range Weather Forecasts (ECMWF), highlighted the continued increase in heat stress across Europe during a presentation of the report.

Globally, the last decade has marked the hottest years on record. However, Europe is experiencing even faster warming, doubling the global average since the 1980s.

The extreme heatwave in Southeast Europe during the summer of 2024 was particularly striking. It was marked by the longest recorded heatwave in the region in July, lasting for 13 consecutive days and affecting 55 percent of the area.

Southeast Europe also experienced 66 days of heat stress this summer, compared to an average of only 29 days.

Understanding Heat Stress

Heat stress negatively impacts the human body not only due to high temperatures but also because of factors like humidity and wind conditions. The assessment of heat stress is based on the maximum daily 'feels-like' temperature, known as the Universal Thermal Climate Index (UTCI).

• Severe heat stress occurs when UTCI reaches at least 32 degrees.
• Very severe heat stress is indicated when UTCI hits 38 degrees.
• Extreme heat stress occurs at or above 46 degrees.

According to the UN's Intergovernmental Panel on Climate Change (IPCC), a global temperature rise of 1.5 degrees could result in an additional 30,000 deaths annually in Europe due to extreme heat. In 2023, approximately 48,000 heat-related fatalities were reported, while the figure was around 62,000 in 2022. Estimates for 2024 are not yet available, but the World Health Organization (WHO) notes a 30 percent increase in heat-related deaths over the past two decades.

As southern Europe grapples with increasingly warmer nights, the Arctic continues to warm at an alarming rate. The year 2024 marked the third hottest year recorded for the Arctic as a whole, particularly around Svalbard, which experienced its third consecutive record-breaking summer.

This rapid warming is having significant effects on glaciers in Scandinavia and Svalbard, with 2024 witnessing the largest mass loss recorded. The average thickness loss was noted to be 1.8 meters in Scandinavia and 2.7 meters in Svalbard. Celeste Saulo, the WMO's Secretary-General, emphasized the unprecedented nature of glacier melting and announced that 2025 will be recognized as the International Year for Glacier Preservation. She noted that climate adaptation is not a future choice but an immediate necessity.

Climate Data for Europe in 2024

• Temperature: 2024 was the hottest recorded year in Europe, with unprecedented annual temperature highs across nearly half the continent.
• Sea Surface Temperature: The average sea surface temperature for the year was the highest ever recorded for the European region, exceeding the average by 0.7 degrees and by 1.2 degrees in the Mediterranean.
• Precipitation: There was a notable east-west disparity in precipitation levels, with Western Europe experiencing one of the ten rainiest years since 1950.
• Flooding: Europe faced the most extensive flooding since 2013, affecting an estimated 413,000 people and resulting in at least 335 fatalities.
• Heat Stress: The number of days with strong, very strong, and extreme heat stress were among the highest ever recorded, with 60 percent of Europe experiencing more days of at least strong heat stress than average.
• Renewable Energy: The share of electricity generated from renewable sources in Europe reached a record high of 45 percent in 2024.
• Extreme Cold Days: The portion of Europe experiencing fewer than three months of frost days was the largest on record, approximately 69 percent, compared to an average of 50 percent.
• Cold Stress: There was a record low number of days experiencing at least strong cold stress.
• Glaciers: All European regions experienced ice loss, with glaciers in Scandinavia and Svalbard showing the largest reductions ever.
• Wildfires: In September, around 110,000 hectares in Portugal burned within a week, accounting for roughly a quarter of Europe's total annual wildfire area, and approximately 42,000 people were affected by wildfires across the continent.