The June 2026 European heatwave and climate change
Roberto Buizza, Full Professor at the Interdisciplinary Research Centre on Sustainability and Climate, analyzes the heatwave that swept across Europe during the final days of June 2026, highlighting its connection to climate change.
The ongoing European heatwave (20-30 June 2026) is a warning call for all of us, who are responsible for the ongoing global warming. As we keep emitting greenhouse gases and postpone actions to achieve net-zero emissions, we are making extremes more frequent and intense, with major impacts on people and ecosystems. Impacts that are very often more severe for the hundreds of millions who have less resources to adapt, and who also bear less responsibilities for global warming. We must act, and reduce emissions drastically and very quickly. We must phase out fossil fuels.
Figure 1. Upper level meteorological situation on 24 June 2026 at mid-day: the black lines show the flux at about 5000 meters (represented by the 500 hPa geopotential height) and the contour shadings show the temperature at about 1500 meters (more precisely, at 850 hPa). (from ECMWF, https://www.ecmwf.int/ ).
As Europe has been facing a second heatwave between 20-27 June, with peak temperatures in excess of 40°C and health issues reported by many countries, surprisingly very little has been reported in the news on the link between the heatwave and climate change. And there is very little talking in the mainstream news about the fact that not enough is done to reduce greenhouse gas (GHG) emissions that have been causing climate change. Emissions that globally continue to increase, as they did in 2014-2023 (by on average 0.9% a year).
The causal links ‘human GHG emissions > climate change > health impacts’ must be discussed very clearly, to convince politicians, decision makers, and the wide public that we must reduce emissions drastically very quickly, to avoid that even more dramatic phenomena will affect the world in the future. Let me remind that studies have reported that the European heatwaves of 2022 and 2023 caused about 60.000 and 47.000 extra deaths.
Action to reduce GHG emissions is too slow also in Europe, and in particular in Italy. If we consider the countries who bare most of the responsibility for the ongoing climate change (if we consider, e.g., the CO2 emissions accumulated between 1960 and 2023, the United States of America, China and Europe contributed respectively to 21%, 18% and 14%) have not been reducing the emissions as they should to achieve the European Union ‘fit-for-55’ target by 2030 and net-zero emissions by 2050. Italy is among them, as in the last decade 2013-2022 they have reduced their emissions on average by 1.7%, while they need to reduce them by about 7% to achieve by 2030 the ‘fit-for-55’ objective, and by 13.5% to achieve by 2050 net-zero.
A great disparity continues to exist between the GHG emissions per capita of different regions, with, for example in 2024, North America characterized by 17.5 tCO2-eq per capita, China 9.9, Europe 6.7 (Italy 6), and about 50% of the world population emitting less than 3 (data from Our World in Data). Thus, the countries mostly responsible for the ongoing climate change and with the higher levels of GHG emissions per capita keep emitting, while the countries less responsible for climate change and with the lower levels of emissions per capita are more affected by the impacts of climate change.
- Why has Europe been affected by this latest heatwave? And was it predicted?
Several factors contributed to the June 2026 heatwave. For many days, the atmospheric flow over the Euro-Mediterranean region has been locked into a so-called omega-pattern, with a region of high pressure centred over central Europe, and two regions of low pressure centred over easter Atlantic and the Caspian sea (see e.g. the situation on 24 June at midday in Fig. 1). This pattern led very hot air from Northern-western Africa, with temperatures between 35-45°C at the surface, to flow towards Europe. The fact that the temperature of the Mediterranean sea was about 3-to-10°C warmer than the average between 1981-2010 (due to climate change), contributed to keep the air flowing above the Mediterranean very hot.
The area of high pressure at the centre of the omega-shape patter was characterized by high-stability, sinking air that do not favour the formation of clouds, factors that contributed to the increase of the surface temperature. Very little rain on the days before the heatwave and the continuous hot temperatures caused the soil to dry up, thus reducing its capacity to reduce surface temperature by evapotranspiration.
The combination of the large-scale, upper level flow, the sea and the land-surface states led to the record surface temperatures.
In terms of predictions, the seasonal forecast issues on 1 May correctly indicated positive anomalies for Europe for May and June. The sub-seasonal forecasts issued 2-yo-3 weeks before the event also gave correct indications of the large scale flow that affected Europe between 15 and 29 June, and the local extreme temperature values were correctly predicted about a week ahead.
Three examples of these local surface temperature forecasts for London, Paris and Milano are shown in Fig. 2. Note how extreme are the predicted temperatures compared to the climatology computed over the past 20 years: for all cities, forecasts exceed for many days the 90th percentile and for a few days also the 99th percentile (indicating that values with a return period of 100 years were predicted).
Weather forecasters that followed a ‘zooming-in’ approach, whereby initially large-scale forecasts are considered months and weeks ahead of target dates to assess the probability of occurrence of potentially severe weather conditions, followed by finer-scale, local forecasts issued between 10 and a few days ahead, are today capable to provide warnings of these types of events. Warnings that can be used to take the most effective decisions to avoid the most catastrophic impacts on lives and properties starting from two weeks before the event.
Thus, coming back to the second question posed at the start of this section, the answer is that the large-scale pattern was correctly predicted 2-to-3 weeks ahead, and the local extremes were correctly predicted say between 10-to-3 days ahead.
Figure 2. Surface temperature (represented by the temperature at 2 meters) forecasts generated at 00 UTC of 20 June and valid for 15 days, for London (top), Paris (middle) and Milano (bottom). Daily probabilistic forecasts of the minimum (blue) and maximum (red) 2-meter temperature forecasts are shown in terms of their main quantiles (box-and-whiskers diagrams), together with the climatological distribution (shading) (from ECMWF, https://www.ecmwf.int/ ).
2. Can we link the current heatwave to climate change? How?
The World Weather Attribution (WWA) service of Imperial College, London, has developed a way to assess the impact of climate change on single weather events. The assessment is based on the comparison of the probability that weather events occur in two model climatologies, a reference generated with a pre-industrial level concentration of CO2 concentration in the atmosphere (say around 280 parts per million), and an actual generated with the current level of CO2 concentration (say around 400 ppm). By comparing the probability of occurrence of events with the same characteristics as the one under investigation in the reference and actual climates, they can answer to the question pose in the title of this section.
As the current heatwave is still underway, we do not have yet the results of the comparison for this heatwave, but it is worth reminding results from their studies for past extreme weather events linked to floods and heatwaves.
The WWA first study focused on the flood that affected Valencia in 2024. Their work indicated that '.. it was an extreme event with a return period of 20 years. The comparison between the statistics of this type of event in a pre-industrial climate and today's (+1.3°C in the simulations) indicates that intense 1-day rainfall events, as intense as the one observed, are about 12% more intense and about twice as likely in today's climate.'
Their second study focused on the 2024 record-breaking temperatures, that also fuelled heatwaves, drought, wildfire, storms and floods that killed thousands of people and forced millions from their homes. Their work indicated that ‘Climate change contributed to the deaths of at least 3,700 people and the displacement of millions in 26 weather events we studied in 2024. Note that these were just a small fraction of the 219 events that met our trigger criteria, used to identify the most impactful weather events. … Thus, it’s likely the total number of people killed in extreme weather events intensified by climate change this year is in the tens, or hundreds of thousands.’
Their third study considered the ten deadliest extreme weather events between 2004 and 2024 as identified by EM-DAT (the EMergency DATabase; which included not only heatwaves and droughts, but also extreme precipitation events and floods, and windstorms), and concluded that ‘… climate change contributing to the deaths of at least 570,000 people’.
A fourth very recent study that is worth considering is from the Grantham Institute on Climate and the Environment at Imperial College (London), who discussed the impact of the heat wave that hit Europe in 2025. Their analysis focused on 854 European cities, and reported an increase linked to the heatwave of about 24,000 deaths out of a population of 158 million. This number is consistent with the impact on the EU of the heat waves of 2022 (+60,000 deaths) and 2023 (+47,000 deaths).
These four studies confirm the conclusions of the 6th Assessment Report by Working Group II on Adaptation of the Intergovernmental Panel on Climate Change (IPCC), that stated that “Climate-related illnesses, premature deaths, malnutrition in all its forms, and threats to mental health and well-being are increasing (very high confidence). Climate hazards are a growing driver of involuntary migration and displacement (high confidence) and are a contributing factor to violent conflict (high confidence).’.
Looking into the future, it is worth reminding what the IPCC AR6 WGII report stated in 2022:‘Climate change is expected to significantly increase the health risks resulting from a range of climate-sensitive diseases and conditions, with the scale of impacts depending on emissions and adaptation pathways in coming decades (very high confidence).”
3. What are the prospects to limit global average warming below 2.0°C and 3.0°C?
The state of the climate is that, to date, 2024 was the warmest year on record, with a global average temperature 1.61°C above the pre-industrial (1850-1900) level. This year was followed by 2025 and 2023, with temperatures around 1.5°C. The ten warmest years on record all occurred in the most recent 10 years.
In the past 20 years, global warming has been accelerating, from about +0.11°C every decade in 1980-2001, to about +0.25°C every decade in 2002-2023. As global emissions keep increasing, predictions under business-as-usual scenarios indicate that annual-mean global warming will very likely reach 2.0°C sometime between 2037 and 2050.
Recent seasonal forecasts indicate that 2026 and 2027 are very likely to be very warm years, with 2027 predicted to have a global average temperature possibly up to 1.7°C due to the very intense El Niño that is developing in the tropical Pacific. An El Niño that is predicted to be the warmest El Niño event of the past 50 years. If this jump in the global average temperature occurs, it would increase the probability that global warming reaches 2.0°C by 2040.
Although the prospect for keeping the global average warming below 2.0°C is extremely slim, we could still decide to try to achieve it. Indeed, based on the Paris agreement reached at the 21st UNFCCC Conference of the Parties of 2015 in Paris, the 194 countries and Europe, who signed the agreement, are expected, and must be asked, to do more than what they have done to limit global warming below 2.0°C, possibly even below 1.5°C.
All countries, especially the ones who bear most of the responsibility of the ongoing climate change, must act swiftly to abandon fossil fuels and reduce the exploitation of land. Continued warming could bring some of the Earth system components over some tipping points, and trigger quasi irreversible changes, e.g. at the polar ice sheets, the Greenland glaciers or the Amazon forest. For example, in the Arctic as the cold season gets warmer and shorter, we could see an accelerated reduction of ice formation, and this could accelerate the melting in the warm months. The effect would be a substantial reduction in the sea-ice extent both in the warm and cold months, that could lead to ‘blue Arctic’ conditions (this year is likely to be characterized by one of the lowest Arctic sea-ice extension), with substantial positive feedback on the Earth albedo, the decrease of which will potentially further accelerate global warming.
4. How can we limit global warming?
The only way to limit future warming is to immediately and substantially reduce greenhouse gas emissions (CO2 and CH4) in the atmosphere.
In fact, to date, methods alternative to reducing emissions, such as the absorption and storage of greenhouse gases (‘Carbon Capture and Storage’, CCS) have proven capable of removing only a small percentage of the emissions onto which they have been acting. Current estimates report that in the future, even in the best case scenario in which they can be improved, CO2 absorption and storage capacities will be able to absorb a maximum of between 5% and 10% of global emissions. It has also been estimated that natural greenhouse gas removal systems (‘Natural Based Solutions’, NBS), for example grounded in afforestation, could contribute to the absorption of between 10% and 20% of global emissions, although care should be taken to use these numbers, as recent studies indicate that due to climate change, nature is finding it increasingly difficult to keep absorbing the CO2 it used to absorb.
These two estimates indicate that in the most optimistic scenarios CCS and NBS might be able to absorb and remove between 15% and 30% of global emissions, and therefore current emissions must be reduced by at least 70%, most likely by 85%, to achieve net zero emissions.
Let me stress that we have working, and cost-effective decarbonisation solutions for all but a very few sectors that require very high energy intensity, the iron and steel industry, which is responsible for about 7% of total emissions, and aviation, which is responsible for about 3% of total emissions. For these two sectors solutions exist but are either still too expensive or underdeveloped. Decarbonisation solutions are already being implemented today, albeit too slowly, and can also bring significant cost reductions, as it is already the case for electricity production in countries who have increased substantially the percentage of their renewable electricity production (see, e.g., the 50% extra cost of the electricity in Italy compared to Spain, due to the fact that Spain has been investing very heavily in the past decade in renewable electricity generation).
5. What should Italy do to achieve its GHG emissions reduction targets?
Italy in 2022 had about 0.7% of the world population, and in 1850-2022 emitted about 1% of the GHG accumulated emissions. In the past decades, Italy’s per capita emissions have been in line with European per-capita emissions: for example, in 2022 Italian emissions per capita were 6.5 t CO2-eq, and the European ones 7.5 t CO2-eq, while in 2024 they were, respectively, 6.0 and 6.7 t CO2-eq. These numbers indicate that Italy has to acknowledge its responsibility for the ongoing climate change.
If we consider the last decade 2013-2022 for which data are available, Italy reduced emissions on average by 1.7% per year, making it almost impossible to achieve the European Union 'fit-for-55' target (a reduction of the emissions by 55% compared to the emissions in 1990) in 2030. Italy could still reach this target if in the years 2023-2030 it reduces them on average by 7% per year. While to reach the 'net-zero' target by 2050, Italy has to reduce them by on average by about 13.5% per year. Recent policies and emission estimates do not suggest that Italy will succeed.
As the Mediterranean is one of the most subject to warming areas (‘a hot spot’), with an average warming that is twice as much as the global warming (thus about 3.0°C since the pre-industrial level) it should be one of Italy’s top priorities to support the efforts to reduce global emissions very fast, and lead by example. Failure to do so, will increase the negative impacts of climate change on its region, on health, water access, agriculture.
GHG emissions must be reduced starting without any delay, as any molecule of CO2 put into the atmosphere remains there about 300 years. This means that priority must be given to avoid injecting the molecules into the atmosphere, rather than delaying decarbonisation actions and invest in projects that might lead to GHG reductions in 10+ years from now.
To reduce GHG emissions linked to the electricity production (which in 2023 contributed to about 20% of the Italian total GHG emissions), Italy should invest more in renewable energy (solar, wind and hydro) and completely phase out the use of fossil fuels as quickly as possible. Nuclear energy could be a contributing factor in the electricity generation mix in 10+ years, since the time it takes to complete a nuclear power station from the time of approval to production is more than 10 years. But investments in nuclear energy do not reduce emissions now, when we must reduce them. It is worth also reminding that nuclear energy is a very expensive form of renewable energy, several factors more than renewable energy. As Italy can easily harvest solar and wind energy, priority should be given to these forms of production.
To reduce GHG emissions linked to transport (which in 2023 contributed to about 24% of the Italian total GHG emissions), Italy should invest more in electric mobility and in public transport infrastructures. Investments should be made in infrastructures to make it possible to use electric vehicles, and public transport capability should be increased, and goods transport should be moved from roads to rail.
6. Conclusions
Extreme weather conditions like the heatwave that affected Europe between 20-to-29 June 2026 are now more frequent and intense due anthropogenic climate change. The continuous use of fossil fuels and the exploitation of land keep increasing the concentration of greenhouse gases in the atmosphere, thus intensifying global warming. With the current trend of GHG emissions, global warming will reach 2.0°C by around 2040, and 3.0°C by 2100. This means essentially that the future generations will experience a doubling of the warming that we have experienced since the industrial revolution.
Considering Italy, climate projections included in the most recent IPCC 6th Assessment Report indicate an increase in the probability of more frequent and intense heat waves (with negative impacts on health), summer droughts (with negative impacts on agriculture and livestock) and fewer but heavier precipitation events (with an increased number of floods), a faster melting of the Alpine glaciers (with negative impacts on water access), and an increased net immigration of climate refugees.
Let me stress again the message that I gave already in September 2024, in my contribution to the Sant’Anna news titled ‘Climate change calls for urgent mitigation actions’:
‘There is not a safe level of global warming. The more we consume fossil fuels, the more we emit greenhouse gases, the warmer the globe gets, and the more intense the damages are going to be, especially on the communities that have less resources to adapt to climate change.’
The latest June 2026 European heatwave is another warming bell. We have to act, and call for the adoption and enforcement of laws that reduces GHG emissions. Politicians and decision makers have to listen to science rather than to the oil, gas and combustion-engine lobby.
Further reading and reference data links:
- European Centre for Medium-Range Weather Forecasts (ECMWF): https://www.ecmwf.int/
- Climate Trace: https://climatetrace.org/
- Copernicus Climate Change Service (C3S): https://climate.copernicus.eu/
- Grantham Institute on Climate and the Environment, Imperial College London: https://www.imperial.ac.uk/grantham/
- Intergovernmental Panel on Climate Change (IPCC): https://www.ipcc.ch/
- Our World in Data: https://ourworldindata.org
- United Nations Framework Convention on Climate Change: https://unfccc.int/
- World Weather Attribution service (WWA): https://worldweatherattribution.org
