Extreme weather events in 2025 pushed adaptation capacity to its limits

The WWA 2025 Report insists that we are already living in a profoundly altered climate, with uneven impacts, uneven scientific evidence and clear limits to adaptation. Faced with all this, the only realistic way to avoid catastrophic and irreversible consequences of climate change is to rapidly reduce emissions while simultaneously strengthening adaptation, science and global equity.

The report concludes that since the signing of the Paris Agreement in 2015, while global warming has increased by 0.3 °C, some heatwaves have become almost ten times more likely, providing further evidence that, when it comes to climate change, every fraction of a degree matters. The report emphasises that heatwaves are the deadliest extreme weather events and were also the deadliest in 2025, although most heat-related deaths remain underreported and undervalued globally. Unlike other extreme events, such as floods or wildfires, heatwaves can rightly be called the “silent killer”, as they do not leave a trail of destruction in their wake like storms or wildfires do.

The real-time attribution studies carried out by the WWA initiative are extremely valuable because they scientifically link specific extreme weather and climate events to human-induced climate change. The increase in the frequency and intensity of these extreme events is perhaps one of the most affecting and noticeable consequences of climate change for the population, which is why this type of study greatly contributes to communicating the problem of climate change.

The burning of fossil fuels has released enough CO₂ into the atmosphere to change the climate in just a couple of centuries. This is a remarkable process even in the long history of the Earth, as there is no known precedent for such a rapid atmospheric change. The climate is a chaotic system by nature, with a very high degree of natural variability, and attribution studies emerged to understand the extent to which extreme weather events are due to climate change or natural variability. They are based on modelling extreme phenomena and comparing their probability of occurrence with and without climate change.

The WWA report therefore makes it possible to quantify the extent to which climate change has increased the probability of these extreme weather events. In this regard, some of the data is shocking. In Sudan, for example, the probability of experiencing a heatwave like this year's was one in 1,600 in 1850, whereas today it is one in two. The data indicate how heatwaves, droughts and torrential rains are becoming more frequent due to climate change.

There are processes for which we still do not know to what extent climate change is increasing their frequency, such as tropical cyclones. Recent studies (such as this one from Nature Geoscience) indicate that the recent increase in their activity is probably temporary, as it is due to processes unrelated to climate change. The WWA report does not yet include these new studies.

The report gives too much influence to climate when discussing processes such as fires and floods. We must separate purely meteorological processes, such as heat waves, from those that result from the interaction between climate and infrastructure. There is no doubt that climate change has lengthened the fire season and contributes to drier fuel, for example, but fire burns fuel and fire activity is not entirely attributable to climate change. Nor are floods, as they again depend on the interaction between meteorology and forest and hydraulic infrastructure.

In this sense, just as denialism is fatal to climate inaction, “climatism” that exaggerates the influence of climate change can generate antibodies and encourage the rise of denialism. This year's heatwave in Spain, with an anomaly of 4.6 °C during the first two weeks of August, undoubtedly fuelled the extreme fire season we are experiencing. The WWA report indicates that this heatwave was 40 times more likely with climate change. However, fire activity could have been reduced to a large extent with adequate preventive management.

Climate change is here to stay, and what we are seeing in recent years is just the beginning. We cannot prevent heatwaves from increasing, but we can, and must, adapt in advance to the negative impacts of climate change.

The report is a new call to action from the scientific community for climate action, highlighting that in 2025 global warming once again had an unequivocal impact in the form of extreme weather events. The World Weather Attribution team includes leading experts in climate change attribution studies, which is a guarantee of quality.

A decade has passed since the signing of the Paris Agreement and, in this regard, it is a good approach to highlight how the planet has continued to warm since then, which has resulted in an increase in extreme weather events.

The report's conclusions are consistent with those of previous studies. There is evidence that anthropogenic climate change is causing an increase in adverse weather events across the planet. In Spain, various analyses carried out by the State Meteorological Agency show that heat waves are increasing in Spain by around three days per decade, which coincides with one of the findings of the global study.

It is important to highlight the main messages of the report:

• Every tenth of a degree of warming matters: since the signing of the Paris Agreement, the planet has warmed by 0.3 °C, a figure that may seem small, but which represents eleven more days of extreme heat per year than a decade ago.

• Adaptation to climate change is essential, given that it is already affecting us, but mitigation through a rapid reduction in greenhouse gas emissions is also essential, as this would prevent the worst effects associated with this phenomenon.

• The scientists who authored the report also believe that extreme weather events disproportionately affect marginalised communities and, within these communities, women in particular, due to the role they play in these communities. They also emphasise, and it is important to bear this in mind, that in less developed countries there is also marked inequality in terms of climate science, due to the lack of data in these areas.

The climate change attribution studies on which the report is based are highly complex, although the methodology has been peer-reviewed, which provides scientific guarantees. Basically, the method consists of identifying an extreme weather event, delimiting it spatially and temporally, and analysing the data (temperatures reached or accumulated precipitation, for example). Based on the results of the analysis, they calculate whether similar events have become more frequent and/or intense in recent decades.

In addition, they compare the data obtained with simulations carried out using advanced climate models, which recreate a planet that is 1.3 °C cooler. Based on the difference between the observations and the simulations, they try to determine the role that climate change plays in the increased frequency and intensity of adverse phenomena.

The conclusions are always statistical: ‘Climate change has made extreme heat waves such as the one experienced in Spain and Portugal in June 2017 ten times more likely’ is one example. In some cases, they have concluded that a particular episode would have been virtually impossible without climate change, i.e. on a planet that had not warmed by 1.3 °C.

The main limitations of this type of study are due to the lack of data in certain areas, both on the episode in question and, above all, on historical information that would allow an assessment of whether the frequency and intensity of similar phenomena has increased. It should also be borne in mind that simulations using climate models, although they are undergoing continuous improvement, are not an exact recreation of reality and, therefore, there are always uncertainties about the results that must be taken into account in a rigorous analysis.

This report compiles the most significant extreme weather events that occurred during 2025 and analyses their possible relationship with climate change. This analysis enables what is known as climate attribution to be carried out, which, on the one hand, can indicate a higher probability of events such as heat waves, fires, droughts, as well as heavy rains, floods or hurricanes, as a consequence of climate change; and, on the other hand, can point to possible changes in the intensity or extent of these events.

Over the last ten years, the global average temperature has risen by 0.3°C. Although this increase may seem small, it translates into an average of 11 additional days of extreme heat per year. In addition, heatwaves have become ten times more likely, underscoring that every tenth of a degree we manage to avoid is, in itself, a significant achievement.

The impacts of the extreme events of 2025 highlight the vulnerability of certain regions of the Global South, with the disproportionate risk faced by women in places such as South Sudan being particularly notable, where their lower job qualifications force them into more exposed jobs, such as agriculture or street vending.

Another injustice of the climate crisis highlighted in the report concerns the scientific studies themselves, as climate models are better calibrated for the northern hemisphere. This, together with the lack of observational data in the southern hemisphere, hinders the accuracy of analyses and the quality of predictions for countries in the Global South.

The report urges improved adaptation measures in response to the climate emergency, but also warns that in some cases, as happened during Hurricane Melissa, these measures may prove insufficient. This highlights the need to drastically reduce emissions in order to curb the escalating impacts.

It is an excellent summary of how the impacts of climate change are felt most intensely in the Global South. It is especially challenging there because we lack sufficient station data to accurately calibrate simulations and correctly attribute the effects of climate change. We must urgently intensify mitigation efforts and strengthen adaptation strategies to prevent the worst consequences of climate change.