OIKOS Analysis - Heatwaves

Why are they soaring faster in Europe than in the rest of the planet?

Western and central Europe warms up in summer at a rate well above the global average—up to three times faster—. It is one of the most marked climate "hotspots" on the planet outside the polar regions. Why?

The usual answer—"because of climate change"—is true but incomplete, and American climatologist Roger Pielke Jr. has devoted two recent articles in his newsletter The Honest Broker to breaking it down with greater rigor. The articles are:

1. Pielke, R., Jr. (2026a, July 13). Why Europe's heat waves are getting worse. The Honest Broker. https://rogerpielkejr.substack.com/p/why-europes-heat-waves-are-getting
2. Pielke, R., Jr. (2026b, July 20). Why cutting emissions can't fix Europe's heat waves. The Honest Broker. https://rogerpielkejr.substack.com/p/why-cutting-emissions-cant-fix-europes

We find it a useful exercise for Spanish public debate, because it helps distinguish between what science firmly knows and what is still the subject of active research—a distinction that is often lost in media and political debate

European warming: several pieces to fit together

What is most interesting—and where scientific uncertainty is greatest, something that the IPCC itself explicitly recognizes—is why Western Europe warms so much above the global average. Pielke reviews several factors that scientific literature points to as relevant, without a robust quantification yet of how much each weighs, and it is worth distinguishing between them because not all of them have the same nature.

Some are, in a way, intuitive. When the soil loses moisture, the solar energy previously used to evaporate water—cooling the environment—directly warms the air instead; some modeling studies attribute a very substantial part of the excess heat on extreme days in Central Europe to this effect. Similarly, the air arriving in Europe during a heatwave—from the Mediterranean, Atlantic, or North Africa—comes from regions that have also warmed, so it already brings "more heat from the factory"; and natural cycles spanning several decades in North Atlantic temperature (Atlantic Multidecadal Variability, AMV) also modulate the frequency of Euro-Mediterranean heatwaves. Dry soils, warm seas, ocean cycles amplifying the background signal: these are mechanisms that, once explained, are easy to accept.

Another factor, on the other hand, is more surprising and counterintuitive: cleaner air. The drastic reduction in particulate pollution in Europe since 1980—an indisputable success of air quality policies that has saved many lives—has had the side effect of allowing more solar radiation to reach the surface, with an estimated additional warming of around half a degree according to Schumacher et al. (2024). It is an uncomfortable reminder that not all successful environmental policies work in the same direction on climate, and that reducing everything to CO₂ obscures real but distinct human mechanisms.

And finally, there is a factor on which we do have the ability to act directly and in the short term: urban heat islands. A large part of the human and health impact of heatwaves is concentrated in cities, where asphalt and lack of vegetation significantly exacerbate temperatures and associated mortality. Unlike global atmospheric circulation or Atlantic temperatures, this is a factor that depends on urban planning decisions within the reach of local councils and regional governments right now.

The IPCC itself (AR6) stresses that scientific confidence in how these "dynamic" processes affect the magnitude and location of extremes is low, unlike the high confidence in global trends of extreme heat.

Why decarbonizing does not "fix" heatwaves in the short term

In his second article, Pielke poses a public policy question: if the world reached net zero emissions, when would we notice the effect on European heatwaves?

His response, supported by scientific literature (including Tebaldi and Friedlingstein, 2013, and Cassidy et al., 2023), is that the effect would be real but very slow and only noticeable on the scale of future generations, not those living today. An illustrative exercise he presents—not a prediction, but a thought experiment with idealized data—suggests that, even if net zero were reached by 2060, the number of heatwave days in Europe in 2160 would remain similar to that of the 2020s, before starting to decrease clearly later on.

The climate system behaves, in this sense, like a large ocean liner: even if the rudder turns today, the ship continues moving in the same direction for a good while before the new course is noticeable. Here that "good while" is measured at around a century, not years or legislative terms. It is a time-scale difference that should be kept in mind when designing and communicating climate policy.

To this he adds an additional warning: if the air pollution hypothesis mentioned earlier is correct, reducing fossil fuel burning also reduces the particles that currently reflect some solar radiation, which could add additional warming in the short term—an effect known in literature as aerosol "unmasking".

Pielke is explicit that none of this is an argument against decarbonization: he considers it justified as long-term risk management, and has defended it for years. His argument is rather one of communication and public policy: promising that "lowering emissions" will bring cooler summers within a political-electoral timeframe is a promise that science does not back up, and which can erode the credibility of climate action when unfulfilled.

Why all this matters in the Spanish debate

This analysis is relevant to Spain, a country particularly exposed both to heatwaves and to the politicization of the climate debate. We believe that the main lesson is not "climate change is not serious"—it is, and observed trends in Europe confirm it with scientific solidity—but rather that the quality of public debate improves when we distinguish between:

1. what science establishes with high confidence (more energy in the system, upward trend in heatwaves, detectable human footprint),
2. what is still the subject of active research (the relative weight of soils, aerosols, atmospheric circulation and natural variability), and
3. what mitigation can and cannot offer within timeframes that matter to voters today (reduction of future risks a century out, not immediate air conditioning).

Precisely because the "rudder" of mitigation takes so long to change the ship's course, the most direct practical conclusion of this analysis—and one that we at Oikos have been defending for some time—is the urgency of investing in **adaptation**, in parallel with decarbonization and without posing them as alternatives to each other. Two fronts stand out:

1. At national level: guaranteeing access to air conditioning and energy efficiency in housing, instead of stigmatizing it as an "anti-climate" gesture. As Pielke himself shows, much of the debate in France has treated air conditioning as a problem in itself, when in reality it is a protection tool against a risk that is already present and will take decades to reverse, whatever emissions policy is adopted.
2. At urban level: acting on urban heat islands—more vegetation, surfaces that better reflect radiation, urban design that favors natural ventilation—given that much of the mortality associated with heatwaves is concentrated in cities and depends on local planning decisions, not on the global trajectory of emissions.

In short, an ambitious climate policy in mitigation and a decisive commitment to adaptation are not incompatible: they are, in fact, two sides of the same serious response to climate risk.