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    New MIT-LUMA Lab created to address climate challenges in the Mediterranean region

    The MIT School of Architecture and Planning (SA+P) and the LUMA Foundation announced today the establishment of the MIT-LUMA Lab to advance paradigm-shifting innovations at the nexus of art, science, technology, conservation, and design. The aim is to empower innovative thinkers to realize their ambitions, support local communities as they seek to address climate-related issues, and scale solutions to pressing challenges facing the Mediterranean region.  The main programmatic pillars of the lab will be collaborative scholarship and research around design, new materials, and sustainability; scholar exchange and education collaborations between the two organizations; innovation and entrepreneurship activities to transfer new ideas into practical applications; and co-production of exhibitions and events. The hope is that this engagement will create a novel model for other institutions to follow to craft innovative solutions to the leading challenge of our time.The MIT-LUMA Lab draws on an establishing gift from the LUMA Foundation, a nonprofit organization based in Zurich formed by Maja Hoffmann in 2004 to support contemporary artistic production. The foundation supports a range of multidisciplinary projects that increase understanding of the environment, human rights, education, and culture.These themes are explored through programs organized by LUMA Arles, a project begun in 2013 and housed on a 27-acre interdisciplinary campus known as the Parc des Ateliers in Arles, France, an experimental site of exhibitions, artists’ residencies, research laboratories, and educational programs.“The Luma Foundation is committed to finding ways to address the current climate emergencies we are facing, focusing on exploring the potentials that can be found in diversity and engagement in every possible form,” says Maja Hoffmann, founder and president of the LUMA Foundation. “Cultural diversity, pluralism, and biodiversity feature at the top of our mission and our work is informed by these concepts.” A focus on the Mediterranean region“The culturally rich area of the Mediterranean, which has produced some of the most remarkable civilizational paradigms across geographies and historical periods, plays an important role in our thinking. Focusing the efforts of the MIT-LUMA Lab on the Mediterranean means extending the possibilities for positive change throughout other global ecosystems,” says Hoffmann. “Our projects of LUMA Arles and its research laboratory on materials and natural resources, the Atelier Luma, our position in one of Europe’s most important natural reserves, in conjunction with the expertise and forward-thinking approach of MIT, define the perfect framework that will allow us to explore new frontiers and devise novel ways to tackle our most significant civilizational risks,” she adds. “Supporting the production of new forms of knowledge and practices, and with locations in Cambridge and in Arles, our collaboration and partnership with MIT will generate solutions and models for the future, for the generations to come, in order to provide them the same and even better opportunities that what we have experienced.”“We know we do not have all the answers at MIT, but we do know how to ask the right questions, how to design effective experiments, and how to build meaningful collaborations,” says Hashim Sarkis, dean of SA+P, which will host the lab. “I am grateful to the LUMA Foundation for offering support for faculty research deployment designed to engage local communities and create jobs, for course development to empower our faculty to teach classes centered on these issues, and for students who seek to dedicate their lives and careers to sustainability. We also look forward to hosting fellows and researchers from the foundation to strengthen our collaboration,” he adds.The Mediterranean region, the MIT-LUMA Lab’s focus, is one of the world’s most vital and fragile global commons. The future of climate relies on the sustainability of the region’s forests, oceans, and deserts that have for millennia created the environmental conditions and system-regulating functions necessary for life on Earth. Those who live in these areas are often the most severely affected by even relatively modest changes in the climate. Climate research and action: A priority at MITTo reverse negative trends and provide a new approach to addressing the climate crisis in these vast areas, SA+P is establishing international collaborations that bring know-how to the field, and in turn to learn from the communities and groups most challenged by climate impacts.The MIT-LUMA Lab is the first in what is envisioned as a series of regionally focused labs at SA+P under the conceptual aegis of a collaborative platform called Our Global Commons. This project will support progress on today’s climate challenges by focusing on community empowerment, long-term local collaborations around research and education, and job creation. Faculty-led fieldwork, engagements with local stakeholders, and student involvement will be the key elements.The creation of Our Global Commons comes as MIT works to dramatically expand its efforts to address climate change. In February 2024, President Sally Kornbluth announced the Climate Project at MIT, a major new initiative to mobilize the Institute’s resources and capabilities to research, develop, deploy, and scale-up new climate solutions. The Institute will hire its first-ever vice president for climate to oversee the new effort. “With the Climate Project at MIT, we aim to help make a decisive difference, at scale, on crucial global climate challenges — and we can only do that by engaging with outstanding colleagues around the globe,” says Kornbluth. “By connecting us to creative thinkers steeped in the cultural and environmental history and emerging challenges of the Mediterranean region, the MIT-LUMA Lab promises to spark important new ideas and collaborations.”“We are excited that the LUMA team will be joining in MIT’s engagement with climate issues, especially given their expertise in advancing vital work at the intersection of art and science, and their long-standing commitment to expanding the frontiers of sustainability and biodiversity,” says Sarkis. “With climate change upending many aspects of our society, the time is now for us to reaffirm and strengthen our SA+P tradition of on-the-ground work with and for communities around the world. Shared efforts among local communities, governments and corporations, and academia are necessary to bring about real change.” More

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    Responding to Ukraine’s “ocean of suffering”

    Within 72 hours of the first Russian missiles striking Kyiv, Ukraine, in February 2022, Ian Miller SM ’19 boarded a flight for Poland.

    Later, he’d say he felt motivated by Kyiv’s “tragic ocean of suffering” and Ukrainian President Zelensky’s pleas for help. But he arrived with little notion of what to do.

    As he’d anticipated, his hotel in Rzeszów turned out to be a hub for aid workers and journalists. Miller was on his laptop, using the lobby Wi-Fi to work remotely as an MIT Energy Initiative (MITEI) project manager, when he overheard a reporter interviewing a Finnish man about his efforts to get bulletproof vests and helmets to the front lines.

    Miller soon found himself loading supplies onto trains that had brought huge numbers of refugees — mostly women, children, and the elderly — to the station in Rzeszów. The trains ran back at night, their empty seats filled with medical supplies, generators, and baby food, their lights dimmed to reduce the chances of attack.

    In April 2022, Miller and volunteers from a half-dozen countries planned and drove a convoy of trucks packed with tourniquets, bandages, and bulletproof vests across the border, arriving at the site of the Bucha massacre soon after the Russians retreated.

    Miller peered into a mass grave. “They were still excavating it, and those weren’t soldiers, you know?” he says. “I try to avoid looking at things like that too often, because it doesn’t help us save lives to be horrified all the time.” He downplays any potential danger to himself, telling his family he’s safer where he is than in parts of the United States.

    Soon after his first trip across the border, Miller convinced his former MIT roommate, Evan Platt SM ’20, to come help. “Just for a week,” he told Platt.

    Inspired by energy

    Miller and Platt met in 2008 in Washington, where Platt was interning at the White House and Miller was about to start his senior year at Georgetown University.

    Miller majored in government, but his interest in energy policy and technology grew during the years after graduation he spent teaching science to primary and secondary school students in New York, where he’d grown up; in Boston; and in Kampala, Uganda. “Some of the most fun, inspiring, engaging lessons and modules I did with the kids were focused on energy,” he recalls.

    While pursuing an MIT master of science in chemical engineering from 2016 to 2018, he started researching photovoltaics and wind power. He held leadership positions with the MIT Energy Conference and the MIT Energy Club.

    After joining MITEI, Miller worked on electric vehicles (EVs), EV charging patterns, and other applications. He became project manager and research specialist for the Sustainable Energy System Analysis Modeling Environment (SESAME), which models the levels of greenhouse gas emissions from multiple energy sectors in future scenarios.

    Miller and Platt reconnected and shared an apartment for three years. Platt studied systems design and management through a joint MIT School of Engineering and Sloan School of Management program, then stayed on to work for the MIT Technology Licensing Office.

    Platt left MIT to pursue other interests in 2020. The next time the two would see each other would be in Poland.

    “It’s not easy living and working in an active combat zone,” Platt says. “There is nobody on Earth I would rather be navigating this environment with than Ian.”

    Navigating the last mile

    In Rzeszów and Ukraine, Miller and U.S. Air Force veteran Mark Lindquist oversaw fulfillment for the new team. With the help of Google Translate, their phones lit up with encrypted texts to and from Polish customs agents and Ukrainian warehouse operators.

    Platt and two Ukrainian team members took the lead on a needs analysis of what was most in demand at the front. Another team member led procurement. Their efforts crystallized in the creation of Zero Line, a tax-exempt nonprofit that works closely with the Ukrainian government at the front line (a.k.a. “the zero line”).

    With Platt on board, “we got more rigorous and quantitative in terms of lives-saved-per-dollar,” Miller says. A hundred dollars buys four tourniquets. A thousand dollars adds crude steel armor to a Jeep. Two thousand dollars provides a small observation drone or a satellite phone, equipment that locates Russian artillery and detects Russian attacks.

    “Russian artillery shells are the No. 1 killer of Ukrainians, causing around 80 percent of casualties,” he says. “Tourniquets save people injured by Russian shells, vehicles help evacuate them, and communications equipment prevents deadly injuries from occurring in the first place.”

    Miller’s skills in transportation and power system modeling, developed at MITEI under Principal Research Scientist Emre Gençer, helped the team transport more than 150 used vehicles — Nissan Pathfinders and vans for moving civilians away from the front, Ford pickups for transporting anti-missile defense systems — and hundreds of batteries, generators, drones, bulletproof vests, and helmets to the front through nightmarish logistical bottlenecks.

    Typically, supplies from the United States, Asia, and elsewhere in Europe move through Gdansk and Warsaw, then proceed via train or vehicle to warehouses in Lviv, around 70 kilometers east of the border. Next is the seven-hour trip to Kyiv or the 12-hour drive to Dnipro (the current southern edge of the safe “green zone”) and the final 200 kilometers to the front. Here, says Miller, drivers with training and protective gear, often members of the Ukrainian military, take vehicles and supplies to front-line end users.

    “From day one, we asked our Ukrainian members and partners for introductions, and we’re constantly looking for more,” Miller says. “When our vehicles reach the front lines, Evan’s team always does interviews about needs, and what’s working, what’s not. What’s saving the most lives.”

    “From my early days with Ian, it’s clear he was always looking for ways to help people. Connections were really important to him,” says MITEI Director Robert C. Armstrong. “When war broke out, he found the call to answer human need irresistible. I think many of us think of doing that, but we get bogged down in the mechanics of everyday life. He just picked up and went.

    “Ian is just a terrific person and a great role model,” Armstrong says.

    Accelerating peace

    From the time Miller arrived in late February through October 2022, he continued working remotely for MITEI. He now works full time as co-director of Zero Line. For the foreseeable future, Miller will remain in Ukraine and Poland.

    He wants to see Ukrainians “follow in the happy, free, prospering footsteps of other ex-Soviet states, like the Baltics,” he says. He’d like to see the supply-chain innovations he and Platt achieved applied to humanitarian crises elsewhere.

    To date, Zero Line has raised more than $5 million in donations and delivered hundreds of tons of high-impact aid. “A key part of our approach has always been to support Ukrainians who excel in saving lives,” Miller says. To that end, the group works with Ukrainian software programmers and military units to create digital maps and processes to replace paper maps and operations “reminiscent of World War II,” Platt says. “Modernizing the intelligence infrastructure to facilitate better military operations is an important part of how a smaller military can beat a larger, more powerful military.”

    The fact that energy underlies so many aspects of the war is never far from Miller’s mind. Russia cut off energy supplies to Europe, then targeted Ukraine’s energy infrastructure. On one hand, he understands that billions of people in developing countries such as India need and deserve affordable energy. On the other hand, he says, oil and gas purchases by those countries are directly funding Russia’s war machine.

    “Everyone wants cheap renewables and we’re getting there, but it’s taking time. Lowering the costs of renewables and energy storage and supporting nascent commercial fusion — that’s a very important focus of MITEI. In the long run, that’ll help us reach a more peaceful world, without a doubt.”

    Work at MITEI and at Zero Line, Miller says, “truly could accelerate peace.” More

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    Greening roofs to boost climate resilience

    When the historic cities of Europe were built hundreds of years ago, there were open green spaces all around them. But today’s city centers can be a 30-minute drive or more to the vast open greenery that earlier Europeans took for granted.

    That’s what the startup Roofscapes is trying to change. The company, founded by three students from MIT’s master of architecture program, is using timber structures to turn the ubiquitous pitched roofs of Paris into accessible green spaces.

    The spaces would provide a way to grow local food, anchor biodiversity, reduce the temperatures of buildings, improve air quality, increase water retention, and give residents a new way to escape the dense urban clusters of modern times.

    “We see this as a way to unlock the possibilities of these buildings,” says Eytan Levi MA ’21, SM ’21, who co-founded the company with Olivier Faber MA ’23 and Tim Cousin MA ’23. “These surfaces weren’t being used otherwise but could actually have a highly positive contribution to the value of the buildings, the environment, and the lives of the people.”

    For the co-founders, Roofscapes is about helping build up climate resilience for the future while improving quality of life in cities now.

    “It was always important to us to work with as little contradictions to our values as possible in terms of environmental and social impact,” Faber says. “For us, Roofscapes is a way to apply some of our academic learnings to the real world in a way that is tactical and impactful, because we’re tapping into this whole issue — pitched roof adaptation — that has been ignored by traditional architecture.”

    Three architects with a vision

    The founders, who grew up in France, met while studying architecture as undergraduates in Switzerland, but after graduating and working at design firms for a few years, they began discussing other ways they could make a difference.

    “We knew we wanted to have an impact on the built environment that was different than what a lot of architectural firms were doing. We were thinking about a startup, but mostly we came to MIT because we knew we’d have a lot of agency to grow our skills and competency in adapting the built environment to the climate and biodiversity crises,” Faber explains.

    Three months after coming to MIT, they applied to the DesignX accelerator to explore ways to make cities greener by using timber structures to build flat, green platforms on the ubiquitous pitched roofs of European cities’ older buildings.

    “In European city centers, two thirds of the roofs are pitched, and there’s no solution to make them accessible and put green surfaces on them,” Cousin says. “Meanwhile, we have all these issues with heat islands and excessive heat in urban centers, among other issues like biodiversity collapse, retention of rain water, lack of green spaces. Green roofs are one of the best ways to address all of these problems.”

    They began making small models of their imagined green roofs and talking with structural engineers around campus. The founders also gained operational knowledge from MIT’s Center for Real Estate, where Levi studied.

    In 2021, they showcased a 170-square-foot model at the Seoul Biennale of Architecture and Urbanism in South Korea. The model showed roofs made from different materials and pitched at different angles, along with versions of Roofscapes’ wooden platforms with gardens and vegetation built on top.

    When Levi graduated, he moved to Paris, where Cousin and Faber are joining him this spring. “We’re starting with Paris because all the roofs there are the same height, and you can really feel the potential when you go up there to help the city adapt,” says Cousin.

    Roofscapes’ big break came last year, when the company won a grant from the City of Paris as part of a program to improve the city’s climate resilience. The grant will go toward Roofscapes’ first project on the roof of a former town hall building in the heart of Paris. The company plans to test the project’s impact on the temperature of the buildings, humidity levels, and the biodiversity it can foster.

    “We were just three architects with a vision, and at MIT it became a company, and now in Paris we’re seeing the reality of deploying this vision,” Cousin says. “This is not something you do with three people. You need everyone in the city on the same side. We’re being advocates, and it’s exciting to be in this position.”

    A grassroots roof movement

    The founders say they hear at least once a week from a building owner or tenant who is excited to become a partner, giving them a list of more than 60 buildings to consider for their systems down the line. Still, they plan to focus on running tests on a few pilot projects in Paris before expanding more quickly using prefabricated structures.

    “It’s great to hear that constant interest,” Levi says. “It’s like we’re on the same team, because they’re potential clients, but they’re also cheering us on in our work. We know from the interest that once we have a streamlined process, we can get a lot of projects at once.”

    Even in just the three years since founding the company, the founders say they’ve seen their work take on a new sense of urgency.

    “We’ve seen a shift in people’s minds since we started three years ago,” Levi says. “Global warming is becoming increasingly graspable, and we’re seeing a greater will from building owners and inhabitants. People are very supportive of the notion that we have a heritage environment, but as the climate changes drastically, our building stock doesn’t work anymore the way it worked in the 19th century. It needs to be adapted, and that’s what we are doing.” More

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    Energy, war, and the crisis in Ukraine

    Russia’s invasion of Ukraine is having a global impact on many areas of the world today, affecting the balance of power among states and creating a contest between democratic and authoritarian alliances. It is also having a major impact on the global energy supply. European states have scrambled to reorient their consumption away from Russian natural gas, while Russia has used its energy assets as political leverage while finding new economic partners.

    In short, there is also a battle over energy surrounding the invasion, as a panel of experts analyzed at a public MIT event on Friday. The online discussion, “Energy As a Weapon of War,” was the latest Starr Forum, MIT’s prominent event series on foreign policy and international relations.

    The forum’s two featured speakers both discussed energy issues as well as the larger course of the war. Margarita Balmaceda, a professor of diplomacy and international relations at Seton Hall University and an associate of the Harvard Ukrainian Research Institute, listed three key aspects of the energy issue implicated in the invasion.

    In the first place, she noted, European reliance on Russian natural gas is a long-term issue that also existed with the Russian occupation of Crimea in 2014, but is only now being managed differently.

    “If we look at the case of Germany … you can see that the temptation of this reliance in particular on Russian natural gas was not simply something that you could ascribe to one or two corrupt politicians,” said Balmaceda, author of the book “Russian Energy Chains: The Remaking of Technopolitics from Siberia to Ukraine to the European Union.” Instead, she said, “it’s something that went to all levels of economic life,” including industrial consumers of natural gas, regional governments, and other stakeholders. 

    Secondly, Balmaceda observed, many core manufacturing industries, especially in Germany, have been particularly dependent on Russian energy, making the need for alternatives something that has direct effects in key production sectors.

    “In my view, the real story, and the story we have to pay much more attention to, has to do with … industrial users of natural gas,” Balmaceda said. In fact, she noted, gas consumption is a major part of the production cycle in Europe’s chemical, cement, steel, and paper industries, supporting about 8 million jobs.

    Finally, Balmaceda observed, European boycotts of Russian energy may have temporarily stymied Russia, but the regime has subsequently found new markets in China, India, and elsewhere.

    “It’s very important to understand that this story does not end in the European Union and North America, and if we don’t deal with the real energy concerns of global South countries, we will not get very far in trying to reduce Russia’s energy power moving forward,” she said.

    Constanze Steinmuller, director and Fritz Stern Chair of the Center on the United States and Europe at the Brookings Institution, offered some political context as well as her own perspective on paths forward in the war.

    While policymakers in Europe frequently praise the response of the Biden administration in the U.S., in support of Ukraine, “It’s also remarkable how steadfast the European response has been,” Steinmuller said. She added, “It’s something I was very worried about.” She also praised the German government for “decoupling German dependence from Russian gas and oil imports in ways I honestly would not have thought possible.”

    While the alliance supporting Ukraine has been valuable, Steinmuller said, she believes the U.S. and Europe need to give Ukraine even more backing in terms of weaponry in particular. “It is unclear, at this point still, whether Ukraine will have the means to retain full control over its territory.”

    Meanwhile, Russia’s relationship with China, she added, is profoundly consequential for the long-term trajectory of the war. So far, China has been nominally pledging broad support of Russia while publicly de-escalating the nuclear rhetoric arising from the war. However, Steinmuller added, if China decides to “actively support” Russia militarily, “That would be, I think, the worst game-changer of all, and one that … would be the single greatest challenge that I can envision to our ability to help Ukraine win, and to maintain our own security in Europe.”

    The Starr Forum is organized by MIT’s Center for International Studies (CIS). Friday’s event was co-sponsored by MIT’s Security Studies Program and the MIT-Eurasia program, in addition to CIS.

    The event’s moderators were Elizabeth Wood, a professor of history at MIT, author of the 2016 book “Roots of Russia’s War in Ukraine,” and co-director of the MISTI MIT-Eurasia Program; and Carol Saivetz, a senior advisor in MIT’s Security Studies Program and expert on Soviet and Russian foreign policy. Wood and Saivetz have helped host a series of Starr Forum events over the last year scrutinizing several aspects of Russia’s invasion and Ukraine’s defense.  

    Understanding the role of energy in the war “is obviously of critical importance today,” Wood said in her opening remarks. That includes, she noted, “How energy is being used by Russia as a tool of aggression, how Ukraine is suffering from attacks upon its critical infrastructure, and how the alliance of European [states] and the U.S. is responding.” 

    In response to audience questions, the scholars outlined multiple scenarios in which the war could end, either on more favorable terms for Ukraine or in ways that strengthen Russia. One audience member also queried about the extent to which the current war could also be thought of as a “carbon war, or climate war,” in which a move toward clean energy also lessens global dependence on large gas and oil suppliers, such as Russia.

    In response, Balmaceda noted that the ongoing infrastructure development in Ukraine might, in theory, leave it with no choice but to modernize its energy infrastructure (though its own orientation toward fossil fuels represents just a small portion of global demand). Steinmuller added that “Ukraine will need much more than just to reorient its energy [demand]. … It will have to change its role in the global economy,” given its own industrial reliance on coal and other fossil fuels.

    Overall, Balmaceda added, “Regardless of whether Russia wins this conflict or loses, the rottenness within Russia is deep enough to be bad news for all of us for a long time.” For her part, Steinmuller underscored again how vital increased alliance support would be.

    “We should show that we are willing and able to defend not just a country that has been attacked by a great power, but willing to defend ourselves,” Steinmuller said. Otherwise, she added, “If we didn’t do that, we would have set for all the world to see a precedent of giving in to blackmail, including nuclear blackmail, and allowing this to happen without us being willing to see the defense of Ukraine through to the end.” More

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    3Q: Why Europe is so vulnerable to heat waves

    This year saw high-temperature records shattered across much of Europe, as crops withered in the fields due to widespread drought. Is this a harbinger of things to come as the Earth’s climate steadily warms up?

    Elfatih Eltahir, MIT professor of civil and environmental engineering and H. M. King Bhumibol Professor of Hydrology and Climate, and former doctoral student Alexandre Tuel PhD ’20 recently published a piece in the Bulletin of the Atomic Scientists describing how their research helps explain this anomalous European weather. The findings are based in part on analyses described in their book “Future Climate of the Mediterranean and Europe,” published earlier this year. MIT News asked the two authors to describe the dynamics behind these extreme weather events.

    Q: Was the European heat wave this summer anticipated based on existing climate models?

    Eltahir: Climate models project increasingly dry summers over Europe. This is especially true for the second half of the 21st century, and for southern Europe. Extreme dryness is often associated with hot conditions and heat waves, since any reduction in evaporation heats the soil and the air above it. In general, models agree in making such projections about European summers. However, understanding the physical mechanisms responsible for these projections is an active area of research.

    The same models that project dry summers over southern Europe also project dry winters over the neighboring Mediterranean Sea. In fact, the Mediterranean Sea stands out as one of the most significantly impacted regions — a literal “hot spot” — for winter droughts triggered by climate change. Again, until recently, the association between the projections of summer dryness over Europe and dry winters over the Mediterranean was not understood.

    In recent MIT doctoral research, carried out in the Department of Civil and Environmental Engineering, a hypothesis was developed to explain why the Mediterranean stands out as a hot spot for winter droughts under climate change. Further, the same theory offers a mechanistic understanding that connects the projections of dry summers over southern Europe and dry winters over the Mediterranean.

    What is exciting about the observed climate over Europe last summer is the fact that the observed drought started and developed with spatial and temporal patterns that are consistent with our proposed theory, and in particular the connection to the dry conditions observed over the Mediterranean during the previous winter.

    Q: What is it about the area around the Mediterranean basin that produces such unusual weather extremes?

    Eltahir: Multiple factors come together to cause extreme heat waves such as the one that Europe has experienced this summer, as well as previously, in 2003, 2015, 2018, 2019, and 2020. Among these, however, mutual influences between atmospheric dynamics and surface conditions, known as land-atmosphere feedbacks, seem to play a very important role.

    In the current climate, southern Europe is located in the transition zone between the dry subtropics (the Sahara Desert in North Africa) and the relatively wet midlatitudes (with a climate similar to that of the Pacific Northwest). High summertime temperatures tend to make the precipitation that falls to the ground evaporate quickly, and as a consequence soil moisture during summer is very dependent on springtime precipitation. A dry spring in Europe (such as the 2022 one) causes dry soils in late spring and early summer. This lack of surface water in turn limits surface evaporation during summer. Two important consequences follow: First, incoming radiative energy from the sun preferentially goes into increasing air temperature rather than evaporating water; and second, the inflow of water into air layers near the surface decreases, which makes the air drier and precipitation less likely. Combined, these two influences increase the likelihood of heat waves and droughts.

    Tuel: Through land-atmosphere feedbacks, dry springs provide a favorable environment for persistent warm and dry summers but are of course not enough to directly cause heat waves. A spark is required to ignite the fuel. In Europe and elsewhere, this spark is provided by large-scale atmospheric dynamics. If an anticyclone sets over an area with very dry soils, surface temperature can quickly shoot up as land-atmosphere feedbacks come into play, developing into a heat wave that can persist for weeks.

    The sensitivity to springtime precipitation makes southern Europe and the Mediterranean particularly prone to persistent summer heat waves. This will play an increasingly important role in the future, as spring precipitation is expected to decline, making scorching summers even more likely in this corner of the world. The decline in spring precipitation, which originates as an anomalously dry winter around the Mediterranean, is very robust across climate projections. Southern Europe and the Mediterranean really stand out from most other land areas, where precipitation will on average increase with global warming.

    In our work, we showed that this Mediterranean winter decline was driven by two independent factors: on the one hand, trends in the large-scale circulation, notably stationary atmospheric waves, and on the other hand, reduced warming of the Mediterranean Sea relative to the surrounding continents — a well-known feature of global warming. Both factors lead to increased surface air pressure and reduced precipitation over the Mediterranean and Southern Europe.

    Q: What can we expect over the coming decades in terms of the frequency and severity of these kinds of droughts, floods, and other extremes in European weather?

    Tuel: Climate models have long shown that the frequency and intensity of heat waves was bound to increase as the global climate warms, and Europe is no exception. The reason is simple: As the global temperature rises, the temperature distribution shifts toward higher values, and heat waves become more intense and more frequent. Southern Europe and the Mediterranean, however, will be hit particularly hard. The reason for this is related to the land-atmosphere feedbacks we just discussed. Winter precipitation over the Mediterranean and spring precipitation over southern Europe will decline significantly, which will lead to a decrease in early summer soil moisture over southern Europe and will push average summer temperatures even higher; the region will become a true climate change hot spot. In that sense, 2022 may really be a taste of the future. The succession of recent heat waves in Europe, however, suggests that things may be going faster than climate model projections imply. Decadal variability or badly understood trends in large-scale atmospheric dynamics may play a role here, though that is still debated. Another possibility is that climate models tend to underestimate the magnitude of land-atmosphere feedbacks and downplay the influence of dry soil moisture anomalies on summertime weather.

    Potential trends in floods are more difficult to assess because floods result from a multiplicity of factors, like extreme precipitation, soil moisture levels, or land cover. Extreme precipitation is generally expected to increase in most regions, but very high uncertainties remain, notably because extreme precipitation is highly dependent on atmospheric dynamics about which models do not always agree. What is almost certain is that with warming, the water content of the atmosphere increases (following a law of thermodynamics known as the Clausius-Clapeyron relationship). Thus, if the dynamics are favorable to precipitation, a lot more of it may fall in a warmer climate. Last year’s floods in Germany, for example, were triggered by unprecedented heavy rainfall which climate change made more likely. More