AMS Institute research is turning climate projections into tools cities can use for extreme summers. Amsterdam is getting hotter, drier, and wetter. AMS Institute, working with Wageningen University & Research, TU Delft, MIT Senseable City Lab, and city partners, runs the research that shows where heat and drought will hit hardest and what to do about it. Across monitoring, tree selection, shade mapping, and water reuse, the aim is the same: preparedness.
The threat
The country has endured several hot summers in recent memory, but the summer of 2018 had record-breaking heat that buckled rail tracks across the Netherlands, seized bridges, and halted metro services. Roads were damaged, water quality dropped, and blue-green algae resulted in closed swimming spots. Amsterdam spent more than €1.4 million replacing dead plants and trees and close to half a million euros on extra irrigation water, according to figures from Een EXTREEM Rapport (An Extreme Report) from the KNMI (the Royal Netherlands Meteorological Institute) in 2025 on weather extremes with major social consequences.
AMS Institute's Gerben Mol and others contributed to the chapter on heat of the KNMI report. Under a high-emissions scenario, days at or above 30°C in Amsterdam are projected to rise from around 4 per year today, to as many as 27 by 2100. The RIVM estimates heat causes around 110 deaths a year in the city. Without adaptation, it projects 215 to 680 a year by 2100 as the population ages and the climate warms. In addition, indirect effects like additional costs of hospital admissions and lower productivity would add to the severity.
"An extreme heatwave puts pressure on transport, water, health, and energy at the same time," said Gerben Mol, Program Developer for Climate Resilient Cities at AMS Institute. "We treat heat as a system problem, and the case for structural investment is strongest before the next event."
Photo credits: Alex Schröder
Measuring where heat hits
Preparation starts with measurements. Gert-Jan Steeneveld, an AMS Institute Principal Investigator and associate professor at Wageningen University, coordinates the Amsterdam Atmospheric Monitoring Supersite, a 24-station network tracking temperature, moisture, wind speed across the city, and the urban carbon footprint. The data shows Amsterdam runs about 3.4°C warmer than the surrounding countryside at night. His group also developed a heat-mapping method used in the city's climate stress tests.
"We measure how heat accumulates over time in the city and how it moves into homes, because you cannot adapt what you have not mapped," Steeneveld said.
Indoor heat is the next layer. In the EU-funded I-CHANGE project, AMS Institute and WUR monitor around 100 Amsterdam homes, where indoor temperatures often pass 24°C for long stretches and sometimes exceed 30°C, holding after the outdoor air has cooled. Residents take part in the monitoring, and the team also draws on citizen science and crowdsourcing to widen coverage and connect it to the wellbeing of the residents.
Analyzing indoor heat using I-CHANGE monitoring data and historical measurements dating back to 1988, WUR researcher Esther Peerlings (AMS researcher and WUR PhD Candidate Urban Meteorology under Steeneveld's supervision) found summer indoor temperatures are rising about 0.5°C per decade. For her study published in the Quarterly Journal of the Royal Meteorological Society in November 2025, her team analyzed long-term indoor temperature data from seven Dutch houses, spanning up to 27 years, to better understand how indoor temperatures respond to summer heat.
Photo credits: Alex Schröder
They developed a physics-informed statistical model that integrates outdoor–indoor convection, building conduction, and solar + thermal radiation. "We found that indoor temperatures respond more slowly to outdoor changes, with a typical lag of 260 minutes, and that heatwave signals can persist indoors for about five days," Peerlings said.
This work provides new insights into understanding and improving indoor climate resilience in the face of rising heat events. "That is enormous, and it raises both health risks and energy demand," added Steeneveld, commenting on his student's work. "Most people spend 80 to 90% of their time indoors, so indoor temperature decides how livable a home really is."
Choosing trees that cool
Trees are the city's most effective cooling tool. They can lower air temperature by an average of 2.6°C through evapotranspiration, and reduce radiant heat from streets and buildings by up to 34.5°C. i-Tree 2.0 NL, a three-year project funded by CLICKNL with 28 partners, from TU Delft and internationally renowned design firms (MVRDV, Arcadis), to tree nurseries and eight municipalities, measured the cooling performance of more than 300 urban tree species across their life cycles and mapped over 100 million Dutch trees using satellite imagery. The result is a species shortlist matched to use: linden for narrow street canyons, London plane for parks and open spaces with steady all-day cooling, western red cedar for the full set of cooling traits, and common beech for long-term value as it keeps growing into old age.
Two trees on the same street can cool very differently, depending on canopy density, leaf thickness, and how the branches reflect sunlight. Closing this knowledge gap gives cities the insight they need to plant trees that are prepared for the conditions they will face in forty years.
Explore the entire public report on openresearch.amsterdam.
