IE University x RAIA Research Program 2025

The 2010s were a decade of climate change accountability, showcasing the extreme deterioration and loss of ecosystems, as well as the direct impact on human life all across the globe. During that decade, global mean temperatures increased by 1.10°C with a plus/minus margin of 0.12°C, above pre-industrial times. Moreover, it was marked by an increasing number of extreme weather events worldwide, from droughts in East Africa between 2011 and 2012 to massive heatwaves in the Northern Hemisphere in 2018 and 2019, setting record temperatures. More than just a decade of accountability, the 2010s were a decade of global realization, a wake-up call to the whole world about the insufficient action to mitigate climate change. 

In Europe, the region introduced the Effort Sharing Decision, setting yearly greenhouse gas emission limits for 2013-2020, which helped cut EU emissions by 16.3% by 2020. While state policies have national targets, mayors have been able to strengthen and help achieve EU climate and energy goals. For example, London’s mayor, Sadiq Khan, introduced the ‘Ultra Low Emission Zone’ in 2023 to improve London’s air quality by taxing drivers with vehicles up to 3.5 tonnes. As of 2025, there has been a city-wide reduction of nitrogen oxide emissions by 27%. The role that mayors can play in meeting climate goals is crucial to addressing climate change, as metropolitan cities like Paris and London generate approximately 70% of global CO2 emissions. Mayors can adapt urban areas to mitigate the impacts of climate change. Paris, one of Europe’s densest cities with 52,218 inhabitants per km², faces significant exposure to climatic factors like rising temperatures, heatwaves, flooding, extreme rainfall, and air pollution ever-present.

Rising Temperatures

Since pre-industrial times, the city of Paris has experienced an overall average temperature increase of 2.3°C. Paris has failed to keep its average temperature under the target of 2°C threshold compared to pre-industrial times set by the Paris Agreement. Overpassing this threshold has already resulted in visible climate instability: heatwaves have become more frequent, rainfall has increased in volume but is less frequent, and flood risks have increased. All of which are undermining urban resilience and public safety. The following section of this report will focus on the risks posed by rising temperatures in Paris, while other hazardous climate events will be discussed in detail later. 

When looking at the case of the French capital, a study conducted by the IPCC forecasted that in the worst-case scenarios, current trends will lead to an average temperature increase of 4.5 to 5°C by the end of the century. This will result in a significant reduction in the water supply due to a 16% increase in evaporation of the Seine River by 2050. Furthermore, rising temperatures will lead to a 10% decrease in water recharge, significantly reducing the ability of underground aquifers to replenish themselves, ultimately resulting in a reduction of the water supply (both in its quantity and quality). Moreover, with an expected 5% growth in the population of the Île-de-France region (17% concentrated in Paris, from a peak of 12.53 million by 2070), the demand for water services will saturate the system’s capacity. 

Health is another factor that is being affected by the rise in average temperatures in Paris. Heat alone can lead to exhaustion and heatstroke, which can temporarily incapacitate a person. Accordingly, in a study conducted by Pascal et al., they were able to link cardiovascular, cerebrovascular, and respiratory adverse impacts, as well as mortality, to warm days or heatwaves. Additionally, renal mortality, diabetes, and mental health issues were related to extreme heat. 

In a 2023 interview with Le Journal du Dimanche, Anne Hidalgo explained that her goal in addressing the effects of rising temperatures is to protect the most vulnerable populations: the elderly, people with disabilities, young children, the homeless, and migrants. Indeed, within this vulnerable group, adults aged 65 or older showed a higher mortality risk when the mean temperature was 29.4°C. This is especially alarming, as the number of elderly people aged 65 or higher is expected to increase by a 1:4 ratio per inhabitant in the Greater Paris Metropolis by 2040. Overall, rising temperatures are associated with several health risk factors that put a strain on Parisians, especially the elderly aged 65 and older. 

In the wake of the impact of rising temperatures, Anne Hidalgo has prioritized improving the health and livelihoods of Parisians in her policies. As part of her ambitious Paris Climate Action Plan, ‘fairness’ is a key component of her motto, aimed at tackling social injustices and protecting and supporting vulnerable groups. This is crucial for the elderly, as they are more sensitive to the impact of rising temperatures, especially those 65 or older, whose age increases their risk factor. 

Additionally, her policies reflect her perspective on alleviating and mitigating the health and stress in the lives of Parisians. Still, they are also aimed at preparing the city for increasingly hot days and hotter summers. This aligns with her commitment to helping the city adapt to new climatic conditions while spreading solidarity to protect the most vulnerable, with a focus on those who are most sensitive to global warming and pollutants. 

Greenhouse Gas Emissions 

As temperatures rise, the scientific community has reached a consensus that carbon dioxide and other greenhouse gas emissions have contributed to global warming and shifts in climate patterns. Greenhouse gases are linked to both short-term and long-term health issues and air quality deterioration. Alone, CO₂ is responsible for 64% of the warming effect from the burning of fossil fuels. In 2022, the carbon footprint and local emissions had decreased to 19.3 million of CO₂ equivalent (Mt CO₂e) and 4.72 Mt CO₂e compared to 2004, however current trends still forecast a 3.5°C temperature increase by 2100. Nonetheless, the concentration of CO2 is not the only greenhouse gas affecting the environment; ozone and nitrogen dioxide (NO2) also play a role in the deterioration of air quality in Paris and the deterioration of health in areas of high concentration. 

Figure 1: Paris’ Carbon Neutrality Trajectory Source: Ville de Paris

Air quality in Paris, due to the concentration of inhabitants in a reduced area, has been a significant concern for Mayor Anne Hidalgo. Pollutants such as CO2, NO2, and O3 have been present in high concentrations as a consequence of the increased circulation of vehicles, heating, and other factors that contribute to the emission of these gases.  In 2021 alone, despite the global health crisis, there was a concentration of 37 Mt CO₂e (CO2, CH4, and CO) in the Paris region, although only 4.78 Mt CO2e was concentrated in the Paris center. While it represents a significant reduction compared to 2004, at 28.3 Mt CO2e, these levels are still focused in Parisian areas where there is a high population density, resulting in direct exposure to these pollutants. These pollutants tend to target the lungs as they infiltrate the human circulatory system, causing inflammation and potentially leading to carcinogenicity. NO₂, PM, CO, and O₃ are also linked to strokes, ischaemic heart disease, and lung cancer. Short-term exposure to high concentrations of particulate matter can create aggravated lung irritation, asthma, and respiratory infections. 

Forty thousand premature deaths per year from 2016 to 2019 have been caused by greenhouse gases in France, according to Santé Publique France. In the Île-de-France region, 7,900 deaths per year could be avoided if the pollutant levels of greenhouse gases were below the threshold levels appointed by the World Health Organization (WHO). In 2023, approximately 2,000 Parisians were affected by NO2 levels exceeding the 40 µg/m³ annual threshold, and 70% of Parisians were exposed to poor air quality conditions in the last decade. Major concerns are focused on the concentration of nitrogen dioxide in the air produced by traffic and the urban heating network. Airparif estimated that, in 2019, vehicular traffic accounted for 45% of the NO2 emissions in the Greater Paris Metropolis. In the case of PM10 and PM2.5, out of 10 million and 8 million, respectively, a majority of these were attributable to the Greater Paris Metropolis. However, not only is there a clear repercussion for human health, but also the amount of financial resources that must be allocated to it. In 2015, a French Senate report, “Air Pollution: the cost of inaction,” estimated that the impact of air pollution created a financial burden of €100 billion, with €68-97 billion attributed to health-related problems and €4.3 billion to non-health-related issues, such as lower crop yields.

In addition to the existing pressures stemming from the impact of greenhouse gases on health and global warming, the World Health Organization and the European Union have significant influence over the policies that state and local leaders implement. These regional pressures translate into the form of regulations such as the European Climate Law and the Effort Sharing Regulation. The former is a legally binding target to achieve carbon neutrality in the EU by 2050. This target sets different greenhouse gas emissions limits for each country; for France, the limit for 2026 is approximately 290 Mt CO₂e. Additionally, with the Effort Sharing Regulation, the EU has set a target for each member state to reduce greenhouse gas emissions in the domestic transport, buildings, agriculture, small industry, and waste sectors by 2030 (France is expected to reduce emissions by 47%). Those member states that fail to comply can be subject to an infringement procedure, which may lead to a litigation case. If found guilty by the Court of Justice of the European Union, the court can impose sanctions on the member state. 

Moreover, the WHO’s global air quality guidelines add external pressure to comply with procedures that will prevent premature deaths (between 4 and 9 million deaths attributed to air pollution) caused by greenhouse gas emissions. With the target audience of these guidelines being policymakers, it is crucial that leaders, such as Anne Hidalgo, advocate for policies that comply with the WHO’s global air quality standards to decrease the number of premature deaths in Paris. Additionally, as a member of the C40 Cities and a signatory of the Clean Air Accelerator, the city of Paris, under the leadership of Anne Hidalgo, has committed to enforcing regulations and policies that align with the WHO air quality emission recommendations. 

Extreme Weather Events

With the rise in temperatures and increase in greenhouse gas emissions, the likelihood of damaging weather events is increasing. An extreme weather event is a rare moment in time and space that deviates from average weather standards in terms of location, timing, magnitude, or scale. With the rise in temperature in Paris, it has been predicted that the likelihood of extreme weather events, such as flooding, heat waves, and droughts, will increase. The previously mentioned events are those that the city of Paris has identified as having a higher occurrence rate and a meaningful impact on Parisian health and vital infrastructures. 

Floods

Evermore, rainfall is expected to increase as warmer temperatures increase levels of evaporation and the formation of rain clouds. The risk of a decennial flood has increased by 20%, and the risk of a 100-year flood has risen to 40% now that rainfall patterns are likely to intensify due to a predicted rise in precipitation from now until the end of the decade (633 mm for 2030).  This is becoming an alarming problem since the chances of centennial floods have increased. The city of Paris experienced a similar event in January 1910 when the Seine River flooded, affecting about 200,000 people and causing €1.5 billion, in today’s euros, in damage. Therefore, with 65% of the Paris Metropolitan Area’s population residing in the Seine-Normandy River Basin, a flood similar to the 1910 Paris flood could significantly impact a large portion of the Seine River basin. 

Moreover, a flood in the Greater Paris Metropolis could completely impair the electricity, water, and heating networks. For example, in Paris, the residential heating system relies on the production of water vapor, which is generated from the Seine. It is susceptible to flooding as it disrupts and saturates the evaporation process. In the case of the 2016 flood, the impact of the flood left 10,000 people without access to hot water. In the case of a 100-year flood, it could cause the complete breakdown of the water vapor heating system, leaving 1.5 million Parisians without heating.

Furthermore, the potable water and sewage systems are vulnerable to damage if flooding affects the surface infrastructure located near the Seine River Basin, such as substations, junction boxes, and transformer stations. Their breakdown could effectively shut down water treatment plants for potable water, leaving more than 2 million Parisians without access to drinking water ⁴. Additionally, in the case of a flood, the sewerage system can become completely saturated, forcing it to discharge wastewater into the Seine, which in turn affects its biodiversity. In 2014, the OECD forecasted that the potential damage to electricity, water, heating, and other vital city systems, similar to the 1910 flood, would cost between €3 billion and €30 billion. 

Given the significant impact of the flood on the city of Paris and its inhabitants, Anne Hidalgo has played a crucial role in collaborating with the Île-de-France region and her team to develop the Paris Resilience Strategy. This strategy aims to address and mitigate the risks associated with decennial and 100-year floods for the remainder of the century. 

Heatwaves 

While the health effects of rising temperatures during extreme heat events, or heatwaves, were discussed in the previous section, the infrastructural costs that heatwaves can cause are significant. Heatwaves are regarded as periods of prolonged extreme atmospheric heat during which maximum and minimum temperatures diverge from the averages for the location and may last for a few days to several months. Already, days exceeding 30°C are expected to increase, reaching almost 20 days during summer. In Europe, the number of heatwaves similar to that of 2018, which caused severe droughts in central and northern Europe, is likely to occur every two out of three years in a world where average temperatures increase by 1.5°C and every single year in a 2°C warmer world.  Heat waves that reach a 35°C or more wet-bulb temperature will cause deaths due to hyperthermia.

An increase in heatwave frequency will put greater stress on the electrical infrastructure, similar to the damage that floods cause (to junction boxes and substations). For instance, during the 2003 heatwave, 230,000 Parisians experienced a brief power outage due to a junction box failure. Heatwaves are not only affecting the electricity supply network but also impacting the potable water supply. The increasing temperature during heat waves creates an environment that fosters microbial growth, thereby creating stress on the system.

With the rise in heatwave occurrences, which is a clear signal of global warming and disturbed climate trends, the health impacts of heatwaves need to be presented differently from the effects of rising temperatures in the city of Paris. The cardiovascular system can be stressed in extremely high heat as it attempts to thermoregulate by transferring heat to the skin. This process is less efficient in the elderly, whose renal and thermoregulation functions become limited. Additionally, with the elderly being more susceptible to cardiovascular and respiratory illnesses, heat waves further exacerbate their impact, putting them at a higher risk of mortality. 

Moreover, for those people who live on the top floors or alone, they have a greater risk of mortality during heat waves. This is especially true for the elderly who live alone or in nursing homes, where inadequate care can leave them completely vulnerable to the effects of heat waves. The toll on health has already been seen in France during the 2003 heatwave, with a death toll of 14,802 people from August 1-20, with an excess in mortality in the cities of Paris, Dijon, Poitiers, Le Mans, and Lyon. 

The increasing likelihood of extreme climate events due to rising temperatures and still high greenhouse gas emissions in Paris underscores the criticality of climate change, which poses a significant threat to the city’s health, integrity, and structural stability. Still, Anna Hidalgo has been committed to the fight against climate change, marked by her essential contribution during the Conference of the Parties 21. Anne Hidalgo not only propelled herself as a climate activist but also as an international figure in the fight against climate change.

IExRAIA Summer Research Program:

This article is an excerpt from a report on Claudia Sheinbaum produced as part of an RAIA research program on climate leaders. For a full picture of Ruto’s climate leadership, including the sources, read the full report. This project was fully financed by IE University’s IE School of Politics, Economics and Global Affairs.

Author: Alice Girotto & Bryan Thorne

Editor: Roxane de Bergevin

Project Leads: Roxane de Bergevin & Stefani Obradovic