# Warming climate and hot cities foster cool solutions in China

Marc Gronwald, Eric Lichtfouse

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## To cite this version:

Marc Gronwald, Eric Lichtfouse. Warming climate and hot cities foster cool solutions in China. Environmental Chemistry Letters, 2026, 24, pp.1-4. 10.1007/s10311-025-01872-1. hal-05220399

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Submitted on 23 Aug 2025

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# Warming climate and hot cities foster cool solutions in China

Marc Gronwald<fnref n="1" />,<fnref n="2" /> ID · Eric Lichtfouse<fnref n="3" /> ID

> Surely the day is coming; it will burn like a furnace. All the arrogant and every evildoer will be stubble, and the day that is coming will set them on fire. Not a root or a branch will be left to them.

Malachi 4:1

Climate change is already inducing substantial adverse economic and health effects. Here we show that climate is warming faster in China versus the global Earth, and that this warming is more pronounced in the northern Chinese provinces. The recent rise in extreme events such as heatwaves, drought and floods have increased related deaths and risk of diseases such as dengue and infectious diarrhoea. Climate-related economic loss has increased by 1.5 fold from 2022 to 2023. In cities, the total urban warming is now the addition of both the recent, global-warming related extreme heat exposure, and the classical urban heat island effect (Fig. 1). This has fostered the recent development of urban cooling strategies such as ventilation corridors in Guangzhou.

## Faster climate warming

Some regions of the world are warming faster than others [1], and the fact that global warming has already surpassed the + 1.5 °C safety threshold is debated [2, 3]. For

example, whereas the mean global land-surface temperatures increased by +1.5 °C from 1850 to 2024, the mean temperature in China increased by about +2 °C (Fig. 2) [4]. In other words, temperatures are getting warmer faster in China, and this gap started rather recently, around the year 2000. Moreover, the comparison of northern and southern regions in China shows that temperatures are rising much faster in the north. For instance, the Inner Mongolia Autonomous Region, bordering Russia, shows an approximate temperature anomaly of +0.5 °C higher than that of the southern Yunnan province, bordering with Myanmar, Laos, and Vietnam. Coincidentally, Mongolia sandstorms and desertification appear as an example of future adverse effects of climate change [5].

## More diseases and fatalities

In 2023, China experienced its highest recorded average temperature of 10.71 °C, its second-lowest rainfall since 2012, and significant flood and drought events [6]. As a result, China is one of the most vulnerable countries to climate-related health risks. Specifically, in 2023, the average number of heatwave exposure days per person reached 16, which is more than three times the historical 1986–2005 average. This increased heatwave-related deaths by 1.9-fold. Similarly, a 15.4% rise in the annual excess risk of dengue fever incidence is projected, compared to 2013–2019 levels.

There is also concern about the augmentation of infectious diarrhoea that currently causes 1.32 million cases annually in China, because diarrhoea is linked to both extreme rainfall and extreme drought events. From 2004 to 2022, the dengue vector transmission increased across 17 eastern provinces, with the highest transmission observed in southern China, particularly in Hainan, Guangxi, and Guangdong [7]. By the 2060s, the risk of dengue is expected to increase by 15.3–15.5% compared to the 2013–2019 average, with even sharper rises of 30–60% in provinces such as Hainan, Guangdong, Jiangsu, and Shanxi.

<footnote>☒ Marc Gronwald
marc.gronwald@xjtlu.edu.cn</footnote>

<footnote>☒ Eric Lichtfouse
eric.lichtfouse@icloud.com</footnote>

<footnote n="1">¹ International Business School Suzhou and Centre for Culture, Communication, and Society, Xi’an Jiaotong-Liverpool University, 8 Chongwen Road, Suzhou 215123, Jiangsu, China</footnote>

<footnote n="2">² CESifo and Ifo Institute, Poschinger Strasse 5, Munich 81679, Germany</footnote>

<footnote n="3">³ International Research Center for Renewable Energy, State Key Laboratory of Multiphase Flow in Power Engineering, Xi’an Jiaotong University, Xi’an 710049, Shaanxi, China</footnote>
<figure><img src="image_3.png" /><figcaption>**Fig. 1** The total urban warming effect now results from the addition of both the classical heat island effect, and the new extreme events induced by global warming. Artistic drawing. Credit: Eric Lichtfouse 2025</figcaption></figure>

## Billions of economic losses

More heat also impacts the economy, with a 24% increase in the potential loss of work hours, and a 60% rise in reduced time for safe outdoor activities. More generally, calculations reveal that heat-related loss of labor capacity led to a record national economic cost of $283.4 billion, equivalent to 1.65% of the Chinese global domestic product (GDP). Moreover, in 2023 in China, economic losses from climate-related extreme events have increased to $77.1 billion, approximately 1.5 times higher than in 2022. Future economic impacts of heat are projected to be significant, with heat-related potential work hours loss expected to increase by +28–37% during 2051–2070, compared to historical baseline levels. The largest increase is anticipated in the north-eastern provinces.

## Fast urbanization

China's rapid urbanization began in the late 1970s, with the urban population rising from 20% in 1980 to 60% in 2018 [8]. This growth is expected to continue, reaching 70% by 2030 and 80% by 2050. China has six megacities with populations exceeding 10 million, and more than 120 cities with a population of more than 1 million [9]. Moreover, China is home to many of the world's fastest-growing cities. Globally, cities with populations of 500,000 or more grew at an average annual rate of 2.4% between 2000 and

2018. Yet, 36 cities in this category far outpaced this trend, expanding at over 6% per year—more than double the global average. Remarkably, 17 of these high-growth urban centers are located in China.

Concomitantly, the East Asian and Pacific area is undergoing a rapid population aging driven by a sharp decline in fertility rates. This area has now the world's largest elderly population of 65 and above. This aging population is especially vulnerable to extreme weather events. In particular, population exposure to hot-dry days in China has sharply increased from 697 million person-days in 1986 to 21 billion person-days in 2022, a 30-fold increase [6]. These extreme conditions were most frequent in Northern China, particularly in Heilongjiang, Inner Mongolia, Xinjiang, and in the Yangtze River Basin.

## Hot cities

Heat exposure is particularly problematic in cities due to the 'total urban warming' effect, which adds extreme heat exposure with the classical 'urban heat island' effect [10] (Fig. 1). This is due to the urban built environment, which acts as a heat reservoir. This warming is explained by impermeable and nonreflective surfaces, poor airflow design, and the lack of vegetation and water feature heat traps, significantly raising local temperatures compared to surrounding areas. For a sample of 100 East Asian cities, this temperature difference is +2 °C [10].

Total urban warming threatens the sustainability of rapidly growing urban settlements worldwide [11]. For instance, global exposure to extreme heat nearly doubled, increasing by almost 200% from 1983 to 2016. Total urban warming contributed an additional 52% to the annual increase in exposure, compared to the effects of urban population growth alone. Many municipalities in China saw significant annual increases in urban population exposure to extreme heat, particularly in Northeastern and Eastern China. Interestingly, the rise in exposure was more closely linked to population growth than to warming itself. Overall, East Asia's cities are at risk of becoming uninhabitable due to extreme heat [10].

## Urban cooling solutions

There are several strategies to adapt and combat climate change [12] such as the use of sponge cities [13]. In their report 'Combating heat in cities', Lee et al. propose three solutions [14]. First, direct support should be provided to vulnerable groups, such as cooling equipment for workers and shelters for at-risk populations. Second, urban cooling strategies should be implemented, including heat-sensitive
<figure><img src="image_4.png" /><figcaption>**Fig. 2** Comparison of atmospheric temperature anomalies from 1850 to 2024 in China versus mean global Earth temperature (top graph), and in Inner Mongolia in the north versus the southern Yunnan province. Temperature in Celcius are reported as anomalies relative to the January 1951–December 1980 average. Data from Berkeley Earth (www.berkeleyearth.org)</figcaption></figure>

planning, energy-efficient buildings, and urban greening. Third, city preparedness should be enhanced through awareness campaigns, institutional coordination, early warning systems, and data monitoring.

Guangzhou stands out as an example of strategical urban cooling [15], with the following measures. First, an urban climatic planning recommendation map has been developed using thermal load and airflow dynamics analysis. The zoning units are classified into four levels based on current climate conditions and projected heat risks, with tailored development restrictions and cooling strategies assigned to each category. Second, wind pattern studies have allowed to design six major ventilation corridors, which integrate green belts, water bodies, low-rise, low-density areas, and artificial pathways like highways and major roads, to optimize airflow across the city. By combining traditional knowledge with nature-based solutions, Guangzhou has implemented pilot projects for passive urban cooling.

**China, the leader in renewable energies**

The recent withdrawal of the United States of America from the Paris Agreement has created a leadership vacuum in the global climate action, thus offering China the unique opportunity to step into the leading role. With its dominant position in renewable energy technologies such as solar panels, electric vehicles, and lithium-ion batteries, China is well-positioned as a global green energy leader. China is rapidly expanding its renewable energy capacity domestically. In 2023 alone, the country added 302.2 gigawatts (GW) of renewable energy capacity, accounting for more than half of the global increase that year [6]. Nonetheless, ironically, extreme weather events such as droughts and water shortages in the Southwest have reduced the renewable energy output and increased reliance on coal power [6]. For example, in 2023, the annual operational hours of coal power plants rose from 76 to 4,466 h, reversing the recent downward trend in coal power generation.
Declaration

EL declares that he is Chief Editor of Environmental Chemistry Letters. Figure 1 has been drawn by the canva.com tool that may use artificial intelligence.

References

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3. Jasper JP, Lichtfouse E (2025) Connecting records of global-to-regional climate. Environ Chem Lett 23:363–366. https://doi.org/10.1007/s10311-024-01800-9

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