World Environment Day was celebrated throughout the world on June 5 with the theme “Inspired by Nature. For Climate. For Our Future.” The planet does not argue, nor does it negotiate. Instead, it sends signals through rising seas, raging wildfires, heatwaves and melting glaciers. “We said 1.5°C was the limit. We are crossing it,” reads the theme description of this year’s World Environment Day celebration organizing committee.
Hosted by Azerbaijan, this year’s global campaign focuses on Nature-based Solutions (NbS) as an urgent call to action to restore our ecosystems, combat global warming and secure a sustainable future. What is important is that the 1.5°C warming threshold that the world treated as a distant red line is no longer a future concern; it has become an everyday reality. Given these circumstances, this year’s campaign calls for urgent action to restore ecosystems, reduce climate risks, and secure a sustainable future through NbS.
Global Heatwave and NbS
When we talk about climate adaptation, we normally talk about other visible hazards rather than heat. However, scientific research has confirmed that natural variability and environmental changes, among others, are rapidly driving up global temperatures. This crisis is severely compounded by rapid urbanization. The transformation of natural green and blue infrastructures, such as forests, wetlands and water bodies, into concrete buildings and asphalt roads has intensified the urban heat burden. Combined with greenhouse gas emissions, this has increased the frequency, intensity and duration of heatwaves all over the world.
Global Heatwave
South Asia, Europe, and North America have all experienced a significant rise in hot days in recent years, with the elderly, children and people with underlying health conditions disproportionately affected by extreme heat. The Lancet estimated in 2024 that between 2000 and 2019, nearly 489,000 annual deaths were linked to extreme heat. The Intergovernmental Panel on Climate Change in 2021 projected that all regions will face more intense and frequent heatwaves, characterized by longer warm periods and shorter cold periods. Recent weather patterns in South Asia and Europe already validate these projections, revealing an upward trend toward persistently hot days and warm nights that create a “heat island” effect.
NbS and their co-benefits
The International Union for Conservation of Nature (IUCN) defines NbS as actions that protect, sustainably manage and restore natural or modified ecosystems while simultaneously addressing societal challenges and enhancing human well-being as well as biodiversity. In the context of rising temperatures and increasingly frequent heatwaves, NbS offers one of the most sustainable and cost-effective approaches to cooling communities and building long-term climate resilience.
While several measures have been found effective to help people cope with heatwaves, many are reactive and often energy-sensitive. NbS, when appropriately designed and implemented, has demonstrated long-term sustainability. Solutions such as restoring greenery, conserving wetlands, promoting rooftop and vertical gardens, and protecting water bodies have all emerged as promising options. As temperatures continue to rise, the implementation and scaling of NbS have become an urgent need.
The cooling effect of these solutions comes from their ability not only to naturally regulate temperatures but also with additional benefits such as enhanced biodiversity and improved air quality and evapotranspiration that contribute to greater well-being. Green spaces can reduce local temperatures by several degrees Celsius, particularly during summer (Aram et al., 2019), while rooftop and vertical gardens moderate indoor temperatures, reducing heat stress in homes and buildings.
When we talk about heat mitigation through NbS, an important factor is surface reflectivity, which is commonly measured through the concept of albedo. Albedo refers to the proportion of solar radiation reflected by a surface. Surfaces with higher albedo reflect more heat and therefore contribute to cooler surroundings. Albedo values of vegetated surfaces range from 0.1 to 0.25, while grey infrastructure is typically below 0.1. Thus, vegetation with a higher albedo value is ideal for undertaking heat action. Integrating vegetation and selecting suitable plant species can therefore play a significant role in reducing heat accumulation and mitigating urban ‘heat island’ effects.
Beyond cooling communities, these nature-based approaches provide multiple social, environmental and economic benefits. They create green jobs, strengthen food security through rooftops and vertical gardens, improve water quality and flood regulation through ecosystem restoration, and enhance physical and mental well-being through accessible and recreational green spaces.
By reducing the urban heat island effect, NbS also lowers energy demand for cooling and reduces household expenses. While traditional grey infrastructure is expensive, NbS are cost-effective, locally adaptive, and long-term sustainable solutions for building resilience to increasing heat risks.
A Pathway Toward Climate Resilience
In a warming world, resilience is a necessity rather than a luxury. Building shade-rich, breathable and biodiverse spaces through nature-based approaches is not only a climate solution but also a survival strategy. Investing in NbS for heatwave adaptation offers a comprehensive approach that addresses escalating risks of extreme heat while strengthening food and water security, fostering economic opportunities and enhancing climate resilience across urban and rural settings.
To achieve this, policymakers, planners, development partners and communities must place NbS at the core of climate adaptation strategies and development agendas.
Global success stories already illustrate the transformative potential of these approaches. For example, Singapore’s ‘Biophilic Garden in a City’ initiative successfully integrated green spaces such as vertical gardens, green roofs, and tree-lined streets into buildings and urban planning that reduced urban temperatures through shading, increased beneficial evapotranspiration and improved air quality. Similarly, the ‘Million Trees’ initiatives in Los Angeles expanded the urban tree canopy and green infrastructure, reducing surrounding temperatures by up to 2°C to 4°C and lowering the city’s energy consumption costs.
Integrated and Inclusive Actions
NbS must be rooted in local priorities and practices if they are to succeed in the long-term. Ensuring local ownership is critical for the long-term success and sustainability of these interventions. One of the most effective ways to localize NbS is by aligning them with livelihood opportunities, such as rooftop gardening, nursery development, and community-based wetland conservation, so that climate-vulnerable populations directly benefit from and invest in these solutions.
Inclusive climate action also demands the active engagement of those most exposed to heat risks, including informal workers, women and marginalized groups. Their involvement in planning and managing green and blue infrastructure ensures that solutions are context-specific and equitable.
Mainstreaming these practises into urban design, land-use planning and public infrastructure is essential for long-term climate resilience. This requires an enabling policy environment, cross-sectoral collaboration and dedicated funding. Governments, development partners and local authorities must work hand in hand with communities to scale up NbS to mitigate extreme heat and improve everyday well-being.
Act Now!
As heatwaves become more frequent and the world pushes past the critical warming thresholds, the time to act is now! This World Environment Day, the message is clear and loud: nature is not only the victim of climate change, but our strongest ally in combating it. Implementing NbS is no longer a mere environmental choice; it is a vital necessity for public health, development and human survival. We must invest in nature today to avoid hefty environmental costs tomorrow, before extreme heat becomes the new normal.
Chapagain is a Climate Change and Disaster Risk Reduction Researcher.
Bhuju works for Mercy Corps Nepal under Zurich Climate Resilience Alliance program.
