Adapt to extreme heat risks with nature-based solutions

In 2024, the world experienced 58 natural disasters (such as floods, wildfires, droughts, heatwaves, and storms) that caused over USD $1 billion in damages each (1). At the same time, Swiss Re estimates that insurance losses from natural disasters are rising at 5–7% annually, reaching USD $145 billion by the end of this year (2). In particular, commercial buildings and infrastructure, ranging from office buildings to production facilities, warehouses, roads and power grids, face increasing exposure to the growing risk of natural hazards. For businesses, this requires shifting from reactive recovery efforts towards proactive prevention strategies.

Research by UNEP has shown that Nature-based Solutions (NbS) - which are defined as actions to protect, conserve, restore, and sustainably manage different types of ecosystems to address business and societal challenges - can reduce the negative effects of natural hazards and simultaneously provide tangible benefits for the implementing business (3). By applying NbS at the landscape level with the involvement of local experts and stakeholders, these solutions achieve their greatest impact in terms of cost savings and protection potential against natural hazards.

The city of Adelaide in Southern Australia provides a clear example of the risks that are associated with exposure to high temperatures. Between June and early September, extreme heat events are common, with heatwaves typically occurring 4 to 6 times every year, each lasting three or more days. The city has recorded temperatures above 45°C (113°F) during severe heatwaves. Therefore, Adelaide Airport has decided to implement a Nature-based Solution to protect their commercial infrastructure from heatwaves.

In 2015, Adelaide Airport introduced a new land management approach to determine the cooling benefits of restoring a 4-hectare airside area by planting and irrigating Lucerne crops (otherwise known as Alfalfa), which are commonly used in Australian agriculture. These crops have large stomata, which means that they have higher transpiration rates compared to other plant species (such as eucalyptus). When combined with efficient irrigation, these higher transpiration rates ultimately result in a cooler microclimate, which can be seen in the images below.

To set up the improved land management approach, two temporary reel irrigators (mobile irrigation systems consisting of a large hose wound on a reel) were installed to enable removal if risks to airport operations increased. Over 40 temperature and humidity sensors were deployed around and within the irrigated area to monitor microclimate conditions. These sensors were placed upwind and downwind to measure the cooling effect and its spatial reach, while soil moisture probes helped maintain consistent soil moisture and guide irrigation scheduling.

Irrigation was conducted at night during airport curfew hours (11 pm – 5 am) to minimize disruption and avoid the attraction of birds to the airfield, and was later extended to 9 pm – 5 am. Water was sourced from a local Managed Aquifer Recharge (MAR) scheme that collects stormwater in winter, stores it underground, and supplies it in summer. Approximately 25 megalitres (ML) of water were applied in the first season, and 16 ML in the second, irrigating a 4-hectare plot at rates of 12–15 mm per event.

Real-time telemetry data from soil moisture probes supported efficient irrigation scheduling (using smart irrigation software). The combined use of climatic and soil data helped assess the effectiveness of cooling across the site and ensured sustained soil moisture levels throughout the irrigation season, enhancing both operational reliability and environmental monitoring.

Ultimately, the improved land management approach showed an average temperature reduction of 2.4°C within the irrigation area. A financial and economic assessment was conducted, considering the hypothetical expansion to 200 hectares. Benefits included reduced energy use for terminal cooling and improved aviation safety.

Figure 1: Mobile reel irrigators were used to irrigate the airside area during airport curfew hours

Figure 2: Monitoring of the irrigated area showed a temperature reduction of over 2°C on average

Figure 3: Strong potential to upscale this land management approach to cover the entire airfield

Sustainability impact

Climate

At Adelaide Airport, irrigating the airside area with a lucerne crop proved highly effective for climate adaptation, reducing local air temperatures by an average of 2.2–2.4 °C and by over 3 °C on 70% of days exceeding 30 °C. This cooling effect directly addresses the operational risks posed by heatwaves - such as payload restrictions, increased fuel consumption, and potential flight cancellations - by improving aircraft performance in hot conditions. Additionally, this land management approach demonstrated that expanding the irrigated area could potentially achieve a 4 °C reduction, which would result in substantial operational and economic benefits (e.g., lucerne production could generate an net present value (NPV) benefit of around AUD 1.8 million over 25 years compared to current land management, even accounting for infrastructure costs and water/operational costs).

Nature

The lucerne crop provided year-round ground cover, reducing dust generation and soil erosion, which improved the air quality for operations and safety. Using recycled water from local sources avoided drawing on potable supplies, and the trial indicated potential for future carbon credit generation through crop cultivation. Lucerne also has very deep roots (up to several meters), which help break up compacted soil and increase water infiltration. It fixes nitrogen through symbiotic bacteria in its roots, enriching soil fertility. This increase in nutrients in the soil feeds soil microbes, fungi, and earthworms, leading to healthier and more diverse soil ecosystems. The root system also adds organic matter to the soil, which helps it hold more water and stay cooler. As a side-benefit, the lucerne crops helped deter certain bird species that might otherwise pose wildlife strike risks, supporting both biodiversity management and safe airport operations.

Social

The Nature-based Solution, if expanded to include the entire airside area, would significantly improve thermal comfort for airside workers, who are regularly exposed to direct sun and reflective heat from surrounding infrastructure. By lowering ambient temperatures in the working area, the intervention would help reduce the risk of heat stress, fatigue, and related health issues during periods of extreme heat, thereby supporting worker safety, productivity, and well-being.

S.A. Water is considering scaling up this land management practice to other airports that are directly affected by heat stress. Current plans include airports in Northern Africa, Southern Europe, and Eastern Asia. However, it is crucial that these airports are located close to local sources of recycled water to minimize the impact that this land management approach has on freshwater consumption.

Business Impact

Benefits

• The trial demonstrated a financial advantage over current management practices, with a NPV showing at least AUD $1 million in savings over 25 years. Lucerne production is estimated to provide AUD $1.8 million benefit to the airport.

• Modelling showed that the cooling benefit would reduce fuel use during take-off, and decrease the risk of heat-influenced payload reductions on aircraft (i.e., on hot days, payload may need to be reduced to lower the weight of the aircraft to ensure a safe take-off).

• The cooling effect of irrigation reduces energy use for airport terminal cooling towers and improves aviation safety outcomes. The trial also provided an opportunity to gather data on the extent of cooling achievable with irrigation.

• Cooler temperatures lead to a potential reduction on wear of aircraft tyres and brakes, mainly due to the ability to stop faster during landing if the air is denser.

Costs

• The trial involved minimal costs to obtain a “proof of concept”. Expansion to the entire airside area would, however, require significant upfront investments into irrigation infrastructure (approx. AUD 2.3 million), expected to have a neutral return on investment (ROI) after 7-8 years compared to the ongoing costs of current management. Costs included labor, reel irrigators, a network of temperature/humidity sensors, soil moisture probes, and the necessary connections to the stormwater retention area.

Figure 4: Comparison of net present value ($’000) over 25 years between business as usual (base case) and growing lucerne at three different yield levels.

• Sensitivity analysis showed that lucerne production generates a solid ROI even with a 50% increase in water charges. Potential cost-sharing with third parties could further enhance financial benefits. According to the sensitivity analysis, the cost of irrigation with recycled water (that would otherwise be released to the environment) is offset after approx. 7-8 years.

Impact beyond sustainability and business

Co-benefits

The restored landscape enhances the airport’s aesthetics, improves the customer experience and (potentially) attracts more visitors.

Typical business profile

Airports and other businesses operating in dry, high-temperature regions with large unused land areas represent the typical business profile for this type of nature-based intervention.

Approach

1. Identify suitable land: Select underutilized, non-operational airside areas with high heat exposure and minimal vegetation.

2. Assess water availability: Confirm access to a sustainable water source, such as recycled stormwater retention ponds.

3. Design irrigation layout: Plan for temporary or mobile irrigation infrastructure (e.g., reel irrigators) that can be removed if operational risks arise.

4. Install monitoring equipment: Deploy temperature and humidity sensors and soil moisture probes to track microclimate and soil conditions.

5. Select and plant crops: Choose native, heat-tolerant, low-risk plant species that restore nature and ideally provide ground cover and economic value.

6. Schedule irrigation strategically: Operate irrigation during low-traffic hours (e.g., 9 PM–5 AM) to avoid disruption to airport operations or bird attraction.

7. Monitor and adjust: Use real-time telemetry to optimize irrigation based on soil moisture and weather data.

8. Evaluate impact: Measure temperature reduction, energy savings, and operational benefits. Conduct a financial analysis to assess return on investment.

9. Mitigate risks: Monitor for unintended consequences (e.g., bird attraction) and adjust crop or irrigation strategy as needed.

10. Scale or replicate: Use trial results to inform potential expansion or adaptation at other sites with similar climate and land conditions.

Stakeholders involved

• SA Water: Developed the concept, provided water, and managed irrigation infrastructure.

• Adelaide Airport: Partnered in trial implementation and data analysis.

  • Airport Operations team

  • Airport Building Controller

  • Environment and Sustainability team

  • Finance Team

  • Risk Governance

  • Executive team

  • Airport media and communications team

• Stantec: Consulted on trial design and monitoring.

While the main interactions between the SA Water project lead and the Adelaide Airport teams were with the Environment and Sustainability team (who were responsible for managing the project from the airport side), there was constant interaction with the airport operations team from a project operational perspective, along with other airport governance teams and Federal government regulatory bodies.

Key parameters to consider

At Adelaide Airport, the NbS demonstrated the importance of considering several additional parameters before implementation. From a technical perspective, it was essential to ensure the feasibility of using recycled water for irrigation, both in terms of infrastructure and long-term availability. Cost factors also played a key role, as the investment had to be weighed against anticipated savings in heat-related damages and operational disruptions. Beyond risk reduction, the project highlighted significant economic opportunities: crop growth provided the potential to generate high-quality carbon credits, which could attract investment from airlines, while the greener airport landscape improved aesthetics and customer experience, potentially boosting visitation. Together, these parameters underline how an innovative approach can deliver both climate adaptation benefits and wider economic value.

Implementation and operations Tips

Effective implementation of this particular NbS requires careful planning, strong monitoring, and consideration of both technical and strategic factors. One key element is robust monitoring and data collection to quantify the benefits of NbS over time. Using recycled water where possible can significantly reduce freshwater consumption while also lowering operational costs.

Generally, based on guidance and experience from leading organizations such as the International Union for Conservation of Nature (IUCN), the World Resources Institute (WRI), and Arcadis, several critical success factors have been identified for corporate implementation of NbS:

Address a business challenge directly: NbS must be framed as part of a company’s business solutions toolkit to drive investment and adoption. For example, NbS designed for heatwaves can deliver measurable resilience benefits to the implementing business, as illustrated in this case study.

Deliver multiple benefits: NbS inherently provide biodiversity gains while contributing to climate mitigation and offering societal benefits. With limited sustainability budgets, prioritizing projects that deliver multiple outcomes increases their attractiveness to companies.

Implement at a landscape level: Deploying NbS across a landscape maximizes their effectiveness and cost efficiency, enabling collective resilience that protects multiple stakeholders from natural hazards. Therefore, upscaling NbS is crucial.

Accurately value benefits: Proper valuation should capture avoided losses, operational savings, and enhanced asset value, which strengthens the case for private investment and ensures long-term maintenance and sustainability.

Leverage technical and local expertise: Successful NbS implementation depends on technical know-how, thorough planning, and understanding of local environmental conditions. Working in a multistakeholder, landscape-level context requires strong project management, stakeholder coordination, and potentially support from funding partners to overcome long lead times and landscape-specific challenges.

By focusing on these success factors and integrating monitoring, cost-effective resource use, and holistic benefits evaluation, companies can overcome implementation challenges, drive adoption at scale, and ensure the long-term operational success of Nature-based Solutions.