Urban environments in arid climates face escalating challenges—rising temperatures, air pollution, water scarcity, and biodiversity loss. As cities expand, the integration of nature-based solutions has become imperative. One of the most effective approaches is afforestation—the large-scale planting of trees—to cool cities, improve air quality, and create healthier urban environments.

The Green Riyadh project is one of the most ambitious urban greening efforts in the world. With 7.5 million trees planned, it aims to transform Riyadh’s landscape and make the city more livable. As part of Saudi Vision 2030, the initiative is a blueprint for integrating nature into urban planning, proving that even in the harshest climates, greenery can thrive with the right strategy.

By combining large-scale tree planting with sustainable water use, Green Riyadh is showing how cities can adapt to climate change while enhancing biodiversity and quality of life.

Green Riyadh is not simply a reforestation effort—it’s a complete reimagining of urban design. Spanning 500 square kilometers, the initiative integrates trees into the city’s streets, parks, and public spaces to increase per capita green space, improve climate resilience, and foster ecological sustainability.

Cooling the City and Improving Air Quality

With summer temperatures reaching 50°C, Riyadh needs natural cooling solutions. Trees provide shade and release moisture into the air, helping to reduce land surface temperatures by 7-10°C, with dense greenery lowering ambient temperatures by up to 15°C.

Certain tree species are particularly effective in providing cooling benefits. Ficus microcarpa and Acacia confusa, for example, have dense canopies and high moisture release, making them excellent choices for reducing heat in urban areas.

Beyond temperature regulation, Green Riyadh will improve air quality by reducing CO2 concentration by 3-6% and filtering airborne pollutants such as dust and particulate matter. Trees act as natural air filters, with some species capable of reducing particulate pollution by up to 60% in street corridors. The project’s integration of greenery into urban infrastructure will directly contribute to healthier living conditions for Riyadh’s residents.

Sustainable Water Management

A key challenge in arid region afforestation is water availability. Green Riyadh addresses this through an extensive water recycling network, expanding the city’s reuse of treated wastewater from 90,000 cubic meters per day to over 1 million cubic meters. This ensures that the project does not strain potable water supplies while providing an eco-friendly solution for large-scale irrigation.

The success of afforestation also depends on choosing the right trees. Native and drought-resistant species, such as Cupressus arizonica and Pinus eldarica, have been selected for their ability to retain water efficiently and withstand long dry periods. These trees require less maintenance while still providing shade and cooling benefits.

Economic and Social Impact