Bordeaux Métropole and the city of Bordeaux are pursuing widespread vegetation and renaturation as a central urban policy to combat heat islands and improve air quality, with trees described as natural air conditioners.

As the tree canopy grows, officials must manage pollen and allergens, excluding certain species such as poplars, birches, and plane trees from the 1 million trees plan for allergy reasons.

A core challenge is selecting species that balance climate resilience, air quality, biodiversity, and carbon storage, guiding the Sésame project to map suitable candidates for a warming climate.

To address allergen concerns, Bordeaux plans a 'pollinarium sentinelle' to monitor pollen impacts and craft community guidelines for higher allergen levels, drawing on examples from Nouvelle-Aquitaine and beyond.

Urban renewal includes planting in unlikely areas, such as the Grand-Bersol economic zone in Pessac and the Mérignac Soleil redevelopment, where 8,000 trees will be planted.

Over 600,000 trees have already been planted to form a cooling armature integrated into planning documents, public works, private development, and local associations.

Since 2020, Bordeaux Métropole has been pursuing the 1 million trees plan to plant by 2030, aiming to offset decades of artificialization and shield its 831,534 residents across 28 communes from intensifying heatwaves projected to rise dramatically by century's end.