Cities are now at the center of global efforts towards achieving the Sustainable Development Goals (SDGs). Moreover, it is increasingly recognized that cities are at the forefront of battle against climate change, at the same time being most vulnerable to its effects but also embodying the potential to counter it.

Planting more trees in urban areas holds a considerable potential to tackle some effects of climate change and contribute to the achievement of urban-related SDGs. Under auspices of the UNECE, mayors are invited to undertake a “Trees in Cities Challenge”, whereby they will pledge to plant a pre-determined number of trees in their city.

Within the UNECE, the Committee on Housing and Land Management and the Committee on Forests Industry will provide strategic and expert support to participating mayors, in line with their respective expertise. The “Trees in Cities” Challenge will be hosted by the UNECE and implemented in cooperation with local governments in beneficiary countries.

There are four main phases of the campaign: 1) Pledge. The mayor of a city formally pledges by committing to plant a pre-determined number of trees by 2020 by exchanging letters with UNECE; 2) Keep track of the progress. The mayor will realize the challenge in a timely manner and keep UNECE informed of the progress; 3) Monitor. UNECE will monitor progress and regularly update the website. This will include a “tree-meter” showing the number of planted trees and indicating measurable economic, social and environmental benefits for the city in question; 4) Report and share experience. Upon successful implementation of the initiative, UNECE will provide the beneficiary city with a progress report and invite the mayor to share their experience at a relevant UNECE forum. The campaign will initially be launched on 23 September until the end of 2020.

To honor the effort many mayors have already made, we will take into account the trees that have been planted before mayors accepted the challenge, as long as this has been done during their last mandate.

Expected benefits and impact on cities (methodology for measuring is still TBD) include:

- Climate change mitigation and greater urban resilience. By absorbing C02 and providing a natural way of air-cooling, trees help mitigate climate change and save energy by reducing the need for air conditioning.
- Cleaner air and the environment. Trees exchange gases with the atmosphere and capture particulates and urban pollutants.
- Healthier cities. Presence of trees in urban areas is known to have a positive effect on human health by reducing levels of stress, preventing obesity, and accelerating the recovery from illnesses.
- Improved public spaces for greater biodiversity. Trees provide shelter, food and home to animals and plants, contributing to urban biodiversity.
- Stronger communities. Increased presence of urban green areas has been shown to have a positive impact on social cohesion and help to form stronger communities.
- Increased property values. Healthy trees can increase surrounding property values by 2-10%.

In progress.