Global restoration of degraded environments – if done correctly – brings environmental, societal and economic benefits. Thomas Crowther, professor of global ecosystem ecology at ETH Zürich, where he formed the Crowther Lab, offers four principles for getting it right
We need nature. It is the foundation of healthy societies and strong economies.
As forests grow, they provide clean air, food and water for millions of species, including humans. Wetlands, grasslands and other ecosystems support unique wildlife and provide filtered water, rich soils and protection from floods and drought. Biodiverse ecosystems suppress diseases – a critical benefit considering the recent pandemic. They also store more carbon and help mitigate climate change.
So, why aren’t we doing more to help ourselves by conserving and restoring ecosystems? One reason, perhaps, is that it was unclear how much land worldwide could naturally support restoration. That is, until now.
0.9 billion hectares of potential
Our science shows that the potential for tree restoration is tremendous. Huge. There are up to 0.9 billion hectares of degraded land outside of existing forest, urban or agricultural land that might support added tree cover. This is an area larger than Brazil and nearly the size of the United States. Restoring these ecosystems would increase forested area by more than 25% globally and, over their lifetimes, these new trees could ultimately sequester between 133 and 276 gigatons of carbon in woody biomass and soils. For context, human industrial activity has added approximately 300 gigatons of excess carbon to the atmosphere to date.
Additional opportunity exists to plant trees in agricultural areas and cities, with great co-benefits. In agricultural settings, agroforestry can increase crop yields, thus incentivising native tree restoration. Planting trees in urban areas can help reduce the urban heat island effect, mitigate stormwater run-off and enhance quality of life – not to mention the significant employment opportunities.
More than 20% of the 0.9 billion hectares of tree restoration potential is found in G7 countries. Globally, the top six countries represent more than 50% of the total potential:
• Russia: 151 million hectares
• United States: 103 million hectares
• Canada: 78.4 million hectares
• Australia: 58 million hectares
• Brazil: 49.7 million hectares
• China: 40.2 million hectares
Four principles for getting IT right
Countries that invest in nature-based solutions, including conservation, restoration and green infrastructure, have the potential to reap dividends. Earlier this year, a group of civil society experts and business leaders aligned on the Together with Nature principles for nature-based solutions to responsibly tackle the climate crisis, restore biodiversity, and benefit planetary health and human well-being:
① Cut emissions.
Nature-based solutions are powerful tools to capture carbon from the atmosphere, but they are not a substitute for cutting greenhouse gas emissions. From a climate change perspective, we must rapidly cut fossil fuel emissions, decarbonise economies, and also maintain, sustainably manage and restore ecosystems.
② Conserve and protect existing ecosystems. Intact soils, forests, grasslands, shrublands, wetlands and aquatic ecosystems are vital repositories of carbon and biodiversity. Yet we’re losing them at an alarming rate. Protecting these last remaining strongholds of nature is critical.
③ Be socially responsible.
We must fully engage Indigenous peoples and local communities, and respect and uphold their rights and leadership. We must also proactively contribute to fair and sustainable economic models that create new employment opportunities while avoiding competition with existing activities such as food production. Only when local communities benefit from the social, economic and ecological benefits that ecosystems provide can restoration be sustainable.
④ Be ecologically responsible.
Nature-based solutions must be founded on rigorous ecological principles. Biodiversity is vital for healthy ecosystems that are more productive, resilient and beneficial. Diverse mixtures of native species are most likely to provide desired benefits such as carbon storage, food production and protection from floods, drought and disease. Monocultures of exotic species or low-diversity plantations are unlikely to provide these desired benefits.
Embracing the challenge, together
We live at a time when Earth’s ecosystems are more vulnerable and depleted than they have ever been. But this is also an exciting time because we now understand both the scale of the problem and the potential scale of the solution. We have unprecedented capacity, momentum and scientific information to successfully implement nature-based solutions.
International initiatives such as the Trillion Tree Campaign and the Bonn Challenge incentivise global conservation and restoration. Yet nearly half the countries that signed up to the Bonn Challenge could more than double the area they are currently targeting for restoration. And, despite global outcries, forest clearing and ecosystem loss continue to rise, particularly due to poor policies and protections. The G7 members could set a leadership example. For the benefit of our local and global environments, societies and economies, it is time to embrace the challenge of moving from commitment to systemic action, together.