Restoring and protecting nature is one of the greatest strategies for tackling climate change, but not just for the obvious reason that it helps remove carbon from the atmosphere. Forests, wetlands, and other ecosystems also play a vital role as buffers against extreme weather, protecting houses, crops, water supplies, and crucial infrastructure.
The strategy of using nature as a defense against climate impacts is called ecosystem-based adaptation (EbA) – in essence, look after nature and it will look after you.
The UN Environment Programme (UNEP) and the Global Environment Facility have collaborated on over 30 projects around the world in ecosystem-based adaptation, from reforesting mangroves to fighting flooding in Tanzania, to regreening land near crops to prevent desertification in Sudan, and reforesting mountain slopes to hold back erosion in the Comoros.
Here are six ways that nature can help defend us from climate change impacts:
To secure water supplies, societies have traditionally used ‘grey infrastructure’ such as pipelines, dams, and man-made reservoirs. However, ‘green infrastructure’ uses natural or semi-natural systems to provide similar benefits with positive long-term environmental consequences.
For example, natural wetlands like streams and lakes act as sponges, drawing water down through the ground and recharging groundwater supplies. When healthy, these ecosystems capture water during intense rainfall and store it for times of drought. Similarly, healthy forests recharge groundwater supplies by absorbing water through their roots, and in doing so, filter drinking water for millions of people worldwide, including more than 68,000 communities across the US.
The State of Rajasthan, India, endured a devastating drought in 1986. In the following years local communities began to regenerate forests in the region, leading to a rise in groundwater levels by several meters. In Gambia, one of the largest development projects in the history of the country is currently centered around restoring ecosystems to increase water supplies.
First the Amazon, then California, then Australia – wildfires were catastrophic in 2019. Our preventative efforts to reduce the spread of wildfires often involve the removal of forests to create a firebreak or ‘fuel break’, a strip of land devoid of flora.
But there’s a new strategy for firebreaks that involves more nature, not less. This discovery was made after a severe forest fire in Spain in 2012, where the Mediterranean cypress trees were able to resist the blaze. The cypresses retain high levels of water in their leaves, even in sweltering heat, and the fallen leaves form a wet environment at the base of the trunk. Plans are now underway to plant the trees as ‘natural firebreaks’ throughout the Mediterranean region.
Cities are significantly warmer than the surrounding countryside. This ‘urban heat island effect’ has many causes, including the propensity of concrete and asphalt to absorb heat. In an absurd irony, our air conditioning systems produce astonishing amounts of carbon emissions, which heat the atmosphere. Our houses stay cool, but the planet doesn’t.
Urban tree cover is a win-win solution for our cities. Trees cool the surrounding air by releasing water through their leaves, similar to how humans keep cool by perspiring. Imagine the cooling power of ten air conditioning units - that’s how much a single healthy tree provides on a sunny day from evaporation alone. And that doesn’t include the shade that trees provide, which according to a study in the US, can reduce the air conditioning costs of detached houses by 20-30 percent.
Major cities are now turning to nature to cool down. Melbourne, Australia, is on track to plant more than 3,000 trees each year to tackle heatwaves, almost doubling its urban tree cover by 2040.
By 2050 sea levels could be so high that 300 million people in coastal communities will face severe floods at least once a year. There are some coastal ecosystems that can act as cost-effective seawalls combatting the two primary threats of rising seas: coastal flooding and shoreline disintegration.
Mangroves and coral reefs, for instance, cause waves to break before they hit the shore, lowering both the force and height of the swell, and in the process reducing the likelihood of the sea breaching over into people’s land. A study across 52 sites found that natural habitats were 2-5 times more cost-effective than engineered structures when it came to lowering wave heights.
In the town of Kisakasaka in eastern Tanzania, seawater had been creeping into people’s farms and killed the crops. That is, until the villagers fought back and reforested hundreds of hectares of mangroves. Within two years the salt poisoning of their crops ended and the wells returned to normal.
Landslides & erosion
The erratic weather patterns associated with climate change are already exacerbating landslides in many parts of the world. On the Canadian outpost of Banks Island landslides have increased by a stunning 6,000% in the last few decades, largely due to thawing permafrost caused by a succession of hot summers.
All landslides are caused by loose soil. There are two ways to prevent them: increase the ‘binding capacity’ of the soil, and reduce soil erosion from surface water runoff. Vegetation does both by absorbing water and anchoring the soil in place. In light of this, the government of Comoros is planting 1.4 million trees to protect people’s farms in mountainous areas.
Desertification & sandstorms
Desertification is an ongoing threat in places where the climate is drying, and where there is overgrazing and biodiversity loss. When we cut down forests, the desert further expands due to the way in which trees retain moisture in the ground. Since 1920, the Sahara Desert has expanded by 10%, decimating waterholes and arable land.
This was the motivation behind the Great Green Wall in Africa. To halt the spread of the Sahara and its consequent sandstorms, 21 African countries are working together to grow a ‘8,000 km natural wonder’ of trees and shrubs across the width of Africa. The initiative has the potential to create 10 million green jobs by 2030, according to the UN Convention to Combat Desertification.
In Sudan, desertification has given rise to violence in some areas, as groups struggle over dwindling resources. In 2017, the government launched a project to help communities adapt to the drying climate by planting ‘shelter belts,’ lines of trees or shrubs that protect an area – especially crops – from extreme weather. The project is building climate resilience in the hopes it will instil peace, making shelter belts not only a nature-based solution for climate change, but also a nature-based solution for conflict.
This piece was originally published by the UN Environment Programme. Find out more about UNEP’s work in ecosystem-based adaptation here.