Climate change impacts, from heatwaves to more severe flooding, are surging around the world.
In response, demand for action on climate risks is rising fast, as activists from Greta Thunberg’s school strike movement to Extinction Rebellion protesters take to the streets.
Scientists say efforts to reduce climate-heating emissions must happen very quickly, or an international goal to prevent the worst effects of climate change could be lost within a decade.
What could help stop global emissions increasing?
Some scientists, environmentalists, politicians and even fossil fuel companies think planting trees is an important part of the solution.
To grow, trees absorb carbon dioxide, the main gas heating up the planet. Planting new trees could lead to more carbon dioxide being sucked out of the air – and less warming of the climate.
Conveniently, pretty much everyone likes doing it too. It’s the one piece of environmental action politicians both conservative and liberal can agree on, whether or not they worry about climate change. Children can take part and it makes for great photos.
But could we really plant enough trees to deal with climate change?
Scientists say if we planted 1.2 trillion more trees over an area about the size of the United States, they could absorb about two-thirds of the climate-heating emissions from human activity.
But they take decades to grow – and just planting them doesn’t ensure they will survive and grow into big carbon-absorbing trees.
Some of the land where they could be planted is owned or used by people who might want to do other things with it, from grazing sheep to installing solar farms, growing food or opening mines.
Some of it belongs to indigenous groups and others who could face threats to their rights to the land.
With the world’s population still growing, along with demand for food, turning over much more land to trees could lead to rising hunger too.
Planting trees to deal with climate change is gathering interest just as the world’s existing forests are being rapidly cut down for fuel, development projects and more farmland – or being lost to wildfires.
Existing natural forests, particularly in the tropics, are the best at absorbing carbon dioxide and safeguarding the world’s wildlife and other biodiversity. Protecting those forests should be a top priority, scientists and conservationists say.
FOSSIL FUEL COP-OUT?
Among those supporting “nature-based solutions” to climate change, such as tree planting, are oil and gas companies.
As pressure to slash climate-changing emissions grows, they see planting trees as a way to contribute while offsetting their own company emissions.
But scientists say tree planting must come alongside a reduction in gases from burning fossil fuels - not as a replacement for those cuts.
Emissions from using oil, gas and coal need to fall to nearly zero by mid-century or earlier to avoid the worst impacts of climate change, scientists say.
So while planting more trees is great for everything from cutting air pollution to improving mental health and keeping us cooler in heatwaves, it’s not going to deal with climate change on its own.
For that we also need to protect existing forests, swap fossil fuels for renewable energy, and make our own behaviour and economies greener.