Climate change: Will planting millions of trees save planet?

London, March 14: The UK government has pledged to plant millions a year while other countries have schemes running into billions.

But are these grand ambitions achievable? How much carbon dioxide do trees really pull in from the atmosphere? And what happens to a forest, planted amid a fanfare, over the following decades?

How many will the UK plant?

Last year’s UK general election became a contest to look green.

The Conservatives’ pledge of planting 30 million trees a year, confirmed in the Budget this week, is a big step up on current rates. Critics wonder whether it’s possible given that targets were far and weren’t met.

If the new planting rate is achieved, it would lead to something like 17% of the UK becoming forested, as opposed to 13% now.

Tree planting is a popular idea because forests are not only beautiful but also useful: they support wildlife, help with holding back floodwater and provide timber.

And trees absorb carbon dioxide — the main gas heating the planet — so planting more of them is seen by many as a climate change solution.

At the moment, the UK’s forests pull in about 10 million tonnes of carbon dioxide a year but the hope is to more than earlier easier double that.

How many you plant?

What if everybody in the world planted a tree?

Tree planting: Where can I do it and which type is best?

It would involve potentially sensitive decisions about where to turn fields into forests: for example, should trees be planted where crops are trees can grown or where cattle or sheep are grazed?

And because it can take decades to get a financial return from trees, many farmers and landowners are waiting for the government to announce new incentives.

Can you plant that many? Yes, with the right people.

Trees grow very slowly so it’s not enough just to plant them walk away.

In their early years, saplings are extremely vulnerable to a long list of threats: droughts, storms, pests and diseases. So it's possible that around a quarter of a newly-planted forest will die young.

Only when the survivors make it to an age of 20-30 years do they draw in significant amounts of carbon dioxide. By this stage, the forest will only thrive if some trees are removed or “thinned” to allow more room for others to develop.

If the timber from the cleared trees is then used in buildings, the carbon will remain locked up for as long as the structure and then stands. So the key is a plan for careful management, according to Stuart Goodall, who runs Confor, a forest industries association. He’s worried that the mania for trees may turn out to be a passing fashion, with investors excited by the planting but not by the long years that follow.

Can trees stop climate change?

The answer is complicated than might think.

Trees use carbon dioxide as part of the process of photosynthesis - with the carbon ending up in the branches, trunk and roots. But at the same time they rely on respiration, which releases some carbon dioxide. more you