Trees are our friends in climate change

In our efforts to avoid the worst impacts of climate change, trees are our allies. They absorb carbon dioxide and other gases that would otherwise be circulating in the atmosphere, contributing to the greenhouse effect that is rapidly warming our planet.

The Intergovernmental Panel on Climate Change recommends planting forests and restoring ecosystems as a way of lessening the impact. So our Government’s billion-tree planting project, for all its flaws, is likely to help us in the long run.

But trees serve another purpose, the value of which scientists are just starting to quantify. They absorb and transpire rainwater as water vapour. The forest canopy also stops the soil from drying. This has a cooling effect.

At the same time, the dark forest foliage absorbs more of the sun’s energy than bare ground, which has a warming effect. Brazilian scientists have modelled the effects of these two forces, known as transpiration and albedo respectively and just published their results in the journal PLos One.

They found that if the current level of illegal deforestation in the Brazilian rainforests continues, it could result in a 1.45 degrees Celsius increase in the local temperature by 2050.

They found similar warming and cooling patterns elsewhere, though the effect isn’t as pronounced in the temperate forests we have in New Zealand.

But the message is clear. Deforestation leads to local temperature increases that will likely contribute to bumping up the global temperature.

That’s particularly relevant to Brazil. Last year alone the Amazon rainforest lost 7900 square kilometres of forest cover – about 7.3 times the area covered by urban Auckland – and the worst rate of loss in a decade.

From England to China, trees are being planted like never before. In one day alone in 2017,

1.5 million people planted 66 million trees in the Indian province of Madhya Pradesh.

But the Amazon is the big one, it absorbs gigatons of carbon dioxide gas. If Brazil can act to stop the illegal tree felling, it will help all of us and literally take the heat off itself.

Last year alone the Amazon rainforest lost 7900 square kilometres of forest cover.