China's approach to tree-planting cannot get us out of the climate crunch

As the climate heats up, so does the debate on what to do about forests. China, facing regional environmental challenges, such as dust storms and wood shortages is investing in large-scale reforestation. A huge swath of the country is covered with trees planted in recent decades to attempt to stabilise the land and provide resources. It is described as a "green wall", and China claims that the CO2 from the atmosphere as the trees grow is providing a global climate benefit, offsetting some emissions from the country's rapid economic growth.

But it's not so simple, of course. I co-authored a report back in 1992 called Deserts of Trees, which set out some of the dangers inherent in tree planting as a strategy to halt climate change. Since then the arguments have only become stronger. For a start the planting of fast-growing non-native species is often disastrous from the point of view of wildlife and local cultural values. And even if newly planted, fast-growing trees are taking carbon from the atmosphere, it seems that the effect has in some cases been over-estimated, compared with the climate benefits of keeping existing natural forests standing.

For example, it has recently been estimated the natural tropical rainforests that remain are not only a vast carbon store, but are also taking up about 15% of overall anthropogenic emissions.

That is a huge benefit, and because of carbon storage and the wide range of other environmental services they provide, the overriding priority of the international community towards forests must be to stop the clearance of these ecosystems — rather than to plant new ones. Not only would that help ensure the continuing provision of essential services, it would also cut the vast emissions that come withdeforestation.

We are reminded again today, however, that no single strategy will get us through the climate crunch. The results of a new Met Office modelling exercise are published in Copenhagen, and the findings back up earlier fears that climate change could lead to changed weather patterns. In turn, those new patterns could cause large-scale die-back of tropical rainforests, with dense, moist ecosystems turning into sparser savannah, and even grasslands.

This will cause the release of tens of billions of tonnes of CO2, asbiomass decays and burns, and thereby further fuelling the process of global warming. This is, in some senses, the nightmare scenario. If we reach this point (and the models paint an ever more alarming picture for the prospects of doing so), then we will have probably have lost our chance of taking effective action. Feedback emissions from nature will overwhelm any belated strategy to cut emissions from fossil fuels, and we will have put in train a mass extinction of species comparable to that which marked the demise of the dinosaurs.

I do wish all of this was science fiction, but unfortunately it is mainstream research. The warnings are now there for all to see, although irrational denial is still a fashionable pursuit in some fringe networks [hello everyone]. Knowing what we know, we must find the means to take decisive action: stop deforestation by enabling countries with the remaining forests to embark on genuinely sustainable development that doesn't involve deforestation.

This must involve large scale financial transfers. The Stern reviewsuggested $15bn a year is the kind of sum needed to decisively turn the trend of tropical rainforest loss, which accounts for up to 96% of emissions from deforestation. Although this once seemed like a lot of money, the fact that we are piling hundreds of billions of pounds to prop up failing banks perhaps puts the figure into context as the biggest bargain in history. For if we succeed, we won't have simply propped up some rather questionable financial institutions, we might have secured a future for life on Earth.

We do need to plant trees, to stabilise land and to provide timber and pulp. But this needs to be done as a complimentary measure to the clear priority of retaining the last natural forests.

Tree-planting, even on the grand scale of the Chinese approach, cannot get us out of the climate crunch, not least because we can never plant enough to offset industrial and transport emissions, and because we need the best land in any event to grow food.

The message is simple and clear: save the rainforests, and cut out fossil fuels. In both respects it is the rich industrialised countries that must take the lead.

Originally published by The Guardian.