If the air feels just a bit fresher, it may be because the trees are making a comeback. Despite a lot of bad news on climate, our planet has become measurably greener, as seen from space. And that points to a way out of the climate crisis.
A group of scholars at Australian, Chinese, Dutch and Saudi Arabian universities recently published, in the journal Nature Climate Change, a 20-year study measuring the precise quantity of the Earth's "terrestrial biomass" – that is, the total mass of living organisms, most of which are plants. They used two decades of microwave satellite readings (which are an accurate way to measure biological material) to determine how the world's stock of living things has changed over time.
Because biological matter absorbs and stores carbon, it is crucial to protecting the Earth from climate change: If we diminish the amount of plant matter, then more carbon dioxide, the main greenhouse gas, ends up in the atmosphere.
What the study found was, in the initial years, predictably depressing: Between 1993 and 2002, the world's stock of plants declined – in large part because of large-scale deforestation in the tropical rain forests of Brazil and Indonesia.
But then, between 2003 and 2012 (the last year they analyzed), something surprising happened: The trees started growing back. Their results showed that deforestation in Brazil and Indonesia slowed sharply, while better growing conditions in the savannahs of northern Australia and southern Africa added mass, and – most dramatically – the vast forests of China and Russia grew back at a considerable pace. The last point is especially significant: The boreal forest, which stretches across Northern Canada and Russia, stores almost 60 per cent of the world's carbon (tropical rain forests store about half that much).
The result was, they reported, "an overall gain" in the world's carbon-absorbing green matter – a result that has been reproduced in other recent studies showing an expansion of the global carbon sink. Another study, published in July, found that the share of carbon emissions caused by deforestation has declined by a third in the past decade.
What is most significant is not that the world's forests are growing back, but the reasons why. Almost all of the regreening of the post-2003 years was caused, whether through explicit policy or happy accident, by countries increasing their level of urbanization, their proportion of commercial agriculture or their rate of economic growth – all of which created the conditions for a more carbon-friendly ecology.
A lot of the regreening was caused by explicit policies devoted to that task: Starting in the 1990s, both China and the European Union introduced "afforestation" programs to return former croplands to forest – in the case of Europe, which produces far more food than it needs, by paying farmers grants to convert fields to forests – in the process converting at least 6,000 square kilometres of land back to forest.
China's program, popularly known as the "Great Green Wall," is intended to replant almost 400 million hectares of forest in a 4,500-kilometre strip across northern China by 2050, making it the world's largest reforesting program, and it appears to have had dramatic results.
This was only possible because China shifted from being a deeply impoverished, rural economy based on small-hold peasant farming (which tends to denude the land of forests, as well as producing very little food) to one that is urbanized and based on higher-production agriculture – so it both no longer needs all that former forest land, and also has the financial and infrastructural resources to replant forests.
Brazil, likewise, now has the scale of economy and government to end the ruin of the Amazon forest – and, for the past decade, the political will. That ruin was largely based on wasteful large-scale methods of soy and cattle farming that chewed rapidly into virgin forest. Starting in 2004, Brazil launched a Program for the Prevention and Control of Deforestation in the Amazon that, in the words of Jonah Busch from the Center for Global Development, has included satellite monitoring, law enforcement, new protected areas and indigenous territories, restrictions on rural credit, and moratoriums on unsustainable soy and cattle production. This has caused Amazon deforestation to fall by almost 80 per cent – but has actually increased Brazil's soy and cattle production, because farms were forced to find commercial-agriculture efficiencies rather than simply eating up more land.
Brazil is one of several ex-developing countries that now have the resources and urbanization level to get their forests under control – but even Brazil is getting help from Germany in a program, announced this week, in which Berlin will finance a program, initially costing $830-million, to reduce Amazon deforestation to zero by 2030 – something ecologists say is easily possible.
That's modelled on a deal struck between Norway and Indonesia in 2010 in which the Scandinavian country is paying to stop the wasteful cutting of Indonesia's rain forests – a program which, in combination with modernization of Indonesia's economy, is bearing fruit, according to the satellite measures.
The return of the trees teaches us a lesson. To reduce our destructive carbon output, the solution is not to reduce economic activity; rather, it's to combine a booming urban economy with smart policies that make growth and ecology work in harmony.
Follow me on Twitter: