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Science
| 09/03/15

Forests making a comeback

TCE

The story of climate change and the wider biocrisis sometimes appears like an unending series of bad news, but the truth is that it’s not all doom and gloom—policy changes can make a difference. Humanity has managed to turn back the clock on the shrinking ozone layer, and it appears that we’re now doing the same with deforestation.

This week, a widely shared Globe and Mail article highlighted a pair of important recent scientific papers that conclude that forests are growing back, with boreal and temperate forests rebounding most successfully of all. The first, a 20-year study appearing inNature Climate Change, making some of the most accurate estimates yet of the extent of global forest and non-forest biomass above ground.

The researchers found that while for the first decade of their survey, from 1993 to 2002, widespread deforestation continued to worsen, particularly in Brazil and Indonesia. But according to the Nature study, since then the situation has reversed. From 2003 onwards, forests in Russia and China have expanded and tropical deforestation has declined. In addition, wetter conditions in the northern Australian and southern African savannahs have permitted an increase in biomass carbon. Taken together, these phenomena have led to “an overall gain”, reversing decades of biomass carbon loss.

The second paper, appearing in the journal Global Change Biology, found that the share of greenhouse gas (GHG) emissions from deforestation had dropped by a third in the last decade. In addition, while land-use change had historically been the single biggest cause of emissions from the agriculture and forestry sectors, since 2010 emissions from crop and livestock production has outstripped this source, contributing 11.2 percent of total emissions. GHG emissions from crop and livestock production are largely a product of loss of carbon from the soil, methane emissions from rice cultivation and ruminant livestock, and nitrous oxide from over-application of nitrogen-based fertilizers.

The authors argue that this change suggests new policy efforts to combat emissions in the agriculture sector need to be mounted with the scale of ambition that has led to such success in forestry and land-use change.

Much of the forest regrowth success is due to explicit policies to reverse deforestation, particularly in the European Union, China, Brazil and Indonesia, where ongoing economic development has facilitated implementation of stronger environmental protection legislation and more sustainable and intensive agricultural practices. Even as Amazon deforestation has declined by 80 percent over this period, soy and cattle production has continued to rise, as intensification allows more land to be released back to nature.

Further gains are at our fingertips: a UN study in 2014 found that a quick win of 30 percent reductions in emissions from livestock could be achieved by embracing existing best practices in the sector. Emissions intensity is highest in low-productivity regions in south Asia, Latin America and Africa, and could be reduced simply by boosting animal health and enhancing husbandry practices, as well as improving manure management.

At the same time, the good news needs to be balanced with findings reported last week in Science, that the boreal forests of the world, largely in Canada and Russia, are primed for radical transformation into savannah and scrubland as the world warms in the coming decades, complicating the good news from afforestation.

Nonetheless, the two recent papers should remind decision-makers that good policies, implemented with sufficient will, can work.

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Climate news and analysis that's relevant for you, every week.