A rare reason for optimism about climate change
To read more of The Economists data journalism visit our Graphic Detail page THERE HAS been some small progress in the fight against climate change. The Global Carbon Budget, a forecast of the sources of greenhouse-gas emissions and the sinks which absorb it, showed that growth in carbon emissions is slowing (see chart). In the early 2000s the rate at which humans produced these pollutants increased by about 3% a year. In the past decade it has fallen to 0.5%. A lot more progress is needed. Still, a near-plateau offers hope that emissions may eventually decline. This drop in emissions growth is the result of two factors. The first is that the global economy is much less carbon-intensive than it used to be. The amount of energy required to produce a unit of GDP has fallen by 26% since 2000. Unlike in earlier periods of growth, increases in prosperity no longer require a similar rise in global energy use. Slower growth in the use of fossil fuels to supply that energy (especially coal, the dirtiest one) has further helped curb the growth of emissions. The second factor concerns emissions due to land-use change. Getting rid of carbon sinks, by cutting down forests for farmland or digging up peatland for fuel, has a big impact on global emissions: a farm absorbs less carbon than does a rainforest. The Global Carbon Project, the outfit that calculates the budget, estimates that deforestation produces about 7 gigatonnes of carbon dioxide each year. Although the pace of deforestation continues unchanged, reforestation elsewhere has stepped up. New forest growth is absorbing nearly 4 gigatonnes of carbon dioxide annually, up from about 2 gigatonnes in 1990. These estimates come with a wide range. Measuring the emissions from land-use changes is generally harder than measuring those from the use of fossil fuels. Some data, such as hectares of forest, reported by national agencies, may not capture the differences in how much carbon dioxide different sorts of forest absorb. Nor do governments always keep a good track of what is going on in the wilderness. Satellite imagery offers one potential solution, but there is only so much that can be learned from space. Such problems make it difficult to discourage deforestation by offering carbon credits and other incentives to landowners to keep forests standing. Paying farmers not to cut down one forest may spur deforestation elsewhere. And monitoring deforestation throughout the Amazon or Congo basin is difficult and expensive. Still, most plans for achieving net zero emissions require a better use of land as carbon sinks. However difficult, preventing deforestation will remain a top priority. For more coverage of climate change, sign up for the Climate Issue, our fortnightly subscriber-only newsletter, or visit our climate-change hub.