Collective farming ended with the collapse of the USSR in 1991 (Image: 2006 RIA Novosti/TopFoto)

The fall of the Soviet Union created the largest ever human-made carbon sink – abandoned farmland.

In 1991, the USSR formally split into separate republics. The subsequent collapse of industry reduced the amount of greenhouse gas emissions Russia produced – helping it to easily meet the climate targets set by the Kyoto protocol.

But as well as cutting emissions, the fall had another effect. The privatisation of land led to one of the biggest land-use changes of the 20th century. Huge tracts of farmland were abandoned when the collectivised farming system introduced by Stalin collapsed, and farmers simply left the land and headed for the cities.


Ever since, plants have been reclaiming the land and locking in carbon as they grow.

Researchers have tried to put a figure on the size of this effect but estimates have varied dramatically, and haven’t always taken account of the fact that plants grow at different rates on different types of soil and lock up more carbon as they grow larger.

To get an answer to how much carbon is sequestered in Russian territory, Irina Kurganova from the Russian Academy of Sciences in Pushchino and colleagues mapped the distribution of soil types for the Russian part of the former USSR and overlaid it with a map of land-use change. They then looked at every study of carbon storage they could find and collated them to estimate the amount of carbon captured at each point on their map.

Largest human-made sink

They found that in total, the 455,000 square kilometres of land abandoned in the part of the USSR that is now Russia has locked away an average of 42.6 million tonnes of carbon every year since 1990. This means that each year, the land has been locking away the equivalent of 10 per cent of Russia’s carbon dioxide emissions from fossil fuels, the researchers calculate.

“Everything like this makes a difference,” says Jonathan Sanderman, a soil chemist at CSIRO Land and Water in Australia. “Ten per cent is quite a bit considering most nations are only committed to 5 per cent reduction targets. So by doing absolutely nothing – by having depressed their economy – they’ve achieved quite a bit.”

He says the abandoned farmland is probably the largest human-made carbon sink, but notes it came at the cost of enormous social and economic hardship.

Modelling the effect into the future, Kurganova estimates that, since the land has remained uncultivated, another 261 million tonnes will be sequestered over the next 30 years. At this point, the landscape will reach equilibrium, with the same amount of carbon escaping into the atmosphere as is being taken up.

She adds that the stored carbon should now be taken into account if recultivation of the land is contemplated.

Journal reference: Global Change Biology, doi.org/n2k