Paris soil carbon sequestration goals called unrealistic

April 21, 2017

The goal to offset rises in atmospheric greenhouse gas concentrations by increasing soil carbon storage by 4 per mille (0.4%) per year is unrealistic, say scientists from The Netherlands, The United Kingdom and the United States in an opinion piece in the journal Environmental Science and Technology.

The plans to store more in the ("4P1000") were launched at the 2015 United Nations Framework Convention on Climate Change (UNFCC) in Paris. The soils of the world contain approximately three times the amount of carbon in organic matter as currently held in carbon dioxide in the atmosphere." Increasing this soil organic matter stock at a rate of 4 per mille per year could, in theory, fully compensate the rise in atmospheric CO2. Such an increase could come about by e.g. changes in land management, or by using different crop rotations.

"In principle, the 4P1000 is great," says Jan Willem van Groenigen, Professor at Wageningen University & Research and lead author of the paper. "Generally speaking, more carbon is good for almost any soil. If we could combine that with slowing , that would be a double win. The problem is that the numbers don't add up."

Extra nitrogen needed

To store additional carbon in the soil, you need other nutrients, such as nitrogen. "You cannot build a house with only a pile of bricks but no mortar. Similarly, you cannot produce soil organic matter with only carbon," explains Kees Jan van Groenigen, co-author of the paper and senior lecturer at the University of Exeter. "You need enormous amounts of nitrogen, and it is unclear where that nitrogen would come from. For example, to store the quantity of carbon mentioned in the 4p1000 goals, you would need extra nitrogen equivalent to 75% of current fertilizer production, and for it to be in the right places. Practically speaking, that is just impossible."

Does that mean that we should abandon the 4p1000 goals? "Absolutely not," says Jan Willem van Groenigen: "Let's not throw away the baby with the bathwater. The 4p1000 goals are a great inspiration to do everything we can as farmers, soil scientists, agronomists and policy makers to help fight global warming and at the same time improve our soils." Instead, the authors appeal to the scientific community to think about the role of nutrients in reaching the 4p1000 goals. "For instance, this could mean that additional soil carbon should be stored in areas where nutrients are also available," van Groenigen explains. "In other soils the best approach might be to focus on minimizing emissions of other greenhouse gases such as nitrous oxide and methane."

Explore further: Carbon levels in soil affected by climatic conditions

More information: Jan Willem van Groenigen et al. Sequestering Soil Organic Carbon: A Nitrogen Dilemma, Environmental Science & Technology (2017). DOI: 10.1021/acs.est.7b01427

Related Stories

Carbon levels in soil affected by climatic conditions

August 18, 2016

Researchers from The University of Western Australia and the Department of Agriculture and Food Western Australia have discovered that hot and dry climatic conditions can limit the organic carbon build up in soil, which can ...

Grow, mow, mulch: Finding lawn's value

February 8, 2017

Cranking up the lawn mower on a Saturday afternoon may be a child's most dreaded chore. But little does he or she know that it also affects how much carbon and nitrogen are present in the soil below the grass.

Earthworms as nature's free fertilizer

September 16, 2014

Earthworm presence in the soil increases crop yield, shows a new study that was published this week in Scientific Reports. "This is not unexpected," says Jan Willem van Groenigen, associate professor in the Soil Biology group ...

Recommended for you

2020 deadline to avert climate catastrophe: experts

June 28, 2017

Humanity must put carbon dioxide emissions on a downward slope by 2020 to have a realistic shot at capping global warming at well under two degrees Celsius, the bedrock goal of the Paris climate accord, experts said Wednesday.

Concurrent hot and dry summers more common in future: study

June 28, 2017

A combination of severe drought and a heatwave caused problems for Russia in the summer of 2010: fires tore through forests and peat bogs. Moscow was shrouded in thick smog, causing many deaths in the local population. At ...

Climate change impacts Antarctic biodiversity habitat

June 28, 2017

Ice-free areas of Antarctica - home to more than 99 per cent of the continent's terrestrial plants and animals - could expand by more than 17,000km2 by the end of this century, a study published today in Nature reveals.

The common insecticide poisoning our rivers and wetlands

June 28, 2017

Urban streams and wetlands play an important role in the proper functioning of our cities. They protect our houses from floods, provide green spaces for recreation, trap and breakdown pollutants and provide valuable habitats ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.