{"id":46662,"date":"2020-02-14T13:24:21","date_gmt":"2020-02-14T12:24:21","guid":{"rendered":"https:\/\/blogs.bmj.com\/bmj\/?p=46662"},"modified":"2020-02-14T18:53:36","modified_gmt":"2020-02-14T17:53:36","slug":"sequestering-carbon-by-regenerating-soil-planting-trees-and-changing-land-use","status":"publish","type":"post","link":"https:\/\/blogs.bmj.com\/bmj\/2020\/02\/14\/sequestering-carbon-by-regenerating-soil-planting-trees-and-changing-land-use\/","title":{"rendered":"Sequestering carbon by regenerating soil, planting trees, and changing land use"},"content":{"rendered":"

Robin Stott, a doctor and ardent environmentalist has been campaigning on climate change for the past 20 years. He offers some thoughts on the potential benefits of simultaneously enriching soil and sequestering carbon.<\/span><\/p>\n

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Regenerating soil<\/b><\/p>\n

Carbon regeneration of soil will bring benefits to human and planetary health such as the ready availability of non-polluted, locally grown food, a move to a diet richer in vegetables and fruit, an increase in rewarding rural jobs, and the psychological benefits of having easy access to a much more biodiverse natural environment. But I\u2019m concentrating here on how it can sequester carbon.\u00a0 My objective is to show how a transformation of our agricultural system and land use can help us in the UK get to carbon net zero by 2030 and when applied worldwide will be a major factor in tackling climate\u00a0heating.\u00a0<\/span><\/p>\n

The agricultural soil carbon story is important because of the need to use natural systems to sequester carbon\u00a0if we are to get nationally, or indeed globally, to carbon net zero in time to avoid exceeding 1.5 degrees warming. Our UK contribution should be to aim for carbon net zero by 2030 at the latest.<\/span><\/p>\n

I don\u2019t think we can remove all fossil fuels from the UK economy by 2030, but even the Committee on Climate Change say we could and should reduce emissions sufficiently by 2050 to enable the UK to be\u00a0carbon net zero by then. As I understand it, they also suggest we should have achieved a 50% reduction\u00a0from 1990 levels by 2030.\u00a0<\/span><\/p>\n

So to get to carbon net zero by 2030 ( assuming we don\u2019t manage to increase the rate of our decarbonisation, which I hope we will do) we have to sequester a lot of carbon. The best book I know of which looks at all forms of sequestration is <\/span>Countdown<\/span><\/i> by Paul Hawken and Tom Steyer.<\/span><\/p>\n

In their book they look at the whole range of sequestration possibilities, including\u00a0many of nature\u2019s way of sequestering. In this context, they look at the capacity of soil to sequester and say that globally much of the soil we have now which has been ploughed and artificially fertilised has depleted soil carbon levels to between 1 and 2%. With regenerative agriculture the percentage can increase to between 5 and 8% over 10 to 20 years, by which time the soil will become carbon replete. According to them, each percentage increase represents 8.5 tons of carbon sequestered per acre: so between 25 and 60 tons per acre over 10 -20 years.\u00a0<\/span><\/p>\n

As the name implies, regenerative agriculture rehabilitates soil, which is otherwise depleting at an alarming rate. I am assuming the UK soil is similar to that elsewhere.\u00a0<\/span><\/p>\n

I think Hawken and Steyer get the figure of 8.5 tons per 1% increase, a figure they quote on page 194 of their book, from research done at the Rodale\u00a0Institute\u00a0in the USA. A figure from an Australian group is 5 tons of carbon per 1% increase. In looking at the UK potential I use this lower\u00a0figure of 5 tons\/acre\/1% percent increase. And I assume that our depleted soil now has 2% carbon per acre and that we will get to 6% of carbon per acre\u00a0over 10-20 years through regenerative practice, which means 20 tons of carbon sequestered\/acre.\u00a0<\/span><\/p>\n

To get to carbon net zero by 2030, how much carbon do we need to sequester?\u00a0<\/span><\/p>\n

The figures are:<\/span><\/p>\n