Stop abusing land, scientists warn

Kubica · 发表于 2019-8-6 22:29:37

Stopabusing land, scientists warn

By Roger Harrabin BBC environment analyst

Scientists are to deliver astark condemnation of the damage being done to the land surface of the planet.

Humanactivities have led to the degrading of soils, expanded deserts, felledforests, driven out wildlife, and drained peatlands, they will say.

Inthe process, land has been turned from an asset that combats climate changeinto a major source of carbon.

Thescientists will say this land abuse must be stopped to avoid catastrophicclimate heating.

Uncultivated land covered with vegetationprotects us from overheating because the plants absorb the warming gas CO2 fromthe air and fix it in the soil.

Butthe scientists meeting in Geneva, Switzerland, will say the way we farm andgrow timber often actually increases emissions of carbon dioxide.

Betweena quarter and a third of all greenhouse gas emissions are now estimated to comefrom land use.

The scientists will warn of a battle for landbetween multiple competing demands: biofuels, plant material for plastics andfibres, timber, wildlife, paper and pulp - and food for a growing population.

Theirreport will say we need to make hard choices about how we use the world’s soil.

Andit will offer another warning that our hunger for red meat is putting hugestress on the land to produce animal feed, as well as contributing to half ofthe world’s emissions of methane - another greenhouse gas.

What is the report?

Thedocument’s being finalised this week among scientists and government officialson the UN's Intergovernmental Panel on Climate Change (IPCC).

Itwill become the most authoritative report yet on the way we use and abuse theland. Scientists hope it will give the issue of land use greater prominence innegotiations on climate change.

At its heart will be the paradox that the landcan be a source of CO2 emissions, or a sink for CO2 emissions.

Thequestion is how we use it.

Why is that an issue?

Takethe fenlands in the east of England – a huge expanse of lowland peat.

Inits natural state, it’s saturated with water. But over centuries, 99% of it hasbeen drained for farming. Food crops don’t grow in peat bogs.

Theremaining un-drained 1% is Wicken Fen, a plot owned by the charity the NationalTrust, where the soft black soil is still 4m deep.

Thesurrounding drained farmland is noticeably lower, because as it’s been drainedthe peat has shrunk to just 50cm thick.

Between1-2% of the soil on the drained farmland is still being lost every year.

That’s because when peat is exposed to theair, it oxidises and produces CO2.

Buthere’s the problem: the peaty fields are also some of the most productivecropland in the UK – they’re known as Black Gold.

Farmerswant to grow food on them – not soak them to save carbon.

Oneyoung farmer, Charles Shropshire, told me he was concerned about carbon lossfrom his fields.

He’salready finding that existing climate change is disrupting growing patterns.

So now he’s adopting so-called “regenerative farming” techniques- such as shallow ploughing, keeping the land covered in vegetation in thewinter, and using drip-feed watering.

He’s willing to experiment with National Trust ideas such asre-wetting the soil over the winter, or growing sphagnum moss for use in beautytreatments or hanging baskets.

But many other farmers don’t want to change the way they runtheir business.

And all round the world you’ll find similar stories as farmersstrive to increase production of the food people want, which can negativelyaffect land in the long term.

Part of the problem is that consumption of meat and vegetableoils has doubled since the 1960s.

Can we solve the problem?

Scientists say the problem is huge. They admit it will be hardto solve, especially as conservation-style farming would involve teaching halfa billion farmers to work differently.

They believe we need to:

§ Protect as much naturalforest as we can, particularly in the tropics

§ Change diets to eatless red meat and more vegetables

§ Safeguard peatlandsand restore them where possible

§ Grow plants and treesto produce energy… but only on a small local scale

§ Do moreagro-forestry, where food crops are mixed in with trees

§ Improve cropvarieties

Are the solutions agreed?

There’s still some debate. One option is toconcentrate intensive farming into the smallest possible area of land, in orderto leave as much natural land as possible to soak up CO2.

Anotheroption is to farm in a less intensive, more climate-friendly way – but thatmeans taking up more natural land to compensate.

Eitherway, the report will warn that the poorest farmers will be hardest hit byglobal warming, and they’ll be least able to afford new technologies to changethe way they farm.

KellyLevin, from the US green think tank WRI, told BBC News the report should heappressure on politicians to cut fossil fuel emissions.

Shesaid: “If we consider the climate problem hard now, just think about how muchharder it will be without the land serving as a large sink for carbon dioxideemissions.”

Will the report changepolicies?

ProfJohn Boardman, from the Oxford Environmental Change Institute, told us climatechange was already causing soil erosion in southern England through moreintense rain.

Buthe warned: “We should recognise that in most parts of the world, a little moreor less rain or heat is an irrelevance compared to human pressures.

“(Insome areas) if we change the land use from winter wheat to maize, we triple therisk of erosion.”

ProfJane Rickson from Cranfield University, UK, told us: “Increased temperaturesand heavier rainfall will aggravate soil erosion, compaction, loss of organicmatter, loss of biodiversity, and landslides… many of which are irreversible.

“Ihope the final IPCC report will be robust enough to motivate politicians andland managers to implement policies and practices that will reverse, mitigateand adapt to the climate crisis”.