To save civilisation, try rewilded farmland. But that salvation depends on which land goes back to forest and savannah.
LONDON, 2 November, 2020 − An international consortium of scientists has worked out − once again − how to conserve life on the planet and absorb dramatic quantities of the atmospheric carbon that is driving potentially calamitous climate change: go for rewilded farmland, fields of crops and livestock returned to prairie and forest. And they have identified the most cost-effective way to do it.
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Global salvation requires the world’s nations to do simply what they have already undertaken to do: restore 15% of cultivated land to natural forest, grassland, shrubland, wetland and desert ecosystem.
If such restoration happened in the highest priority zones, then almost two-thirds of the wild things now threatened with imminent extinction could survive.
And the restored wilderness that would protect them would also start absorbing atmospheric carbon at an accelerating rate: it could sequester an estimated 229 billion tonnes of the greenhouse gas carbon dioxide (CO2). This is almost a third of all the CO2 spilled into the atmosphere by coal, oil and gas combustion in the last 200 years.
All that would be possible if the world’s nations delivered on vows made 10 years ago in Japan, to restore 15% of ecosystems worldwide. If the 196 nations that signed up went further, and restored a carefully chosen 30%, they could save more than 70% of the million or so species sliding towards extinction, and absorb 465 billion tonnes of CO2: almost half of all the extra atmospheric carbon loaded into the atmosphere by human societies since the Industrial Revolution.
“Pushing forward on plans to return significant sweeps of nature to a natural state is critical to preventing ongoing biodiversity and climate crises from spinning out of control,” said Bernado Strassburg, of the Pontifical Catholic University in Brazil, who led the study.
“We show that if we’re smarter about where we restore nature, we can tick the climate, biodiversity and budget boxes on the world’s urgent to-do list.”
There is a catch. To be most effective, and for the lowest costs, nations would have to work together.
Right now, scientists report in the journal Nature, each nation has undertaken to restore 15% of its wilderness. But to save the greatest number of species, and absorb the highest levels of carbon, with the lowest cost to farmland and food security, humankind would have to assess the world as a whole, and restore those ecosystems that would serve the goals most effectively.
There is a second catch: barely a month ago, a UN report confirmed that although 196 nations agreed on 20 targets to protect biodiversity − to be achieved by 2020 − a decade ago, there has been “partial progress” in just six of them. The million species then threatened with extinction are still threatened.
“Many good things are happening around the world and these should be celebrated and encouraged,” said Elizabeth Maruma Mrema, executive secretary of the Convention on Biological Diversity.
“Nevertheless the rate of biodiversity loss is unprecedented in human history, and pressures are intensifying. Earth’s living systems as a whole are being compromised.”
And that threat starts with the green things on which all life depends: in September, the Royal Botanic Gardens at Kew in London published a new study on ways to identify and care for the plants and fungi that underwrite survival for what could be seven million or more species alive on the planet, and more than seven billion humans.
The study, involving 210 scientists in 42 countries, said Alexandre Antonelli, director of science at the Royal Botanic Gardens, paints a picture “of a world that has turned its back on the incredible potential of plant and fungal kingdoms to address some of the biggest challenges we face.
“We have particularly earmarked the gaps in our knowledge, the changes we are seeing, the species being named new to science and the shocking pace of biodiversity loss.”
“The rate of biodiversity loss is unprecedented in human history, and pressures are intensifying. Earth’s living systems as a whole are being compromised”
The most recent finding builds on the drive not just to fulfil the obligations undertaken 10 years ago, but to identify the very best ways to fulfil them, so as to benefit the greatest number of people.
It delivers the evidence that restoration in the most carefully chosen regions would have the most profound impact: put simply, restoration could be 13 times more cost-effective if it happened in what the Nature researchers have identified as the highest priority locations.
They used sophisticated mathematical tools and detailed geographic data to take a closer look at the 28.7 million square kilometres of natural wilderness that have been converted to farmland: 54% of these were originally forest, 25% grasslands, 14% shrublands, 4% arid lands and 2% wetland.
They then tested these areas against three considerations: their value as habitat, their capacity for carbon storage and their cost-effectiveness. And they came up with recommendations that would deliver 91% of the potential benefit for plants and animals of the wilderness and 82% of the climate mitigation benefit, and reduce costs by 27%.
And then they considered the nation-by-nation approach: were each country to restore 15% of its own forests, the biodiversity boon fell by 28%, the climate benefits by 29%, while the costs would rise by 52%.
They then considered the impact on the world’s food supplies, to find that 15.78 million sq kms, or 55% of wilderness converted to farmland, could be restored without squeezing food supplies, always providing nations encouraged what they call the “sustainable intensification” of farming, along with a reduction in food waste and a move away from meat and dairy products.
The findings simply extend a procession of such outcomes by other teams. It has been a given for decades that, if forest and other ecosystems become farmland, greenhouse gas levels rise. If wilderness is restored, then the carbon dioxide levels in the atmosphere will fall.
Researchers have repeatedly argued that simply planting more trees could have a dramatic impact on global heating; that a switch towards a plant-based diet could help stem biodiversity loss and reduce emissions; and that without concerted global action, precious ecosystems could collapse altogether.
They have over and over again confirmed that conservation delivers real rewards. And they have pointed out that although nations have promised to act, such promises have not always been kept. The latest study highlights the need for action to be concerted, and global.
“These results highlight the critical importance of international co-operation in meeting these goals,” Dr Strassburg said. “Different countries have different, complementary roles to play in meeting overarching global targets on biodiversity and climate.” − Climate News Network