Restore ecosystems to prevent extinctions

Restoring just under a third of Earth’s ecosystems to their natural state could protect more than two-thirds of land-based mammals, amphibians and birds at risk of extinction while soaking up 465 billion tonnes of carbon dioxide, according to a new report.

Published in the journal Nature by an international team of scientists from 12 countries, it identifies key priority areas that if rejuvenated could optimise biodiversity and climate benefits while minimising costs and impacts on food production.

This could be a major boon for conservation and climate mitigation. The authors estimate that restoring the targeted ecosystems could reduce 71% of the world’s extinction debt and sequester 49% of carbon dioxide emitted since the Industrial Revolution.

While ambitious targets have been set to address these problems, focussing on the total area needed to be restored, the new study pinpoints locations where the greatest impact can be made at the lowest cost.

Rather than just planting trees, the team’s unique approach also explored a diverse range of ecosystems, including grasslands, shrublands, wetlands and arid ecosystems.

“Previous research has emphasised forests and tree planting, something at the expense of native grasslands or other ecosystems, the destruction of which would be very detrimental for biodiversity and should be avoided,” says lead author Bernardo Strassburg from Pontifical Catholic University, Brazil.

“Our research shows that while reviving forests is critical for mitigating global warming and protecting biodiversity, other ecosystems have a massive role to play.”

Each has different and complementary benefits, the authors note. While restoring forests and wetlands reaps the most rewards, for instance, reviving grasslands and arid ecosystems costs the least.

The researchers used a multi-criteria optimisation framework and mapping technologies to assess 2870 million hectares of ecosystems that have been converted to farmland globally. They evaluated 1200 different scenarios to balance biodiversity and climate benefits and costs across an array of implementation strategies.

Calculations showed that achieving the best outcomes would require a multifaceted approach and international collaboration.

If restoration is focussed at the national level, with each country restoring 15% of its forests, the researchers estimate benefits would drop by nearly a third while increasing costs by 52%.

This scenario would miss out on 61% of global priority areas identified, largely in the tropics of Asia, Africa and South America, underscoring the importance of international cooperation to achieve affordable targets that benefit the whole planet.

“Restoration benefits and costs vary markedly across space,” says co-author Hawthorne Beyer from Australia’s University of Queensland. “Hence, being strategic about where restoration is prioritised profoundly influences its cost-effectiveness.”

To address concerns about encroaching on land needed for crops, they calculated that 55%, or 1578 hectares, of ecosystems that had been converted for agriculture could be restored without impacting food production.

This would need to go hand in hand with other initiatives such as sustainable food production, reduction in food waste and moving away from unsustainable products such as meat and cheese.

The report follows the UN’s warnings that we stand to lose a million species in the coming decades and are struggling to meet biodiversity protection objectives. Climate change targets set by the Paris Agreement are also slipping out of reach on current trajectories.

It offers a very promising framework, says Simon Ferrier from Australia’s Commonwealth Scientific and Industrial Research Organisation in a related News and Views commentary.

“These findings have major implications for the setting and implementation of global targets for ecosystem restoration,” he writes, noting that drops in species extinctions can vary by up to six-fold depending on spatial allocations for restoration.

He also applauds the dual focus on biodiversity and climate, considering research suggests not considering climate change could lead to gross underestimations of extinction risk.

The report comes in time for the Post-2020 Biodiversity Framework preparations.

But the proposed regeneration won’t happen overnight, notes report co-author Robin Chazdon from Brazil’s International Institute for Sustainability.

“The process of restoration is not instantaneous and will take multiple generations, particularly in the case of forests,” she says. “This requires serious societal commitment and needs to build in socio-economic benefits to people. Major structural transformations are needed.”