- The number of marine species threatened with global extinction has decreased from 18 per cent in 2000 to 11.4 per cent in 2019.
- Notable rebounds from the brink of extinction include humpback whales, which have increased from a few hundred animals to more than 40,000; and northern elephant seals, from just 20 breeding animals to more than 200,000 today.
- Scientists say the focus should be on rebuilding depleted wildlife populations and ecosystems, not simply on conserving what remains.
A “substantial” recovery of life in the oceans could be achieved by 2050 if major threats such as climate change are dealt with, a study has said.
The oceans are important sources of food, water and clean energy and key for tackling global warming as they store heat and carbon, but many marine species, habitats and ecosystems have suffered catastrophic declines.
Climate change, which is hitting areas such as the coral reefs, is further undermining the oceans’ productivity and rich wildlife, researchers writing in the journal Nature warn.
But substantially rebuilding marine life, so that populations rebound by 50-90 per cent, within a human generation is largely achievable, if action including tackling climate change and restoring habitats happens at a large scale.
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The scientists behind the report point to examples of “impressive resilience” in marine wildlife, such as the recovery of fish stocks during the First and Second World Wars when fishing was reduced.
Deploying conservation measures such as curbing hunting, better management of fisheries, regulating harmful pollutants, creating marine protected areas and restoring habitat such as seagrass, saltmarsh and mangroves have had an impact on life in the oceans.
The number of marine species threatened with global extinction has decreased from 18 per cent in 2000 to 11.4 per cent in 2019, partly because more species have been assessed, but also because of conservation wins.
These include notable rebounds from the brink of extinction including humpback whales migrating from Antarctica to Australia which have increased from a few hundred animals in 1968 to more than 40,000 today. And northern elephant seals have increased from just 20 breeding animals in 1880 to more than 200,000 today.
The scientists said the focus should be on rebuilding depleted wildlife populations and ecosystems, not simply on conserving what remains, and efforts to remove pressure on the oceans must be expanded.
It will require a series of actions including protecting vulnerable habitats and species, exercising caution in harvesting things such as fish stocks, restoring habitats, reducing pollution and, critically, curbing climate change.
Rebuilding the richness of marine life can only succeed if the most ambitious goals to limit global temperature rises within the international Paris Agreement on climate change are reached, the experts warn.
It could cost an estimated 10 to 20 billion US dollars (£8-£16bn) a year to extend protection efforts across 50 per cent of the oceans.
But it would deliver far more in returns, for example through ecotourism, sustainable fishing and reductions in insurance claims from storms if coastal areas are protected by mangroves or saltmarsh.
Lead author Carlos Duarte, professor of marine science at King Abdullah University of Science and Technology (KAUST), Saudi Arabia, said: “We have a narrow window of opportunity to deliver a healthy ocean to our grandchildren’s generation, and we have the knowledge and tools to do so.
“Failing to embrace this challenge – and in so doing condemning our grandchildren to a broken ocean unable to support high-quality livelihoods – is not an option.”
Reader Q&A: Do we really know what climate change will do to our planet?
Asked by: Jennifer Cowsill, via email
There is no doubt that greenhouse gas emissions caused by humans are changing our climate, resulting in a progressive rise in global average temperatures. The scientific consensus on this is comparable to the scientific consensus that smoking causes lung cancer.
Our climate is a hugely intricate system of interlinking processes, so forecasting exactly how this temperature increase will play out across the globe is a complex task. Scientists base their predictions on powerful computer models that combine our understanding of climatic processes with past climate data.
Many large-scale trends can now be calculated with a high degree of certainty: for instance, warmer temperatures will cause seawater to expand and glaciers to melt, resulting in higher sea levels and flooding. More localised predictions are often subject to greater uncertainty.