While efforts are being made to reverse the damage caused by human activity globally, the challenges around habitat restoration continue to mount.
From the pollution of land by chemicals and the disappearance of lakes, to the destruction of forests, the desertification of once-fertile areas, the problems caused by previous human behaviour are becoming more visible.
Land degradation is one of this year's World Environment Day themes, an issue the UN Environment Programme says has afflicted one fifth of the planet’s land.
In 2021 the UN Decade on Ecosystem Restoration was launched, sparking pledges from nations to restore one billion hectares of land.
"The interest in ecosystem restoration is increasing," said Prof Gerald Jurasinski, professor of peatland science at the University of Greifswald in Germany.
"This is driven by the fact that the problems we get from what we did in the past become more visible.
"The activists but also the scientists that raised the alarm, they get heard … this together leads to increasing interest in ecosystem restoration.
"When global environmental or societal [organisations] like Unesco or Unep are producing the Decade on Ecosystem Restoration, that’s something."
Up to 90 per cent restoration goals
The EU has had a particular focus on habitat restoration, with the European Parliament having adopted a law in February requiring its 27 member states to restore at least 30 per cent of degraded habitats by the end of the decade.
By 2040, 60 per cent must be restored and by 2050, 90 per cent.
More than 80 per cent of the continent’s habitats are considered to be in poor condition despite the EU's Life Programme supporting more than 6,000 habitat restoration projects since 1992.
This year, more than €500 million ($544 million) are being allocated through the scheme.
Peatlands
Among the natural environments that have benefited from funding are peatlands, which are waterlogged areas that contain large quantities of incompletely decomposed organic matter.
A study in Nature has reported that at least two billion tonnes of carbon dioxide – about five per cent of global carbon emissions – are released by damaged or drained peatlands each year, exacerbating climate change.
Protecting remaining peatlands and restoring those that have been degraded could reduce the amount of carbon released.
Aside from the impact on climate change, degrading natural environments such as peatlands or forests also contribute to a loss of biodiversity and cause species extinctions.
"Due to the shrinking habitat many species are endangered and many of them are especially adapted to specific conditions – very poor or wet or dry," Prof Jurasinski said.
"We make everything the same so these species are on the brink of extinction."
Forests
Forests are another key habitat to have experienced significant losses, with about 3.7 million hectares of primary forests in the tropics destroyed last year, according to World Resources Institute figures.
In some parts of the world, however, forest cover is increasing, although the environmental benefits are not always clear.
"Take for instance China, they’ve been restoring a lot of forest areas in the last decade," said Georg Winkel, professor of forest and nature conservation policy at Wageningen University and Research in the Netherlands.
"If you look at the statistics, forests are coming back in that country."
Prof Winkel said in Europe there have been many forests planted since the mid 19th century and several European countries, which now have more forest cover than a century ago, although the plantations typically lack the diversity of natural forests.
"Later there was a policy shift 20, 30 years ago not to cut the old forests, and in the plantations to go for different management strategies so they become more rich," he said.
Renewable energy obstacles
Much of the destruction of natural habitats has been because of agriculture, with environments destroyed so crops can be grown.
As the world increases investments in renewable energy, new threats to natural environments are sometimes emerging, given that wind and solar energy generation require, according to the Brookings Institution, "at least 10 times as much land per unit of power produced than coal or natural gas-fired power plants".
While not a factor in the large-scale solar installations in the Gulf, there are concerns in North America that the removal of vegetation to allow for solar power farms has resulted in land erosion and threatened animal species.
Prof Tadhg O’Donovan, of Heriot Watt University Dubai, said renewable energy such as solar power could be used to prevent land degradation by providing sustainable energy for the desalination of water that can be used in irrigation.
"The unit cost of irrigated water or potable water is quite high, especially here in the Middle East, where a huge proportion is coming from desalination sources taken from the Gulf, maybe run through reverse osmosis and used for drinking or irrigation," Prof O'Donovan said.
"If that can be displaced by renewables instead of fossil fuels, you’re taking a huge amount of carbon intensity off the process."
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