Challenge 3

The ways in which human life is supported by a healthy functioning planet goes on:

• The oceans help to regulate our climate, produce the oxygen we breathe, drive the water cycle we rely on, and are home to the primary source of food for billions of people, as well as their livelihoods and economies.
• Plants on land fix carbon, contribute more oxygen, and form the basis of most food chains, providing the energy and nutrients required for almost all other life forms.
• Ecosystems such as forests and wetlands stabilise soils, reduce flooding, provide crucial habitats and protect people from natural disasters.
• Green spaces wherever they are help manage local climate variations, reduce the impacts of extreme weather events and create more livable local environments for people.
• Insects pollinate the crops we rely on for food.
• Healthy ecosystems keep pests and disease in check.

But planetary boundaries for ocean acidification, freshwater disruption, and land conversion are beyond their safe operating limits. Climate change, biodiversity breakdown, pollution of novel entities (plastics and chemicals), and nutrient cycle disruptions are dangerously in the ‘high risk zone’ where there is the strong possibility of severe, irreversible damage [Reference: Planetary health check 2025].

Innovations in engineering are already tackling this challenge head on. Infrastructure and industry are being pushed to reduce their environmental impact and incorporate regeneration of local natural ecosystems. Digital technologies are helping us to monitor, track and better manage ecosystems. Models and digital twins are unlocking opportunities to design future infrastructure mindful of planetary impacts.

Key issues

Restoring, regenerating and protecting life on land and below water is challenged by a number of issues. This list is not exhaustive and we encourage you to explore further.

Biodiversity and species extinction:

• All major species groups are in decline (e.g. mammals, birds, corals, amphibians). Over 47,000 species are already threatened with extinction, with rising threats to freshwater species threatened by pollution, dams, agriculture, invasive species and overharvesting [Reference: 2025 UN SDG Report].
• Illegal, unreported and unregulated fishing remains a major threat to the sustainability of the world’s fisheries, undermining marine ecosystems, food security and economies. [Reference: 2025 UN SDG Report].

Changing acidity and temperate of the ocean:

• The ocean absorbs around a quarter of human-caused CO2 each year. This helps to regulate the Earth’s climate, slowing the impacts of excessive carbon in the atmosphere. But this results in ocean acidification which threatens marine ecosystems, with knock-on impacts to food security, and limits the ocean’s future carbon uptake. [Reference: 2025 UN SDG Report]
• The ocean is also the planet’s largest heat reservoir, absorbing around 90 per cent of the excess heat trapped by greenhouse gases. Since 2005, the rate of ocean warming has more than doubled and this is expected to continue. This warming is driving widespread and often irreversible degradation. Coral reefs, home to a quarter of marine life and supporting approximately a billion people worldwide, are under severe stress.

Ocean pollution:

• Close to two thirds of the 120 million tonnes of reactive nitrogen produced by human activities each year ends up polluting air, water, soil, marine and coastal areas. Half of the 20 million tonnes of phosphorus mined each year enters the world’s oceans, equivalent to 8 times the natural rate of input [Reference: UNEP fact sheet].
• Excess nutrients has meant that millions of people now depend on water where nitrate levels are well above recommended levels and over 500 coastal areas worldwide have now been affected by eutrophication. In 405 locations this has resulted in so-called ‘dead zones’ across the world’s oceans.
• Plastic is also a major concern. The amount of plastic in the ocean is expected to double in the next 15 years. Some estimates highlight that by 2050 there could be more plastic in the ocean than fish.

Land use changes, degradation and pollution:

• Between 20-40 per cent of the Earth’s land surface is already degraded or degrading, putting livelihoods at risk, threatening food security and increasing vulnerability to extreme weather events [Reference: UNCCD Global Land Outlook Second Edition].
• Half of the world’s habitable land is used for agriculture, more than three-quarters of that is for livestock and the majority using unsustainable agricultural practices [Reference: Our World in Data].
• Wetlands are disappearing faster than any other ecosystem. Their loss reduces resilience to storms and floods alongside habitat destruction leading to biodiversity loss.

Deforestation / forest cover decline:

• Global forest area continues to decline, although at a slower rate than in previous decades. The proportion of forest cover to total land area decreased from 31.9 per cent in 2000 to 31.2 per cent in 2020.
• The biodiversity of trees is also at risk. 38 per cent of the estimated 47,282 species of tree face extinction as a result of habitat loss, overexploitation, climate change, pests and diseases. [Reference: 2025 UN SDG Report]

Overuse of freshwater systems:

• Freshwater demand is predicted to exceed available supply by 40% by 2030 [Reference: World Economic Forum]. Overextraction for agricultural purposes, and excessive use by heavy industries such as mining and manufacturing being key contributors.