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Climate change and water

Rivers and lakes supply drinking water for people and animals, as well as being vital for agriculture and industry. Oceans and seas provide food for billions of people. Climate change will have major and unpredictable effects on the world's water systems, including more floods and droughts...

Rivers and lakes

Freshwater environments around the world are already under excessive pressure from drainage, dredging, damming, pollution, extraction, silting and invasive species.

Climate change inter-relates with these other stresses, making impacts worse, but also causing new threats because of changing rainfall and evaporation patterns. Extremes of drought and flooding will become more common, causing displacement and conflict.

In mountainous regions, glacial melt is having a big impact on freshwater ecosystems. Himalayan glaciers – giant rivers of ice that contain the largest store of fresh water outside of the poles – feed great Asian rivers like the Yangtze, Yellow, Ganges, Mekong and Indus. Over a billion people rely on these glaciers for drinking water, sanitation, agriculture and hydroelectric power.

Widespread floods, as the glaciers melt, will be followed by long-term water shortages, and massive humanitarian, social and environmental problems in western China, Nepal and northern India. Less fresh water means less agriculture, food and income.

Species are affected too: the Ganges river dolphin – which lives in the river systems of Nepal, India and Bangladesh – is very vulnerable to changes in its limited habitat. Increases in water temperatures may dramatically affect fish populations that are the dolphins’ food source.

The river-dwelling gharial – a critically endangered crocodile-like reptile found mostly in India and Nepal – is under threat from the growing number of irrigation schemes cropping up along rivers in the wake of increased drought conditions.

Here in the UK, several of the iconic chalk streams of southern England are drying up – not just a worry for local wildlife and landscapes, but a serious risk to water supplies for some large communities.

What WWF is doing
We’re working with partners across the world to assess the vulnerability of key freshwater ecosystems to climate-related impacts.

Particular ‘hot spots’ include arid regions, areas highly dependent on groundwater, small island developing states, low-lying deltas and fragile mountainous areas.

Management of water resources is central to successful adaptation planning and implementation, and to building the resilience of communities and countries.

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Oceans and seas

Like forests, oceans are vital ‘carbon sinks’ – they absorb huge amounts of CO₂, preventing it from reaching the upper atmosphere.

But increased water temperatures and higher than normal CO₂ concentrations, causing ocean acidification, are already having an impact.

Coral reefs and shellfish are particularly at risk – sensitive coral (and algae living on it) is starved of oxygen, causing dramatic bleaching and eventual death of the coral. The increasing number of tropical storms doesn’t help.

And as seawater becomes more acidic (less alkaline), it’s harder for many alkaline-loving sea creatures to grow proper hard calcium shells.

In the ‘Coral Triangle’ – a vast area of ocean around Malaysia and the Philippines, also called the “Nursery of the seas” because of its ecological importance – more than 85% of the precious coral is endangered.

If global warming stays on its upward path, by 2050 just 5% of Australia's Great Barrier Reef – the world's largest coral reef – will remain.

It’s not only a tragedy for wildlife: around half a billion people – a 12th of the entire population of the world – rely on fish from coral reefs as their main source of protein. If the coral reefs are destroyed, so is this vital larder for the planet.

On some beaches in northern Australia and in Latin America, there are already signs that more female marine turtles are being born than males – warmer nests tend to produce female hatchlings in this species, so it’s another indication of rising temperatures.

Whales may well suffer from climate change too – on top of all the other manmade hazards they face – because their usual food sources, such as tiny shrimp-like krill and squid, may die off or migrate away from warming seas.

Warming seas around Britain could diminish shellfish stocks here, as well as causing damage to rare species like pink sea ferns, already threatened by seabed trawling methods.

It’s also very possible that cod – an iconic cold-water fish that’s at its southern limit in our seas, and already seriously depleted from overfishing – may move north and be lost from UK waters altogether.

What WWF is doing
We’re working in key marine areas around the world to increase resilience to climate change. We’re assessing the impacts on coral reefs and mangroves in the Coral Triangle, the MesoAmerican reef, coastal East Africa, North-East Atlantic, Barents Sea, Bering Sea and the Southern Ocean around Antarctica.

New innovative approaches are being tested, such as ‘coral nurseries’ where corals can be grown under controlled conditions and then transplanted to damaged areas.

It’s also important to reduce other pressures, including tourism, development, pollution, unsustainable fisheries, invasive species and extraction industries. This will help marine systems to mobilise their natural defences to climate threats.

We work closely with a wide range of partners, such as governments, research organisations, other NGOs and local communities to increase resilience and raise awareness.