When you think of water, you might picture rivers rushing to the sea or waves crashing on a tropical shore. But the quiet giants of our freshwater systems – lakes – hold 90 per cent of the planet’s surface fresh water. They are life-support systems for millions, providing drinking water, irrigation, food and recreation. They shelter biodiversity, regulate climate and buffer communities against floods and droughts. Yet, like many freshwater ecosystems, lakes are often overlooked in global discussions on water solutions.
From the Great Lakes of Africa to the mountain reservoirs of Asia, lakes sustain billions of lives. They store water, moderate temperature, support fisheries and underpin agriculture. They are also biodiversity havens for countless species.
But lake ecosystems are fragile. Today, they are being put under increasing pressure from climate change, pollution and unsustainable land use. Evaporation rates are rising as global temperatures climb. Nutrient runoff from agriculture fuels algae blooms, turning once-clear waters into oxygen-starved dead zones. Water abstraction for farms and cities shrinks lakes, while invasive species disrupt ecological balance.
Protecting the heart of freshwater systems
A recent analysis by the United Nations Environment Programme (UNEP) revealed a stark figure. Surface water bodies, such as lakes, are shrinking or being lost entirely in 364 basins worldwide. The degradation of lakes is not just an environmental threat; it also affects communities that rely on them for survival.
Indonesia is leading the fight to protect lakes. Since championing the first-ever United Nations Environment Assembly resolution on Sustainable Lake Management in 2022, the country has helped place lakes at the centre of global water discussions, including during the United Nations 2023 Water Conference and the tenth World Water Forum, in which lakes featured prominently in the Ministerial Declaration.
With the recent adoption of the United Nations System-wide Strategy on Water and Sanitation, the stage is set for even greater cooperative action. But why this urgency? Because lakes are under siege.
Glaciers, lakes and the global hydrological cycle
To understand the fate of lakes, we need to zoom out to the global hydrological cycle – the invisible thread linking glaciers, rivers, wetlands, aquifers and seas. Glaciers, often called “water towers of the world”, feed many of the planet’s lakes and rivers. Nearly 1.9 billion people depend on these frozen reserves for drinking water, irrigation and hydropower.
But climate change is melting glaciers at unprecedented rates. Recognizing this, 2025 marks the United Nations International Year of Glaciers’ Preservation. The year 2024 was the warmest year on record, and in 2023 alone, glaciers lost more than 600 gigatons of ice – the greatest loss in five decades. As they retreat, a new phenomenon is reshaping mountain landscapes: the explosive growth of glacial lakes. These lakes can be both lifelines and risks. They store meltwater, acting as buffers during drought. But they also pose catastrophic risks through glacial lake outburst floods, which can devastate entire valleys.
The knowledge gap
Despite their importance, lakes remain among the least monitored water bodies on Earth. Unlike rivers, which often have established gauging stations, lakes are poorly studied, particularly in low- and middle-income countries.
UNEP is working to change this. Through tools and initiatives such as the Freshwater Ecosystems Explorer, the UNEP lakes portal, the United Nations Decade on Ecosystem Restoration and integrated water resources management frameworks, efforts are underway to close data gaps and improve policies, plans and approaches. But we need to scale up, and scale up fast.
UNEP launched a landmark, transboundary initiative in the Lake Tanganyika Basin that works across Burundi, Democratic Republic of Congo, Tanzania and Zambia to protect biodiversity, restore critical wetlands and degraded landscapes, support sustainable fisheries management and enhance water security. It will rehabilitate 1,700 hectares of ecosystems and foster catchment-wide governance through community engagement and basin-level monitoring, all underpinned by the commitment of UNEP to integrated water resource management.
Why it matters for all of us
Lakes may seem remote, but their health determines our own. They are essential parts of the global hydrological cycle – a topic that is on the table for discussion at the seventh session of the United Nations Environment Assembly, to be held in December 2025. Like other freshwater ecosystems, lakes are important buffers against drought, engines of local economies and cradles of biodiversity. They are also sentinels, warning us of the accelerating impacts of the climate crisis.
Protecting freshwater ecosystems like lakes is not optional. It is central to biodiversity, water, energy and food security, and offers climate resilience.
Member States, guided by the leadership of Indonesia, must adopt an integrated water resources management approach to enhance lake protection and restoration. Greater investments in infrastructure, data and innovative solutions are crucial to meet the targets of Sustainable Development Goal 6 – clean water and sanitation for all – and ensure long-term sustainability for both human and ecosystem needs.
Now, the challenge is global: to safeguard these blue jewels. Not just for their beauty, but for the billions who depend on them. Because when lakes thrive, life flows everywhere.
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