More Than Half the World's Largest Lakes Are Losing Water — Here's Why It Matters

Redacción HC
06/12/2023

A silent crisis is unfolding across the globe. From the high plateaus of Tibet to the wetlands of South America, the Earth’s largest lakes are shrinking — and satellites are sounding the alarm. A recent study published in Science reveals that over half of the world’s major lakes and reservoirs are experiencing significant water loss. The implications are far-reaching: dwindling freshwater supplies, disrupted ecosystems, and mounting pressure on communities that rely on these water bodies for drinking, agriculture, energy, and more.

This landmark study, led by Fangfang Yao and a team of international researchers, marks the first comprehensive global analysis of long-term trends in lake water storage using satellite data. Spanning nearly three decades (1992–2020), the research paints a sobering picture of a world losing one of its most vital resources — quietly and rapidly.

A Disappearing Reservoir of Life

Lakes may only cover about 3% of the Earth's land surface, but they store nearly 87% of the planet’s surface freshwater. They are lifelines for billions — supporting agriculture, biodiversity, and local economies. Yet, consistent long-term monitoring of these water bodies has been lacking, leaving many shrinking lakes unnoticed until visible damage is done.

Yao and colleagues sought to fill this gap by asking: how have the volumes of the world’s 1,972 largest lakes and reservoirs changed over the past 28 years, and why? Their answer: 53% of these lakes are losing water, and human activity is to blame more often than not.

How Satellites Unveiled a Global Trend

To quantify this trend, the team combined nearly 250,000 satellite images, altimetry from nine different satellites, hydrological modeling, and climate data. They assessed both natural lakes (1,051) and human-made reservoirs (921) larger than 4 square kilometers.

The study integrated:

• Satellite imagery to measure lake surface area
• Altimetry data to assess water levels
• Climate models to account for temperature, precipitation, and evaporation
• Hydrological simulations to estimate human water consumption

The researchers acknowledged some limitations, particularly the underrepresentation of local-scale factors like illegal water extraction or sediment buildup. Nevertheless, the methodology captures over 96% of natural lake storage and 83% of artificial reservoir capacity, making it the most robust global lake monitoring dataset to date.

Shocking Findings: 21.5 Gigatons Lost Annually

One of the most striking revelations: natural lakes are losing approximately 21.5 gigatons of water per year — a loss equivalent to 17 Lake Meads (the largest reservoir in the U.S.) evaporating into thin air each year.

While the causes vary, a clear pattern emerged:

• In natural lakes, climate warming and human consumption account for around 56% of the net decline.
• In older reservoirs (constructed before 1992), sediment accumulation is the dominant factor.

Notably, water loss is not confined to dry regions. Lakes in wet or high-latitude regions — traditionally thought of as climate-resilient — are also drying. This supports the theory that “the wet is getting wetter and the dry drier,” even in freshwater storage.

Some lakes are gaining volume, particularly those in the Tibetan Plateau, the Arctic, and parts of Africa where increased precipitation or glacial melt is at play. But these gains (24% of lakes) don’t offset the losses elsewhere.

“These findings underscore lakes as sentinels of climate change and human influence,” the authors write.

Human Consequences: 2 Billion People at Risk

This global decline affects more than just the environment — it impacts human lives. Over 2 billion people live in basins where lake water storage is decreasing. The effects are tangible:

• Water scarcity for drinking and agriculture
• Biodiversity loss in aquatic ecosystems
• Reduced hydroelectric power generation
• Food insecurity in fishing communities

Some of the most vulnerable regions include:

• South America: Argentina’s Mar Chiquita is one of the most severely impacted lakes, highlighting risks across Latin America.
• Central Asia: Long-term decline in the Aral Sea has already led to health crises and economic collapse.
• Africa and the Middle East: Lake Chad and the Tigris-Euphrates basin are both suffering from chronic water loss.

A Call to Action: Managing Lakes Before It’s Too Late

The authors offer urgent recommendations to halt and potentially reverse these trends:

1. Integrate global satellite data into regional water governance strategies.
2. Enhance climate adaptation policies focused on lakes and reservoirs.
3. Tailor responses to specific drivers — for instance, sediment management for reservoirs and water-use efficiency for natural lakes.

They also point to success stories. Lake Sevan in Armenia, once heavily depleted, has shown signs of recovery following stricter regulations and policy reforms. Such examples offer hope — but require political will, funding, and long-term monitoring.

Crucially, the authors argue that satellite-based systems must become a staple of water management policy worldwide. With near real-time monitoring, early intervention becomes possible, potentially averting the kind of collapses seen in lakes like Poopó in Bolivia or the Aral Sea in Central Asia.

Conclusion: Lakes as the Climate’s Pulse

This study reinforces the idea that lakes are early warning systems for both climate stress and unsustainable water use. The rapid decline of these water bodies reflects not just natural shifts, but our collective impact — and it demands an equally collective response.

The question now is: can we act in time to protect the freshwater lifelines of our planet?

Take action: Learn more about how satellite monitoring can help shape water security policy and support science-based governance in your region.

Topics of interest

 Climate Biodiversity