A method to identify positive tipping points to accelerate low-carbon transitions and actions to trigger them | Sustainability Science
https://link.springer.com/article/10.1007/s11625-025-01704-9

Meeting the Paris Agreement to limit global warming to “well below 2 °C” requires a radical acceleration of action, as the global economy is decarbonising at least five times too slowly. Tipping points, where low-carbon transitions become self-propelling, could be key to achieving the necessary acceleration. We deem these normatively ‘positive’, because they can limit considerable, inequitable harms from global warming and help achieve sustainability. Some positive tipping points, such as the UK’s elimination of coal power, have already been reached at national and sectoral scales. The challenge now is to credibly identify further potential positive tipping points, and the actions that can bring them forward, whilst avoiding wishful thinking about their existence, or oversimplification of their nature, drivers, and impacts. Hence, we propose a methodology for identifying potential positive tipping points, assessing their proximity, identifying the factors that can influence them, and the actions that can trigger them. Building on relevant research, this ‘identifying positive tipping points’ (IPTiP) methodology aims to establish a common framework that we invite fellow researchers to help refine, and practitioners to apply. To that end, we offer suggestions for further work to improve it and make it more applicable.

https://www.science.org/doi/10.1126/sciadv.adx0298

An Unprecedented Drying of the Continents: A Decline in Freshwater Availability

This study analyzes changes in terrestrial water storage—which includes all forms of water stored on land, such as ice, snow, surface water, vegetation water, soil moisture, and groundwater.

It reveals that since 2002, the continents have experienced an unprecedented loss of terrestrial water storage—a critical indicator of freshwater availability.

Each year, areas undergoing drying have expanded by an amount equivalent to twice the size of California, creating “mega-dry” regions across the Northern Hemisphere. While most of the world’s dry areas are getting drier and wet areas wetter, the rate of drying is now outpacing the rate of wetting. This shift is driven by water losses in high latitudes, severe droughts in Central America and Europe, and widespread groundwater depletion—which alone accounts for 68% of the non-glacial continental water loss.

“The drying of the continents has profound global consequences. Since 2002, 75% of the world’s population has lived in 101 countries that have lost freshwater. Furthermore, continents now contribute more to sea level rise than ice sheets do, with drying regions contributing more than glaciers and ice sheets combined. Urgent action is needed to prepare for the major impacts highlighted by these findings.”

The Rise of Mega-Dry Regions on Land

Previous studies identified key features of changing terrestrial water storage across continents, consistent with climate model projections, glacier and ice sheet melt, global groundwater depletion, and shifts in flood and drought extremes. This study demonstrates how recent regional and continental trends in water storage are accelerating continental drying.

Implications for Freshwater Availability

Today, excessive groundwater pumping is the main driver behind the decline in terrestrial water storage in drying regions. It significantly worsens the effects of rising temperatures, increased aridity, and extreme drought. Continued overexploitation of groundwater—such as what's happening in California at an accelerating pace—threatens both regional and global water and food security in ways that remain largely underrecognized worldwide.

Groundwater depletion is directly influenced by water management decisions—and can also be stopped by them.

In many areas, once groundwater is depleted, it will not naturally replenish on a human timescale. The disappearance of groundwater from the Earth’s aquifers represents a new and serious threat to humanity, creating cascading risks that are rarely considered in environmental policy, water management, or governance. This is an intergenerational resource that is being poorly managed—or not managed at all—by today’s societies, at a tremendous and deeply underestimated cost to future generations.

Protecting the world’s groundwater reserves is essential in a warming world and on continents we now know are drying out.

A Call to Action

Just as efforts to slow climate change are faltering, so too are efforts to curb the drying of the continents.

Key policy decisions and new management strategies—particularly those promoting groundwater sustainability at both national and regional levels—alongside international initiatives for global groundwater sustainability, can help safeguard this vital resource for generations to come.

Major, coordinated efforts—national, international, global, and transdisciplinary—are urgently needed to raise awareness and spur action on the drying of the continents and the decline in freshwater availability.