The authoritative guide to ensuring science and technology make life on Earth better, not worse.

DIGITAL MAGAZINE

March 2025

DIGITAL MAGAZINE

March 2025

Cover by Thomas Gaulkin

Introduction: (Almost) everything you wanted to know about tipping points, but were too afraid to ask

By Jessica McKenzie

The evidence is mounting that vast changes are not only possible, but increasingly likely as the Earth warms. But how close the world is to crossing so-called “tipping points” is a matter of vigorous scientific debate.

Introduction: (Almost) everything you wanted to know about tipping points, but were too afraid to ask

By Jessica McKenzie

The evidence is mounting that vast changes are not only possible, but increasingly likely as the Earth warms. But how close the world is to crossing so-called “tipping points” is a matter of vigorous scientific debate.
close-up of one portion of AMOC

Is the AMOC headed for a tipping point? Interview with Henk Dijkstra

By Dan Drollette Jr

At some point, melting ice in the North Atlantic—caused by increased global warming—will cause so much freshwater to be introduced that the Atlantic Meridional Overturning Circulation (AMOC) system will reach an abrupt threshold, beyond which there could be large, accelerating, and possibly irreversible changes in this circulatory system and its salinity, pushing it toward collapse. This is more than speculation; it’s happened in the past. But there’s a catch: Evidence for a modern-day implosion of the AMOC is still relatively new—only a few decades old—and the computer models themselves have sometimes been called into question.

The shrinking of the Greenland Ice Sheet can’t be stopped—but it can and must be slowed

By Twila Moon

Ice loss in Greenland is already large, irreversible, and greatly accelerated after centuries of near stability. Though a tipping point for future ice loss has already been crossed, the pace of this loss is not set in stone. What humans do now—especially before the end of this decade—will set that pace, and determine how fast impacts grow, and how much time society has to adapt.
permafrost researcher Vladimir Romanovsky on Alaska's North Slope

(Trying to) keep it cool: Vladimir Romanovsky on permafrost fieldwork

By Dan Drollette Jr

As the name suggests, permafrost was long considered to be permanent. But more recently, researchers have come to realize that this frozen ground is steadily disappearing, with the full consequences of this situation still being worked out for the global carbon budget.
smoke from Amazon wildfire

Carlos Nobre on tipping points in the Amazon rainforest

By Dan Drollette Jr

For roughly about 65 million years, the forests of the Amazonian were resilient to changes in the climate. But that is changing rapidly, as the region is exposed to unprecedented stress from global warming, extreme droughts, and fires, leading to massive deforestation—even changing the biome itself, from that of a rainy forest rich in biodiversity to a much drier and less-diverse savannah.
windmills and sunset sky

How to leverage positive tipping points for climate action

By Femke Nijsse, Steve Smith, Tim Lenton

Negative tipping points for the Earth’s climate system are approaching fast, adding further urgency to climate action. But well-designed climate action may be able to trigger its counterpart: beneficial, or “positive,” tipping points.
scientists launching balloon to collect atmospheric gases

Is scientific reticence hindering climate understanding?

By David Spratt

The bulk of climate research has tended to underplay worst-case scenarios, preferring cautious projections and scholarly reticence. This reticence is clearly displayed in the work of the IPCC, which consistently errs on the side of “least drama,” and downplays the more extreme possibilities. Increasing numbers of scientists have spoken out on the dangers of such an approach.
oil painting of collapse of civilization

“Fragile, impermanent things”: Joseph Tainter on what makes civilizations fall

By Jessica McKenzie

Do civilizations have tipping points that determine their rise and fall?
Iceberg in Antarctica

Climate change will surprise us, but so-called ‘tipping points’ may lead us astray

By Robert Kopp, Elisabeth Gilmore, Rachael Shwom

The increasingly broad application of the phrase "tipping point" across biogeophysical and social phenomena muddles its meaning, and its use can conceal the multidimensional complexity of processes that can drive rapid change. The term is better viewed as a metaphor than as describing a technically defined class of processes.

Apocalypse now? Mortality and mental health correlates of the Doomsday Clock

By Samuel Justin Sinclair, David A. Silbersweig

Is there an association between Doomsday Clock settings, mortality data published by the US Centers for Disease Control and Prevention, and mental health diagnosis prevalence rates?

Chinese nuclear weapons, 2025

By Hans M. Kristensen, Matt Korda, Eliana Johns, Mackenzie Knight

The modernization of China’s nuclear arsenal has both accelerated and expanded in recent years. We estimate that China now possesses approximately 600 nuclear warheads, with more in production to arm future delivery systems.
close-up of one portion of AMOC

Is the AMOC headed for a tipping point? Interview with Henk Dijkstra

By Dan Drollette Jr

At some point, melting ice in the North Atlantic—caused by increased global warming—will cause so much freshwater to be introduced that the Atlantic Meridional Overturning Circulation (AMOC) system will reach an abrupt threshold, beyond which there could be large, accelerating, and possibly irreversible changes in this circulatory system and its salinity, pushing it toward collapse. This is more than speculation; it’s happened in the past. But there’s a catch: Evidence for a modern-day implosion of the AMOC is still relatively new—only a few decades old—and the computer models themselves have sometimes been called into question.

The shrinking of the Greenland Ice Sheet can’t be stopped—but it can and must be slowed

By Twila Moon

Ice loss in Greenland is already large, irreversible, and greatly accelerated after centuries of near stability. Though a tipping point for future ice loss has already been crossed, the pace of this loss is not set in stone. What humans do now—especially before the end of this decade—will set that pace, and determine how fast impacts grow, and how much time society has to adapt.
permafrost researcher Vladimir Romanovsky on Alaska's North Slope

(Trying to) keep it cool: Vladimir Romanovsky on permafrost fieldwork

By Dan Drollette Jr

As the name suggests, permafrost was long considered to be permanent. But more recently, researchers have come to realize that this frozen ground is steadily disappearing, with the full consequences of this situation still being worked out for the global carbon budget.
smoke from Amazon wildfire

Carlos Nobre on tipping points in the Amazon rainforest

By Dan Drollette Jr

For roughly about 65 million years, the forests of the Amazonian were resilient to changes in the climate. But that is changing rapidly, as the region is exposed to unprecedented stress from global warming, extreme droughts, and fires, leading to massive deforestation—even changing the biome itself, from that of a rainy forest rich in biodiversity to a much drier and less-diverse savannah.
windmills and sunset sky

How to leverage positive tipping points for climate action

By Femke Nijsse, Steve Smith, Tim Lenton

Negative tipping points for the Earth’s climate system are approaching fast, adding further urgency to climate action. But well-designed climate action may be able to trigger its counterpart: beneficial, or “positive,” tipping points.
scientists launching balloon to collect atmospheric gases

Is scientific reticence hindering climate understanding?

By David Spratt

The bulk of climate research has tended to underplay worst-case scenarios, preferring cautious projections and scholarly reticence. This reticence is clearly displayed in the work of the IPCC, which consistently errs on the side of “least drama,” and downplays the more extreme possibilities. Increasing numbers of scientists have spoken out on the dangers of such an approach.
oil painting of collapse of civilization

“Fragile, impermanent things”: Joseph Tainter on what makes civilizations fall

By Jessica McKenzie

Do civilizations have tipping points that determine their rise and fall?
Iceberg in Antarctica

Climate change will surprise us, but so-called ‘tipping points’ may lead us astray

By Robert Kopp, Elisabeth Gilmore, Rachael Shwom

The increasingly broad application of the phrase "tipping point" across biogeophysical and social phenomena muddles its meaning, and its use can conceal the multidimensional complexity of processes that can drive rapid change. The term is better viewed as a metaphor than as describing a technically defined class of processes.

Apocalypse now? Mortality and mental health correlates of the Doomsday Clock

By Samuel Justin Sinclair, David A. Silbersweig

Is there an association between Doomsday Clock settings, mortality data published by the US Centers for Disease Control and Prevention, and mental health diagnosis prevalence rates?

Chinese nuclear weapons, 2025

By Hans M. Kristensen, Matt Korda, Eliana Johns, Mackenzie Knight

The modernization of China’s nuclear arsenal has both accelerated and expanded in recent years. We estimate that China now possesses approximately 600 nuclear warheads, with more in production to arm future delivery systems.

Cover by Thomas Gaulkin

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Albert Einstein in Washington, D.C., between 1921 and 1923. Harris & Ewing, photographers. Courtesy of the Library of Congress. https://www.loc.gov/pictures/item/2016885961/

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