Course correction needed quickly to avoid pathway to ‘hothouse Earth’ scenario, scientists say

Oregon State University

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Allan Hills, Antarctica

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Credit: Photo by Austin Carter, COLDEX.

CORVALLIS, Ore. – Scientists say multiple Earth system components appear closer to destabilization than previously believed, putting the planet in increased danger of following a “hothouse” path driven by feedback loops that can amplify the consequences of global warming.

Published today in the journal One Earth, “The risk of a hothouse Earth trajectory” is an analysis by an international collaboration led by Oregon State University’s William Ripple that synthesizes scientific findings on climate feedback loops and 16 tipping elements – Earth subsystems that may undergo loss of stability if critical temperature thresholds are passed.

Those sharp changes could likely result in a cascade of subsystem interactions that would steer the planet toward a path to extreme warming and sea level rise – conditions that could be difficult to reverse on human timescales, even with deep emissions cuts.

“After a million years of oscillating between ice ages separated by warmer periods, the Earth’s climate stabilized more than 11,000 years ago, enabling agriculture and complex societies,” said Ripple, distinguished professor of ecology in the OSU College of Forestry. “We’re now moving away from that stability and could be entering a period of unprecedented climate change.”

Tipping elements include ice sheets in Antarctica and Greenland, mountain glaciers, sea ice, boreal forests and permafrost, the Amazon rainforest and the Atlantic Meridional Overturning Circulation or AMOC, a system of ocean currents that’s a key influencer of global climate.

The researchers note that nearly 10 years after the Paris Agreement, which sought to limit long-term average warming to 1.5 degrees Celsius above preindustrial levels, global temperature increases exceeded 1.5 degrees Celsius for 12 consecutive months – a period that also included extreme, deadly and costly wildfires, floods and other climate-related natural disasters.

“Temperature limit exceedance is usually evaluated using 20-year averages, but climate model simulations suggest the recent 12-month breach indicates the long-term average temperature increase is at or near 1.5 degrees,” said study co-author Christopher Wolf, a former OSU postdoctoral researcher who is now a scientist with Corvallis-based Terrestrial Ecosystems Research Associates, known as TERA. “It’s likely that global temperatures are as warm as, or warmer than, at any point in the last 125,000 years and that climate change is advancing faster than many scientists predicted.”

It’s also likely that carbon dioxide levels are the highest they’ve been in at least 2 million years, the scientists say. At more than 420 parts per million, the atmospheric CO2 concentration is about 50% higher than it was prior to the Industrial Revolution.

When the climate changes, the researchers note, responses can be triggered that circle back to affect the climate itself, amplifying or dampening the original change. These processes are known as climate feedback loops.

“Amplifying feedbacks increase the risks of accelerated warming,” Ripple said. “For example, melting ice and snow, permafrost thaw, forest dieback and soil-carbon loss can all magnify warming – and in turn affect the climate system’s sensitivity to greenhouse gases.”

Ripple, Wolf and their collaborators – Wolf’s TERA colleague Jillian Gregg and top climate scientists in Germany, Denmark and Austria – say current data coupled with the inherent uncertainties of climate forecasting should be taken as a signal that urgent climate mitigation and adaptation strategies are needed.

“Existing climate mitigation approaches, including scaling up renewable energy and protecting carbon-storing ecosystems, are critical to limit the increase in global temperatures,” said Ripple.

Strategies that embed climate resilience into governmental policy frameworks should be a priority as well, the authors say, along with a socially just phaseout of fossil fuels. The scientists also discuss the need for novel approaches, including coordinated global tipping-point monitoring and better plans for managing risk.

“Uncertain tipping thresholds underscore the importance of precaution – crossing even some of those thresholds could commit the planet to a hothouse trajectory with long-lasting and possibly irreversible consequences,” Wolf said. “Policymakers and the public remain largely unaware of the risks posed by what would effectively be a point-of-no-return transition. And while averting the hothouse trajectory won’t be easy, it’s much more achievable than trying to backtrack once we’re on it.”

Tipping may already be happening with the Greenland and West Antarctic ice sheets, the scientists say, and boreal permafrost, mountain glaciers and the Amazon rainforest appear on the verge of tipping.

In the Earth’s tightly coupled climate system, destabilization in one region can reverberate across oceans and continents as melting ice accelerates warming by reducing albedo and altering the Atlantic Meridional Overturning Circulation, resulting in changes to tropical rain belts.

For example, as the Greenland ice sheet melts, it could further weaken the AMOC, which in turn could trigger parts of the Amazon to tip from rainforest to savanna.

“The AMOC is already showing signs of weakening, and this could increase the risk of Amazon dieback, with major negative impacts on carbon storage and biodiversity,” Ripple said. “Carbon released by an Amazon dieback would further amplify global warming and interact with other feedback loops. We need to act quickly on our rapidly dwindling opportunities to prevent dangerous and unmanageable climate outcomes.”

Working with Ripple, Wolf and Gregg on the analysis were Johan Rockström and Nico Wunderling of the Potsdam Institute for Climate Impact Research; Katherine Richardson of the University of Copenhagen; Thomas Westerhold of University Bremen; and Hans Joachim Schellnhuber of the International Institute for Applied Systems Analysis.

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Journal

One Earth

Method of Research

Data/statistical analysis

Subject of Research

Not applicable

Article Title

The risk of a hothouse 1 Earth trajectory

Article Publication Date

11-Feb-2026

 

Not all gigs are equal: Informal self-employment linked to lower pay, poorer health and instability

University of Michigan

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Image of the researchers

 

Not all self-employment guarantees financial security, with informal arrangements posing the greatest risks to well-being for many workers. 

 

Using machine learning to classify self-employment, a new University of Michigan study analyzed narrative job descriptions from the 2003-2019 Panel Study of Income Dynamics, a longitudinal dataset with approximately 10,000 U.S. families. 

 

They divided self-employment into three categories: business owners, formal self-employed and informal self-employed, such as gig workers and those performing odd jobs.

 

The study, published in the journal ILR Review and funded by the National Science Foundation, found large differences in financial outcomes, health and stability among these groups. It also discovered a significant shift in the labor market. Informal self-employment has increased in recent years, while formal self-employment has declined.

 

Informal self-employed workers make up the largest segment of the self-employed workforce, but fare the worst. They earn less, report poorer physical and mental health, have lower life satisfaction and face a higher risk of unemployment.

 

The study found that informal self-employment is concentrated among lower-income workers, women, Hispanic people and Black people—patterns shaped by language barriers, discrimination and limited access to opportunities.

 

"This group is worse off across multiple dimensions," said Joelle Abramowitz, associate research scientist at U-M's Institute for Social Research. "It often lacks benefits, stability and a path to growth. These workers are also far more likely to cycle in and out of unemployment. And it becomes a revolving door—when health falters, people fall out of work, turn to informal jobs to get by, and then slip back into unemployment again."

 

On the opposite side, business owners earn the highest incomes and report the highest levels of life satisfaction and physical health, the study found. They own more business assets than the other groups. Formal self-employed workers, such as consultants, rank second on all measures. 

 

"If we lump all self-employed people together, we mask critical economic trends and realities," Abramowitz said. "And more: There's a real concern that informal self-employment locks people into work that doesn't pay much and doesn't lead to long-term growth. At the same time, what's striking is how fluid self-employment can be—some people move from informal gigs into more stable or even entrepreneurial roles, and that's something we're actively studying."

 

Abramowitz and co-author Andrew Joung, a U-M graduate student, recommend policy changes to address the workforce shift, underscoring the need for targeted support. 

 

These include extending unemployment benefits to self-employed workers, increasing access to health insurance and expanding job training and entrepreneurship programs to those in informal work. Support during the transition phase may help more workers move into better opportunities and improve overall economic security.

 

Study: Opening the Black Box of Self-Employment: Identifying Alternative Work Arrangements in the United States (DOI: 10.1177/00197939251411)

 

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Journal

ILR Review

DOI

10.1177/00197939251411263