Claim That ‘2-Degree Target Is Dead’ Sparks Debate on Climate Scenarios

Keeping global warming under 2°C—the fallback goal of the Paris Agreement—is now “impossible,” according to a controversial new study by prominent climatologist James Hansen and his team. Published in Environment: Science and Policy for Sustainable Development, the paper argues that Earth’s climate is more sensitive to greenhouse gas emissions than previously thought.

Adding to the crisis, Hansen warns that reduced aerosol pollution from shipping, which had been masking some warming, is now accelerating temperature rise. The UN’s climate panel previously estimated a 50% chance of staying below 2°C by 2100, but Hansen dismissed that scenario as “impossible.”

“The two-degree target is dead,” he declared. He and his co-authors predict that global temperatures will exceed 1.5°C in the coming years, causing coral reef destruction and more extreme storms, before reaching 2°C by 2045.

Disputed Findings

Not all experts agree. Valerie Masson-Delmotte, former co-chair of the UN climate panel’s working group, cautioned that the study “requires vigilance” and noted it was not published in a climate science journal. “It includes hypotheses that don’t align with all available data,” she told AFP.

The paper also predicts that melting polar ice and freshwater influx will disrupt the Atlantic Meridional Overturning Circulation (AMOC) within 20–30 years. This ocean current regulates global temperatures and supports marine ecosystems. Its collapse, Hansen warns, would be a catastrophic “point of no return,” triggering several meters of sea level rise.

The Paris Agreement set 1.5°C as a critical threshold to prevent irreversible climate damage, such as collapsing ocean currents, thawing permafrost, and vanishing coral reefs. Recent data from the EU’s Copernicus system shows this limit has already been breached in the past two years, though the agreement refers to long-term trends.

At 2°C, impacts would be even worse—permanent ice sheet loss, glacier retreat, and widespread permafrost melt. Despite the bleak outlook, Hansen insists that honesty is crucial.

“Downplaying the severity of climate change and failing to call out weak policies does not help young people,” he said. However, he remains optimistic, believing that action is still possible.

Other scientists remain skeptical. “There’s still a lot of speculation,” said Karsten Haustein, a climate scientist at the University of Leipzig. “I remain unconvinced by their claims.”

Read Original Article: Science Alert

Read More: An African Strontium Map Provides Insights Into the Origins of Enslaved Individuals