The swift expansion of renewable energy is beginning to shift emissions patterns, yet anticipated temperature increases remain elevated as the United Nations intensifies efforts to enforce stricter national commitments.
For years, a worst-case climate scenario served as a grim caution about the potential outcomes if the world neglected to reduce fossil fuel consumption. A temperature rise exceeding 4 degrees Celsius (7.2 degrees Fahrenheit) by century's end would trigger catastrophic effects, such as lethal heat waves, surging sea levels, crop failures, and widespread displacement.
However, a scientific paper released in April indicates that this doomsday trajectory—designated as RCP8.5 and later SSP5-8.5—is now less likely. Originally crafted as a reference point to aid governments in preparing for hazardous possibilities, the worst-case scenario was never a forecast.
Climate researcher Detlef Van Vuuren, the lead author of the new study, told UK-based climate science platform Carbon Brief that it had always been considered a "low-probability, high-risk scenario."
It mirrored the understanding and energy patterns of the late 2000s, when the world was more dependent on burning coal, oil, and gas that heat the planet. However, those patterns have since shifted.
The world is not moving toward the worst-case scenario "because we've actually taken political measures allowing us to move away from that," French climate scientist Christophe Cassou told the AFP news agency.
The updated evaluation attributes this change to the faster-than-anticipated deployment of renewable energy, with numerous governments adopting policies that have curbed projected emissions growth.
Friederike Otto, a climate scientist at Imperial College London, noted that the worst-case scenario had "assumed humanity would continue an unchecked coal-driven fossil fuel boom, which fortunately did not happen."
While recognizing this as "fundamentally good news," she cautioned that it "should by no means lead to complacency."
Climate skeptics exploit revised scenario
US President Donald Trump seized on the revision to assert that climate scientists had been "wrong," fueling attacks on climate science from skeptics and politicians in both the United States and Europe.
The far-right Alternative for Germany is among those groups. During a parliamentary debate on Wednesday, the AfD used the new narrative to advocate for rolling back the country's climate policies.
Niklas Höhne, executive director and founder of Germany's NewClimate Institute, described that tactic as "a blatant diversionary tactic by climate deniers and the far right." With the world in the midst of another energy crisis, he said fossil fuel defenders "will stop at nothing to fabricate a supposed scandal with outrageous arguments and divert attention from the real problems."
Cassou also emphasized that scientists "haven't been alarmist at all."
Beyond discarding the worst-case scenario, researchers have also abandoned their most optimistic climate pathway. They caution that the world is now likely to temporarily exceed 1.5 degrees Celsius of warming above pre-industrial levels—the threshold set in the 2015 Paris Agreement as a way to avert the most severe climate effects.
The current message is unambiguous. Since emissions have not declined quickly enough, despite years of warnings and climate pledges, the world could still warm by roughly 3 degrees Celsius by 2100.
That would sharply intensify climate impacts already visible today, including more frequent deadly heat waves, floods, storms, and droughts. It would also result in widespread crop failures and sea-level rise affecting up to 600 million people—all with far-reaching consequences for food security, economies, and human health.
UN climate resolution faces opposition
Meanwhile, the United Nations General Assembly has approved a nonbinding resolution reinforcing countries' obligations to address climate change.
The UN body voted overwhelmingly to endorse the advisory opinion issued last year by the International Court of Justice. That ruling stated that countries could be in violation of international law if they fail to adequately protect people from dangerous planetary warming.
"The world's highest court has spoken. Today, the General Assembly has answered," UN Secretary-General Antonio Guterres said in a statement. "This is a powerful affirmation of international law, climate justice, science, and the responsibility of states to protect people from the escalating climate crisis."
The US, which withdrew from the Paris Agreement under Trump, along with petrostates Russia, Iran, and Saudi Arabia, opposed the measure.
It is hoped that the resolution, spearheaded by Pacific island nation Vanuatu—which is already experiencing rising seas and intensifying storms—will strengthen the principle that governments have a legal duty to cut greenhouse gas emissions.
The approved text calls for the phaseout of subsidies for fossil fuel exploration, production, and exploitation, and demands that damages be paid by those in violation.
Edited by: Tamsin Walker
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