Current Climate Trajectory Points to Major Ice Loss and Sea-Level Rise, Even at 1.5°C

The world is currently on track for nearly 3°C of global warming by the end of this century, relative to the late 1800s—before the widespread burning of fossil fuels began. This projection is based on existing government policies to cut carbon emissions and other pollutants.

However, even if global warming is limited to 1.5°C, significant ice loss from Greenland and Antarctica will likely continue, according to researchers. That’s because changes in temperature take centuries to fully impact vast ice sheets.

“Limiting warming to 1.5°C would be a major success and should remain our goal,” said lead author Professor Chris Stokes, a glaciologist at Durham University. “But it won’t stop sea-level rise or the melting of ice sheets.”

The 2015 Paris Agreement set the goal of keeping global warming “well below” 2°C—ideally below 1.5°C. But that 1.5°C threshold is often misunderstood as “safe,” something glaciologists have warned against for years.

A new paper published in Communications Earth and Environment draws on three main lines of evidence to reinforce the seriousness of this issue:

1. Historical Evidence: Geological records show that during past warm periods—like 125,000 years ago—sea levels were several meters higher than today. Around 3 million years ago, when atmospheric CO₂ was at similar levels to today, global sea levels were 10–20 meters higher.

2. Current Observations: Data already shows accelerating ice melt, particularly in Greenland and West Antarctica, though year-to-year variations exist. “Dramatic changes are happening,” noted co-author Professor Jonathan Bamber of the Bristol Glaciology Centre. East Antarctica, for now, remains more stable.

   A graph from 1992 to 2024 shows a rising contribution of Greenland and West Antarctic ice sheets to global sea-level rise—nearly 25mm in total—with the rate of ice loss clearly accelerating.

   “We’re witnessing some of the worst-case scenarios unfold in real time,” said Prof. Stokes.

3. Future Projections: Climate models simulating future ice sheet behavior paint a sobering picture. “Very few models show sea-level rise slowing, even if warming is limited to 1.5°C—and none show it stopping,” said Prof. Stokes.

The risk is that warming may trigger tipping points, accelerating melt in ways scientists don’t yet fully understand.

Professor Andy Shepherd, a glaciologist at Northumbria University who wasn’t involved in the study, praised the research: “Its strength lies in using multiple lines of evidence to show our current climate resembles past periods when major ice loss occurred.”

The consequences would be devastating for coastal areas. Around 230 million people today live within one meter of the current high tide line.

Determining a “safe” warming limit is inherently difficult, especially as some communities are more vulnerable than others. But if sea-level rise reaches 1 cm per year by century’s end—driven mainly by melting ice and warming oceans—it could overwhelm even well-resourced nations.

“At that point, adaptation becomes incredibly difficult,” warned Prof. Bamber. “We could see mass migrations on a scale unseen in modern history.”

Still, the researchers emphasize that this is no reason for defeatism. Action matters.

“The faster the warming, the faster the ice loss and sea-level rise,” Prof. Stokes concluded. “Every fraction of a degree matters.”