Sea Level Rise Set to Accelerate Even if Global Warming is Capped at 1.5°C.

Despite hopes pinned on limiting global warming to 1.5 degrees Celsius, scientists warn that sea level rise is likely to accelerate throughout the 21st century and beyond, placing immense pressure on global resilience efforts. A new study led by Professor Chris Stokes from Durham University reveals that even if this critical climate target is achieved, the consequences of rising seas will be challenging to manage.

According to the research, the pace of sea level rise has already doubled over the last 30 years. If current trends continue, it could double again by the end of the century, reaching a rate of one centimeter per year by 2100. "Limiting global warming to 1.5°C would be a major achievement and avoid many dire climate impacts," said Stokes. "But even if this target is met, sea level rise is likely to accelerate to rates that are very difficult to adapt to."

Without robust coastal defenses such as sea walls, an extra 20 centimeters (7.8 inches) of sea level rise by 2050—roughly the width of a standard sheet of paper—could result in annual flood damages of around $1 trillion across the 136 largest coastal cities worldwide. This rising threat looms over the 230 million people who currently live within one meter of sea level, and more than a billion who reside within ten meters of it.

The drivers behind this phenomenon are both the melting of ice sheets and mountain glaciers and the thermal expansion of ocean waters, which absorb over 90% of the heat trapped by greenhouse gases. Current global temperatures, averaged over the last two decades, are already 1.2°C above pre-industrial levels—enough, researchers warn, to commit the planet to several meters of sea level rise over the long term.

The study, published in Communications Earth & Environment, draws on recent scientific literature and builds upon the last major climate assessment by the UN’s Intergovernmental Panel on Climate Change (IPCC). Notably, the researchers highlight the growing and underestimated role of ice sheet melt in sea level projections. While the IPCC in 2021 estimated a likely sea level rise of 40 to 80 centimeters by 2100, that estimate excluded significant contributions from ice sheets due to uncertainty. Since then, the picture has become more concerning.

"We are probably heading for the higher numbers within that range, possibly higher," Stokes noted. The research team analyzed satellite data, historical climate records, and projections of future ice sheet behavior. Satellite observations have shown that the Greenland and West Antarctic ice sheets—holding enough ice to raise sea levels by around 65 meters—are more vulnerable to warming than previously understood.

Melting from these regions has now reached about 400 billion tonnes annually, a fourfold increase in three decades. These losses have now surpassed those from mountain glaciers.

Tipping points—thresholds beyond which ice sheet loss becomes irreversible—are also being revised. Previously thought to lie around 3°C of warming, these thresholds are now estimated at about 1.5°C. “We used to think that Greenland wouldn’t do anything until the world warmed 3°C,” Stokes said. “Now the consensus for tipping points for Greenland and West Antarctica is about 1.5°C.”

Supporting this concern are data from previous warm periods in Earth’s history. Around 125,000 years ago, during an interglacial era with slightly cooler global temperatures and significantly lower CO2 levels (287 ppm compared to today’s 424 ppm), sea levels were between two and nine meters higher than today. In another warm period 400,000 years ago, oceans stood 6 to 13 meters higher. Even further back, some three million years ago—when CO2 levels were similar to today’s—sea levels were 10 to 20 meters higher.

The findings underscore that simply stabilizing temperatures is not enough. “If you want to slow sea level rise from ice sheets, you clearly have to cool back from present-day temperatures,” said Stokes. According to the team, managing future sea level rise effectively would require a long-term temperature goal near or even below 1°C above pre-industrial levels.

As the planet continues to warm—potentially reaching 2.7°C by the century’s end—the challenge of adapting to rising seas grows steeper, with major implications for coastal infrastructure, economies, and human populations worldwide.

Source:https://phys.org/news/2025-05-sea-limited-15c.html

This is non-financial/medical advice and made using AI so could be wrong.