In Summary
  • Most models and predictions underestimated potential warming by up to 15 per cent, some experts say.
  • End-of-century temperatures could be 0.5 degrees Celsius higher than currently predicted.
  • A half-degree increase on the thermometer could translate into devastating consequences. With only a single degree Celsius of global warming so far, the planet has already seen a crescendo of deadly droughts, heatwaves and superstorms engorged by rising seas.

PARIS

The UN's forecast for global warming is about 15 per cent too low, which means end-of-century temperatures could be 0.5 degrees Celsius higher than currently predicted, said a study released on Wednesday.

The prediction makes the already daunting challenge of capping global warming at "well under" 2.0 degrees Celsius (3.6 degrees Fahrenheit) — the cornerstone goal of the 196-nation Paris Agreement — all the more difficult, the authors said.

STUDY

"Our results suggest that achieving any given global temperature stabilisation target will require steeper greenhouse gas emissions reductions than previously calculated," they wrote.

A half-degree increase on the thermometer could translate into devastating consequences.

With only a single degree Celsius of global warming so far, the planet has already seen a crescendo of deadly droughts, heatwaves and superstorms engorged by rising seas.

The United Nations' Intergovernmental Panel on Climate Change (IPCC), which provides the scientific foundation for global climate policy, projects an increase in the earth's average surface temperature of about 4.5 Celsius by 2100 if carbon pollution continues unabated.

UNCERTAINTY

But there is a very large range of uncertainty — 3.2 to 5.9 degrees Celsius — around that figure, reflecting different assumptions and methods in the dozens of climate models the IPCC takes into account.

"The primary goal of our study was to narrow this range of uncertainty, and to assess whether the upper or lower end is more likely," lead author Patrick Brown, a researcher at the Carnegie Institution for Science at Stanford University in California, told AFP.

By factoring in decades of satellite observations which track how much sunlight gets bounced back into space, the study showed that the more alarming projections are clearly aligned with that data and the warming that has been measured so far.

"Our findings eliminate the lower end of this range," Brown said.

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