A slowdown in global warming that climate sceptics cite in favour of their cause was partly induced by one of the world's most successful environment treaties, a study said on Sunday. The UN's Montreal Protocol, designed to phase out industrial gases that destroy Earth's protective ozone layer, coincidentally applied a small brake to the planet's warming, it said.
Without this treaty, Earth's surface temperature would be roughly 0.1 degrees Celsius (0.2 degrees Fahrenheit) higher today, according to its authors.
"Paradoxically, the recent decrease in warming, presented by global warming sceptics as proof that humankind cannot affect the climate system, is shown to have a direct human origin," according to the paper, published in the journal Nature Geoscience.
Signed in 1987 and implemented in 1989, the Montreal Protocol committed signatories to scrapping a group of chlorine- and bromine-containing chemicals. Used in aerosol sprays, solvents and refrigerants, these substances destroy ozone molecules in the stratosphere that filter out cancer-causing ultraviolet light.