The decrease in global warming between 1998 and 2008 – often cited as evidence against man-made climate change – was actually caused by an increase in coal use in China, a study has found.
It seems that while geoengineers have been dreaming up a range of schemes to get sulphur into the atmosphere and reflect the sun’s rays, the Chinese have been doing just that – not on purpose, you understand, but as a result of soaring energy requirements.
China’s increase in coal use has put more carbon dioxide into the atmosphere, leading to global warming. But it’s also, say Boston University scientists, injected large quantities of sulphates, reflecting the sun’s rays back into space.
There are other reasons for the plateau, say the researchers. These include a particularly powerful El Nino in 1998, which means that making comparisons with that particular year gives a misleading result. Others include natural fluctuations in the Sun’s output, volcanoes and water vapour.
But the coal use appears to have had a singificant effect, says the team.
“The masking of CO2-induced global warming by short term sulphur emissions is well known – it’s believed that the flattening off of global mean temperatures in the 1950s was due to European and US coal burning, and just such a mechanism could be operating today from Chinese coal,” Leeds University’s Piers Forster told the BBC.
Geoengineers have for years been proposing that sulphur particles could be injected into the atmosphere to create precisely this cooling effect.
But, says the team, we can’t breathe easy and assume that sulphur emissions will continue to counteract the increase in CO2. The CO2, unfortunately, will remain in the atmosphere for a lot longer.
Indeed, a similar, natural phenomenon is believed to be at the root of Venus’s runaway global warming.