Has global warming come to a halt? For the last decade or so the average global surface temperature has stabilising at around 0.5°C above the long-term average. Can we all relax and assume global warming isn’t going to be so bad after all?
Unfortunately not. Instead we appear to be measuring the wrong thing. Doug McNeall and Matthew Palmer, both from the Met Office Hadley Centre in Exeter, have analysed climate simulations and shown that both ocean heat content and net radiation (at the top of the atmosphere) continue to rise, while surface temperature goes in fits and starts. “In my view net radiation is the most fundamental measure of global warming since it directly represents the accumulation of excess solar energy in the Earth system,” says Palmer, whose findings are published in the journal Environmental Research Letters.
So why aren’t surface temperatures keeping pace with ocean heat content and net radiation? The answer, according to a recent study in the journal Nature Climate Change, may be some unusually strong trade winds in the Pacific Ocean, which have buried the surface heat deep underwater, reducing the amount of heat flowing back into the atmosphere. Once the trade winds relax again that heat will likely be released and surface temperatures will bounce up again. In the meantime we’d be wise to keep a closer eye on ocean heat content (using the Argo array of ocean profiling floats) and net radiation (using satellites). Like it or not Earth’s future is looking hot.