An anonymous reader writes:
One of the scientists who demonstrated conclusively that global warming was an unnatural event with the famous “hockey stick” graph is now warning that giant jetstreams which circle the planet are being altered by climate change. Jetstreams are influenced by the difference in temperatures between the Arctic and the equator. But the Arctic has been warming much faster than tropical climates – the island of Svalbard, for example was 6.5 degrees celsius warmer last year compared to the average between 1961 and 1990. The land has also been warming faster than the sea. Both of those factors were changing the flow of these major air currents to create “extreme meanders” which were helping to cause “extreme weather events”, Professor Michael Mann said. In a paper in the journal Scientific Reports, Professor Mann and other researchers wrote that evidence of the effect of climate change on the jetstreams had “only recently emerged from the background noise of natural variability." They said that projections of the effect on the jetstreams in “state-of-the-art” climate models were “mirrored” in “multiple” actual temperature measurements. The jetstream normally flows reasonably consistently around the planet, but can develop loops extending north and south. The researchers, who studied temperature records going back to 1870 as well as satellite data, said these loops could grow “very large” or even “grind to a halt” rather than moving from west to east. The effect has been most pronounced during the past 40 years, they found.
