Very interesting work in the Antarctic is reported by Jo Nova in two recent posts. Today the report concerns the long-term temperature extracted from a massive study recently published. The most recent shift is downwards after a very slight shift upwards late in the 20th century following a very long cold spell that extended from the Little Ice Age deep into the 20th century.
The other story is the change from expansion to retreat of the Antarctic ice. Remarkably the scientists involved have refrained from linking this to global warming and most remarkably New Scientist has shown admirable restraint “To argue that this recent dip is evidence of the start of a longer term decline driven by greenhouse warming is premature.” They are still talking about the cooling of the water in the vicinity and clearly the system is so large and complex that things like the the measured retreat of ice can lag cooling effects that will tend to reverse it.
The long term trend is still rising, but its now only half the rate it was in 2014. On this blog, Mike Jonas recently demonstrated that the Southern Ocean had cooled, not warmed as all the models predicted. But what matters here is that sea ice covers 7% of the world and we don’t know what caused it.
Decades of expanding sea ice in Antarctica have been wiped out by three years of sudden and dramatic declines, leaving scientist puzzled as to why the region has flipped so abruptly. However, researchers cautioned against pinning the changes on climate change and said it was too early to say if the shrinking is the start of a long-term trend or a blip.
The decline may just be natural variability, driven by shift in wind patterns which influence the extent of Antarctic sea ice, says Mark Serreze, director of the US National Snow and Ice Data Center. “To argue that this recent dip is evidence of the start of a longer term decline driven by greenhouse warming is premature.” — New Scientist.