Climate Change Made Sea Levels Fall In 2010 And 2011, Climate Scientists Claim
Global warming and climate change are usually thought to mean that world sea levels will rise, perhaps disastrously. But according to US government boffins, in recent times (2010 and 2011, to be precise) phenomena driven by human carbon emissions have actually caused world sea levels to fall.
The seas have, of course, been rising steadily as the climate has changed for thousands of years, ever since the end of the last ice age. During the 20th century, according to estimates mostly from erratic tide gauges, sea levels rose by around 1.7mm a year. Since the early 1990s, satellites have also been used to measure sea levels, and by contrast have suggested a steady unchanging rise of about 3mm annually – that is, until 2010.
For an 18-month period beginning in 2010, the oceans mysteriously dropped by about seven millimeters.
This is pretty wacky, as warming ocean temperatures ought to mean that the oceans expand. Furthermore, there’s no disagreement about the fact that the world’s ice sheets and glaciers have been steadily melting for a long time – otherwise Europe would still be covered in ice. And there’s no reason they’d suddenly stop melting. So how could sea levels actually godown?
In short, it’s probably human-caused climate change that did it: specifically the Australian flooding of 2010 and 2011, which is generally thought by climate scientists to be at least partly attributable to rising atmospheric carbon levels caused by human fossil-fuel burning.
“It’s a beautiful illustration of how complicated our climate system is,” says John Fasullo of the US National Center for Atmospheric Research.
“The smallest continent in the world can affect sea level worldwide.”
Australia’s dry Outback interior, being ringed to a large extent by coastal mountains, doesn’t tend to let go of any rain once it’s got some: and in 2010 and 2011, huge amounts of rain fell there. Essentially, an awful lot of the world’s oceans turned into clouds and then fell on Australia – and stayed there.
The NSF boffins explain how this came about