|A dust storm approaches Stratford, Texas, in 1935. From: Wikipedia: Dust Bowl|
Rapid creation of farms and use of gasoline tractors had caused erosion at massive scale.
Extensive deep plowing of the virgin topsoil of the Great Plains in the preceding decade had removed the natural deep-rooted vegetation that previously kept the soil in place and trapped moisture even during periods of drought and high winds.
So, when the drought came, the dust storms emerged. But what caused the drought?
A 2004 study concludes that the drought was caused by anomalous tropical sea surface temperatures (SST) during that decade and that interactions between the atmosphere and the land surface increased its severity (see image above right with SST anomalies).
Sea Surface Temperature Anomalies in the Arctic
As the above chart shows, SST anomalies in the days of the Dust Bowl were not greater than one degree Celsius. It is in this context that the current situation in the Arctic must be seen. This year, SST anomalies of 5 degrees Celsius or more are showing up in virtually all areas in the Arctic Ocean where the sea ice has disappeared; some areas are exposed to sea surface temperature anomalies higher than 8°C (14.4°F), as discussed in the post Arctic Ocean is turning red.
High SST anomalies can change weather patterns in many places, as discussed in an earlier post on changes to the Polar Jet Stream. The world is now stumbling from one extreme weather event into another, and things look set to get worse every year.
Feedbacks in many ways make things even worse in the Arctic, as described in the post Diagram of Doom. A recent paper by Feng et al. notes that river runoff has significantly increased across the Eurasian Arctic in recent decades, resulting in increased export of young surface carbon. In addition, the paper says, climate change-induced mobilization of old permafrost carbon is well underway in the Arctic. An earlier paper already warned about coastal erosion due to the permafrost melt. In conclusion, the Arctic is hit by climate change like no other place on Earth.
As the ice thickness map below shows, holes have appeared in the sea ice in places that once were covered by thick multi-year sea ice.
One such hole, for its proximity to the North Pole, has been aptly named the "North Hole". On the sea ice concentration map below, this hole shows up as a blue spot (i.e. zero ice).
The "Methane Catastrophe"
Why do we care? For starters, methane appears to be rising up from these holes in the sea ice, forming a cloud of high methane concentrations over the Arctic Ocean.
Perhaps this is a good occasion to again look at the methane plume over one km in diameter that appeared in the Laptev Sea end September 2011. The image is part of a paper on the unfolding "Methane Catastrophe".
Back in 2008, Shakhova et al., in the study Anomalies of methane in the atmosphere over the East Siberian shelf: Is there any sign of methane leakage from shallow shelf hydrates? considered release of up to 50 Gt of predicted amount of hydrate storage as highly possible for abrupt release at any time.
For more on the methane threat, please read the post methane hydrates or view the FAQ page.