Saturday, October 17, 2015

Two articles for weekend worrying

The AGU website, which I should probably visit more often, has two climate change articles of concern:

1.  Diatoms are not doing well:
The world’s oceans have seen significant declines in certain types of microscopic plant-life at the base of the marine food chain, according to a new study. The research, accepted for publication in Global Biogeochemical Cycles, a journal of the American Geophysical Union, is the first to look at global, long-term phytoplankton community trends based on a model driven by NASA satellite data.

Diatoms, the largest type of phytoplankton algae, have declined more than 1 percent per year from 1998 to 2012 globally, with significant losses occurring in the North Pacific, North Indian and Equatorial Indian oceans. The reduction in population may reduce the amount of carbon dioxide drawn out of the atmosphere and transferred to the deep ocean for long-term storage.
2. Methane blooms off the coast of Washington and Oregon seem to be related to warming waters:
Warming ocean temperatures a third of a mile below the surface, in a dark ocean in areas with little marine life, might attract scant attention. But this is precisely the depth where frozen pockets of methane ‘ice’ transition from a dormant solid to a powerful greenhouse gas.  New research suggests that subsurface warming could be causing more methane gas to bubble up off the Washington and Oregon coast.

The study shows that of 168 bubble plumes observed within the past decade, a disproportionate number were seen at a critical depth for the stability of methane hydrates. The study has been accepted for publication in Geochemistry, Geophysics, Geosystems, a journal of the American Geophysical Union
Most of this methane is not making the surface, but it's increasing the acidity of the oceans anyway:
 If methane bubbles rise all the way to the surface, they enter the atmosphere and act as a powerful greenhouse gas. But most of the deep-sea methane seems to get consumed during the journey up. Marine microbes convert the methane into carbon dioxide, producing lower-oxygen, more-acidic conditions in the deeper offshore water, which eventually wells up along the coast and surges into coastal waterways.
Not very encouraging...

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