Geoengineering comes in many forms from the benign (planting more trees to soak up carbon, biochar, etc.) to the downright dangerous. This is about one of the latter: Simulating a volcanic eruption by pumping sulphur particles into the atmosphere. This idea has been poo-pooed plenty of times before, and some new research in the journal Nature Geoscience only adds to the warnings about unintended consequences:Northwestern University's Matthew Hurtgen examined the amount of sulphur isotopes on the floor of the what used to be a vast inland sea in the middle of North America. We're talking 94 million years ago, when volcanoes were spewing so much sulphur into the atmosphere that 27% of marine species went extinct.
Ancient Eruptions Caused Huge Dead Zones
Here's the connection: Hurtgen told New Scientist that these volcanic eruptions trigged vast phytoplankton blooms in this inland sea, causing large amounts of oxygen to be sucked out of the water. Think ocean dead zones caused by fertilizer run off and the like today.
Like this inland sea prior to these volcanic eruptions, "most modern lakes are poor in sulphate, so it's possible that geoengineering the climate [using sulphate aerosols to reflect sunlight] could trigger blooms and ultimately anoxia in some lakes."
Which is not to say, I suppose, that more research shouldn't be done into this or any geoengineering scheme, but let's not get distracted by the techno-solution when the real change has to remain with us.
Here's Hurtgen's original paper: Volcanic triggering of a biogeochemical cascade during Ocean Anoxic Event 2
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