And outside the energy sector: Biological CO2 capture via photosynthesis and storage in ecosystems (e.g. forests, grasslands, wetlands, oceans) and / or agricultural lands (e.g. soils, biomass); and chemical CO2 capture via
enhanced weathering of rocks that natural react (albeit quite slowly) with CO2 in the air.
Not exact matches
Your story on
enhanced rock weathering to remove carbon dioxide from the atmosphere (7 April, p 4) quoted some «back -
of - the - envelope...
This chemical
weathering process is too slow to damp out shorter - term fluctuations, and there are some complexities — glaciation can
enhance the mechanical erosion that provides surface area for chemical
weathering (some
of which may be realized after a time delay — ie when the subsequent warming occurs — dramatically snow in a Snowball Earth scenario, where the frigid conditions essentially shut down all chemical
weathering, allowing CO2 to build up to the point where it thaws the equatorial region, at which point runaway albedo feedback drives the Earth into a carbonic acid sauna, which ends via rapid carbonate
rock formation), while lower sea level may increase the oxidation
of organic C in sediments but also provide more land surface for erosion... etc..
It is true that more practical research has been done on some CDR techniques, but to imply that large - scale biochar or BECCS plantations, ocean iron - fertilisation (OIF), ocean alkalinisation or
enhanced weathering by spreading
rock dust over millions
of square kilometres — to name but a few CDR options — are well tested and low - risk is (to put it bluntly), also «nuts».
«
Enhanced weathering»
of minerals is a twist on a slow moving process that naturally turns CO2 in the air into
rocks.
One proposed solution to the first question involves the outgassing
of massive amounts
of carbon dioxide by volcanoes, which could have warmed the planetary surface rapidly by
enhancing the planet's so - called greenhouse effect, especially given that major carbon dioxide sinks (
rock weathering and photosynthesis) would have been dampened by a frozen Earth.