00:00In June 1991, one of the largest eruptions of the 20th century took place when Mount
00:07Pinatubo erupted, sending over 4 cubic kilometers of rock, ash and gases into the atmosphere.
00:16Today the Pinatubo landscape is unrecognizable.
00:20Vast fields of ash over 25 feet deep cover what was once a maze of low hills, streams
00:26and dirt roads leading to villages.
00:29Fields of ash formed lakes where streams once ran.
00:32But more significantly for this story, global warming appeared to pause for around two years.
00:39The Mount Pinatubo eruption in 1991 was a very large one and many people know about
00:46the effect that the dust, the aerosols that blew into the outer atmosphere cooled the
00:52planet by a third of a degree.
00:55But separate from the cooling, there was also the fact that ash from the volcano fell
01:00into the ocean and the CO2 level stayed steady in 1992.
01:07And our industry was running at a rate that we were producing 20 billion tons of CO2 a
01:13year, 20 gigatons a year.
01:15And that much was absorbed by the ocean after the volcano.
01:21So we are pretty sure that we can reproduce that by using just the iron and perhaps some
01:28other micronutrients to produce the same effect.
01:33This graph shows the steady increase of CO2 levels and there's a distinct pause after
01:38the Pinatubo eruption.
01:40When Pinatubo erupted, it was about 5 cubic kilometers of rock.
01:45We don't, the amount that we need is an incredibly small portion of that.
01:50That's about 20,000 tons a year or a fraction of an ocean tanker of iron each year.
01:58And that would be distributed by maybe 5 or 10 ships in just the right places in the right
02:05times and that's all it would take.
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