for farming i’m more worried about the knock-on effects on the weather patterns rather than the direct effect of the shade. again i’m far from a climate scientist so I’m just going offa the possible mpacts I’m reading in the piece
Yeah, this is a much more serious issue. In particular, we have a lot of very good reasons to think that the impact on precipitation levels and distribution would be significant at even the levels that would be necessary to effect rather minor temperature reduction. The eruption of Mt. Pinatubo in the early 1990s dropped the global average temperature by about half a degree C, but also seems to have caused both severe droughts and severe flooding in various places. The precipitation disruption signal appeared and disappeared at basically exactly the same time that the temperature reduction signal did, so we’re pretty confident that the sulfur compounds Pinatubo put into the atmosphere caused both of them. The overall land-based precipitation on the planet decreased significantly:
Just as worrying (or maybe even more worrying) was the change in how the remaining precipitation was distributed. This is a heat map of the Palmer Drought Severity Index values over the relevant time period. Warmer colors represent anomalously low precipitation levels, and cooler colors represent anomalously high precipitation levels:
As you can see, to a very great extent the precipitation patterns are almost exactly inverted. Places that tend to be dry–the Amerikkkan southwest, parts of Africa, parts of Australia, etc.–were unusually wet. Places that tend to be wet–the Amazon, equatorial Africa, and southeast Asia in particular–were spectacularly dry. Both of those are bad: places that rely on the monsoons didn’t really get them, and places that aren’t used to large amounts of rain were flooded. We think now that this is largely attributable to complex changes in evaporation patterns as a result of the decreased solar intensity, and that was with only enough albedo modification to reduce the global temperature by half a degree. If we were to pursue this policy, we’d probably be looking at reductions at least two or three times as intense as that, which would almost certainly be associated with similarly increased precipitation disruptions. That might end up being more damaging than the warming itself.
for farming i’m more worried about the knock-on effects on the weather patterns rather than the direct effect of the shade. again i’m far from a climate scientist so I’m just going offa the possible mpacts I’m reading in the piece
Yeah, this is a much more serious issue. In particular, we have a lot of very good reasons to think that the impact on precipitation levels and distribution would be significant at even the levels that would be necessary to effect rather minor temperature reduction. The eruption of Mt. Pinatubo in the early 1990s dropped the global average temperature by about half a degree C, but also seems to have caused both severe droughts and severe flooding in various places. The precipitation disruption signal appeared and disappeared at basically exactly the same time that the temperature reduction signal did, so we’re pretty confident that the sulfur compounds Pinatubo put into the atmosphere caused both of them. The overall land-based precipitation on the planet decreased significantly:
Just as worrying (or maybe even more worrying) was the change in how the remaining precipitation was distributed. This is a heat map of the Palmer Drought Severity Index values over the relevant time period. Warmer colors represent anomalously low precipitation levels, and cooler colors represent anomalously high precipitation levels:
As you can see, to a very great extent the precipitation patterns are almost exactly inverted. Places that tend to be dry–the Amerikkkan southwest, parts of Africa, parts of Australia, etc.–were unusually wet. Places that tend to be wet–the Amazon, equatorial Africa, and southeast Asia in particular–were spectacularly dry. Both of those are bad: places that rely on the monsoons didn’t really get them, and places that aren’t used to large amounts of rain were flooded. We think now that this is largely attributable to complex changes in evaporation patterns as a result of the decreased solar intensity, and that was with only enough albedo modification to reduce the global temperature by half a degree. If we were to pursue this policy, we’d probably be looking at reductions at least two or three times as intense as that, which would almost certainly be associated with similarly increased precipitation disruptions. That might end up being more damaging than the warming itself.
Thank you for this, very helpful.