Highest Rated Comments

peteirvine_geo357 karma

There's been lots of proposals, many of which don't make much sense and only a couple that do. People proposed mirrors in space (very expensive!), desert albedo geoengineering (which I showed would shut down the monsoons), and cirrus cloud thinning (unlikely to actually work).

The leading proposal is stratospheric aerosol geoengineering. It would mimic the cooling effect of volcanic eruptions. They add millions of tons of sulphuric acid to the stratosphere (about 60,000 foot up), producing a global layer of haze that persists for a couple of years. We could do this artificially with high-altitude jets at a cost of a few billion dollars per year and offset all future warming.

The other proposal is marine cloud brightening. Here the idea is to spray up sea-salt from the ocean surface into low-lying clouds and whiten them in the same way that ship tracks do. This is only applicable in some places but is being seriously considered as a way to save the great barrier reef.

peteirvine_geo261 karma

Stratospheric aerosol geoengineering, which would spray stuff from aircraft, happens to overlap with the chemtrails conspiracy theory. This has led to some geoengineering researchers getting death threats. :(

peteirvine_geo193 karma

Stratospheric aerosol geoengineering is the leading proposal and it has some side-effects. This idea would create a global haze of tiny "aerosol" particles. It's goal is to offset the climate changes from global warming and it looks like it would be pretty good at that, though it may lead to reductions in rainfall in some places. If we copy volcanoes and release sulphuric acid it would have some side-effects:

- To offset 1C of global warming, which is roughly the difference between where we're heading currently (2.5 - 3C) and where we'd like to go (1.5C), would require a reduction in incoming sunlight of about 1%

- However, the tiny particles would scatter light making the sky about 4% hazier. This means solar PV would generate 1% less power and concentrating solar power would generate 5% less.

- It would affect the ozone layer, perhaps delaying the recovery of the ozone hole by a few decades (which is recovering from its minimum in the 90s). Though, as it scatters light it may actually reduce the amount of UV reacing the surface.

- It would add to the acid rain problem, perhaps adding 10 million tons of sulphur on top of the ~100 Million tons we emit today as a by-product of burning fossil fuels.

All of these side effects may be reduced if we use a different type of particle,like calcite, but sulphur is the devil we know and we know from recent volcanic eruptions (Pinatubo 1991) that it's side effects wouldn't be that bad.

peteirvine_geo177 karma

Plastic straws - trivial

Not eating meat - large contribution to personal emissions

Solar power is fantastic and the pros far outweigh the cons, same with EVs: https://www.carbonbrief.org/factcheck-how-electric-vehicles-help-to-tackle-climate-change/

peteirvine_geo131 karma

The 1% reduction in sunlight will have some impact, but it's likely small compared to the large fertilization effect of CO2 and the impacts of climate change. There's also some research that suggests the haziness would boost productivity