Thread by @safiume

1/How much Carbon needs to get removed from the air (and oceans) reach pre-Anthropocene, CO₂ 281 ppm?
A)At 2018, latest emissions reported from Global Carbon Budget Project bit.ly/31gq2TV, we need to remove about 460 Gt Carbon or ≈1.6 Tt CO₂.
bit.ly/2m7GNB3

2/And what’s the fastest rate could we pull this out of the atmosphere?
This question isn’t simple, as we don’t know what’s the optimal rate to pull Carbon out of the atmosphere.

2.1/Here are some hypotheticals. If were to remove all Carbon from human emissions, in the next twenty-five years, we’d need a fast rate of removal, say slightly over 18 gigatonnes of Carbon (or about 67 gigatonnes of CO₂) per year.

2.2/If we expect to reach restoration in a somewhat longer time, say 30 to 40 years, then that number could lower. If we want to finish by 2100, when much of us have passed on, then we can reduce that number even further.

2.3/If we lose the carbon sequestration of the land sink, meaning the Carbon trapped underground or in plants goes into the atmosphere and subsequently pushed into the ocean, then the total goes up.

2.4/We actually should plan on the amount being high initially such to steer us clear of tipping points.

3/Why are tipping points bad?
There are large deposits of Carbon locked up in frozen methane, ice, and permafrost. Should these large quantities of Carbon get released quickly in a matter of years, or less, it will radically increase global warming.

3.1/There are other tipping points, such as removing large amounts of ice cover, which would also quickly increase global warming.This radical increase in warming presents a much more difficult path where carbon dioxide removal is theoretically not able to keep pace with warming.

3.2/For CDR to be successful, we need to get to emission neutral and practice removal to stop the planet from warming enough to set off the tipping points bit.ly/2kVW3AX.

3.3/Why is the amount of Carbon so much larger than the figure quoted by IPCC and popular press? The IPCC lowest scenarios target reaching an allowable Radiative Forcing 1.9, which is a bit below 1.5ºC of allowable warming.

3.4/Reaching 281 ppm equals a Radiative Forcing of 0, and 0ºC of allowed warming. Reaching a Radiative Forcing of 1.9 equates to climate of 1984, whereas a Radiative Forcing of 0 is roughly the climate just after the global cooling in the 1790s. bit.ly/2uIKr7N

4.1/How do we get to the climate of the 1790s and why 281 ppm?We need everyone to do everything in Project Drawdown bit.ly/2MWPoDf to get us nearly emission neutral and get involved in Carbon Dioxide Removal and carbon tech.

4.2/281 ppm was the global average Carbon Dioxide concentration from 600 BCE to 1750. We need scientists to identify if 281 ppm is the optimum carbon dioxide concentration. We don't know what the optimum carbon dioxide concentration is.

4.3/ More info: bit.ly/2m7GNB3

5/By when do we need to hit Carbon neutral or emission neutral? We need to hit emission neutral ASAP, not by 2030, or later, but as fast as humanly possible. We need to start carbon removal as fast as humanly possible to steer Earth’s climate clear of tipping points.

5.1/We ought to hit double-digit gigatonnes of Carbon removed in the next couple of years. We have to scale an industry that doesn’t exist.

6/Go back to the safety of this much removal, how safe is it?At this point, we don’t know. We need scientific labs to find the upper limit of how fast we can remove Carbon and not cause the climate to fall into a mini ice-age.

6.1/ We need labs to identify what’s the slowest we can remove and not hit off the tipping points, and not have the climate extremes like the present time.

6.2/ While labs are working to find the fastest and safest rate, since it takes time to scale the technologies to remove gigatonnes; we need entrepreneurs, scientists, and engineers to create, enhance, and scale Carbon Dioxide Removal technologies.

6.3/ #Climateaction? We’ll need many early adopters to buy or try open CDR solutions. Get involved in CDR and lets go carbon negative.

Refs: ClimateAction# Q&A blog pg: bit.ly/2m7GNB3
Global Carbon Budget Project: bit.ly/31gq2TV
ONC CDR Modeling Project: bit.ly/2m8s20T
PNAS Tipping Point Paper:bit.ly/2kVW3AX
NOAA RF 1.9:bit.ly/2uIKr7N
Drawdown: bit.ly/2MWPoDf