Re: [CDR] I Have a Question
John Nissen
You had SRM as #3. I think Robert is arguing it should be #1. But the Arctic has the most critical tipping points, so I am splitting off SRM to cool the Arctic as #1 as of critical urgency for the safety of humanity on the planet. My priorities would be:
#2 is SRM in other regions and globally, to deal with other tipping points and to start reducing temperatures everywhere which will help to stop sea level rise, reverse climate change and maintain biodiversity.
#3 is CDR and methane suppression/removal to reduce CO2e: my suggested target is to reduce CO2e from current >500 ppm to somewhere around its 1980 level by 2050.
#4 is emissions reduction to reduce dependency on fossil fuels and allow long-term sustainability without continued SRM.
Ambitiously, I believe that a planetary state better than that in 1980 could be reached by 2050 if we pull out all the stops for planetary restoration. Isn't that what we want for our children and grand-children, wherever they may live?
--Jim
My view is that CDR is much more important than emission reduction, and that brightening the planet through solar radiation management is by far the most urgent climate security priority to limit the risk of dangerous phase shifts.
My calculations are as follows. These only reflect my own understanding of the linked sources, aiming for order of magnitude numbers, so grateful any corrections.
Total emissions to date according to https://www.globalwarmingindex.org/ are 2.45 trillion tonnes of CO2, or 0.67 trillion tonnes C. Your trillion tonne figure for CO2 in the air is much less than that.
The total weight of the atmosphere is 5 quadrillion tonnes. Multiplying this by the current CO2 concentration of 422 ppm gives 2.1 trillion tonnes CO2.
I find this surprisingly high as I had thought much more CO2 from historic emissions had dissolved into the ocean, although this site says it is less than 3 Gt CO2 per year, just 10% of emissions.
CO2 emissions are estimated at 36.3 gigatonnes per year. Adding other GHGs increases that by nearly 50% to about 52 Gt CO2 equivalents according to https://climateactiontracker.org/data-portal/ data download.
The annual CO2 emissions of 36.3 billion tonnes equates to 1.8% of the total CO2 weight, or 2.5% including methane and other GHGs, recognising the equivalence depends on assumptions.
CO2e was calculated at 460 ppm in 2019, so we can say it is now 464 ppm.
Considered in terms of radiative forcing, only the 142 ppm CO2 above the Holocene norm of 280 ppm counts, or 186 ppm if we add another 44 ppm for other GHGs. The weight of GHGs producing radiative forcing is approximated by 186/464 x 2.1 trillion tonnes = 845 Gt. That means we are worsening radiative forcing by 52/845 = 6.2% per year, meaning RF would double in 13 years at the current rate.
The problem is that the political power and will to cut emissions is too weak. Decarbonisation is too small, slow and contested to be the main climate policy. By contrast, if we implement geoengineering solutions now to brighten the planet, we will buy time to mitigate extreme weather, sea level rise, biodiversity loss and temperature rise in this decade. Cutting emissions does almost nothing to slow any of these problems until much later in the century, if ever, given the tipping point problem.
Net Zero by 2050 has to mainly be delivered by CDR, as this is the only way that gives a trajectory to then ramp up to the much larger needed net negative emissions to stabilise the climate.
Decarbonisation has a hard limit below new total emissions, which are as noted only about 2% of the total GHG load each year, or 6% of RF, marginal to the total heating problem.
Resources for climate action should be assigned proportionally to the main problem, using CDR for the 94% of committed warming from past emissions, and to the SRM stopgap needed to mitigate the risk of tipping points.
Robert Tulip
From: carbondiox...@googlegroups.com <carbondiox...@googlegroups.com> On Behalf Of Jim Lerner
Sent: Wednesday, 20 April 2022 7:16 AM
To: CarbonDiox...@googlegroups.com
Subject: [CDR] I Have a Question
Congress has done nothing about the emissions in the USA. So my question is this: Aren’t emissions as important as CDR? Reason I ask is that until we get the emissions to near zero about half of the emissions will stay in the atmosphere. So after say 50 years there will be 1 trillion MORE tons of CO2 in the atmosphere in addition to the legacy emissions which are equal to about 1 trillion tons of CO2 already in the atmosphere.
So in addition to finding ways to reduce CO2 emissions as soon as possible we also have to find ways to reduce the CO2 that’s, so in the atmosphere now.
Maybe it’ll happen faster say by 2050 (the goal).So in approximate numbers if both go to near zero by 2050 or in 30 years, then the emissions will leave 600 gT of CO2 in the atmosphere in addition to the legacy CO2. So we’ll have to remove 1.6 trillion tons of CO2 from the atmosphere.
What do you say?
Jim
--
Jim Lerner, Ph.D.
Senior Policy Advisor
Sacramento Chapter
Citizens Climate Lobby--
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John Nissen
The group which I chair, the Planetary Restoration Action Group (PRAG) is demanding (if anyone will listen) a crash programme of Arctic cooling, in order to deal with the tipping points already accelerating climate change and sea level rise:
Firstly, rapid warming in the Arctic is disrupting the jet stream, causing it to get stuck in patterns, hence producing stuck weather: heat domes, massive floods, etc. This sticking behaviour was the cause of many local catastrophes last year. The situation will continue to get worse, and the jet stream might go into a permanent new configuration, upsetting the climate all over the world.