"The Paris Agreement’s aspirational 1.5C target, in particular, has more or less become defined as an overshoot scenario."
In my opinion, it is media vibes that have "more or less defined" 1.5C to be an actual "uncrossable" threshold, rather than rigorous analysis. There may be an optimal warming threshold for defining overshoots or the carbon debt, but computing that would involve Nordhaus-type socioeconomic cost estimates that are highly uncertain and controversial.
I'm all for rapid emission reductions to limit global warming. I also support modest funding of research/experiments on CDR/geoengineering. I'm much less enthused about models or scenarios that rely on the actual deployment of CDR/geoengineering. Modeled scenarios of how much CDR we'll need are popular with CDR proponents, but they seem to be distraction from the main task at hand: mitigation+adaptation+research. If anything, focusing on any non-zero CDR deployment lessens the pressure for strong mitigation measures now.
We don't know how much CDR should be used to correct for overshoots because we don't know 1) the optimal warming threshold, 2) the viability/costs of currently unproven CDR techniques, and 3) the cost of un-adapting to warming that we may have already adapted to by the time the CDR becomes viable.
If and when when effective affordable CDR is identified, it would then be useful to include it in modeling scenarios.
Well, there are really two issues here: one, the amount of residual emissions we will have that cannot otherwise be mitigated (at least cost-effectively), and two, the amount of net-negative global emissions that will be needed to deal with overshoot.
I agree that the latter is a second-order consideration until we actually get to net-zero, but its important for policymakers to understand that whatever warming we end up with once we get to that point is more or less permanent in the absence of extremely costly CDR.
I'd point out that the cost/feasibility of CCS/CDR depends on the cost of energy whether for the reduction reaction itself or the manipulation of the the reactants. This id true even for exothermic reactions such as serpentine carbonization as the material has to be brought into contact with CO2 dissolved in water.
This clear analysis of the true nature of the climate crisis should be required reading for all students in University, and for our policymakers. The analysis reveals the enormous challenge that the world now faces!
The question of what is an acceptable atmospheric CO2 target is an important one. If the projections of the International Energy Agency hold true, we are "bending the emissions curve" and will hit worldwide anthropogenic CO2 emissions this decade, perhaps as soon as 2025. This is an important milestone objective that leads to the subsequent milestone objective of achieving a balance between anthropogenic emissions and removal by sinks, both of which are explicitly identified in the 2015 Paris Agreement. With ongoing removals by the natural sinks (ocean and land), which so far continue to pull CO2 down at rates that are directly proportional to atmospheric levels, we can expect atmospheric levels to peak, then fall. Hence, we need international agreement on targets for atmospheric CO2 levels.
I wrote this commentary on the subject 4 months ago.
The question of removing excess atmospheric CO2 if we overshoot 1.5°C or 2°C over pre-industrial temperature is problematic.
First, a target for the acceptable atmospheric CO2 concentrations must be set. This is not a scientific exercise because this value reflects a level of acceptable climate disruption. One suggestion is to set this to pre-industrial CO2 levels (~280 ppm), which implies a return to pristine conditions. Another is the level associated with the first recognized climate-related impacts (e.g., premature cherry blossoms in Japan in late 1980's, ~350 ppm). Perhaps it should be set at the level when the first devastating climate event occurred (Hurricane Katrina, August 2005, ~375 ppm). Should it be set to 1.5°C (425-430 ppm)? There is no easy answer.
Secondly, how would the costs for reaching this target be allocated? Should it be proportional to the total mass of CO2 originating from each country? Should it be based on a country's GDP? Can a country escape its responsibility during a recession?
Thirdly: it is likely that we will overshoot whatever limit we set during the transition period to a fossil fuel-free world. During this transition, we will build a substantial capacity for carbon removal, whether DAC plants or enhanced weathering systems or other. This capacity will remain available after our emissions flattened out and is likely to be used to drawdown excess CO2. However, there will be a discrepancy between where this capacity is located and which country needs to pay for removals. This is not an insurmountable problem, but it will require thoughtful negotiation.
One thing is certain: this is a clean-up exercise and paying for this obligation will be a drag on any economy. This means that every country will argue for paying the least possible amount. It is also likely that we will be cleaning up the atmosphere for the rest of this century, so the question of costs is not trivial. That's a good reality-check to anyone proposing that we remove excess atmospheric CO2.
I find that the current political climate in Oklahoma and my community is that government and even the press refuse to disclose any evidence information to the public and mitigation measures that individuals can follow. Climate change is not even debated or discussed here except in the mode of misinformation.
It’s up to individuals and the groups they form to inform and take action. Grassroots efforts are gaining momentum but not fast enough; the majority of the people(family and community) listen with their ears shut or decide not to pursue any action now. They are too busy trying to keep solvent, raise their children, care for aging parents….
Willful ignorance is rampant.
However it does irk people when you try to live deliberately:
-no single use plastic items like water and beverages in single use containers
-recycling and composting
-no mow yards, no pesticides, no herbicides, no synthetic fertilizers
-Only native plants in the landscape
-replacing all gas appliances 5 yr plan
-driving to accomplish errands once a week
-limiting extraneous flights and travel
-hanging the sheets and towels outside to dry
-Using bar soap instead of liquid soap
-Open windows at night
-grow your own veggies and a row for the food bank
-give talks to your book group, coffee group,
-share your yard and gardening ideas at an open house
-never use the plastic grocery bags at the grocerystore
-never by fast food and drinks in a plastic container
YOUR ACTIONS SPEAK VOLUMES
WHY?? For THE FUTURE OF YOUR CHILDREN AND THE NEIGHBORS CHILDREN
SHARE THIS NEWSLETTER WITH YOUR FAMILY GROUP FACEBOOK OR GROUP MESSAGE
Regarding halting GHG releases, and proposed cheap effective ways of carbon sequestration:
1.We must clarify - people must learn: The climate crisis is not like an incurable disease, it results from what we keep doing, itis a side effect of misguided economic growth, and we as a society (not primarily as individuals) have an ethical duty to halt the ‘crazy’ developments. We urge that all concerned people make efforts to influence influential people so that our leaders will be pressured to act decisively - radically –effectively. We need a "Pearl Harbor moment" – then our economy was turned upside down and the civilian economy was halted.
2. Governments must guide and fund public-private partnership nonprofit enterprises that will reform industries, transportation systems, and land management. We need to plant trees, bamboo, kelp, etc. use extreme white paint in place of more air conditioners, use wood and bamboo instead of steel and concrete, ultra-light vehicles, electric buses and a comprehensive rail system with mostly narrow-track light rail lines, halt the industrialized "animal husbandry" etc.
3.To sequester huge amounts of carbon, we must not only grow much fast-growing plants and utilize wood and bamboo as building materials we must prevent the burning and decomposing of organic material(this includes much of today’s landfill trash and dead wood removed from forests). Material may be kept dry, ice cold, or buried inground that is soaked in stagnant water (to were it gradually becomes peat); water-logged wood may also be sunk into dead zones of cold lakes and oceans.Â
Really interesting post. IMO we'll have to balance well the interest of future generation and the interest of the current one. Degrowth for sure i not an option the majority will agree, but some middle ground has to be reached.
One more thing. Do you think we will also have to filter the sea from CO2? From what I know, if we won't the sea will acidify quite a bit, and the deep sea will probably reach high concentrations of CO2 if we don't do something.
Nice post! The most important point I take for this is the need to include CO2 capture and sequestration research as of equal priority with finding ever less expensive ways to avoid CO2 emissions and incentives given for emission avoidance should apply equally to removal.
At first I thought this was an older article, but no. We have convincingly crossed the 1.5C threshold already and are well on our way to marking 2C in the next decade.
"The Paris Agreement’s aspirational 1.5C target, in particular, has more or less become defined as an overshoot scenario."
In my opinion, it is media vibes that have "more or less defined" 1.5C to be an actual "uncrossable" threshold, rather than rigorous analysis. There may be an optimal warming threshold for defining overshoots or the carbon debt, but computing that would involve Nordhaus-type socioeconomic cost estimates that are highly uncertain and controversial.
I'm all for rapid emission reductions to limit global warming. I also support modest funding of research/experiments on CDR/geoengineering. I'm much less enthused about models or scenarios that rely on the actual deployment of CDR/geoengineering. Modeled scenarios of how much CDR we'll need are popular with CDR proponents, but they seem to be distraction from the main task at hand: mitigation+adaptation+research. If anything, focusing on any non-zero CDR deployment lessens the pressure for strong mitigation measures now.
We don't know how much CDR should be used to correct for overshoots because we don't know 1) the optimal warming threshold, 2) the viability/costs of currently unproven CDR techniques, and 3) the cost of un-adapting to warming that we may have already adapted to by the time the CDR becomes viable.
If and when when effective affordable CDR is identified, it would then be useful to include it in modeling scenarios.
Well, there are really two issues here: one, the amount of residual emissions we will have that cannot otherwise be mitigated (at least cost-effectively), and two, the amount of net-negative global emissions that will be needed to deal with overshoot.
I agree that the latter is a second-order consideration until we actually get to net-zero, but its important for policymakers to understand that whatever warming we end up with once we get to that point is more or less permanent in the absence of extremely costly CDR.
I'd point out that the cost/feasibility of CCS/CDR depends on the cost of energy whether for the reduction reaction itself or the manipulation of the the reactants. This id true even for exothermic reactions such as serpentine carbonization as the material has to be brought into contact with CO2 dissolved in water.
Glad to see this. Precisely what we have also been saying here: https://osf.io/preprints/osf/b3wkr
Thanks Stephanie, I've always found your work on this and related topics quite valuable!
This clear analysis of the true nature of the climate crisis should be required reading for all students in University, and for our policymakers. The analysis reveals the enormous challenge that the world now faces!
The question of what is an acceptable atmospheric CO2 target is an important one. If the projections of the International Energy Agency hold true, we are "bending the emissions curve" and will hit worldwide anthropogenic CO2 emissions this decade, perhaps as soon as 2025. This is an important milestone objective that leads to the subsequent milestone objective of achieving a balance between anthropogenic emissions and removal by sinks, both of which are explicitly identified in the 2015 Paris Agreement. With ongoing removals by the natural sinks (ocean and land), which so far continue to pull CO2 down at rates that are directly proportional to atmospheric levels, we can expect atmospheric levels to peak, then fall. Hence, we need international agreement on targets for atmospheric CO2 levels.
I wrote this commentary on the subject 4 months ago.
The question of removing excess atmospheric CO2 if we overshoot 1.5°C or 2°C over pre-industrial temperature is problematic.
First, a target for the acceptable atmospheric CO2 concentrations must be set. This is not a scientific exercise because this value reflects a level of acceptable climate disruption. One suggestion is to set this to pre-industrial CO2 levels (~280 ppm), which implies a return to pristine conditions. Another is the level associated with the first recognized climate-related impacts (e.g., premature cherry blossoms in Japan in late 1980's, ~350 ppm). Perhaps it should be set at the level when the first devastating climate event occurred (Hurricane Katrina, August 2005, ~375 ppm). Should it be set to 1.5°C (425-430 ppm)? There is no easy answer.
Secondly, how would the costs for reaching this target be allocated? Should it be proportional to the total mass of CO2 originating from each country? Should it be based on a country's GDP? Can a country escape its responsibility during a recession?
Thirdly: it is likely that we will overshoot whatever limit we set during the transition period to a fossil fuel-free world. During this transition, we will build a substantial capacity for carbon removal, whether DAC plants or enhanced weathering systems or other. This capacity will remain available after our emissions flattened out and is likely to be used to drawdown excess CO2. However, there will be a discrepancy between where this capacity is located and which country needs to pay for removals. This is not an insurmountable problem, but it will require thoughtful negotiation.
One thing is certain: this is a clean-up exercise and paying for this obligation will be a drag on any economy. This means that every country will argue for paying the least possible amount. It is also likely that we will be cleaning up the atmosphere for the rest of this century, so the question of costs is not trivial. That's a good reality-check to anyone proposing that we remove excess atmospheric CO2.
I find that the current political climate in Oklahoma and my community is that government and even the press refuse to disclose any evidence information to the public and mitigation measures that individuals can follow. Climate change is not even debated or discussed here except in the mode of misinformation.
It’s up to individuals and the groups they form to inform and take action. Grassroots efforts are gaining momentum but not fast enough; the majority of the people(family and community) listen with their ears shut or decide not to pursue any action now. They are too busy trying to keep solvent, raise their children, care for aging parents….
Willful ignorance is rampant.
However it does irk people when you try to live deliberately:
-no single use plastic items like water and beverages in single use containers
-recycling and composting
-no mow yards, no pesticides, no herbicides, no synthetic fertilizers
-Only native plants in the landscape
-replacing all gas appliances 5 yr plan
-driving to accomplish errands once a week
-limiting extraneous flights and travel
-hanging the sheets and towels outside to dry
-Using bar soap instead of liquid soap
-Open windows at night
-grow your own veggies and a row for the food bank
-give talks to your book group, coffee group,
-share your yard and gardening ideas at an open house
-never use the plastic grocery bags at the grocerystore
-never by fast food and drinks in a plastic container
YOUR ACTIONS SPEAK VOLUMES
WHY?? For THE FUTURE OF YOUR CHILDREN AND THE NEIGHBORS CHILDREN
SHARE THIS NEWSLETTER WITH YOUR FAMILY GROUP FACEBOOK OR GROUP MESSAGE
IRKSOME AS IT IS
Excellent article. Thank you. I find it helpful.
Regarding halting GHG releases, and proposed cheap effective ways of carbon sequestration:
1.We must clarify - people must learn: The climate crisis is not like an incurable disease, it results from what we keep doing, itis a side effect of misguided economic growth, and we as a society (not primarily as individuals) have an ethical duty to halt the ‘crazy’ developments. We urge that all concerned people make efforts to influence influential people so that our leaders will be pressured to act decisively - radically –effectively. We need a "Pearl Harbor moment" – then our economy was turned upside down and the civilian economy was halted.
2. Governments must guide and fund public-private partnership nonprofit enterprises that will reform industries, transportation systems, and land management. We need to plant trees, bamboo, kelp, etc. use extreme white paint in place of more air conditioners, use wood and bamboo instead of steel and concrete, ultra-light vehicles, electric buses and a comprehensive rail system with mostly narrow-track light rail lines, halt the industrialized "animal husbandry" etc.
3.To sequester huge amounts of carbon, we must not only grow much fast-growing plants and utilize wood and bamboo as building materials we must prevent the burning and decomposing of organic material(this includes much of today’s landfill trash and dead wood removed from forests). Material may be kept dry, ice cold, or buried inground that is soaked in stagnant water (to were it gradually becomes peat); water-logged wood may also be sunk into dead zones of cold lakes and oceans.Â
Heinz Aeschbach, MD, pres. of Humane Civilization Worldwide, hae.hcw@gmail.com humanecivilization.org Â
Really interesting post. IMO we'll have to balance well the interest of future generation and the interest of the current one. Degrowth for sure i not an option the majority will agree, but some middle ground has to be reached.
One more thing. Do you think we will also have to filter the sea from CO2? From what I know, if we won't the sea will acidify quite a bit, and the deep sea will probably reach high concentrations of CO2 if we don't do something.
Nice post! The most important point I take for this is the need to include CO2 capture and sequestration research as of equal priority with finding ever less expensive ways to avoid CO2 emissions and incentives given for emission avoidance should apply equally to removal.
Bearing in mind that its very often cheaper not to put CO2 into the atmosphere in the first place…
Right now, very much. I just want to keep an equal incentive so that when/if costs fall, CCS will be appropriately encouraged.
Thank you Zeke. You have touched upon several aspects that are of real concern to me, and so many others.
At first I thought this was an older article, but no. We have convincingly crossed the 1.5C threshold already and are well on our way to marking 2C in the next decade.
No, we have not cross the 1.5C target, at least as its been defined by the IPCC. https://www.carbonbrief.org/analysis-what-record-global-heat-means-for-breaching-the-1-5c-warming-limit/