Roger Pielke Jr had a recent guest post on his substack by Tom Wigley called Net-Zero Does Not Mean What You Think it Does. The post concluded that CO2 emissions do not need to be eliminated to meet the Paris targets and that uptake by the natural sinks means that CO2 emissions can remain positive for a very long time. I was slightly surprised, since this didn’t seem consistent with our current understanding, but it was based on some slightly older work and I thought it may not be quite up-to-date with our current understanding.
However, I’ve since watched some of a recording of a debate between Roger Pielke Jr and Steve Koonin on “Is net zero by 2050 both achievable and necessary to address climate change?” The first question you reasonably might ask is why they would arrange a debate on this topic between these two speakers, but that isn’t the point of this post. In the recording Roger explains what net zero is and suggests that it’s the point at which emissions are balanced by the natural sinks (oceans and biosphere) and, hence, that net zero requires emission reductions of about 80%, rather than 100%.
This is simply wrong. It’s very clear that net-zero means that anthropogenic emissions are zero, with any residual positive emissions balanced by negative emissions that lead to essentially permanent geological storage, hence the “net”. The latest IPCC report says explicitly:
Net zero CO2 emissions: Net zero carbon dioxide (CO2) emissions are achieved when anthropogenic CO2 emissions are balanced globally by anthropogenic CO2 removals over a specified period.
The scientific under-pinnings of net-zero go back to papers published in about 2008 (e.g., Matthews & Caldeira 2008) demonstrating that when anthropogenic emissions go to zero, global average surface temperatures would soon stabilise. The reason for this is that we currently have a planetary energy imbalance that – all else being equal – would lead to continued warming so as to return the system to energy balance. When anthropogenic emissions go to zero, the natural sinks continue to take up some of what has been emitted so that atmospheric CO2 concentrations go down in such a way as to compensate for this unrealised warming.
Of course there are uncertainties (there could be some additional warming, or even some cooling) and there are other slower feedbacks that are not considered (carbon released from the permafrost, for example). However, the best estimate today is still that, on multi-decadel timescales, the zero-emission commitment is close to zero.
Roger’s definition of net-zero would lead to stabilised atmospheric CO2 concentrations, rather than stabilised global surface temperatures. Given that the system is not yet in energy balance, stabilising concentrations would lead to continued warming. Since atmospheric CO2 concentrations are already 420 ppm, even if we could achieve ~80% reductions in emissions by 2040, we’d probably have concentrations of ~440 ppm. If you calculate the equilibrium warming for such an atmospheric CO2 concentration, assuming an ECS of 3oC, it’s about 2oC. So, Roger’s definition of net-zero is essentially committing us to at least 2oC of warming. Also, if emissions don’t eventually go to zero, concentrations would start rising again, and warming would resume.
So, to clarify, net-zero does not mean that positive anthropogenic emissions are balanced by uptake by the natural sinks so that emissions just need to be reduced by ~80%, it means reducing anthropogenic emissions by 100% with any positive anthropogenic emissions being balanced by “permanent” anthropogenic negative emissions.
You might be surprised that someone could engage in a high-profile debate about net-zero without properly understanding what the term means and the scientific understanding that underpins the term. Of course, if you’re a long-standing veteran of the public climate debate, this is entirely expected. Evidence would suggest that Roger doesn’t regard being properly informed about a topic as being a pre-requesite for making confident assertions about the topic.
...and Then There's Physics 
Oh… my… gosh… Someone finally spelled Caldeira correctly! It’s a breakthrough and vastly more important than any discussion whatsoever of net zero! Yay ATTP!!!!
As usual, there’s something I meant to add to the post, but forgot. A key point about net-zero is that it allows us to determine carbon budgets. In other words, how much more can be emitted while still giving a good chance of meeting some kind of warming target. A carbon budget clearly implies that there must be a point when emissions stop (i.e., go to zero) which would not be the case if we only reduced them by ~80%.
Thanks, but your argument here is not with me (sorry!) but Tom Wigley, whose post is here: https://rogerpielkejr.substack.com/p/net-zero-does-not-mean-what-you-think
My views on net-zero can be found in The Climate Fix. Good to see you are still fighting the good fight.
Roger,
Most of the post was about what you said in your opening remarks in the debate with Steve Koonin. You did seem to claim that net zero only required emission reductions of ~80% because some goes into the oceans, earth’s surface, plants, biomass.
I see you’re also still fighting the “good” fight.
https://rogerpielkejr.substack.com/p/when-science-influencers-polarize
Yes, that comes straight from Wigley’s post;
“The CO2 budget that determines future CO2 concentrations is the sum of sources — anthropogenic emissions and positive feedbacks — offset by sinks of CO2 into the ocean and terrestrial biosphere. These two sinks, no matter what the emissions, change only slowly over time and remain significant for centuries into the future, and this allows CO2 emissions in both 1.5°C cases to remain positive — of order 3.5 to 7 GtCO2/yr for all times after 2150 out to 2400.”
As I also said in that debate, people love to argue about the last tonne of CO2, when really we should be discussing the next tonne, and the one after that. I’m pretty sure that if we can get to 80% we can get to 90% or 100%. Makes no difference to near term policy options.
I find it funny you decided that between me and Koonin, I’m the one you decided to pick a tiny nit with. It is always personal for you, which is not funny, but kinda sad.
Roger,
Thanks for clarifying, but it’s still not the correct interpretation of what is meant by net-zero. I’ll add that one reason – I think – why Tom’s model was able to meet the 1.5C target while maintaining some positive emissions was because – in his model – emission reductions started (I think) in 2015. Given that this didn’t actually happen means that his claim that we could have sustained emissions while still meeting this target is almost certainly no longer true. Today, the remaining carbon budget for 1.5C is about 250 GtCO2. https://www.nature.com/articles/s41558-023-01848-5
In many respects I agree, but – IMO – it does make a difference if people don’t understand that there is still quite a big distinction between reducing emission by 80% and (net) zero.
Have you ever considered just going “fair enough, I got that one wrong”?
Apologies if you saw multiple comments appearing and disappearing. The comment editor on the blog appears to have changed and I kept messing up the formatting.
My comments at the debate were with respect to balancing out sources and sinks by whatever date we choose to reach net-zero so as to eliminate the energy imbalance cause by accumulating CO2. I don’t think 1.5C was mentioned at the debate at all, and certainly not by me.
Your complaint about hitting 1.5C target, again, is with Wigley. You may have his email (and I can certainly pass along), so if you’d like to send a response to him, I can help. Once again, its not about me. Lots of more significant issues to debate, I’m sure you can identify them.
In my view, 1.5C is, to borrow a phrase, “deader than a doornail” and not particularly useful as a policy target in 2023. In TCF I call for net-zero and also zero-zero (or whatever we call it), if we don’t want to use the oceans as a CO2 sponge. So yes, I’m pretty comfortable with my views here.
Roger,
I think you misunderstand my point about Wigley’s argument. I wasn’t complaining about his argument, simply pointing out that even *if* it were technically correct that we could have hit the 1.5C target while sustaining some positive emissions, this is almost certainly no longer the case.
Except balancing the sources and sinks is not the definition of net-zero. The definition of net-zero very clearly refers only to anthropogenic sources and sinks. If we simply balanced the sources and sinks we’d still have an energy imbalance and would have continued warming until energy balance was achieved.
On the other hand, when we reach net-zero we expect warming to stop fairly quickly (with some caveats) because of the reduction in concentration compensating for this unrealised warming (i.e., the sources and sinks aren’t actually in balance because the sinks would be continuing to take up some of what has been emitted).
Since it’s getting rather late here, can I ask that if anyone else is going to engage in the discussion that they try to meet my initial intentions for the blog of “keeping the discussion civil.”
Again, this is a response to Wigley, as it is not a claim I’ve made or would make:
“even if it were technically correct that we could have hit the 1.5C target while sustaining some positive emissions, this is almost certainly no longer the case”
Under the UNFCCC “net-zero” is actually in regard to GHG forcing overall, and not just CO2. At our debate we focused narrowly on net-zero CO2. The points you are raising here are immaterial to that discussion, and are ones I’ve covered explicitly in TCF.
I acknowledge that you believe 100% emissions reductions should be a target. In contrast, I’m pretty happy with 80% or 90%, at least as a starting aspiration. We can agree to disagree, its OK, no need to hurl aspersions or insults.
In any case, it’s a meaningless distinction when it comes to what sorts of policies make sense in the 2020s.
Tom Wigley is not the one who’s making the claims in that video:
Back in my days, presenters owned their claims.
Besides, if a claim does not matter in the grand scheme of things, why make it?
It makes little sense to argue that we ought to shave 20% off a claim that does not matter to us.
Imagine thinking that I have claimed that we can hit 1.5C
The 1.5 Degree Temperature Target is a Dead Man Walking
https://rogerpielkejr.substack.com/p/the-15-degree-temperature-target
You guys have anything else? 😉
A two-author book tour pitch in an echo chamber is not exactly an Oxford Union debate.
Much as my views have evolved , it’s sincerely flattering to see Steve cleave to the outline of my 1990 National Interest article
https://www.jstor.org/stable/42894680
Imagine if an honest broker came here and said my book is 20% less than the retail price but you should not buy it. The infelicity would be different than with Moorean sentences. There still seems to be some familienähnlichkeit that deserves due diligence.
Insert your favorite emoji.
He’d have to posthumously misrepresent Steve Schneider first, which come to think of it, he just did.
How should I know?
From dining with Tim Wigley and Steve Schneider at an Asilomar Conference 200 miles & twenty years North ,and after, first meeting Steve at General Atomics.
I ,like Tim , and Steve ,meant it about focusing on clean nuclear to span the energy storage gap.
The Steve met at General Atomics in 1989 was, of course, Koonin, rather than Schneider.
Roger,
Again, I didn’t suggest that this is a claim you would make. I was simply commenting on the Tom Wigley post on your substack.
This isn’t really what I believe and I don’t recall hurling aspersion or insults. All I’m pointing out is that the definition of net-zero is that anthropogenic CO2 emissions are reduced by 100%, either by actually stopping all emissions, or by using negative emissions technologies to balance any residual positive emissions.
To be fair, the comments I’ve had on Twitter suggest that there are quite a lot of people who are still confused about this distinction, but there is no doubt that net-zero requires emission reductions of 100%, not 80%.
I agree that the policies we might implement in the near-term probably won’t depend on whether we’re aiming for 80% or 100%, but that still doesn’t change that net-zero is not aiming for 80%. Of course, if you want to argue for something other than net-zero, you’re obviously free to do so.
“I agree that the policies we might implement in the near-term probably won’t depend on whether we’re aiming for 80% or 100%”
I’d strongly disagree with this actually. 100% is far, far more difficult than 80%, and we’d need to make a massive change in infrastructure to get there.
including, but not limited to: regulation on buildings, ending all airport construction, stopping new fossil fuel extraction etc etc. There’s no way we can suddenly change trajectory in 20 years time to achieve net zero, we’d need to do it aggressively now. And even then, we’d probably miss it.
VTG,
That’s a fair point. I agree with Roger that there will probably be similarities between near-term policies, but you’re probably right that mopping up that final 20% could be very challenging and may well require starting now to think about how we would do so.
For the record, here is a copy of a reply by Roger to a comment by Michel de Rougement at THB,
“Yes, 2050 is a big ask. Note that net-zero is not zero, more like -80%. Still huge.”
Ref. https://rogerpielkejr.substack.com/p/can-we-reach-net-zero-and-achieve/comments
We know what the models say, you have to get to net-zero CO2 to stop global warming and they take into account the sinks,
https://www.carbonbrief.org/explainer-will-global-warming-stop-as-soon-as-net-zero-emissions-are-reached/ and https://www.nature.com/articles/s41558-022-01372-y .
If you include aerosols and other GHGs, then because of their relative lifetimes in the atmosphere, you get an initial warming as the aerosols drop out and then cooling as the other GHGs decrease.
If we are looking for agreement about difference in policies today to get to 80% vs. 100%, I mostly agree. I believe that most energy experts, e.g., Jesse Jenkins and John Bistline, would agree that the U.S. can get to an 80-90% reduction in GHG with existing technologies, if we do the following:
– Deploy wind and solar as fast as we can
– Shut down coal as fast we can
– Keep existing nuclear and natural gas where necessary and even add natural gas capacity where necessary if it replaces coal
– Expand the grid.
Refs.: https://www.volts.wtf/p/what-the-sun-isnt-always-shining#details and https://www.nytimes.com/2022/04/10/opinion/environment/ipcc-report-climate-change-debates.html
The last 10-20% is the hard part and will take investment today in long duration energy storage technologies and firm dispatchable generation like advanced nuclear, advanced geothermal, and natural gas with carbon capture.
ATTP,
This is part of the equation but I feel like you’re missing the timescales and temperature values shown on Wigley’s graph. The 1.5a scenario is at 1.9C at 2100, only very slowly descending to 1.5C over the next 300 years. There are vanishingly few people who would consider this consistent with the Paris 1.5C target. I suspect most wouldn’t even consider it consistent with the 2C target given the “well below” wording.
I wonder if Wigley is simply from a generation which typically modelled in terms of concentrations and concentration stabilisation, so in his head net zero means stopping concentration growth. Having said that, Wigley’s emissions graph shows only fossil fuel emissions. What is land use doing? Does Wigley consider that part of natural sinks?
There’s also a little oddity in the 2C scenario that CO2 levels stabilise mid-21st Century at about 450ppm (constant thereafter), after which temperature rise halts pretty quickly then starts declining. There should still be a significant positive imbalance at this time due to elevated CO2 so this indicates a substantial source of increasingly negative forcing change in the model. Presumably this is from declines in non-CO2 GHGs. Methane should have declined sharply with CO2 emissions through the 21st Century so shouldn’t be contributing much to later cooling. One thing I’ve seen before, and I suspect may be happening here is that GHGs like N2O have emissions set to zero after 2100, which is totally unrealistic. This also suggests the model doesn’t adequately factor in aerosol forcing.
Paul,
Thanks. Yes, I did notice some of those oddities and wasn’t quite sure how to interpret them. Good point about the 1.5a scenario peaking at about 1.9C and that declines in non-CO2 GHGs potentially playing a big role in the 2C scenario.
I tend to think that the only way to have a constructive convo with some folks about what those folks have said is to avoid pointing out that it is those in particular who said it. Most often, no matter who it is, otherwise you’ll just get into a form of “identity politics.” This would extend to individuals or groups with which individuals identify (or are identified).
It must be said that Steve Koonin and Tom Wigley’s consistent advocacy of nuclear power, like Steve Schneider’s insistence on giving it a fair hearing, long antedates the climate wars on Capitol Hill.
Nobody ever wanted to turn the sky into a chemical waste repository, and the search for alternatives began at the dawn of the atomic age.
Another intriguing formulation: “I acknowledge that you believe 100% emissions reductions should be a target.” To see its infelicity, transpose it into the following informal dialogue:
(VLAD) This book is 20% less than the retail price.
(ESTR) This is simply wrong. It’s very clear that retail price is 100%, and the Books Retail Price Broker clearly states that…
(VLAD) I acknowledge that you believe that the retail price is 100%.
Estragon’s belief is irrelevant here. Only what the Books Retail Price Broker states matters. In our case, it’s the IPCC.
For more on informal dialogues:
for fucks actual sake if yore going to pick a goal, pick a measurable one
Steven,
I don’t actually know what you’re referring to.
Ironically I felt somewhat more optimistic after watching this
The first comment from Sabine is also worth reading. I find it easier to have confidence in people that own their mistakes and correct them.
I haven’t watched it, but I did see that she had to re-upload it after someone pointed out a major error. Not sure what the error was, though.
Sabine writes:
“That’s because the first version of the video contained a serious mistake, which is that I said that temperatures would continue to increase after reaching net zero. I had forgotten that carbon dioxide is taken up slowly from the atmosphere by natural processes, so left to its own devices the levels will actually slightly decrease. This together with the lag of temperature behind the carbon dioxide level is expected to stabilize temperatures. (Provided no other sources contribute, like methane leaks from the ground etc.)”
Very good science communicator (IMO). Just visiting briefly to post it as I thought it was relevant/useful.
Thanks.
The most accurate assessment is that we can’t be sure what will happen when we hit net zero. We have no reliable means to know how the biosphere will respond to a net zero condition. At this point, the best we can say is that we should do everything we can as fast as we can to reach net zero to reduce harm. After we reach net zero, we should continue to work to begin reducing greenhouse gases in the atmosphere and oceans and hope that our biosphere might rock slightly back toward the planetary conditions that existed in the holocene. The anthropocene looks likes a nasty place for many species on the planet. We need to walk the anthropocene back toward holocene conditions. Net zero is simply a spot on that global emission reduction project, it is a convenient mile marker, it is not a final destination. Sabine seems like an optimist. I enjoy listening to her sometimes.
Regarding whether warming will continue after net-zero, Sabine’s corrected claim is now in line with Zeke Hausfather’s expectation ( carbonbrief.org/explainer-will-global-warming-stop-as-soon-as-net-zero-emissions-are-reached). He thinks natural drawdown will roughly keep pace with greenhouse effect feedbacks, so GMST should remain stabilize at the highest value it reached before net-zero.
Yikes!
Not exactly written from a perspective of journalistic remove, but quite interesting and seems pretty thorough.
When Idiot Savants Do Climate Economics
How an elite clique of math-addled economists hijacked climate policy.
Christopher Ketcham
Thinking about net zero, I would be much happier without the “net”. “Net” adds complication and causes us to emit more today than we should. Look out if we can’t or won’t remove CO2 at scale in the future.
Zero increase, or flat emissions levels, is hard to understand or calculate, but might be more descriptive and easier to understand than net zero. Zero increase or flat emissions doesn’t mean zero emissions. It just means zero increase over past year when the usual variables are smoothed out. The zero increase declaration would need to allow for the wobbles that arise from things like ENSO, etc. Net zero has always made the hairs on the back of my neck stand up because I immediately assume the net zero number is going to be gamed by industries and nation states that want to count offsets and carbon credits that have been purchased, but have not proven to be effective.
In that zero increase or flat emission level context, how are we we doing right now? Not close. No reason to start calculating the wobbles when the raw increase number is 3.08 ppm increase over a year ago.
October CO2
Oct. 2023 = 418.82 ppm
Oct. 2022 = 415.74 ppm
per co2.earth.
And, that’s just CO2, the big dog. We also have methane increase, the little nasty dog, a vicious ankle biter.
Cheers
Mike
SBM, any level of fossil carbon emissions above zero, without a matching increase in reuptake, will result in some positive trend of global heat content.The atmospheric carbon reservoir, which reflects the balance of natural emissions and reuptake, was stable before the transfer of fossil carbon from geologic sequestration began. Without artificial removal, the atmospheric CO2 concentration will continue to rise as long as any fossil carbon is being burned. I’m pretty sure you know all this!
It appears delusional, if not psychotic to discuss whether ‘Net Zero’ is a reduction of CO2 emissions to 0% or 20% of current levels when the fossil fuel companies and state institutions that extract oil and gas have no plans to reduce production. In fact most are planning on expanding production.
https://www.cdp.net/en/articles/media/research-reveals-no-oil-and-gas-companies-have-plans-in-place-to-phase-out-fossil-fuels
“The oil and gas sector’s failure to address emissions from its products and operations hampers international efforts to limit global warming to 1.5C. In the run up to COP28 in Dubai, all eyes are on the oil and gas industry. But these companies are not planning for a low-carbon future and are failing to take responsibility in the immediate and long term. It is deeply concerning that no companies have made a commitment to halt the expansion of fossil fuel activities before 2030.”
In fact most of the big producers of fossil fuels are investing in new sources and are very likely to exceed the levels of oil and gas extracted to remain within the 1.5degC limit by over 15 billion barrels.
Or around 8 Gigatons of extra CO2.
Joshua,
That received mixed reviews on social media. One issue, in my view, is that climate/environmental economics is much broader than simply Nordhaus-like IAMs, which I think the article mostly ignored.
to izen: yes, that commitment to finding and extracting more fossil fuels is startling, isn’t it? How do we reach zero or net zero when we keep burning more fossil fuels? We don’t. Those are the fact on the ground and under the ground that make discussion of emission reduction and capture of some sort that might help us return to any semblance of the “stable” conditions of the holocene sound pretty foolish. Yes, this is the area for the idiots and idiot savants to step in and dazzle the Nobel Committee and the various economic growth thinktank folks. We live in strange times.
Anders –
It’s certainly a polemic. I always take polemics with a grain of salt, but nonetheless it’s information and for me educationsl.
And it’s always a plus to read someone take a shot at Tol.
IZEN:
” likely to exceed the levels of oil and gas extracted to remain within the 1.5degC limit by … around 8 Gigatons of extra CO2″
True enough but demography has changed since global emissions were last in the 8Gt range— in 1913!
:-).
Quite often I see people objecting to the manner in which some criticise climate economics, which I often think ignores that one of the most prominent climate economist that many have encountered is Richard Tol. If Tol really is representative of the discipline then the tone of the criticism seems more justified.
I like to be hopeful that he’s not representative.
He makes some of the worsts arguments I’ve seen in blog comments.
I have to think his reasoning in his science would be better then in his blog comments but his blog comments are so bad it seems reasonable to speculate that perhaps not.
Likewise, but he does provide some doubts.
I do think there is quite a big difference between what he publishes in the academic literature, and the type of stuff he writes in blog comments.
Here are some facts that give me hope that at least most U.S. utility companies have “seen the light” and are working to get to net zero emissions by 2050. Maybe they should send a memo to the fossil fuel industry.
1. Coal is dying in the U.S. The percentage of electrical generation by coal decreased from 51.7% to 19.7% between 2000 and 2022. The last coal plant over 100 MW in the U.S. went online in 2013. It will probably be the last one ever built. Ref. EIA
2. Specific emissions of electrical generation in the U.S. have dropped by 40% between 2000 and 2022 from 650 kg/MWh to 443 kg/MWh. Ref. EIA.
3. Renewable generation surpassed coal and nuclear in the U.S. in 2022. When combined with nuclear, carbon-free sources now account for nearly 40% of the electrical generation in the U.S. Ref. EIA.
4. The only fossil fuel competitive with renewables in the U.S. is natural gas. It emits 57% less CO2 per MWh compared to coal, 443 kg/MWh vs 1025 kg/MWh. If it displaces coal, it is still a win. Most utilities see it as transition source on their way to carbon-free generation. Ref. EIA.
5. Rocky Mountain Institute analyzed the Integrated Resource Plans of 104 utilities in the U.S. through 2035. Those utilities plan to deploy greater than 4 times more carbon free generation than natural gas generation between now and 2035.
6. 80% of U.S. utility customer accounts are served by utilities that have net-zero emission targets by or before 2050. Ref. Smart Electric Power Alliance.
I agree with you, Dean. There is some real progress being made at changing over from the worst forms of emission practices. That is definitely encouraging. The hard part is that Jevon’s Paradox seems to happening, so even as we convert to less polluting practices, our actual emission number and the accumulation numbers in the atmosphere and ocean continue to rise at a pace that should scare any sensible person. This is interesting to watch because it is another demonstration of the Jevon’s thing, but it is also discouraging to watch because the rising numbers in the ghg accumulation columns are indifferent to our improved processes, all they record is that the emissions continue to rise.
I have been hearing for many years that we might be seeing the peak of emissions, that the rate of increase has now levelled off and will start to slip down toward no rise, but looking in the rear view mirror I cannot yet observe a moment or time when the CO2 increase stopped rising at a scary rate. I think the current rate of increase is probably about 2.4 ppm per year. Maybe it is less, maybe it is only 2 ppm?
Here is the current reading of those numbers from co2.earth:
October CO2
Oct. 2023 = 418.82 ppm
Oct. 2022 = 415.74 ppm
There is noise in these numbers. If you look at ten year periods, you can get some of the noise out of the way.
Cheers
Mike
@-rs
“True enough but demography has changed since global emissions were last in the 8Gt range— in 1913!”
I would agree that the planned overshoot looks quite small. The goal of 1.5degC is also arbitary, although it is based on good arguments from likely damage.
However, consider how much more advantageous such a figure would be if it was an undershoot, 8Gt more than the reduction considered nessecary to meet the 1.5degC limit.
Of course if CO2 reductions had been pursued seriously since it became apparent they are required, 8Gt might have been the total emissions planned for next year.
Instead of just the extra over the recommended amount.
@ SBM,
I understand. The CO2 emissions for advanced economies have peaked and are falling. Emissions for developing economies, China and India, are growing and that is why emissions are staying flat. I do believe based on multiple sources that emissions will peak before 2030. I wish I had better news.
Dean
Kate Marvel has an OpEd in today’s NYTimes (https://www.nytimes.com/2023/11/18/opinion/climate-change-report-us.html), reflecting on her experience as a chapter author for the 5th US National Climate Assessment (https://nca2023.globalchange.gov/). I was startled to read this from Dr. Marvel:
Marvel has been pessimistic for as long as I’ve been reading her, so this seems significant to me!
at Dean: I have several problems with the idea that emissions have peaked and are falling. First, the world where we live is a round spinning orb that does not actually lend itself to a meaningful analysis of global emissions on a country by country basis. We are situated solidly in the prisoner’s dilemma where nationstates can and do benefit from all sorts of smoke and mirrors around their nation’s emission numbers.
Second, the whole nation state idea of reducing emissions accumulations is formulated upon nebulous ideas about the rise in “natural” emissions related to warming that are developed in a consensus manner by the IPCC. Is that the way that science should be done? Forget about scientific validity, let’s just take some ideas based on some past science that has graduated from scientific results to the status of common knowledge and then extrapolate together to reach a consensus about how the future might unfold. Hmmm. I am not sanguine about this process.
The only number that I pay great attention to is the global accumulation of CO2 and CO2e in the atmosphere. There is no consensus value for this number. It is simply a hard, cold number that tells us how we are doing.
To talk about falling emissions from first world nations is like getting a report from the highest levels of a cruise ship that indicates there is no sign of water leaking into the ship. Yes, there are reports from below deck that there is water rising and yes, we can see that our cruise ship appears to be floating a little lower in the ocean, but we are quite certain that there is no sign of sea water in the upper levels of the ship.
Finally, I would appreciate a link to support statements like co2 emissions for advanced economies have peaked and are falling. It may be true. I would like to look at the data to support these statements. And of course, there is the caveat that I must raise and point out that attributing emissions to China as they produce the consumer goods that we buy in the West is a bit of misdirection, is it not?
I guess I have to point out that you state that emissions are staying flat. Emissions are not staying flat. To my knowledge, our global emissions are continuing to increase and the rate of increase may not even be flat. I am sorry. I wish things were different. Afaict, emissions are continuing to increase and the rate of increase may still be increasing. Maybe we have reached a state of flat rate of emission increase. I have stopped trying to guess at that particular situation.
Dean, I appreciate that you want to think and feel positively about global warming. I want to support that, but please, don’t make statements about our situation that are just not true. I feel like Winston Churchill stated when he became PM way back when. I have nothing to offer but blood, toil, tears and sweat. I think this is the moment that we are in.
I think we need leaders like Churchill who will accept the gravity of our situation and will talk bluntly about the task before us.
Global emissions have not yet peaked. https://ourworldindata.org/co2-and-greenhouse-gas-emissions#:~:text=We%20see%20a%20rapid%20rise,are%20now%20well%20over%20400ppm.
DG says “Of course if CO2 reductions had been pursued seriously since it became apparent they are required…” Well, sure. You sound like an economist there, buddy. We just need to knuckle down and accept that co2 reduction have not been pursued seriously so far. Now we say that the solution if to hit something called net zero. Starting from where we are right now. Let’s get after that. Might be time to pursue reductions seriously. How do we do that? I continue to travel in the neighborhoods and see folks using gas-powered leaf blowers. WTF?
damn, the Kate Marvel piece is behind a paywall. I will find a link to a non-monetized version of it eventually. Thanks for sharing that, Mal
SBM, my subscription to NYT allows me to “share” up to 10 articles per month. This should get you (and anybody else?) through the paywall:
I’d appreciate knowing if more than one person can use the same link, but maybe let SBM try first!
thank you for the attempted share. I could not get through paywall with the click. I am not great anymore at navigating these things. I will probably have to wait for the article to leak out somewhere else. NYT has my number.
I couldn’t get through to this one either: https://www.nytimes.com/2023/09/05/opinion/ezra-klein-podcast-kate-marvel.html
I can listen to this one: https://www.wbur.org/hereandnow/2023/10/03/climate-change-adaptation-solutions
skimmed this one as well: https://cpo.noaa.gov/a-conversation-with-climate-scientist-dr-kate-marvel/
Let’s try this: “https://www.nytimes.com/2023/11/18/opinion/climate-change-report-us.html?unlocked_article_code=1._Uw.MlYj.pvZKi6O-U8pv&smid=url-share”
that worked. Thanks for the efforts. So, Kate is not going to warn us anymore. She is just going to talk about the solutions. That is worth a try. Kate is clearly excited and happy about the way that green energy is gaining traction. I am curious whether Kate can move forward and follow through on the solution talk and give up on warning talk. I think it will be difficult to give up on warning talk when new fossil fuel reserves are being explored or readied for sale. We can definitely say that we don’t need them because green energy and global warming are going to make them unprofitable. I guess that’s solution oriented talk as long as we stress the green energy part and avoid the global warming and stranded asset talk that the fossil fuel industry does not want to talk about. We will see. Let’s give Kate a year and see if she can stay optimistic. I would love to see that happen.
@SBM,
Let me first address the growth of CO2 in the atmosphere. Because it is cumulative and because of its lifetime, we will not see a significant change in the rate of increase until we have made significant progress towards reducing emissions.
https://www.climate.gov/news-features/understanding-climate/climate-change-atmospheric-carbon-dioxide . I refer you to the last figure in the article which is from IPCC AR6. The amount of CO2 in the atmosphere is a lagging indicator and so I argue that we really need to be looking at emission levels to see if we are making progress.
I see you found your way to ourworldindata.org. There you can also find interactive tools that allow you to plot emissions of various countries, https://ourworldindata.org/co2/country/united-states#what-are-the-country-s-annual-co2-emissions . That link will bring up the plot for U.S. You can add to that any country you like, e.g. U.K. or they also allow you to plot the combined emissions of the E.U. You will see that emissions have peaked for all those.
Perhaps the best source that I have found that talks about emissions from advanced economies vs emerging markets and developing countries is the IEA and their recent report about 1.5C, https://www.iea.org/reports/net-zero-roadmap-a-global-pathway-to-keep-the-15-0c-goal-in-reach . I call your attention to Figure 2.1. on page 60. They are talking primarily about projections required to limit warming to 1.5 C but they also show historical data back to 2010.
The IEA report is quite massive. If you would like to read a good synopsis of the report, I refer you to this CarbonBrief article, https://www.carbonbrief.org/analysis-global-co2-emissions-could-peak-as-soon-as-2023-iea-data-reveals/
I believe there is cause for cautious optimism as reflected in the article by Kate Marvel (MA, cheers for that) and other climate scientists that have voiced similar cautious hope, e.g. Zeke Hausfather, https://swac.umn.edu/events/kuehnast-lecture-2022 . We have bent or flattened the emissions curve and are hoping to see it peak and start declining in a couple years.
netzero talk is not netzero walk.
https://www.desmog.com/2023/11/15/influencemap-study-greenwashing-corporate-climate-commitment-net-zero-greenwash/
Hey Dean. We agree on this: “Let me first address the growth of CO2 in the atmosphere. Because it is cumulative and because of its lifetime, we will not see a significant change in the rate of increase until we have made significant progress towards reducing emissions.”
I am enthusiastic about the growth of green energy as Kate Marvel lays out in her NYT op-ed. I watched Obama bail out the banks when he could have funded a green energy conversion. What a missed opportunity. And it’s not like Obama didn’t have advisors who would have been arguing for green energy. Van Jones was present and was arguing persuasively. Why did the bankers win?
These days, we have Biden talking a good game on green energy, but he has broken campaign promises to open new reserves. And we continue to see over 7 trillion dollars in fossil fuel subsidies per the numbers from 2022. “Globally, fossil fuel subsidies were $7 trillion or 7.1 percent of GDP in 2022, reflecting a $2 trillion increase since 2020 due to government support from surging energy prices.”
Back to paragraph 1. We have not seen a significant change in the rate of increase for emissions because we have not made significant progress toward reducing emissions. I don’t want to be debbie-downer, but I have to sputter when I come across what looks like irrational exuberance. I seek to be reality and evidence based on the question of falling emissions and progress toward the same. I will get very excited and exuberant when I see evidence of falling emisions as shown at places like co2.earth.
Right now, it appears to me that we are running at about 2.4 ppm increase per year on CO2. That rate of increase is simply disastrous. I can’t put enough lipstick on the pig to make me want to crouch down and give it a kiss.
https://www.imf.org/en/Topics/climate-change/energy-subsidies
We agree where we agree. If you make statements that are clearly incorrect, I may call you out. Or I may just let them go. I am getting old and I have tired of this struggle to a certain degree.
Cheers
Mike
There are a couple of other phrases, besides net-zero, which are often bandied about. They are intended to mean the same thing (as each other), but what do they actually mean? The phrases are “green energy” and “clean energy.” Given that all types of energy which can power industrial civilisation are most definitely not clean, what are users of these phrases trying to convey? Should they be using different phraseology?
@Attp
I am getting a bit muddled here between net-zero CO2 emissions, net zero anthropogenic emissions, negative emissions (just CO2 or other anthropogenic greenhouse gases?) and release of carbon (presumably methane?). My understanding is that to stop anthropogenic global warming, we have to stop total anthropogenic GHG emissions. Can you clarify, please?
Dear Mike,
You asked for sources/references and I gave them to you. Choosing not to accept information from sources such as the IPCC, the IEA and EIA is on you.
How is that different than the contrarians on the other end of the spectrum?
I have citable references from respected sources for every one of my positions and statements. They represent consensus of the mainstream climate change community.
To quote Ham from the Sandlot, “You’re killing me, Smalls!”
Dean
Michael,
This is all a bit complicated. Ignoring what the actual policy might be, the fundamental scientific understanding is essentially as follows.
When we get CO2 emissions to zero (either actual zero, or net zero) we expect CO2-driven warming to soon stabilise. There’s uncertainty, but the best estimate is that the zero-CO2-emission commitment is close to zero.
So, what about the other emissions? Well, short-lived pollutants, such as methane, don’t actually need emissions to go to zero to stabilise warming, emissions just need to stabilise. Once they stabilise, the concentration of this species in the atmosphere will soon stabilise, and then warming due to this species will also soon stabilise.
Hence, if our goal is to stabilise global surface temperatures, then what we need is to get CO2 emissions to zero, and then stabilise the emission of the short-lived pollutants.
However, we can go further. If we were to reduce the emission of the short-lived pollutants, then we can actually reverse some of the warming due to these species.
So, you could say that what we should do is aim for CO2 emissions to go to zero (stabilising CO2-driven warming) and substantially reduce the emission of the short-lived species so as to reverse some of their warming.
The problem though is that the two dominant short-lived species are methane (which causes warming) and aerosols (which causes cooling) and they have roughly the same impact. So, one expectation is that they roughly cancel, although not on the same timescale (aerosols should precipitate faster than methane decayse).
Hence, the bottom line is that we should be aiming to get CO2 emissions to zero (since CO2 will continue to accumulate until emissions get pretty close to zero) and reduce the other emissions as much as possible, but that the long-term warming is still likely to depend mostly on how much CO2 we emit in total, since the impact of the short-lived species probably roughly cancels.
@Attp,
Thank you. That is quite clear.
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