I suspect that have an innate bias, but Tom’s questions were basically unanswered. I am a subscriber to Roger’s substack but felt he was extremely weak in his answers. The science of what drivers GW was established in 1980 was poorly answered. Tom’s direct questions were answered by some amazing waffle. That CO2 is affecting global temperatures in a logarithmic way was not addressed nor adaptation. Very disappointed in Roger’s responses. If we do not have definitive proof that CO2 is the control knob then Roger looked a bit silly in many of his waffles. Just saying. The obvious stuff that technology will improve and nuclear is the answer was, well, obvious.
In the movie "North by Northwest", Cary Grant is running away from those who would murder him and he stumbles into an art auction. His only hope is to get arrested so the police will escort him to safety. So he shouts out random bids that are at once provocative and outrageous.
Now you and your friend can imitate Cary Grant if you wish, but who cares what numbers you toss out randomly?
If you go back 500 million years, the CO2 concentration is estimated to be around 1500 ppm and the earth was more than 12 degrees warmer - a veritable hothouse. And the sun was weaker so in today's world it would be worse. Going back further in time there is geological evidence that the earth has at times been very hot or very cold, and one of the main arbiters of that distinction was the CO2 level.
In recent times, over the past couple of hundred years, the earth warmed about 1.15 degrees for a an increase in CO2 of 120 ppm, or about 0.0096 degrees per ppm increase. If that were to persist into the future (it might not for various reasons) the average global temperature would be almost 12 degrees higher than it was in the mid-1800s. That would inflict on the world unimaginable horrors.
I think the world will struggle to reduce CO2 emissions over the remainder of this century but I doubt that the world can get by without utilizing enough fossil fuels to drive the CO2 concentration from its present 415 ppm to about 550 ppm. I don't prefer that but the world would have to adapt to it. The temperature rise above the mid 1800s might be 2.5 degrees.
I suggest that you read my book "Assessing Climate Change 3rd edition" available on amazon, and though it is a bit out of date, not much has happened since it was published in 2014. Actually the 2nd edition had a much longer section on paleontological climate but I reduced that in the 3rd edition because the book was getting very long.
Donald, you appear to assume that if humans never existed, global average temperature in 2023 would be identical to global average temperature in 1850. I think it's a *huge* mistake to assume that human CO2 emissions must be the reason for the warming since 1850.
Until you can tell us exactly what caused the Minoan/Roman/Medieval warm periods, Dark Ages/LIA cooling, early 20th century warming, & mid-20th century cooling, I refuse to believe you understand natural variability enough to rule it out as the #1 post-1850 warming cause.
This is your formal invitation to debate climate change with me on my podcast.
Tom: I am not interested in debating you and I am only responding here because others might be reading this stuff and I don't want to leave them hanging with your reply.
(1) Although climate is heavily influenced by CO2 concentration, CO2 is certainly not the only factor that affects climate. The state of the Pacific Ocean (El Nino - La Nina) has a significant effect that supposedly averages out over a period of decades but actually might not. Ocean currents might vary and these have a significant effect. It is not known how the different levels of clouds respond to increased CO2. Above all, there are random variations in everything. I suppose there is plenty more here. Yet, year after year, CO2 keeps accumulating and its underlying effect keeps multiplying, even though for periods of several years or even a decade or so, the temperature rise from CO2 can be temporarily masked (or amplified) by other factors.
(2) As a result, when you compare the graphs of CO2 concentration and the global average temperature from 1850 to 2020 the two curves move upward roughly together, but there are bumps and dips along the way in the temperature curve that you don't see in the CO2 curve. Of particular note is the flattening of the temperature curve from about 1950 to 1970 associated with large scale aerosol emissions and persistent La Ninas.
(3) There is no way that I know to "prove" that the change in climate since 1850 was mainly due to CO2. I think there is a great deal of circumstantial evidence. It is like a murder where the suspect was found in the vicinity, his fingerprints were on the murder weapon, he made threatening remarks toward the victim, but no one actually saw him murder the victim. This evidence is in the form of understanding and modeling of energy transfer between the sun, the earth and space, the effect of CO2 in reducing the effective temperature range where the earth radiates to space, measurements of the earth's energy balance at the top of the atmosphere, the heat content of the oceans, paleo evidence of warming at high CO2 in the distant past, and the unprecedented recent rate of temperature gain.
(4) I won't attempt to tell you "EXACTLY what caused the Minoan/Roman/Medieval warm periods, Dark Ages/LIA cooling, early 20th century warming, & mid-20th century cooling" which represent small to moderate pimples imposed on the long term trend of temperature gain from CO2, but reasonable explanations have been proposed. CO2 is operating in the background. Other effects also play a role.
(5) Nothing in climate is EXACT. Dealing with climate automatically imposes uncertainty in everything. But the signal for warming from CO2 is strong enough to resolve it from the noise. It is convenient to assume all the warming from 1850 to 2020 was due to CO2 for purposes of calculation. Obviously that is not exactly true. But it is close enough for projecting the future as we continue to emit CO2.
1. CO2 can rise while global temperatures fall for many orders of magnitude longer than a decade, because CO2 is *not* the climate control knob.
2. Specifically what data supports your suggestion that humans were a major factor in the 1940s-1970s global cooling?
3. Sorry, I'm completely unmoved by vague "this is like a murder scene" handwaving in attempts to convince us that humans are the reason that the Little Ice Age ended.
4. Sorry, "reasonable explanations have been proposed" doesn't do anything for me.
If you want us to blow $50 trillion dollars, take away farmland, destabilize our power grids, change our lifestyles, etc, we're going to need a lot more than that.
5. If we don't understand natural variability (and we don't), how exactly can we separate the alleged CO2 "signal" from the "noise"?
6. How, exactly, do you imagine that the next El Nino will make our lives worse?
I remember a Charley Brown cartoon. Charley says to Lucy: "nice day isn't it" Lucy says: "What about the day before?". "What about the day before that" "A good fanatic is always ready for an argument".
I just listened to Tom Nelson's interview of Roger Pielke Jr. It was the first time I was listening to Roger. In his writings he strikes me as a very optimistic person and I got the same impression listening to him.
Pretty much everything Roger says sounds to me very sensible and mainstream. For instance he talks about an "all of the above" energy strategy including fossil fuels, nuclear, wind, solar, geothermal, etc. Compare that to the "mainstream media" which routinely misrepresent IPCC conclusions, make catastrophic predictions about climate, and don't interview scientists such as Roger. To me it goes to show how the media is no longer "mainstream."
And I appreciate that he talks to Tom, who holds a different opinion on some subjects, such as whether we should pursue rapid decarbonization. Respect!
I am genuinely impressed by your skill in turning all your interviewer’s simplistic, pretentious questions into well articulated, easy to understand, yet not dumbed down answers. Kudos to the interviewer for letting you that though.
Alberto, why should a rational person believe that Earth is currently too hot, or that CO2 is the climate control knob, or that the weather is getting worse?
Tom, I am not knowledgeable enough to have a position on the question of climate change, especially because, as Roger said while talking to you, I just have my perspective on the matter. Can’t be a honest broker. I was referring to fact that you seem indeed very very sure about where you stand, and that your questions sounded more like asking Roger to comment on «obviously true» statements. While I actually found out that I agree with you on many things you said in the interview, I think you came across as a person with a black-and-white view on the subject, not really open to doubt your positions. This is the first podcast of yours I listen to, so I’ll check the other ones out too, and I hope that my impression will be proven wrong
Thanks. I started out as a casual believer in anthropogenic global warming, then I became more and more skeptical as I dug into the alleged evidence for myself. *Many* climate skeptics have followed a similar path.
The "climate crisis" house of cards collapses quickly with a little fact-checking.
Over the last 16+ years, I've been immersed in the climate debate for hours most days; as an example, I spent many hundreds of hours reading ClimateGate emails.
Please check out my "notes for climate skeptics" here:
I highly recommend that you watch this entire "Simon Elmer: The Politics of Environmental Fundamentalism" video that I just put up on YouTube. It's long, but it's *very* good:
I think your definition of "decarbonization" as emissions per unit GDP is OK as far as it goes but It doesn't suffice because GDP keeps going up and ultimately it is the absolute amount of emissions that counts, not the emissions per unit GDP. But yes, reducing emissions per unit GDP does help and as you say, that's been going on for a century. Further, one size doesn't fit all. China for example, has drastically reduced emissions per GDP but the GDP went up even faster and absolute emissions are up, up, up. Emissions per GDP for developing nations doesn't convey the actual rise in total emissions from them. I am both optimistic and pessimistic. I am pessimistic that we can hold CO2 concentration below 550 ppm by 2100 even with the most strenuous policies enacted. I am optimistic that even at 550 ppm the world will be OK. 550 ppm seems OK to me because (1) we are already at 415 ppm and the world hasn't ended, (2) The calamities claimed by IPCC at 550 ppm are tied to their perception that even now at 415 ppm we are experiencing heat waves, tornadoes, hurricanes, droughts and floods at unprecedented rates, and as you have shown, that doesn't stand up to the properly interpreted data, so why should we believe the dire predictions for 550 ppm? Furthermore, the exact mechanism by which adding CO2 to the atmosphere generates both droughts and floods remains so obscure as to be science fiction. A crucial issue is how (or even whether) adding CO2 to the atmosphere changes cloud cover at various altitudes, and that seems to be a lot of hand waving. Tom Nelson is fine with 800 ppm but that is really pushing it beyond sensibility.
Specifically why do you think 550 ppm is sensible but not 800 ppm?
On my podcast in October 2022, I asked Patrick Moore (extremely well-informed; also one of the founders of Greenpeace) his opinion of optimum CO2 level for life on Earth. His answer: "I would say it's between 1,500 and 2,000 PPM".
As a partial skeptic - about the degree of warming that is likely, about the costs and benefits of that warming, and certainly about the costs and benefits of any short time horizon policy based on Paris and a 2° hard target I wonder what you think of the argument I find most persuasive.
That is that while life will be mostly just fine overall, especially plant life, our civilizations are built calibrated to the current temperature and a rapid warming of an additional 2° will be inherently costly by virtue of being fast.
With this in mind I find myself willing to support something like a 25% greater decarbonization effort than the base case more influenced by air quality and energy security.
The "iron law" vs. the pace of energy scientific advancement means the move to decarbonization and "net-zero" will be a long, uneven process. Probably will continue for the rest of the 21st century, and perhaps beyond.
I suspect that have an innate bias, but Tom’s questions were basically unanswered. I am a subscriber to Roger’s substack but felt he was extremely weak in his answers. The science of what drivers GW was established in 1980 was poorly answered. Tom’s direct questions were answered by some amazing waffle. That CO2 is affecting global temperatures in a logarithmic way was not addressed nor adaptation. Very disappointed in Roger’s responses. If we do not have definitive proof that CO2 is the control knob then Roger looked a bit silly in many of his waffles. Just saying. The obvious stuff that technology will improve and nuclear is the answer was, well, obvious.
The comment below was addressed to Tom nelson
In the movie "North by Northwest", Cary Grant is running away from those who would murder him and he stumbles into an art auction. His only hope is to get arrested so the police will escort him to safety. So he shouts out random bids that are at once provocative and outrageous.
Now you and your friend can imitate Cary Grant if you wish, but who cares what numbers you toss out randomly?
If you go back 500 million years, the CO2 concentration is estimated to be around 1500 ppm and the earth was more than 12 degrees warmer - a veritable hothouse. And the sun was weaker so in today's world it would be worse. Going back further in time there is geological evidence that the earth has at times been very hot or very cold, and one of the main arbiters of that distinction was the CO2 level.
In recent times, over the past couple of hundred years, the earth warmed about 1.15 degrees for a an increase in CO2 of 120 ppm, or about 0.0096 degrees per ppm increase. If that were to persist into the future (it might not for various reasons) the average global temperature would be almost 12 degrees higher than it was in the mid-1800s. That would inflict on the world unimaginable horrors.
I think the world will struggle to reduce CO2 emissions over the remainder of this century but I doubt that the world can get by without utilizing enough fossil fuels to drive the CO2 concentration from its present 415 ppm to about 550 ppm. I don't prefer that but the world would have to adapt to it. The temperature rise above the mid 1800s might be 2.5 degrees.
I suggest that you read my book "Assessing Climate Change 3rd edition" available on amazon, and though it is a bit out of date, not much has happened since it was published in 2014. Actually the 2nd edition had a much longer section on paleontological climate but I reduced that in the 3rd edition because the book was getting very long.
Donald, you appear to assume that if humans never existed, global average temperature in 2023 would be identical to global average temperature in 1850. I think it's a *huge* mistake to assume that human CO2 emissions must be the reason for the warming since 1850.
Until you can tell us exactly what caused the Minoan/Roman/Medieval warm periods, Dark Ages/LIA cooling, early 20th century warming, & mid-20th century cooling, I refuse to believe you understand natural variability enough to rule it out as the #1 post-1850 warming cause.
This is your formal invitation to debate climate change with me on my podcast.
Tom: I am not interested in debating you and I am only responding here because others might be reading this stuff and I don't want to leave them hanging with your reply.
(1) Although climate is heavily influenced by CO2 concentration, CO2 is certainly not the only factor that affects climate. The state of the Pacific Ocean (El Nino - La Nina) has a significant effect that supposedly averages out over a period of decades but actually might not. Ocean currents might vary and these have a significant effect. It is not known how the different levels of clouds respond to increased CO2. Above all, there are random variations in everything. I suppose there is plenty more here. Yet, year after year, CO2 keeps accumulating and its underlying effect keeps multiplying, even though for periods of several years or even a decade or so, the temperature rise from CO2 can be temporarily masked (or amplified) by other factors.
(2) As a result, when you compare the graphs of CO2 concentration and the global average temperature from 1850 to 2020 the two curves move upward roughly together, but there are bumps and dips along the way in the temperature curve that you don't see in the CO2 curve. Of particular note is the flattening of the temperature curve from about 1950 to 1970 associated with large scale aerosol emissions and persistent La Ninas.
(3) There is no way that I know to "prove" that the change in climate since 1850 was mainly due to CO2. I think there is a great deal of circumstantial evidence. It is like a murder where the suspect was found in the vicinity, his fingerprints were on the murder weapon, he made threatening remarks toward the victim, but no one actually saw him murder the victim. This evidence is in the form of understanding and modeling of energy transfer between the sun, the earth and space, the effect of CO2 in reducing the effective temperature range where the earth radiates to space, measurements of the earth's energy balance at the top of the atmosphere, the heat content of the oceans, paleo evidence of warming at high CO2 in the distant past, and the unprecedented recent rate of temperature gain.
(4) I won't attempt to tell you "EXACTLY what caused the Minoan/Roman/Medieval warm periods, Dark Ages/LIA cooling, early 20th century warming, & mid-20th century cooling" which represent small to moderate pimples imposed on the long term trend of temperature gain from CO2, but reasonable explanations have been proposed. CO2 is operating in the background. Other effects also play a role.
(5) Nothing in climate is EXACT. Dealing with climate automatically imposes uncertainty in everything. But the signal for warming from CO2 is strong enough to resolve it from the noise. It is convenient to assume all the warming from 1850 to 2020 was due to CO2 for purposes of calculation. Obviously that is not exactly true. But it is close enough for projecting the future as we continue to emit CO2.
(6) Watch out for the newly evolving El Nino.
1. CO2 can rise while global temperatures fall for many orders of magnitude longer than a decade, because CO2 is *not* the climate control knob.
2. Specifically what data supports your suggestion that humans were a major factor in the 1940s-1970s global cooling?
3. Sorry, I'm completely unmoved by vague "this is like a murder scene" handwaving in attempts to convince us that humans are the reason that the Little Ice Age ended.
4. Sorry, "reasonable explanations have been proposed" doesn't do anything for me.
If you want us to blow $50 trillion dollars, take away farmland, destabilize our power grids, change our lifestyles, etc, we're going to need a lot more than that.
5. If we don't understand natural variability (and we don't), how exactly can we separate the alleged CO2 "signal" from the "noise"?
6. How, exactly, do you imagine that the next El Nino will make our lives worse?
I remember a Charley Brown cartoon. Charley says to Lucy: "nice day isn't it" Lucy says: "What about the day before?". "What about the day before that" "A good fanatic is always ready for an argument".
Remember Lysenkoism? That was a massive, destructive fraud.
Catastrophic anthropogenic global warming is the most massive scientific fraud in human history.
I just listened to Tom Nelson's interview of Roger Pielke Jr. It was the first time I was listening to Roger. In his writings he strikes me as a very optimistic person and I got the same impression listening to him.
Pretty much everything Roger says sounds to me very sensible and mainstream. For instance he talks about an "all of the above" energy strategy including fossil fuels, nuclear, wind, solar, geothermal, etc. Compare that to the "mainstream media" which routinely misrepresent IPCC conclusions, make catastrophic predictions about climate, and don't interview scientists such as Roger. To me it goes to show how the media is no longer "mainstream."
And I appreciate that he talks to Tom, who holds a different opinion on some subjects, such as whether we should pursue rapid decarbonization. Respect!
I am genuinely impressed by your skill in turning all your interviewer’s simplistic, pretentious questions into well articulated, easy to understand, yet not dumbed down answers. Kudos to the interviewer for letting you that though.
Alberto, why should a rational person believe that Earth is currently too hot, or that CO2 is the climate control knob, or that the weather is getting worse?
Tom, I am not knowledgeable enough to have a position on the question of climate change, especially because, as Roger said while talking to you, I just have my perspective on the matter. Can’t be a honest broker. I was referring to fact that you seem indeed very very sure about where you stand, and that your questions sounded more like asking Roger to comment on «obviously true» statements. While I actually found out that I agree with you on many things you said in the interview, I think you came across as a person with a black-and-white view on the subject, not really open to doubt your positions. This is the first podcast of yours I listen to, so I’ll check the other ones out too, and I hope that my impression will be proven wrong
Thanks. I started out as a casual believer in anthropogenic global warming, then I became more and more skeptical as I dug into the alleged evidence for myself. *Many* climate skeptics have followed a similar path.
The "climate crisis" house of cards collapses quickly with a little fact-checking.
Over the last 16+ years, I've been immersed in the climate debate for hours most days; as an example, I spent many hundreds of hours reading ClimateGate emails.
Please check out my "notes for climate skeptics" here:
https://tomn.substack.com/p/notes-for-climate-skeptics
I highly recommend that you watch this entire "Simon Elmer: The Politics of Environmental Fundamentalism" video that I just put up on YouTube. It's long, but it's *very* good:
https://youtu.be/ibQY0iKW7h0
I'm on Twitter here: https://twitter.com/tan123
Thank you for the interview Tom! I appreciate when two smart and well articulated people can discuss and disagree! I just subscribed to your podcast.
I think your definition of "decarbonization" as emissions per unit GDP is OK as far as it goes but It doesn't suffice because GDP keeps going up and ultimately it is the absolute amount of emissions that counts, not the emissions per unit GDP. But yes, reducing emissions per unit GDP does help and as you say, that's been going on for a century. Further, one size doesn't fit all. China for example, has drastically reduced emissions per GDP but the GDP went up even faster and absolute emissions are up, up, up. Emissions per GDP for developing nations doesn't convey the actual rise in total emissions from them. I am both optimistic and pessimistic. I am pessimistic that we can hold CO2 concentration below 550 ppm by 2100 even with the most strenuous policies enacted. I am optimistic that even at 550 ppm the world will be OK. 550 ppm seems OK to me because (1) we are already at 415 ppm and the world hasn't ended, (2) The calamities claimed by IPCC at 550 ppm are tied to their perception that even now at 415 ppm we are experiencing heat waves, tornadoes, hurricanes, droughts and floods at unprecedented rates, and as you have shown, that doesn't stand up to the properly interpreted data, so why should we believe the dire predictions for 550 ppm? Furthermore, the exact mechanism by which adding CO2 to the atmosphere generates both droughts and floods remains so obscure as to be science fiction. A crucial issue is how (or even whether) adding CO2 to the atmosphere changes cloud cover at various altitudes, and that seems to be a lot of hand waving. Tom Nelson is fine with 800 ppm but that is really pushing it beyond sensibility.
Specifically why do you think 550 ppm is sensible but not 800 ppm?
On my podcast in October 2022, I asked Patrick Moore (extremely well-informed; also one of the founders of Greenpeace) his opinion of optimum CO2 level for life on Earth. His answer: "I would say it's between 1,500 and 2,000 PPM".
As a partial skeptic - about the degree of warming that is likely, about the costs and benefits of that warming, and certainly about the costs and benefits of any short time horizon policy based on Paris and a 2° hard target I wonder what you think of the argument I find most persuasive.
That is that while life will be mostly just fine overall, especially plant life, our civilizations are built calibrated to the current temperature and a rapid warming of an additional 2° will be inherently costly by virtue of being fast.
With this in mind I find myself willing to support something like a 25% greater decarbonization effort than the base case more influenced by air quality and energy security.
The "iron law" vs. the pace of energy scientific advancement means the move to decarbonization and "net-zero" will be a long, uneven process. Probably will continue for the rest of the 21st century, and perhaps beyond.
This was an excellent discussion, thank you Roger
"Honest brokering" is rarer and more valuable than ever. Thanks for doing what you do, Roger.