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When people want to tell me that CO2 is the only control knob for the climate, I point out that Vikings were growing barley and raising sheep in Greenland 1,000 years ago, and Romans were growing grapes and citrus at Hadrian's Wall and olives in the Rhine Valley 2,000 years ago. Nobody is doing either now. Why did it get so cold that they stopped? Did they stop driving automobiles and burning coal to make electricity?

The temperature graph at the bottom of Figure 1 appeared on page 202 of the IPCC 1990 report. It was completely flattened out, replaced by Michael Mann's infamous "hockey stick" on page 134 of the IPCC 2001 report.

More details in my book "Where Will We Get Our Energy?" Everything quantified. No vague handwaving. 350 bibliographic citations so you can check that I did not just make up stuff.

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Great piece, David!

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You lost my sympathy when you pose mitigation and adoption as alternatives. It a simultaneous equation to solve. the less CO2 that goes into the atmosphere, the less adaption we have to do. The cost of emissions include the cost of adapting to those emissions and so the costs one needs to undertake to avoid emitting CO2.

There is probably an argument to be made that we are not allocating investment between mitigation and adaption optimally but the tradeoff is with total investment and indeed with investment vs consumption, not just investment in mitigation and adaption.

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It is entirely pointless to reduce CO2 in the UK when the UK is a minor 1% or so of total global human emissions. There is no realistic scenario where cutting 1% or even 5% of global CO2 emissions makes any plausible difference in outcome

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This is why we should lock the China, India and the US into a room and have them hammer out a tripartite decarbonization agreement and the rest of the world will agree to match their aggregate policy stringency (with exceptions for the very poorest countries).

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Of course, that is true for any one country. Perhaps UK does not aspire to leadership, I think the US should and I do think that if we had a tax on net emissions with a CBAM enough OECD countries would join voluntarily to make it worthwhile for other to join out of narrow self interest.

The argument is even stronger if revenue were used to reduce more distorting taxes like those on business income.

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It probably doesn't make sense in the US either TBH. The main producers of CO2 are China, India and other rapidly developing/industrializing. nations. Noah Smith recently pointed out that (https://www.noahpinion.blog/p/the-elemental-foe )for leaders of those countries lifting their citizens out of poverty is job 1 and they will use fossil fuels to do so,

BTW a carbon tax instead of corporation tax is probably a good thing, I don't disagree with that, in theory. But in practice what we have seen in the last two decades is that such taxes just incentivize producers to move their manufacturing to the aforementioned rapidly industrializing countries. That's great for these countries economies and not bad for the emissions of the developed world, but makes no difference at all to total emissions.

What the developed world probably ought to do is come up with better nukes or other energy technologies that can replace / reduce fossil fuel usage

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China and India should definitely aim for high growth [the US, too!] which will require greater use of energy. I totally agree with Noah. But the deadweight loss of taxation of CO2 emissions is fortunately not high enough to derail that growth. We all just source our energy needs from lower and eventually zero CO2 emitting sources, which is exactly what taxation of net CO2 emissions incentivizes.

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I addressed that point. Mitigation can only work if CO2 is the only climate control knob and everyone else also slashes emissions. Neither condition is met.

So tell me, how much should we spend to cut the remaining half of our emissions that amount to <1% of the global total and what effect will that have on global temperatures and the weather?

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I think it’s enough that CO2 is an important control knob. Which it is. And it’s the one *we* have some control over. I agree that the details of how money is spent and how much matters. That’s where exercises like integrated assessment models can help structure our thinking…

https://www.nber.org/system/files/working_papers/w31112/w31112.pdf

We also shouldn’t neglect a very important co-benefit of decarbonization, namely cleaner air. Air pollution’s significant impact on health at even relatively low levels is becoming clearer and clearer.

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CO2 is not a significant control knob. The doubling sensitivity of the atmosphere is 0.76°C. That is, for EVERY DOUBLING of the CO2 concentration, not every addition of the same amount. the temperature of the atmosphere increases by 0.76 °C. Increasing CO2 by a factor of ten would increase the temperature by at most 2.5°C. Stephen Schneider and S. Ichtiaque Rasool computed this in 1971, and concluded that we could not prevent the coming ice age no matter how much coal we burned [Science 173(3992):138-141, July 9, 1971]. Svante Arrhenius knew in 1896 that the atmospheric temperature has a logarithmic dependency on greenhouse gases.

The extremes predicted by the models require inserting and guessing about "feedbacks" other than CO2. That nobody knows what these actually are is demonstrated by the fact that 101 of 102 climate models utterly fail to reproduce the trajectory of the climate since about 1990. And yet they're used to influence public policy.

Details in my book "Where Will We Get Our Energy?" Everything quantified. No vague handwaving. 350 bibliographic citations so you can check that I did not just make up stuff.

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I'd say we should have the tax on net emissions that we would have if all DID go along wit the tax with fair chance that we coud get Europe to do the same. Together and with an CO2 content import fee this would create an incentive for others to adopt what is after all the least costly policy.

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"I would describe myself as a lukewarmer, by which I mean that I acknowledge the earth is warming and that human emissions of CO2 have made some contribution to that warming. However, it is also true that the climate has changed dramatically without human intervention; clearly, there are other causes of climate change too."

I like the way you put this-- you can count me as a fellow lukewarmer. I'm personally of the opinion that all of these emissions/green efforts are generally worth the effort. Humans will be on this earth indefinitely, we might as put some of our resources and efforts towards doing so in an indefinitely sustainable fashion. With that said, there are often more pressing matters to focus on instead.

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Excellent post!. Humans by and large have used adoption for ages to improve human flourishing. Why stop now?

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David, your posts are excellent, especially this last one 'Risks to Net Zero'. You previously posted a review of the General Election policy's for all of the polictical parties, this needs wider publicity especially as only the Reform party's policy to scrap Net Zero is sensible. Have you circulated your blogs to Labour, Tories, Lib Dems and Greens? Also, are you able to foward these to the media, especially GB News and Talk TV? It's highly likely that the BBC, ITV, Channel 4 & Sky will just ignore you. We can circulate your blogs to our friends and families but our contacts are usually limited.

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David says “I acknowledge the earth is warming and that human emissions of CO2 have made some contribution to that warming”. Discounting the recent unprecedented spike in global temperatures which was so large and sudden that it could not possibly have been caused by man-made CO2 (it was almost certainly due to the 2022 Hunga Tonga volcanic eruption), I would dispute that the earth is currently warming. A WoodForTrees.org graph of the UAH global temperature series from 1998 to 2023 (just before Hunga Tonga manifested) indicates flatlining going into cooling: https://www.woodfortrees.org/plot/uah6/from:1998/to:2023.

As for the impact of man-made CO2 on global warming, the CO2 Coalition has published a study by van Wijngaarden and Happer which concluded that “Doubling the CO2 concentration increases the infrared absorption by only a few percent”: https://co2coalition.org/publications/van-wijngaarden-and-happer-radiative-transfer-paper-for-five-greenhouse-gases-explained/

The global warming impact of atmospheric CO2 is due mainly to the first 50 ppm, after which the effect falls off exponentially. We should be grateful for that 50 ppm worth of CO2 greenhouse gas global warming although if that was all we had we would be below the level at which plant growth shuts down, as shown in this helpful graphic: https://www.therightinsight.org/media/HeatingEffectofCO2-800x600.jpg.

As Emeritus Professor Hal Lewis said back in 2010, “global warming is the most successful pseudoscientific fraud I have seen in my long life as a physicist”: https://www.csmonitor.com/Commentary/Opinion/2010/1019/Climate-change-fraud-letter-a-Martin-Luther-moment-in-science-history

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The "recent spike in global temperatures" is much smaller than in 1930. See, e.g., http://vandyke.mynetgear.com/CO2+HeatWave.png . Other phenomena such as forest fires, droughts, floods, and hurricanes, are not statistically distinguishable from the past.

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Thanks David - a superb analytical summary of the death knell that is net zero - with an incoming Labour Govt, it’s going to be interesting to see reality meet ideology

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Those who want even more flesh on this corpse should read Lomborg's False Alarm and Shellenberger's Apocalypse Never.

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And if you want to put more flesh on a different corpse, read Shellenberger's "San Fran Sicko: Why Progressives Ruin Cities."

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Thank you for another thought-provoking post David.

It is reckoned that the UK's annually emits 1% or so of human global atmospheric carbon dioxide, but our overall contribution is higher, because we've exported so much productive industry and import the goods. (Was that a good idea, I ask in parenthesis?) That 1% will shrink, because while our energy use is relatively steady, the developing world is primarily interested in improving living standards, followed by air quality, and carbon dioxide emissions trailing.

To mitigate that 1% with an at-all-costs approach, given the indebtedness of our economy, makes no sense. With real operating experience of a diversity of power sources, and facing an increasingly unpredictable and possibly hostile world, it is time for the UK to take stock and change tack. It's the government's duty to give energy security, reliability and affordability top priority, as the French did and the Germans didn't (the example for which we must be grateful).

Ironically, I happen to believe that this approach, paying proper attention to physics and energy density (so yes, the N word), would result over time in lower net emissions than the current one, based as it is on wishful thinking and an inflated sense of our county's importance in the world. Bullshit makes a lousy fuel.

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I’ll steal your last sentence

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Feel free - I'm honoured! I don't believe I got it from anywhere else.

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Excellent article summing up the whole issue very well.

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Here is the rub: the alleged 'cure' is, without any shadow of a doubt, going to be much worse than the phantom 'disease' - and it is a phantom until proven otherwise, despite the exhaustive protestations of of the 'settled science' fan club and their ad nauseum appeals to authority. The 'necessity' case made for climate mitigation is a Swiss cheese full of holes you can drive a coach and horses through. The 'safe and effective' argument is also demonstrably false, as shown here in this article by David. Re. 'necessity', here is a comment I've just left on another site:

"From my point of view, the ‘disease’ is a diagnosed 1.2C rise in global mean surface temperature (prior to the sudden and unexplained – by the settled science – acceleration in 2023), roughly coincident with the beginning of the Industrial Revolution, which itself coincided with an upturn in global temperature immediately following an entirely natural and exceptionally cold period known as the Little Ice Age. The diagnosis of the disease is the averaged sum of all climate models which allegedly account for all or most of this recent temperature rise (even though natural causes of climate change are very poorly constrained in the models). The additional diagnosis of the disease is the supposed increase in extreme weather, especially heatwaves, and their alleged attribution on an individual basis to ‘climate change’ (i.e. the observed long term increase in regional mean surface temperature which is presumed to be directly related to the increase in global mean surface temperature – even though there are many other factors which can and do influence regional temperature trends).

The models project a worsening of the ‘disease’ in the years to come, absent a sharp reduction in CO2 emissions.

You can see why I’m somewhat sceptical."

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You should remain sceptical Jaime. " Anthropomorphic Climate Change" is a military grade PsyOp by the Globalist Cabal intent on a global government initiated by Cecil Rhodes would you believe - https://austrianpeter.substack.com/p/cecil-john-rhodes-a-south-african?r=hhrlz&utm_campaign=post&utm_medium=web&triedRedirect=true

BUT the Brits are behind most of this criminal activity: https://austrianpeter.substack.com/p/broken-britain-wartime-edition-abject?r=hkcp6&utm_campaign=post&utm_medium=web

Tell me I am wrong?

Blessings

AP

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I love this: I think it is correct..

Alan Jones on the C02 myth.

https://x.com/wideawake_media/status/1800118436187758793?s=12&t=L2eL_FH-crT9ME_-0pahfA

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The problem with the conjecture of "CO2 causing heating" is that it has the same weight as Brane theory. It cannot be demonstrated and when you start to look at details such as radiative transfer you realise they just copied stellar models (which were wrong for many years). The Blackbody model was used to estimate stellar temperatures up until the late 70s until Kurucz developed his stellar model based on emission patterns. The same leeway and uncertainties that exist in that thinking are all evident in the Man Made Global Warming idea.

None of it has been verified. The precision needed in things as simple as temperature measurements is not there. The IPCC is a collection of papers and opinions not a verification exercise. The UK government has not done any of this either. I asked them. They are applying a conjecture to real life as if it is fact and not allowing that idea to be tested in the engineering and audit process to be safe.

The belief that man may be contributing to heating is predicated on there being a precise temperature record able to resolve down to the 0.01 Deg C variation per year required by the MMGW conjecture. I call it a conjecture because a hypothesis needs a falsification case. We don't seem to have one with the cult of MMGW.

Believing in any significant contributions from man made emission of CO2 is just whimsy. And in the wrong hands as we see today a WMD.

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