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Post by David B. Benson on Oct 27, 2017 19:00:00 GMT 9.5
The atmospheric carbon dioxide concentration is now nicely above 400 ppm. As a thought experiment suppose that it stays there for a long time to come, thousands of years. Such was the case during the mid-Pliocene with global temperatures over 2 °C higher than now and sea levels about 25 meters higher than now, see the Wikipedia page on Pliocene climate. The configuration of the continents has hardly changed in the intervening 3.25 million years nor has the biosphere much changed. If the differences are sufficiently small we may appeal to the conservation of energy and one of Emmy Noether's theorems to conclude that at equilibrium the same global climate will obtain. All we need is that more carbon dioxide results in more warming. Probably Tyndall knew that. Certainly Arrhenius did although we don’t need his logarithmic formula, just more results in more is enough provided the circumstances are sufficiently similar. The most obvious geographic change is the closure of the Panama seaway. But link.springer.com/article/10.1007%2Fs00382-007-0265-6on that closure states that there was little effect. Another paper, summarizing the running of a GCM to equilibrium with first a closed and then an open Panama seaway found a global temperature difference of 0.3 °C, not enough to matter. More interesting is the change in orography, principally for the Himalayan ranges. For this post I will simply assert that for the intervening 3.25 million years the change is globally another minor factor. Possibly later I will need to defend this. Finally, during the mid-Pliocene there was no glacial cycling. Check your own favorite graphic based on the LR04 stack to see that glacial cycling did not begin until, at the earliest, during the late Pliocene around 2.65 million years ago. Therefore the oceans were at equilibrium with the atmosphere and so did not express or take up carbon dioxide. So the past provides a guide to the future in which we continue to burn fossil fuels and other sources of methane. Hot and ever rising sea levels. Eventually we stop so this thought experiment is only suggestive. For a more detailed indication of the future of carbon dioxide in the atmosphere, seethe Model Description page of climatemodels.uchicago.edu/geocarb/geocarb.doc.html |
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Post by David B. Benson on Oct 28, 2017 18:31:54 GMT 9.5
Peter Molnar, in a thorough review of the closing of the Central American seaway and the onset of the subsequent ice age onlinelibrary.wiley.com/doi/10.1029/2007PA001574/fullconcludes by stating that the closure is a red herring in looking for the causes of the subsequent glacial cycling. I found this review to be most helpful. By the way, going to the subsection entitled Pleistocene in the Wikipedia page on Geologic Temperature Record locates a suitable graph of the LR04 stack treated as temperature proxy. |
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Post by David B. Benson on Oct 29, 2017 18:17:26 GMT 9.5
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Post by huon on Oct 30, 2017 15:21:47 GMT 9.5
Even in the relatively near term--80 years--seas may rise dangerously if countries do not change course. "Coastal cities around the world could be devastated by 1.3m of sea level rise this century unless coal-generated electricity is virtually eliminated by 2050, according to a new paper that combines the latest understanding of Antarctic's contribution to sea level rise and the latest emissions projection scenarios. "It confirms again that significant sea level rise is inevitable and requires rapid adaptation. But, on a more positive note, the work reveals the majority of that rise--driven by newly recognised processes on Antarctica--could be avoided if the world fulfils its commitment made in Paris to keep global warming to 'well below 2C'." www.theguardian.com/environment/2017/oct/26/sea-levels-to-rise-13m-unless-coal-power-ends-by-2050-report-says |
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Post by David B. Benson on Oct 31, 2017 12:48:09 GMT 9.5
Huon --- That article in The Guardian is about a paper which for its climatology uses Deconto & Pollard, Nature 2016. That climatology paper is discussed here: www.nature.com/news/antarctic-model-raises-prospect-of-unstoppable-ice-collapse-1.19638pointing to the fact that previously understudied processes are invoked to give the faster rate of ice sheet collapse, 15 meters of sea level rise by 2500 from Antarctica alone. This might be correct, or nearly so. More research is required. However, the undercutting of the glacial fronts from warmer sea water continues apace. This current water devolves from the Gulf Stream around 150--250 years ago. Of course the Gulf Stream water now sinking in the Norwegian Sea is much warmer yet. So even if the coal burners retire by 2050 my prediction is for continued undercutting of Pine Island Glacier and Twaites Glacier for centuries to come with a corresponding sea level rise. The only way I know to avoid as much eventual sea level rise as may be is to lower the carbon dioxide concentration to, say, 285 ppm and wait some centuries for near-equilibrium to be reached. Once again, the reference in the GeoCarb link I gave in the first post may well be helpful regarding the natural timescales. |
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Post by Roger Clifton on Nov 1, 2017 9:11:34 GMT 9.5
"devastated ... unless coal-generated electricity is virtually eliminated by 2050"
That would be totally inadequate to protect the greenhouse. It might be more productive for us to speak of "carbon denial" than "climate denial".
The author of the article is grinding an axe. A naive reader envisions copious emissions of coal dioxide threatening the world we know. Instead of offering a solution to AGW, the author is religiously willing the extermination of steam generation so that the prayer wheels and gas turbines of the faithful can take over.
The faithful could not care a rat's arse that our descendants should fry in hell on earth. Their priority is to ensure that they have forgiveness for their emissions.
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Post by huon on Nov 2, 2017 10:27:57 GMT 9.5
"That [phasing out coal by 2050] would be totally inadequate to protect the greenhouse."
I agree, RC. A phase-out of coal is necessary but not sufficient. Later in the article the author says, "Similarly, those scenarios suggested a global carbon price would have to be well over US$100 per tonne, since at that cost, sea level would rise by 65cm by 2100." With a CO2 price that high, the use of oil and gas would plummet, too.
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Post by Roger Clifton on Nov 3, 2017 8:45:10 GMT 9.5
Sufficient? What would be sufficient to stop the rot is a 100% extinction of fossil carbon emissions. That's what "net zero emissions" implies. Price pressure (ie, a carbon tax) could only move consumption to non-carbon alternatives if those alternatives are available. Joe Public gets little choice in the source of his power, most industries have little more. It requires the State itself(*) to convert electricity production to non-carbon. Electricity production must itself expand and expand again, not just to charge up EVs at night, but also to provide the extra power for heating, metallurgy, cement and the enormous power required to convert CO2 back into synthetic fuel for everything that hasn't been converted yet. However the technology to convert CO2 into synthene for ICE engines requires a global effort in R&D. A total replacement would shift world trade patterns from "coal-oil-and-gas" to synthene. It will be one more revolution driven by natural disaster. We should be preparing for it, anticipating, sidestepping, staying on top of it. (*) UK state should invest in nuclear (WNN) |
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Post by huon on Nov 4, 2017 14:50:35 GMT 9.5
"Price pressure (ie, a carbon tax) could only move consumption to non-carbon alternatives if those alternatives are available." Yes, it would be very helpful to have both a carbon tax--even, to start with, a modest one--and several kinds of small modular reactors. The combination of the two would give us cheap, clean, safe energy in abundance. See, for example, the article "'Father of Climate Change [Awareness]' Sides with GOP on Carbon Tax". "Hansen insisted during his talk with Annie Sneed of Scientific American that there really is no other solution [than a carbon tax] to mitigate future climate change risks.... "Furthermore, Hansen made it clear that his vision of a more resilient world is not one limited to relying on solar and wind power. Nuclear power, he insisted, has to be part of this equation; in his view, it has done much to reduce carbon emissions as well as illnesses and premature deaths from pollution. And as emerging economic powerhouses such as China and India continue to grow, there is no way they could phase out coal consumption without including nuclear as part of their energy portfolios." www.triplepundit.com/2017/04/father-climate-change-sides-gop-carbon-tax/ |
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Post by huon on Nov 7, 2017 6:17:43 GMT 9.5
So where are we? As David Benson has so ably explained in this thread and the one on Antarctic melting, the Earth's atmosphere now has more than 400 ppm of CO2--a level not seen for over 3 million years. As an early consequence, key glaciers in Antarctica are melting, and if countries do not change course, sea levels could rise by over a meter by the end of the century.
We have reached mid-Pliocene CO2 levels. and we need to get back to those of the Holocene. In 1985, for example, CO2 levels were still under 350. To accomplish our goal we can use electric vehicles, small modular reactors (plus some intermittent sources), and a few things to facilitate the other two, such as carbon taxes and reliable grids. Sounds like a reasonable plan to me.
(Sorry for all the edits; this comment may be just a recap but I wanted to get it right.)
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Post by huon on Nov 12, 2017 11:06:40 GMT 9.5
The UK has both a carbon price and support for nuclear power. As a result, a number of private companies are proposing SMRs. One article concludes with the following thought: "In the 1960s, 25 per cent of the UK's power capacity came from nuclear. Schoolchildren were told this was the power of the future. If SMRs can overcome the hurdles, they could take us--and our data centres--back to that future." "Britain's on the brink of a small-scale nuclear reactor revolution" www.theregister.co.uk/2017/05/24/mini_nuclear_reactors_for_british_power |
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Post by David B. Benson on Nov 29, 2017 20:22:26 GMT 9.5
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Post by huon on Dec 3, 2017 5:09:19 GMT 9.5
DBB, the article you refer to really brings the mid-Pliocene to life. I was especially interested in the Arctic camels. This Nature article has more details on these camels, their evolution, and how they came to be in the North American Arctic (I read just the Abstract, the Introduction, and the Discussion): www.nature.com/articles/ncomms2516 Fascinating for those interested in "charismatic megafauna". The Bering Strait is covered in the Discussion section. An excerpt (footnoting omitted): "The terrestrial biotic continuity would have been broken ~5.5 Ma when tectonic rifting led to the opening of the Bering Straight (Fig. 1). Evidence of an oscillating or possibly continuously collapsed Pliocene West Antarctic ice sheet and high Pliocene sea levels suggest that from 5.5 to ~3.0 Ma the Beringian land mass was often, if not always, submerged, hindering intercontinental dispersal of terrestrial organisms." Some possibly helpful details for reconstructing the status of the Bering Strait during the mid-Pliocene. |
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Post by David B. Benson on Feb 25, 2018 15:42:39 GMT 9.5
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Post by David B. Benson on Mar 26, 2018 19:28:14 GMT 9.5
Closure of the Panama Seaway during the Pliocene: implications for climate and Northern Hemisphere glaciation link.springer.com/article/10.1007/s00382-007-0265-6According to the model study, about 5 cm of sea level. This helps substantiate earlier remarks. |
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Post by huon on Oct 12, 2018 14:09:00 GMT 9.5
Looking back 16 million years at the Mid-Miocene Climate Optimum (MMCO) shows us how much we may have imperiled our future. phys.org/news/2018-09-crystals-climate-gold-standard-timeline.html"This 16-million-year-old climate change event is the last time that carbon dioxide concentrations in the atmosphere shot above 400 parts per million--until the last decade. A fine detective story, and a cautionary tale. |
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Post by David B. Benson on Oct 4, 2019 13:19:52 GMT 9.5
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Post by David B. Benson on Jul 11, 2020 8:39:18 GMT 9.5
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Post by David B. Benson on Aug 21, 2020 2:26:59 GMT 9.5
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Post by David B. Benson on Sept 22, 2020 8:08:00 GMT 9.5
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Post by David B. Benson on Sept 24, 2020 3:20:15 GMT 9.5
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Post by David B. Benson on Sept 24, 2020 14:00:31 GMT 9.5
The hysteresis of the Antarctic Ice Sheet Julius Garbe et al. 2020 Sep 23 Nature www.nature.com/articles/s41586-020-2727-5Definite statement of the sea level rise for each degree of warming; nonlinear h/t to nigelj on Real Climate |
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Post by huon on Nov 8, 2020 15:35:52 GMT 9.5
The previous two comments are a clarion call for effective climate action.
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Post by David B. Benson on Jan 8, 2021 22:57:26 GMT 9.5
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Post by David B. Benson on Feb 2, 2022 6:12:26 GMT 9.5
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Post by huon on Mar 17, 2022 13:31:01 GMT 9.5
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Post by huon on Apr 11, 2022 14:10:37 GMT 9.5
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Post by huon on Jun 23, 2022 15:30:05 GMT 9.5
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Post by huon on Nov 5, 2022 12:57:16 GMT 9.5
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Post by huon on Nov 11, 2022 14:25:18 GMT 9.5
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