Summary of Dr. Hansen's roadmap for controlling climate change:
"If phasedown [6 %/yr] of fossil fuel emissions begins soon , improved agricultural and forestry practices, including reforestation and steps to improve soil fertility and increase its carbon content, may provide much [~100 GtC] of the necessary CO2 extraction [~150 GtC by 2100]. In that case, the magnitude and duration of global temperature excursion above the natural range of the current interglacial (Holocene) could be limited and irreversible climate impacts could be minimized. In contrast, continued high fossil fuel emissions today place a burden on young people to undertake massive technological CO2 extraction if they are to limit climate change and its consequences." From the abstract of "Young people's burden: requirement of negative CO2 emissions". www.earth-syst-dynam.net/8/577/2017/ My annotations [in brackets] are taken from the last paragraph of the main paper. www.earth-syst-dynam.net/8/577/2017/esd-8-577-2017.pdf
Post by Roger Clifton on Oct 9, 2017 21:50:25 GMT 9.5
The relatively achievable part of Hansen's roadmap would be the commitment to reduce emissions by 6% per year, every year. If that rate of reduction could be maintained, in the 33 years between now and 2050, global emission rate would be down to 13% of what it is now. (0.94^33=0.13). That would be on track for "net zero emissions" at 2100.
It would have to be a significant effort. Currently 25 million Australians consume 7 kW of thermal energy in the form of carbon fuels. Replacing 6% of that would require replacement of 10.5 GW(t) of fossil generation with non-carbon generation in the year. In nuclear countries, that implies a serious building program, year on year.
In Australia, where we seem hopelessly addicted to extracting and exporting fossil fuels, the equivalent of 10 GW(t) in noncarbon capacity could politically only be achieved by installing that much in new wind farms, backed up by a similar capacity of extra gas turbines. The highly visible wind farms would relieve the conscience of the Left, and the excessive consumption of gas by the inefficient gas turbines would console the Right. For the latter reason, any reduction would be illusory. But heck, if Germany can bluster that it has achieved something useful against carbon, we could follow the precedent and claim to be as virtuous.
Having a good roadmap is one thing; actually getting to the destination is another. For controlling climate change , it is specific technologies and policies which will do the work. Of the technologies, nuclear power deserves special attention. As Dr. Hansen wrote on BNC over eight years ago,
"Prompt development of safe 4th generation nuclear power is needed to allow energy options for countries such as China and India, and for countries in the West in the likely event that energy efficiency and renewable energies cannot satisfy all energy requirements."
Post by Roger Clifton on Oct 12, 2017 16:04:04 GMT 9.5
A mass rollout of nuclear energy worldwide requires mass production of a few well proven reactor designs. Each design has to be factory built with standard factory equipment, or at least, standard workers. Further, each design must be utterly conservative, that is, based on designs with a proven history of service. Fully assembled before leaving the factory, each module has to be small enough to be transported by road.
These designs are the "Small Modular Reactors". The front runner is currently Nuscale. But see the SMR thread elsewhere on this forum.
I referred to the following article on the SMR thread in the Energy section. But perhaps I'll mention it it here, too--the discussion on Open Thread being a little more free-wheeling.
Study Finds Advanced Reactors Will Have Competitive Costs
"The anonymized findings signal a potential end to the economic downsides of nuclear energy. In fact, at the lower end of the potential cost range, these plants could present the lowest cost generation options available."
Neutron star mergers may have created most of the gold, uranium, and other heavy elements in the universe. So suggests the recent observation of just such an event.
"Among other things, the merger gave observers a front-row seat at the birth of a black hole, which the colliding neutron stars likely produced. The discovery that most glitters, though, is smoking-gun evidence that neutron star mergers--rather than run-of-the-mill supernovae--are the cosmic crucibles that forge the universe's heavy elements: substances including uranium, platinum and gold."
Post by Roger Clifton on Oct 19, 2017 18:01:24 GMT 9.5
Yes! This time they were able to catch the coinciding GRB, the gamma ray burst predicted by a modern theory of nucleosynthesis mentioned by Huon back up this thread.
The classical r-process adds neutrons in rapid succession to seed nuclei (like iron) before they can beta-decay (where an internal neutron changes to a proton). During the compression phase of a supernova event, the sudden hail of neutrons rapidly turn existing nuclei of iron and larger into heavier neutron-rich isotopes. Then as the outer shell of the supernova relaxes (explosively!) these excited and neutron-rich nuclei beta decay back towards a rough equality between the number of neutrons and protons in the nucleus. The heavier-than-iron isotopes across the chart of nuclides have appeared. But some isotopes could not have been created this way, including some isotopes of gold and platinum.
The theoretical solution to the puzzle was to reverse the process. That is, instead of making medium-sized nuclei heavier, extremely heavy nuclei became not-so-heavy. The process was predicted to occur in a neutron star collision. In the splatter of extremely neutron rich matter, every droplet rapidly fissions into smaller and smaller droplets. At the same time beta decay is liberated (the electron levels were all full when inside the star) so that the proton number of each droplet grows at the expense of the number of neutrons, becoming giant nuclei with finite (but very short) lifetimes. Still fissioning, some of the fragments populate the missing gold and platinum isotopes. The blast of gamma rays resulting from the surge of beta decay daughters provides the GRB, the gamma ray burst.
Somewhere around the "island of stability" (A~270), spontaneous fission events become less likely than alpha decays, and the super heavy nuclei more gradually become less and less heavy in chains of alpha decay. As the masses of the daughter nuclei drop into the 240s, elements familiar to us begin to appear. As the masses decrease, the alpha decays continue at longer and longer half lives until many of the nuclei will survive the age of the earth. U238 and Th232 are examples. So the process is still ticking! If you track the concentrations of U238 and U235 backwards in time, you will see an equal concentration at 6.0 billion years ago. But was that the date of a supernova, or a neutron star collision?
PS: A recent article in Physics Today explains that immediately after the merger, extreme magnetic fields launch a relativistic jet of plasma through the cloud of decaying debris. As the charged particles decelerate, they emit radiation. Hence the gamma ray burst. It only lasts a couple of seconds (what a squirt!) whereas the beta etc decays in the afterglow die away more exponentially.
"NB: Could you summarise what you'd prescribe as a course of action?
"JH: Yeah, the course of action should be to collect a fee from the fossil fuel companies at the domestic mines and the ports of entry and give the money to the public; an equal amount to all legal residents....
"As the carbon fee rises, products that are made with fossil fuels will become more expensive. So people will tend to buy other products and this will move us off of fossil fuels. Economists all agree: this is the way to do it, let the market help you solve the problem...."
Post by Roger Clifton on Nov 18, 2017 16:34:24 GMT 9.5
I would question the respectability of that website. Either James Hansen is speaking enthusiastically to an enthusiastic audience, or our reporter is selecting enthusiastically from his words. In this fragment below, Dr Hansen appears to contradict science.…
"NB: But even if we stabilise, what you are saying is that we are still going to see the impacts? JH: Well, if we would reduce emissions a few percent each year, which economists say you could easily do if you had a rising price on carbon, then the maximum temperature rise would be 1.5 degrees."
On the face of it, he seems to say that we only need make a token reduction in the annual rate of emissions. We would then be rewarded by the temperature rise coming to a screeching halt. The new average temperature would have changed only by what we have endured so far, and all imminent rises and tipping points in the pipeline will somehow be cancelled.
You and I know that that is technically false. Endlessly increasing CO2 means endlessly increasing temperature. Endlessly! There is no asymptotic 1.5° or 2.0° destination. At any nonzero emission rate, those temperatures are no more than waypoints to be glimpsed briefly as we zoom past them. It is the sort of wishful claptrap that windmill salesmen feed to those who are desperate to believe and willing to pay for a token of reduction to be put on the skyline. That is one reason to question the respectability of that website, suspecting they might have something to do with the windmill-selling industry. However Dr Hansen also could make sure that he is quoted correctly.
Two main factors contribute to changes in atmospheric CO2 levels: how much humans put in and how much nature takes out. (See the excellent graphic here: whrc.org/project/global-carbon )
Extraction by the terrestrial biosphere and by the oceans depends on the total atmospheric concentration and not (much) on yearly additions. If humans were to stop CO2 emissions immediately, extraction by the sinks would continue at about the same rate. A cut in human emissions of around 50% could stabilize CO2 levels. Cuts of more than 50% would cause them to fall. [NOTE (Nov. 29): This paragraph contains errors; see discussion on Nov. 24 and 26 below.]
Dr. Hansen's target for reduction in CO2 emissions is 6% per year. At this rate, emissions would fall to around 50% in 11 years, 25% in 22 years, and 12.5% in 33 years. The latter figure matches RC's calculation in our discussion upthread on Oct 8 and 9.
The bottom line is that if we cut emissions by 6% a year, residual emissions in the out years aren't going to matter much. This is good news.
This post about carbon taxes and nuclear power, written over ten years ago, is still relevant. The author is a professor of economics at Harvard University.
"The two issues that Tierney raises--the carbon tax and nuclear energy--are closely related. One effect of a carbon tax is that it would automatically promote nuclear energy. Right now, production of electricity via nuclear power is not particularly cost-efficient compared to alternatives such as coal. But a carbon tax would make coal-produced electricity more expensive, encouraging utilities to take another look at nuclear power." gregmankiw.blogspot.com/2006/05/three-votes-for-carbon-tax.html
Carbon taxes and nuclear power are a formidable 1-2 punch.
Extraction by the terrestrial biosphere and by the oceans depends on the total atmospheric concentration and not (much) on yearly additions. If humans were to stop CO2 emissions immediately, extraction by the sinks would continue at about the same rate. A cut in human emissions of around 50% could stabilize CO2 levels. Cuts of more than 50% would cause them to fall.
Wrong - why not give us a link? Logging and tilling are reducing land carbon, not increasing it. The amplitude of the annual CO2 oscillations (forest vegetation) has not changed in proportion to CO2 conc either.
And another link, supporting ongoing rapid absorption by the oceans? The sea surface layer (~100 m) absorbs more only as atm conc increases. If there is a tolerable level at all, the Keeling curve would have been flat until recent (post 50%) decades. Far from it - CO2 conc was already in runaway mode before 1957.
The layer below the surface "mixing layer" is high in CO2 and CH4 from anerobic digestion of bio detritus, so we don't want to add any more carbon to that time bomb.
Rock weathering (~100,000 years) is a pressure sensitive sink. But ocean layers are not sinks, only reservoirs, of various timescales.
Where did you get this "50%" BS anyway? At best it is wishful thinking from those who rather deny death than avoid it. Did it come from one of those sites selling the idea of 100% wind, backed by 50% gas? A salesman's lie, preying on popular denial.
RC--Yes, my second paragraph is wrong. I had assumed that natural CO2 extraction follows total atmospheric concentration and that yearly additions don't matter that much. But as you point out, for the oceans this assumption is incorrect: the upper level of the oceans comes to equilibrium with the atmosphere quickly (in about a year). So if yearly emissions by humans are cut, extraction by the oceans would rapidly and significantly fall, too. The whole paragraph is thus wrong. Thanks for keeping this discussion--and me--honest.
Post by Roger Clifton on Dec 1, 2017 12:08:13 GMT 9.5
"... take care"
I wish I could say I've been studying the volcanoes, but in fact I went to Bali to get my teeth done. Darwin is only 1600 km to the southeast, but the backlog from cancelled flights means i must zigzag across SE Asia to get back. After 12 night hours bussing west from Denpasar on battered roads, I'm currently sleepless in Surabaya. Tomorrow I fly west to Jakarta then north to Manila to find an unbooked seat south to Darwin!
But it would be interesting. Hotel staff say they can pick out (from traffic noise) the rumblings at night - as the magma expands its reservoir. The daily risk is low, but the years have many days, so these guys worry for their families.
(PS - To add insult to injury, when southbound from Manila, as the plane flew over Darwin, an another act of Nature, a rainstorm, stopped us landing there, so we were diverted to the alternate, 250 km further south. So we sat on the tarmac at Tyndal for 3 hours before the final leg back north to Darwin. Total of 27 hours in airplanes and airports, SUB-CGK-MNL-KTR-DRW. A long trip back from the dentist! )
After your series of dramatic posts, RC, I've been thinking a lot about volcanoes. Your itinerary was actually a grand volcanic tour: Bali and Mt. Agung; Jakarta, about 150 km from Krakatoa; and then up to Manila, less than 100 km from Mt. Pinatubo. Also it occurs to me that if a fusion reactor is a "star in a jar" then a fission reactor is a "volcano in a can".
Post by Roger Clifton on Dec 18, 2017 8:30:13 GMT 9.5
The chain of volcanoes that run from Sumatra through to New Guinea are due to the Australian plate sliding (at ~100 mm/a) northward underneath the Eurasian plate. The accumulated volcanic ash has provided a rich soil that supports 300 million Indonesians.
A similar statement can be made about the Philippines, where the Philippine plate (one of the Pacific plates) slides westward under the Eurasian plate. Other plates are sliding south-east under North America. The heat energy that drives convection and moves them comes mainly from the alpha decays in the thorium and uranium decay chains.
I'd like to continue the discussion, from Nov. 17 above, of this quotation of James Hansen's:
"JH: Well, if we would reduce emissions a few percent each year, which economists say you could easily do if you had a rising price on carbon, then the maximum temperature rise would be 1.5 degrees [Celsius}."
So if yearly emissions by humans are cut, extraction by the oceans would rapidly and significantly fall, too. The whole paragraph is thus wrong.
Huon, we could discuss topics in the general area of Hansen's statement (see Nov 17), but it would need to be kicked off by you giving us a fresh opinion in that area. In your comment of November 27, you seem to agree with me that Hansen's statement is contradicted by the science. So what's new?
(Out of respect for The Great Man, I hasten to add that Dr Hansen could be interpreted to be saying that the economists believed it, not that he did. His tone may have been sardonic (dic), ridiculing economists and their starry eyed followers.)
Post by David B. Benson on Dec 28, 2017 23:25:51 GMT 9.5
As I read the Young People's Burden, Dr. Hansen stresses that a further 1.5 °C increase is not good enough. Indeed he calls for further afforestation, but without indicating how massive that has to be for a decent outcome.
The abstract for that paper concludes by saying, "Continued high fossil fuel emissions unarguably sentences young people to either a massive, implausible cleanup or growing deleterious climate impacts or both". To some readers, this might sound like a brave call to action, but to me it is cowardly and betrays the very people it speaks of.
In fact, any continuing rate of fossil emissions whatsoever dooms young people to a worsening, hostile climate, with no hope that it will ever pause or get better again.
Perhaps Dr Hansen is trying to bring hope to the doomed before they despair. Perhaps his strategy is to encourage young people to fight, fight, fight with inadequate solutions until they stumble across some effective means of exterminating fossil emissions. Yes, I say "exterminate", as nothing less will suffice to allow convergence on an equilibrium average temperature, let alone restore it to the past value.
Actually, RC, Hansen's Burden paper is open access. See the download box in the upper right hand corner of the abstract page you cite; or just click here: www.earth-syst-dynam.net/8/577/2017/esd-8-577-2017.pdf The two page Discussion section, starting on page 594, is a very good summary, and the last paragraph is a good summary of the summary.
You are quite right, DBB, that according to Hansen a 1.5 degree Celsius increase in temperature is too much. In fact even the 1 degree rise of the last interglacial (the Eemian period) is not safe. We need to get back to near the natural temperatures of our own interglacial, the Holocene: around .75 degrees or less.
To do this, we should nearly eliminate emissions by mid-century, and also start a program to extract CO2 from the atmosphere. Of the ~150 PgC (or GtC) that must be extracted, about 100 PgC could come from relatively natural reforestation and improved agricultural practices. 100 PgC, incidentally, is about the same amount that deforestation and bad agricultural practices have put into the atmosphere.