Monday, July 31, 2017

On Climate Change

David Henderson and I wade in to perilous waters in the July 31 Wall Street Journal. We try to stake out a different and more productive conversation than the usual shouting match between alarmists and deniers.
Climate change is often misunderstood as a package deal: If global warming is “real,” both sides of the debate seem to assume, the climate lobby’s policy agenda follows inexorably.
It does not. Climate policy advocates need to do a much better job of quantitatively analyzing economic costs and the actual, rather than symbolic, benefits of their policies. Skeptics would also do well to focus more attention on economic and policy analysis.
As usual, I have to wait 30 days to post the whole thing.

As economists, we both have a healthy skepticism of large computer based forecasting models. The famous 1972 club of Rome forecast that we would run out of resources, and the grand failure of large scale Keynesian models in the late 1970s are two humbling examples. The "climate" models also feature a lot of questionable economics. A crucial question -- how much carbon will the world's economies add on their own, without Paris-accord policies? That's economics, very questionable economics, and not meteorology.

That said, however, the point of the oped is to try to shift the debate away from climate science and mixed climate-economic computer models. Stop arguing about climate, and let us instead investigate costs and benefits of policies. That strikes us as a much more fruitful place for discussion. If you are wary of the climate policy agenda, the costs and benefits of those policies are more fertile ground for discussion than the science of carbon emissions and atmospheric warming. If you only argue about the climate, then you implicitly admit that if the models are right about climate, the whole policy agenda follows. Do not admit that point. They may be right about climate and wrong about policy.


In California, it is seriously suggested that the way to get more water is to build a high speed train, which will save carbon, which will cool the earth, which will... actually, it goes the other way, but never mind. To address an argument like that, you should not get dragged in to whether human-released carbon warms the planet. A simple dollars per ton and tons per inch of water would do.

If it is not clear enough, nothing in this piece takes a stand on climate science, either affirming or denying current climate forecasts. I will be interested to see how quickly we are painted as unscientific climate-deniers. Shifting a politicized debate is hard. That is, if anyone pays any attention.

A few other choice bits:
Global warming is not the only risk our society faces. Even if science tells us that climate change is real and man-made, it does not tell us, as President Obama asserted, that climate change is the greatest threat to humanity. Really? Greater than nuclear explosions, a world war, global pandemics, crop failures and civil chaos?
No. Healthy societies do not fall apart over slow, widely predicted, relatively small economic adjustments of the sort painted by climate analysis. Societies do fall apart from war, disease or chaos. Climate policy must compete with other long-term threats for always-scarce resources.
As something of a conservative libertarian, I do worry about the end of western civilization and our society falling apart. And I worry about the natural environment as part of that. Still, slow warming in the next two centuries, and a sea level rise (much smaller than the one that happened a mere 10,000 years ago), while a worry, is not obviously the top worry.
Global warming is not even the obvious top environmental threat. Dirty water, dirty air and insect-borne diseases are a far greater problem today for most people world-wide. Habitat loss and human predation are a far greater problem for most animals. Elephants won’t make it to see a warmer climate. Ask them how they would prefer to spend $1 trillion—subsidizing high-speed trains or a human-free park the size of Montana
I'm also something of an environmentalist, with a soft spot for people living in terrible conditions and for the awful permanence of species extinction. Starting with wooly mammoths.
The Intergovernmental Panel on Climate Change’s “scientific” recommendations, for example, include “reduced gender inequality & marginalization in other forms,” “provisioning of adequate housing,” “cash transfers” and “awareness raising & integrating into education.” Even if some of these are worthy goals, they are not scientifically valid, cost-benefit-tested policies to cool the planet.
When I read the IPCC report, starting on p. 26, I had to check that I was not unintentionally reading The Onion. We cut for space. A longer list (from that p. 26) of the IPCC's policy ideas
Reduced gender inequality & marginalization in other forms…. Improved access to & control of local resources; Manipulation of disturbance regimes; Community-based natural resource management…. Provisioning of adequate housing,… Micro finance; Disaster contingency funds; Cash transfers; Public-private partnerships…Patent pools & technology transfer…: Awareness raising & integrating into education; Gender equity in education; Extension services; Sharing indigenous, traditional & local knowledge; Participatory action research & social learning; Knowledge-sharing & learning platforms… behavioural shifts, or institutional & managerial changes that produce substantial shifts in outcomes. (under”practical” subheading) Individual & collective assumptions, beliefs, values & worldviews influencing climate-change responses.
Again, you do not have to get deep into cloud modeling and ice melt feedback loops to wonder if all of this list necessarily follows. And, for the record, I have no qualm with lots of this list. Gender equality and equity in education? Improved access to resources? Who can object? But this is supposed to be about effective policies to cool the planet, not a grab bag of things that would be nice. (I do have qualms with a lot of the list, of course. It's a rather Orwellian and statist vision. "Public-private partnerships" characterizes much of contemporary Russia.)

I like our last paragraph.
Climate policy advocates’ apocalyptic vision demands serious analysis, and mushy thinking undermines their case. If carbon emissions pose the greatest threat to humanity, it follows that the costs of nuclear power—waste disposal and the occasional meltdown—might be bearable. It follows that the costs of genetically modified foods and modern pesticides, which can feed us with less land and lower carbon emissions, might be bearable. It follows that if the future of civilization is really at stake, adaptation or geo-engineering should not be unmentionable. And it follows that symbolic, ineffective, political grab-bag policies should be intolerable. 
For the record, I favor a uniform carbon tax in place of all the other direct energy regulations and subsidies. (A neighbor just showed me his electric car, purchased in addition to a regular car, for one reason only: you can ride it solo  in the HOV lane, a right worth thousands in California.) The rate on such a tax can be raised or lowered as politics and science see fit. If we're going to do something, and if the health of the economy is a prime consideration, then we must do something economically efficient. (David disagrees, but he can explain his views in his own blog.) As I favor a uniform VAT in place of the idiotically complex income and corporate tax system. I recognize the essential failure of our political system to enact simple transparent reforms, but that's a question for another day.

I do think there is hope however. A while ago I went to a meeting organized by the Niskanen Center bringing together free-market and libertarian types with some large environmental organizations. The environmentalists were concerned about climate change, understand that feel-good policies (like the subsidy for my neighbor's car) aren't going to slow down climate change, and will suck resources away from policies that could. The free marketers were largely a bit skeptical about just how much of a threat climate change is, but appalled at the inefficiency of IPCC style regulations. There is a deal to be had -- we'll do something efficient and effective (say, a carbon tax) in return for eliminating the junk.  We can agree to disagree about the level of that tax. My sense is that environmental groups are not ready to say this in public, for fear of angering allies who want to use the environmental label for a grab bag of policies (see IPCC list!), and the libertarians and free market types don't trust the "get rid of" rather than "in addition to" everything else part of the bargain. But there is a bargain to be made, and strong political leadership could bring it about.

(By the way, we didn't choose the figure caption. We know that Rotterdam is not prone to floods. Much of it is below sea level, and Miami is 9 feet above sea level.)

Update: Ian Martin and Bob Pindyk have a classy AER paper on the subject of "insurance" and multiple potential catastrophes. They go beyond our point -- if you buy overpriced insurance for each catastrophe you exhaust GDP quickly -- and consider the general equilibrium interactions. Catastrophes affect marginal utility a lot, so when you insure against one you change the state-contingent valuations of another. Evaluating policies in isolation is doubly bad.

84 comments:

  1. Cost benefit analsis is great, but not enough. Professor Cochrane's op ed analysis depends on his understanding that current climate models predict a 10% GDP loss over 100 years. The public policy Climateers continue to insist on a much more catastophic future, and they continue to insist that 97% of climate scientists agreement with them. I went to the movies in the upper west side of Manhattan recently and saw the trailer for Al Gore's new movie. (Maybe his jet airplanes need replacing.) About a third of the audience applauded the trailer. They applauded the trailer. Sixty seconds of stranded polar bears, crashing ice flows and flooded cities, and they applauded an advertisment. I oppose carbon dioxide taxes and the like for two reasons. One, it takes money from the private economy and gives it to the bureaucrats and rent seekers. Second, it yields the intellectual field to the histerics on the question of whether there is any reason at all to fear carbon dioxide. Ed Kickham, Bloomfield, Michigan

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    1. "...it yields the intellectual field to the histerics on the question of whether there is any reason at all to fear carbon dioxide."

      Dr. Cochrane, posting about how you'll be lambasted as a climate-denier and then approving this comment is a rich irony. I disagree with the certitude expressed by many global warming alarmists, but the attitude in the above comment is that which earns skeptics the scorn they often deserve.

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    2. The comment isn't offensive or objectionable. It appears to be a genuine opinion, and it isn't that far outside the mainstream. Why would you suggest it should be censored?

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    3. Ed, it appears the social cost of "carbon" is negative. The doomed warming won't happen and a luke-warming is outweighed by the much greater efficiency of plants (less water, more food, less farmland needed). Thus, the carbon tax should be negative.

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    4. Don,
      Where on earth do you get the notion that the social cost of "carbon" is negative?
      Any claim of "much greater efficiency of plants" is just plain wrong.
      Increased CO2 concentration in the atmosphere makes hardly any difference to plant productivity.
      More than half of CO2 emitted by burning fossil fuels ends up in the oceans where it dissolves calcium carbonate thus making coral reefs dead.
      --E5

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    5. All, see:

      https://en.wikipedia.org/wiki/Thermocline

      Ocean water temperature is between 2 Deg C and 6 Deg C from 1000 meters to 6000 meters of depth. The pressure at those depths range from 100 bar at 1000 meters to 600 bar at 6000 meters.

      This is the phase diagram for Carbon Dioxide:
      https://hub.globalccsinstitute.com/publications/co2-liquid-logistics-shipping-concept-llsc-–-business-model-report/appendix-1-co2

      Carbon Dioxide starts to become a liquid at a pressure of 40 bar (at 5 Degrees Celsius). Increasing the pressure or decreasing the temperature accelerates the process.

      There have been discoveries of existing underwater lakes of liquid CO2.

      http://www.pnas.org/content/103/38/13903.full

      Anonymous,

      "Any claim of much greater efficiency of plants is just plain wrong."

      See D. Wilson and J. P. Cooper's paper on the effect of CO2 concentration and light intensity on plant photosynthesis.

      https://www.ncbi.nlm.nih.gov/pmc/articles/PMC396144/

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    6. Not all carbon tax schemes give money to the state - the carbon-dividend people rebate all but a small (1-2%) administrative cost back to all citizens, effectively replacing the large concentrated wealth transfer of EPA and the like with a distribution to all that gives a boost to the economy, is fair and balanced (because there is no means test) and much more effective than CPP or similar administrative state approaches. See https://en.wikipedia.org/wiki/Fee_and_dividend for an intro, or https://citizensclimatelobby.org/basics-carbon-fee-dividend/ for more detail.

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  2. A carbon tax could make sense, for the purpose of internalizing an externality--if we had any confidence that we knew that externality's size. We don't even know its sign. For all we know we should be subsidizing fossil-fuel use, i.e., the return of carbon to the cycle of life

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  3. Ed is right. Cochrane and Henderson have effectively ceded the argument to the alarmists by backing a carbon tax. It has yet to be shown (to the satisfaction of many, including some noted scientists) that the late 20th- century relationship between rising CO2 levels and rising temperatures was anything more than coincidental. CAGW is the scientific equivalent of the flat-earth theory.

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    1. Joe, Thomas. Read a bit more carefully. IF we are going to do anything, let it be a carbon tax in place of all the other junk. If. Also nothing in the piece says anything about carbon tax, and Henderson doesn't even go that far.

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    2. Perhaps you should be agnostic as to whether a carbon tax or carbon subsidy is required. There is evidence that the benefits of higher CO2 concentrations may outweigh the costs, at least for small increases (eg from the CO2 fertilization effect, reduced deaths from cold weather). Given the uncertainty over the magnitude of CO2 increases and warming, my suggestion would be to adopt only "no regrets" policies.

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    3. Except, Patrick, that plant growth is not, to any worthwhile extent, constrained by the low CO2 concentration of even the pre-fossil-fuel-burning atmosphere. In practice any one of many other factors comprises the constraint.
      And except that the greater weather extremes of a warmer globe will result in more cold weather deaths as well as more hot weather deaths. And more energy use for heating and cooling.
      It is, however, essential that economists make good use of their expertise to predict effects of policies.
      --E5

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  4. I would like to see climatologists subject their data to the same time series analysis we use. Does CO2 Granger-cause temps, for instance? Unit roots? Levels of uncertainty? How do you use 30 years of data and think you know how the climate works? Seems very iffy to me.
    And that's even before you do any cost-benefit studies. The 'benefits' are going to be based on iffy data with some weak correlations at best. Hmmmmmmm.
    Glad to hear you're taking on this project!

    Pete Bias

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  5. Your use of the slur "deniers" in the first sentence to describe skeptics hardly fills me with confidence.

    Once the mechanism of a carbon tax is in place left-wingers who get back in power can quickly ratchet up the price, plus getting a carbon tax will hardly stop them from creating other economically destructive "solutions" as well.

    But I do acknowledge you for calling out the IPCC's bundling of all manner of left-wing canards into their recommendations.

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    1. I was trying to find the words each side uses for the other, and to slur equally. I guess any attempt at levity in this area is dangerous.

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    2. There is clearly an armwrestling match going on between enthusiastic advocates on each side. These extremes may become a media-highlighted smokescreen hiding the actual reasoning about data.
      That said, it is hard to call one who describes climate science as a hoax anything less than a denialist.
      At the same time it may be appropriate to thank denialists for bringing as boring and non-immediate a subject as climate science to public attention.
      --E5

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    3. Unfortunately most 'skeptics' ARE deniers.. I mean, it's not exactly difficult to puzzle together that CO2 is a greenhouse gas and that adding more greenhouse gasses will increase temperatures. Like, when it's cold you use a blanket..

      'But the data isn't nice and neat! Temperatures fluctuate!' shouldn't really be a barrier - real world data is almost never nice and neat. I do applaud the desire to debate policy options, but that's hard to do with one side is denying the existence of rotating spheres in space.

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    4. The blanket analogy is interesting. Since the stratosphere is warmer than the upper troposphere, more "blanket" would cool the troposphere. See: https://scied.ucar.edu/sites/default/files/images/large_image_for_image_content/mesosphere_diagram_720x440.jpg

      A better analogy for Hansen's global warming would be a less efficient radiator. But that also ignores the temperature inversion.

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  6. If you want to see the state of climate science in 2017 read:

    https://climateaudit.org/2017/07/11/pages2017-new-cherry-pie/

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  7. John,

    I've been enjoying your blog since I found it about a year ago.

    Here's an article attempting to explain in non-physics terms why the "overwhelming consensus on AGW" means little once proponents of urgent action on climate introduce "CAGW", or "Catastrophic Anthropogenic Global Warming" and the "greatest threat facing humanity".

    https://scienceofdoom.com/2017/08/01/the-debate-is-over-99-of-scientists-believe-gravity-and-the-heliocentric-solar-system-so-therefore/

    ---
    Steve Carson, Science of Doom blog.

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  8. I read the article in the Journal earlier. It is very reasonable.

    That is the problem with the ideas you put forth, which are good ideas. The promoters of "global warming" or "climate change" are not interested in solving a problem.

    Their fundamental motive is not concern for the health and welfare of human beings. It is religious. The religious motivation can be seen in their addiction to the literary genre of Apocalypses, such as the one in New York Magazine last week. Apocalypses every bit as lurid as the one written by St. John of Patmos -- and just as "scientific". Men who write Apocalypses to justify their beliefs are engaged in a fundamentally religious activity as are those who study and preach Apocalypses.

    The left that loves climate apocalypse as a motive for adopting worldwide socialist government, one that can micro manage every aspect of human life, believes in “history,” which bends the arc moral universe toward justice; but also, in “climate change,” which is caused by mankind and creates all manner of disorder. Isn’t it obvious that these ideas are substitutes for God and original sin?

    You may ask who are these people, from whence do they come, and how do they arrive at their bizarre religion? They spring from the educated and wealthy urban elites of the American North-eastern and Western Coasts. We can easily observe the collapse of Christian belief in that class. There are a couple of reasons for that.

    First, they are all Marxists now, not industrial grade Stalinists, but cultural Marxists theorized by Adorno, and Gramisci, and the French lumpen-philosophes such as Foucault and Derrida. But, even those variants of Marxism demands atheism.

    Second, atheism, especially, allows them to indulge their favorite pastime -- contempt for the unwashed masses of Americans -- the obese bitter clingers who inhabit fly-over country and cling to their guns and religion.

    Paradoxically, atheism has led the elites to worship pagan idols like the "Environment" and "The Earth (f/k/a Gaia)". The paradox is resolved by understanding that being an atheist does not mean believing nothing. As Umberto Eco wrote:

    "G K Chesterton is often credited with observing: "When a man ceases to believe in God, he doesn't believe in nothing. He believes in anything." Whoever said it - he was right. We are supposed to live in a skeptical age. In fact, we live in an age of outrageous credulity.

    "The "death of God", or at least the dying of the Christian God, has been accompanied by the birth of a plethora of new idols. They have multiplied like bacteria on the corpse of the Christian Church ..."

    http://www.telegraph.co.uk/comment/personal-view/3621313/God-isnt-big-enough-for-some-people.html

    You are wasting your time proposing reasonable solutions to the problems created by a changing climate. They are not interested in reason.

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    1. Wow, that was....a gigantic load of rubbish. I find it particularly hilarious that someone who believes in a deity would mock someone who "believes" in AGW. One is factually true and the other is a complete exercise of faith.

      For what it is worth, I now live in the exurbs of Boston after spending my first 32 years in Florida. I am an atheist. I am "highly educated". I do not believe AGW is the biggest threat to human existence. This holds true for every one of my close friends and colleagues (who are also atheist/agnostic and highly educated).

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    2. Yep, me too. Atheist, Ph.D., and climate skeptic - not that there is nothing going on, but a skeptic in believing that climatologists know as much as they think they do. All it takes is to be an economist to see that...

      Pete Bias

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    3. Congratulations. You are really woke.

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    4. If you don't believe in AGW, then I guess your statement that: "One is factually true and the other is a complete exercise of faith." means that you believe in a deity and that your statement that you are an atheist is incorrect.

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  10. The climate changes? Who knew?

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  11. Thanks for bringing the focus of the climate hysterics to costs! But why tax carbon at all as opposed to a geoengineering strategy (Steven Levitt)? Assuming a causal connection between carbon emissions and global temperatures, carbon dioxide's long half-life, the low odds of an impactful international pact, and immense economic pitfalls of reducing emissions (Bjorn Lomborg) still make reducing emissions and the taxes and regulations with that goal senseless. In a nutshell, the latest idea is for aquatic drones to sail across the north pacific kicking up sea water and seeding clouds to reflect sunlight - we could effectively set a global thermostat at a much lower cost than reducing emissions. Even leftists have begun to recognize geoeningeering in what they see as a last ditch fix. So maybe this concept is not only a economic and scientific solution but a practical policy goal? Perhaps not a long term answer but a pacifier while renewables improve? See the MIT Technology Review in April for more.

    https://www.technologyreview.com/s/604081/the-growing-case-for-geoengineering/

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  12. It's not at all clear why warming over the next two centuries - which would be something in the order of 5C for "business-as-usual" scenarios - is not a worry. Why? The cost of climate change - and therefore how much we should (or shouldn't) spend are just not knowable. I don't mean big or small. I mean literally not knowable. So comparing the costs of nuclear to the costs of climate change is just comparing a dollar number to an unknown number.

    For reference the scale of what's discussed is the same order of magnitude as moving Chicago from being under the better part of a mile of ice to where it is today. We'd expect places currently under a mile of ice to no longer be under that ice. So the cost is a big number whatever it is. Incidentally I'm skeptical of your "healthy societies do not fall apart ..." remark - we simply have no experience of changes of this size.

    It's not at all clear to me that a conventional discount-rate style analysis of sacrificing consumption today to enjoy some benefit tomorrow even works for events of this magnitude and timescale. We know that were someone to have sacrificed the consumption of a loaf of bread at the time of Julius Caesar and invested it in a hypothetical risk-free asset at a real rate of 3%, their ancestors would be unimaginably wealthy as compared to today - at least 25 zeros at the end of their bank balance. But at 1% their ancestor would be merely a billionaire. What I conclude from that is that any economic cost model for sacrificing consumption today for benefits hundreds of years in the future is so sensitive to an unknown parameter, it makes it brittle to the point of uselessness.

    Now when you say "the costs of nuclear power might be bearable" - in order to work out if it's bearable you've plugged a discount rate into the costs of climate change somewhere. Even supposing we knew the cost of climate change in 200 years, the sensitivity to the discount rate makes the questions unanswerable. People who like nuclear will pick one discount rate, people who dislike will pick another.

    So here's my criticism, forgive me for wording it strongly. I think asking whether the costs of nuclear might be bearable is actually just another symbolic, grab-bag kind of totemic point, dressed up as a serious question.

    This makes the problem truly pernicious. I think its pretty clear climate change is bad to some degree. But it's unknowable how much we should spend today to stop it.

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    1. Patrick, fair point but I think you are conflating risk with uncertainty. Discount rates include a premium for risk and assets are insurable. Uncertainty disallows insurance. My point, many innovations couldn't get insurance as there was little or no data
      to quantify probability of failure or loss. That changed with time and technology. While we don't know the cost of climate change in 200 years or the PV of that cost, risk-neutral, time, technology and better policies could make resolving the problem more more present. Thanks for indulging my thoughts.

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    2. I think the point is that it is hard to both argue that climate change is a danger of unbelievable proportions (as you suggest in your comment), and at the same time the relatively small and quantifiable costs of nuclear are unbearable, is difficult. It's either a genuine crisis that we'd do almost anything to avoid, or it's not.

      I agree that it's a bit of a throwaway line using perhaps Prof Cochrane's preferred policy as an example, but I think it also serves to illustrate that some are using this assumed crisis to advance policies they prefer, under the banner that the crisis is so big that previously unthinkable policies should be thought of. I've seen someone arguing for genetically engineering people for reduced resource use, I've seen suggestions of suspending democracy, I've seen suggestions of massive income transfers. Interestingly those same people did not suggest nuclear power, deregulation of energy markets, root and branch reform in third world countries to root out corruption (which impedes efficient markets including those in carbon).

      Bottom line, there seems to be a lot of people following the advice to not waste a good crisis. And they're seeking to advance policy objectives that are only slightly associated with climate change. You can demonstrate that by asking questions about other less favoured measures that are more likely to have an impact on climate change - things such as geoengineering and nuclear power.

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    3. I didn't suggest that. I just suggested that the costs of climate change are unknowable, so if your framework depends upon some "cost of climate change", it's nonsense. E.g weighing up "benefits of nuclear" vs "cost of climate change" is silly.

      Suppose you make a *political* decision to spend up say to 0.5% of GDP on reducing emissions - and then say: pick the cheapest option, nuclear, renewables, gas, efficiencies, whatever, within that budget. That may make sense. But we should be under no illusion that that number (0.5 in my example) is substantially an arbitrary number. There's no sense we can ever know the benefit that we're extracting from that expense.

      Maybe a carbon tax makes a lot of sense in this context. Also if you're going to spend a lot of money, then having decent, uncorrupted accounting and capital allocation mechanisms - and also anti-fraud laws etc - well this is a good thing. Market-based capital allocation mechanisms have a pretty good track record in many domains even for services traditionally provided by government - this is the whole point of the "private-public partnership/PPP" reference which seemed to disturb Prof Cochrane.

      I'm not sure that any of this is terribly controversial, but if your point is that sometimes it doesn't hurt to spell out obvious things in detail, then it's an excellent point.

      That's what I mean about this being a pernicious problem. 0.5 might be massive overkill. But it also might be a massive underspend. We will not know until we know the discount rate over the next 200 years, and really over the next 20 centuries. So what should be the level of carbon tax? It will either be too high or too low - I think either massively too high or too low - and we will never know.

      As for the rest of it - crisis-wasting, genetic engineering people etc - you will find silly camp-followers everywhere, I can't see that it means a lot.

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    4. My pet peeve is the "business as usual" label. That scenario assumes no technological improvements over this century and a world population hitting 16 billion. Both are deceitful. Since the first IPCC report, coal plants are 50% more efficient and honest population estimates are close to 11 billion. With such dishonesty all IPCC work should be discarded and redone.

      A fair estimate is that the world spends 10% of GDP on energy. If the warmists had their way, we'd use energy that is conservatively twice as expensive as optimal. Thus, a better estimate would be 10% of GDP spent on carbon "reduction".

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  13. I agree. As it turns out, the policy debate will continue to be a constant uphill battle.

    One just needs to look at the failure and the list of pro-environmental groups that opposed the revenue-neutral carbon tax initiative last November in Washington State (Initiative 732). It seems these pro-environmental groups want spend the tax revenue on their "grab bag" rather than have any straight-forward policy that internalizes the cost of climate change.

    Another example was the political football surrounding the debate to construct the Keystone XL pipeline. Even the nonpartisan think tank, Resources of the Future, argued that the decision did not matter and that what would matter is to implement a climate change policy that would internalize the cost of climate change. So instead of using the Keystone XL pipeline as a bargaining chip to implement a revenue-neutral climate change policy (i.e., tax emissions and reduce income taxes that would Republicans favor), the Obama administration never considered legislation and prevented its construction. Now the Trump Administration, with a simple stroke of a pen, has reversed course and authorized its construction. I don't think many people saw that the Obama Administration missed an opportunity to pass a nonpartisan (and resilient) national climate change policy.

    As long as pro-environmental groups have the moral high ground, it will continue to be an uphill battle to argue for "efficient" climate change policies. They will continue to want the expensive "grab bag" and want their policy to *show* that society is doing good for the environment (and to relieve other world problems).

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    1. Sure, njanusch, but did we not have a legislature that was hell bent on preventing a half-black president making any mark on history?
      And don't we now have those folks, now fully dominant, hell bent on expunging that half-black president from history? And never mind the consequences on ordinary folks?
      The democrats had, and the Obama administration had, virtually no opportunity to doing anything permanently useful. Yes, holding up Keystone XL construction was a temporary symbolic gesture. It certainly was not possible to use it as some kind of bargaining chip as you suggest.
      The current administration and legislature certainly have the power to implement a revenue-neutral climate change policy. But just as certainly do not have any inclination to do so.
      We are doomed.
      --E5

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    2. njanusch, the leftest moral high-ground is odd. Even the focus on GDP is odd to me. 6 million Africans die each year from bad water, bad sanitation, and indoor pollution. Those things are all fixable with electrification. While the warmists promote solar boondoggles for Africa, people are dying. Where is the moral high ground there? Fortunately, China has a plan to improve infrastructure in Africa. They do it for resources and profit, but the result gives them a claim of the moral high ground.

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  14. "As I favor a uniform VAT in place of the idiotically complex income and corporate tax system. I recognize the essential failure of our political system to enact simple transparent reforms, but that's a question for another day."
    The VAT is invisible to taxpayers. That's why politicians and their media running dogs love the VAT.
    How can the invisible be transparent?

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    1. Canada's VAT (the GST/HST) is added to the retail price. It started at 7% and has been reduced to 5%. Almost 20 years after its introduction it still drives some people on the political right to irrational rage.

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    2. Indeed, George? When did any corporate media or US politicians show any liking of VAT?
      --E5

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    3. "Canada's VAT (the GST/HST) is added to the retail price. It started at 7% and has been reduced to 5%. Almost 20 years after its introduction it still drives some people on the political right to irrational rage."

      The problem with this observation is that Canada's VAT did not, and will never, replace its corporate and individual income tax. This is also the problem with Cochrane's suggestion ---"I favor a uniform VAT in place of the idiotically complex income and corporate tax system".

      The reality is that a VAT would be *in addition to* "the idiotically complex income and corporate tax system". Thus, it would add more, not less, complexity. A VAT would certainly be a good revenue raiser and probably better than raising more revenue through the distortionary income tax system, but it won't replace them. If you want a VAT to replace them and this isn't accomplished on day 1, you will never have a VAT. If you introduce a VAT with the income tax system in place, you will never abolish the latter.

      Viv

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    4. @Viv It is doubtful that any one tax could raise the revenue needed. Canada has income taxes, capital gains taxes, Federal and Provincial sales taxes and payroll taxes (nominally intended to pay for unemployment insurance and the Canada pension plan).

      Canada's VAT was never intended to replace income tax. It was originally intended to increase government revenue to deal with the Federal deficit and replace a hidden "Manufacturers Sales Tax". It was supposed to be at 9%. There was some push back and it was brought in as "revenue neutral" at 7% - just raising the same amount as the old Manufacturers Sales Tax - with the government hoping that efficiency gains would benefit the economy.

      The point I was trying to make is that anyone on the right in the US who thinks a VAT is a good idea in theory better be ready for some major push back from the populist right in practice.

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    5. The bigger problem with Canada's VAT is that Aboriginal and Metis don't have to pay it. This takes a large (and the fastest growing segment of the population) out of the loop of tax responsibility. At any rate, demonizing carbon is ridiculous. Stop breathing!

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  15. Professor: you doubt the accuracy of climate models and call for more emphasis on the economics.

    The problem with that seems to me to be that you need the predictions from accurate climate models to tell you what the climate trade offs are. IIRC, Club of Rome suffered in part from a fairly well recognized problem in trying to use the Euler Method to solve stiff differential equations.

    The DoE puts a lot of effort and has considerable success in solving the differential equations that model nuclear bomb blasts. The effect of releasing carbon dioxide is governed by the laws of physics and chemistry. Modelling the effect on the climate is complex but not totally intractable. Computers are faster and cheaper every year. Numerical analysis techniques get a little better every year.

    The stakes for the world are so high that anyone who thinks there is some serious uncertainty should be advocating spending a some tens of billions of dollars on a definitive answer. Even if we do not completely solve the problem we may get spin-off benefits out better, faster, mathematical modelling techniques.



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  16. John, I am appalled by both sides of climate change. Artificial Light at Night (ALAN) consumes electricity, generates heat, slows nocturnal cooling, disrupts nocturnal ecosystems, disrupts circadian rhythms, disrupts Melantonin secretion (that causes cancers), costs money AND is mostly Unnecessary. Some EU cities and much of France are turning out ALAN, saving a ton of money every, dark night ($10 mil) and experiencing other very positive rewards: Traffic accidents and Crime are down. Yes, DOWN! Because drivers are more careful and criminals are easily seen - and they know it. Lights Out is much more than the Paris Accord and it's Free, and it's Reversible, and it will allow you and your children to see the incredible night sky that is now hidden by ALAN. So, John, from 11 pm until dawn every night everywhere, Lights Out America!

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  17. As a free marketeer and libertarian-ish sort, I am embarrassed by the right-wing on environmental issues.

    Remember, the cost of pollution is not captured by the price signal.

    Ergo, Cochrane is correct to support a carbon tax.

    No one has the right to pollute the air other people breath, or another man's land and water.

    The tort system might be applied to pollution, but as a practical matter...well, it seems impractical. I am sure tort lawyers like the idea.

    Whether or not the burning of fossil fuels will heat up the planet, burning fossil fuels does pollute the air and usually right where people live.

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    Replies
    1. Unfortunately the labelling of CO2 as a pollutant relies on the demonstration that it causes climate change. Absent any suggestion that it causes climate change it would not be considered a pollutant - it's a natural part of the atmosphere and of benefit to plants.

      If when you say "tax pollution" you mean taxing soot, nitrous oxides and other demonstrated pollutants with negative impacts, then your point is clearly (to me) true. If you mean as you say a "carbon tax", then labelling that as taxing pollution does rely on demonstrating that CO2 is pollution, which in turn relies on demonstrating it is harmful, and in turn relies on demonstrating that the burning of fossil fuels will heat up the planet.

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    2. The scientific community tell us with 99.9% agreement that increased CO2 levels result from human activity and that increased CO2 levels warm the planet, and that we can measure the warming which has taken place since we started burning fossil fuels. The science is actually quite simple. Further evidence that it is not natural warming is provided by the understanding of climate cycles, caused by the orbital position of our planet relative to the sun, a cycle which would otherwise have us cooling at present. So, ergo, CO2 is indeed a pollutant. The author points out that a price on carbon would be the better policy approach, and he is correct. If the revenues of such are then used to reduce distortionary taxes, like the absurdly uncompetitive US corporate tax rate, then you can actually net faster GDP growth and increased prosperity for all. If you do such with half the revenues, and recycle the rest to lower and moderate income households, the less well off do even better, and the more well off benefit from reduced taxes. A win win win solution.

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    3. Anonymous, there are many climate related cycles besides Milankovitch (eg, PDO, AMO, Bray, ENSO, Hale,....). Thus your "ergo" is faulty. Also, your assertion that CO2 increases are from human activity (which includes land use) cannot be proven, since ocean upwelling is large and not measurable. 99.99% of scientists would agree;)

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    4. My point was that @Benjamin Cole appeared to be claiming that CO2 should be taxed as pollution _irrespective_ of whether it causes warming. But CO2 is only considered pollution _because_ it causes warming. If you ignore warming then you wouldn't tax it. So his argument makes no sense.

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    5. The consequences of CO2 emissions from fossil fuel burning are not confined to global increasing average temperature and the consequent climate changes. Ocean acidification is a big one. Coral reefs are dying along with the varied life that inhabits them and along with the human communities that depend on them.
      --E5

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  18. From George, commenter above:

    "How can the invisible be transparent?"

    George, you have a way with words….

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  19. "The famous 1972 club of Rome forecast that we would run out of resources"
    The forecast, no doubt, was ill stated.
    However it is basically true that geological resources, once consumed, are gone. Thus, although we have not run out of petroleum, we have exhausted all the deposits of the cheap stuff. The war in Iraq was over control of the last of it (the cheap stuff).
    --E5

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    1. Many (most?) geological resources can be created, it just takes energy--sometimes a *lot* of energy.

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    2. Don - you've given me an opening to segue into a summary of the three laws of thermodynamics that I love:
      1) you can't win (energy is conserved)
      2) you can't break even (entropy increases over time)
      3) you can't get out of the game. (temperature has to stay above absolute zero)

      :-)

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    3. And, Don, most of the energy we consume comes from extracting and burning geological resources.
      --E5

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  20. Take a look at Henrik Svensmark's work on climate change to put the alarmists in perspective.

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  21. I agree with your general thesis Prof Cochrane, the problem I have is that nothing has changed. This same grand bargain has been available for at least as long as I've been following climate change and wondering about the economic sense of many of the suggested policies - which I think is about 15 years or more. In that time there has never been any indication of that bargain being possible. So whilst it would be nice to have such a bargain, I have no evidence that it is close.

    I also note that a carbon tax is desirable in an economic sense. I mean that in the sense of "in an idealised perfect world, a carbon tax is a good way to resolve this." In the real world, we have a problem with international agreements, alignment across countries, emissions being exported, and the ability to sensibly tax something that is invisible and hard to measure. There are also implementation challenges with that tax replacing the existing programs and not simply being additional to them, and some serious equity problems that might need to be resolved through the tax and transfer system, and no clear way to do that on a principle of "noone better or worse off" rather than other policy goals creeping in.

    Unfortunately, as with much economic analysis, the idealised and modelled world may not sufficiently match the real world.

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  22. "Stop arguing about climate, and let us instead investigate costs and benefits of policies"
    Right on!
    The bickering is futile.
    There is a transformation of our energy economy in progress. Heat engines are so 18th century. They are being replaced by photovoltaics as our primary energy source. Large, point source, energy operations are being replaced by distributed networks of collection and redistribution. This change is a huge threat to capital and wealth concentration based on fossil fuel supply. Hence the strident response by those, like the brothers Koch, who feel threatened. It will take a few sharp economists to explain how to maintain capital stewardship and appropriate wealth concentration through this transition.
    --E5

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  23. What is so weird about the environmental discourse is that it's not fundamentally new or unique. The "environment" is just the ultimate "commons." It's not owned or managed by anyone.

    Pollution of the commons is nothing new, and environmental pollution fits exactly into the existing understanding of tragedy of the commons.

    Given that, it's just sad that there aren't more economists that can shout from the hilltops about Pigouvian taxes and all the other solutions devised over the centuries to solve this problem.

    Unfortunately, few realize that the whole point of policy is to change incentives to create a game that aligns desired behavior to helpful behavior.

    Policy without economics is medicine without science.

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  24. At first glance, there are a lot of good points that you bring up in your piece. Upon looking deeper though there are some glaring issues.

    I liked how you stated that we need an actual price on the externalities that climate change is producing. The issue with this though is it is not that simple. There are millions of different factors that are impossible to take into account for this calculation. A good example of factors that would not be counted be quality of life and overall environment well being (both of which are not included in GDP).

    Currently chunks of the Great Barrier Reef have been declared dead due to ocean acidification. This has been attributed to the increase in greenhouse gases being absorbed into the ocean and raising its overall PH. If the Reef fully dies there will be an enormous toll on factors that cannot be truly measured. How do you assign a number to whole generation not seeing a world wonder?

    I believe the only true way to get out of this downward spiral is to invest in cleaner technology and invest in implementation. The idea of a carbon tax can go either way. On one hand it forces companies to have a lower output, but the issue with this is what incentive does the company have to go even lower? I believe we should have a hybrid system of a carbon tax and then using said tax as a subsidy to companies that meet a secondary lower and non required criteria. This would first of all make the required output and at the same time increase the supply of companies that output lower than the tax requires.

    Finally I would like to address your statement that "Nuclear power is bearable." Believe or not nuclear power actually emits less radiation than its coal burning counterparts! Even if a denier pitched that nuclear is taking away jobs from coal, they're wrong! Recently in Texas a coal plant had to lay off 70 workers due to the fact that the plant was not making money. Corporations and public interest is already moving toward renewables, might as well make it more worth wild to make the switch sooner rather than later.

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  25. At first glance, there are a lot of good points that you bring up in your piece. Upon looking deeper though there are some glaring issues.

    I liked how you stated that we need an actual price on the externalities that climate change is producing. The issue with this though is it is not that simple. There are millions of different factors that are impossible to take into account for this calculation. A good example of factors that would not be counted be quality of life and overall environment well being (both of which are not included in GDP).

    Currently chunks of the Great Barrier Reef have been declared dead due to ocean acidification. This has been attributed to the increase in greenhouse gases being absorbed into the ocean and raising its overall PH. If the Reef fully dies there will be an enormous toll on factors that cannot be truly measured. How do you assign a number to whole generation not seeing a world wonder?

    I believe the only true way to get out of this downward spiral is to invest in cleaner technology and invest in implementation. The idea of a carbon tax can go either way. On one hand it forces companies to have a lower output, but the issue with this is what incentive does the company have to go even lower? I believe we should have a hybrid system of a carbon tax and then using said tax as a subsidy to companies that meet a secondary lower and non required criteria. This would first of all make the required output and at the same time increase the supply of companies that output lower than the tax requires.

    Finally I would like to address your statement that "Nuclear power is bearable." Believe or not nuclear power actually emits less radiation than its coal burning counterparts! Even if a denier pitched that nuclear is taking away jobs from coal, they're wrong! Recently in Texas a coal plant had to lay off 70 workers due to the fact that the plant was not making money. Corporations and public interest is already moving toward renewables, might as well make it more worth wild to make the switch sooner rather than later.

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  26. John: In your WSJ op-ed, you wrote

    "If we simply stopped building in flood-prone areas and started building on higher ground, even the costs of moving cities would be bearable. Migration is costly. But much of the world’s population moved from farms to cities in the 20th century. Allowing people to move to better climates in the 21st will be equally possible."

    People won't be selling their home & property, they will be abandoning it. Insurance companies won't be covering it at that point. So who is going to make these property owners whole? It will be taxpayers around the world, especially in OECD countries, including the US.

    How many trillions will taxpayers spend to pay for these losses? To the nearest order of magnitude.... $10 T?

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    1. David's prediction may turn out to be entirely correct, but past predictions of disastrous sea level rise have failed to come true. E.g., in 2005, the United Nations Environment Programme predicted that climate change would create 50 million climate refugees by 2010. These people, it was said, would flee a range of disasters including sea level rise, increases in the numbers and severity of hurricanes, and disruption to food production. Seven years past 2010, none of this has happened.

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  27. It appears to me Dr. Cochrane highlights a strawman in his WSJ Op-Ed.

    The blog post states that "But this is supposed to be about effective policies to cool the planet, not a grab bag of things that would be nice" with reference to “reduced gender inequality & marginalization in other forms,” “provisioning of adequate housing,” “cash transfers” and “awareness raising & integrating into education.” as supposed recommendations by the IPCC.

    First, the IPCC does not make recommendations, it is not part of its mandate. It has exhaustive lists of just about everything that can be considered, including a cost-benefit analysis, but nowhere does it say "we recommend this".

    More importantly, contrary to the suggestion in this blog post and in the WSJ Op-Ed, the IPCC does not list the highlighted policies to *cool the planet*. The long table from which the examples are taken is entitled "Approaches for managing the risks of climate change through adaptation". The table heading even includes the explicit statement that "Mitigation is considered essential for managing the risks of climate change. It is not addressed in this table as mitigation is the focus of WGIII AR5." In other words, they are explicitly listed as examples related to adaptation, and the interested reader may want to check up on what policies are used to manage risks of various natural disasters, *not* as examples of policies to 'cool the planet'.

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  28. I completely agree when John explains to,"stop arguing about climate, and let us instead investigate costs and benefits of policies". There are so many possibilities and factors that we could not possibly take all of them into consideration such as environmental quality because when it comes to climate we can only control the inputs and outputs come on their own. For example, we can put restrictions on factories and various companies on how much carbon dioxide gas they put into the air. The less pollution, the less climate change impacts (something that is in our control). Or we could use William
    D.Nordhaus's DICE model which is "the first dynamic model to include a closed-loop system that includes emissions,
    concentrations, climate change, damages, and emissions controls. The model is useful for estimating the costs and benefits of different paths for slowing climate change and for analyzing
    the impact of control strategies over time". This model is looking at the what changes we as humans can make and analyzing the costs and benefits of policies which is directly aligned with what John was talking about. We must make investments in implementation in better technology (Ex. hybrid cars). Slowly, if we make changes to things that we can control and see the costs and benefits in that, it will surely make a greater change than constantly arguing and worrying about climate change. We must play with the factors and make changes in policies to defeat climate change, not try to control the weather because nothing is going to come out of that.

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  29. Climate change alarmists believe that (1) continuing the current rate of greenhouse gas emissions will have severe economic consequences, and (2) reducing emissions is not as expensive as the consequences of not reducing. These beliefs are backed by every major scientific body in the world and have been independently examined by blue ribbon panels assembled by said bodies. If you contradict them, you're second-guessing the best in the world. This isn't impossible, but it's a big ask.

    Climate change denial comes in many forms. On one extreme is the Trump version -- scientists are united in a worldwide scam. On the other end is the Lomborg version here. It's been debunked as much as the others.

    https://en.wikipedia.org/wiki/Bj%C3%B8rn_Lomborg

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    1. It's certainly been howled down by those who have a strong vested interest in doing so, but that's not the same as 'debunked'.

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  30. Don: It's very well known that the added CO2 in today's atmosphere is anthropogenic, by studying trends of ratios of its carbon isotopes. See:

    http://www.realclimate.org/index.php/archives/2004/12/how-do-we-know-that-recent-cosub2sub-increases-are-due-to-human-activities-updated/

    The ocean is also gaining CO2 (acidifying), so not the source.

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  31. Don wrote:
    "My pet peeve is the "business as usual" label. That scenario assumes no technological improvements over this century and a world population hitting 16 billion."

    There are three other IPCC scenarios given, for just this reason.

    BTW, none of the RCPs are labeled "business as usual."

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  32. Is the emerging topic Climate Finance a promising research direction? For instance, what's the implications of climate change for corporate cashflows and stock market returns? How to hedge the changing climate risks? Will the climate change interacts with business cycles?

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    1. That depends what you mean by "promising." It is certainly very fashionable, and there is a huge amount of funding money available. While the current integrated (economics plus climate) modeling efforts are worthy, there is certainly a lot of progress to be made. Is there a deep new economic idea in here, as for example asymmetric information was? We never know in advance.

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    2. I see. I will keep up with the new model frameworks and empirical works, and hope to make progress in my own research. Thanks for your comment, Professor Cochrane.

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    3. @Yancheng - as a retail investor I would be interested in knowing the sensitivity of my investments to increases in the cost of CO2 emissions. What impact would a $20, $50 or $100 per tonne of CO2 levy for CO2 emissions have?

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  33. "(A neighbor just showed me his electric car, purchased in addition to a regular car, for one reason only: you can ride it solo in the HOV lane, a right worth thousands in California.) "
    Without knowing how economic justifications work I do appreciate that encouraging use, and purchase of, electric vehicles is helping to build the know-how and manufacturing capabilities that will be needed when, soon, the primary (cheapest) energy source will be sunshine.
    --E5

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    1. This neighbor should be friends with the Utah guy from last summer (http://johnhcochrane.blogspot.ch/2016/06/transport-innovation.html)

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  34. A solution can only be derived from a starting point that includes the correct premises. There are two premises that are apparently mistaken in your piece:

    1. That CO2 concentrations are currently 'high' and going 'higher'. The atmosphere's concentration of CO2 has ranged from 3,000ppm down to 180 in the last ice Age. From this range the 'experts' have plucked the level in 1750 - 250 as 'ideal'. It turns out that a) The level of CO2 below which vascular plants cannot survive is 150ppm and b)According to horticulturists the 'optimal' level of CO2 for vascular plant growth is 1,000 to 1,200ppm. This is why growers routinely pump extra CO2 into their greenhouses...and why hothouse plants often don't do as well when you plant them in your garden.
    2. Over the past 100,000 years the temperatures at Greenland and Vostok (South Pole) have varied from between 8C warmer to 8C colder than today. Temperatures there at the start of this interglacial were 2C warmer than today. Temperature changes at these two pole locations have been frequent and radical.

    Now if what I said is true, how differently would you approach the problem of so called "unprecedented climate change"?

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    1. Bill, I don't see any expert putting 250 ppm as "ideal". But maybe you can provide some evidence.

      Over the past 100,000 years, neither Greenland nor Antarctica have seen temperatures that were 8 degrees warmer. We'd have to go many millions (around 500 million to be slightly more precise) to get in that range. There is also no evidence whatsoever that temperatures were 2C warmer than today during the Holocene Climate Optimum. Neither in the Greenland nor Vostok records.

      Where do you get your information? I get them from the scientific literature, and if you claim you do, too, then I'd love to see your references.

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    2. Bill, you will probably find, if you dig into the matter, that the principal reason for putting industrial CO2 into greenhouses is that it is cheaper to do that than to replace the water and heat lost bringing it in from the atmosphere. The plants use it up, you know.
      I believe you will also find that the outdoor tests that have been done found little, or no, effect on plant growth due to supplemental CO2.
      I think you will also find that the Brothers Koch have given up climate-change-denialism and are now focusing their spending on trying to convince us that climate change will be nice.
      --E5

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  35. Bill: There are no "perfect" levels for CO2 and temperature. There is only the level that we and all other species have adapted to. The question is, can we/they adapt to the large changes (geologically speaking) we are now setting in place. In the past, rapid climate change has been a challenge to species, often an existential challenge. This time will be no different.

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  36. Dr. Cochrane,
    I enjoyed your column, though disagreed with most of it. I am relieved to see that here at your blog that you seek to contribute productively to the climate policy debate. The problem in my view with the op-ed is, frankly, that you come across as the hegemonic economist rather than the grumpy economist. I think you do a disservice to debate when put all climate policy makers into one bucket and then summarily dismiss them by accusing them of “mushy thinking”. Perhaps their thinking is different but not mushy. Economic models provide one valid ** but very limited ** way of understanding the world. I am not sure, but I doubt that your models of the impacts of climate policy on GDP capture the relationship between human life and the ecological systems on which it depends. (I also very much doubt that measures of GDP accurately capture the stock of human prosperity and resilience.) It is quite possible that climate change is the mother of all issues, but your models just can't capture that. Your belief that it isn't such an issue really in the end is just that, a belief.
    I appreciate your Burkeian view that climate policy makers needs to be aware of the dangers of sweeping government action. I wish you would be as modest about your own analysis. It is certainly valid and useful, but so are other perspectives and epistemologies. I don't think that comes through in your WSJ piece.

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  37. Dr. Cochrane,
    I enjoyed your WSJ piece, though disagreed with most of it. While I can see from your blog that you seek to contribute productively to public debate, the WSJ piece does not present you in that way. You come across as the hegemonic economist rather than the grumpy economist.

    Economics provides one valid ** but very limited ** way of understanding the world. While I am not sure, I doubt that your models of the impacts of climate change/policy on GDP do not rest on a strong understanding of the relationship between human life and the ecological systems on which it depends. (I also very much doubt that your measure of GDP accurately reflects the stock of human prosperity and resilience.) It could be that climate change is the mother of all issues, but your analysis and perspective just can't capture that. In the end, your belief that it is a secondary issue because its impacts are slow and predictable is just that, a belief.

    I appreciate your Burkeian view that climate policy makers needs to be aware of the dangers of sweeping government action. I wish you would be as modest about your own analysis. Other perspectives and epistemologies are valid too. It appears that you do not believe that. At least that is how the WSJ piece comes across.

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    1. I think we can productively agree here. I hear many economic arguments for climate change policy. These, we have addressed. We did not pretend to address other, non-economic arguments for climate change. (We mentioned species extinction a bit, only that there are other threats to species too and don't starve them for money. )

      So we can agree the economic arguments for climate change policy are weak, and you can still make arguments on other bases if you wish, environmental, moral, ethical, or whatever. Just don't forget to mention there will be economic costs of policies you like, and to quantify them, and to argue that they are worth the non-economic benefits you adduce, and don't say silly things like (last night's TV) we must spend trillions to address climate change, because otherwise we'll have to spend a billion over the next hundred years to upgrade Houston's sewer system.

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  38. Using traditional benefit-cost approaches in the context of global climate policy will (inevitably) result in under-valuation of those policies. See: https://papers.ssrn.com/sol3/papers.cfm?abstract_id=2685447

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Comments are welcome. Keep it short, polite, and on topic.

Thanks to a few abusers I am now moderating comments. I welcome thoughtful disagreement. I will block comments with insulting or abusive language. I'm also blocking totally inane comments. Try to make some sense. I am much more likely to allow critical comments if you have the honesty and courage to use your real name.