DR. X, AN UNDISCLOSED LOCATION
Forecasting is by nature imprecise. Yes, there’s still scientific work to do. But broadly, scientists have delivered the goods: We’re confident that humans are changing the climate.
How should we think about scientific imprecision in climate forecasting? Say a man’s skydiving for the first time. He’s at 10,000 feet, ready to jump out, putting on his radio headset. The instructor says, “Listen carefully. I’ll tell you when you need to open your parachute.” The guy jumps out—and whoa, it’s spectacular out there! He’s enthralled. When he reaches 5,000 feet, he hears the instructor: “Time to open your parachute!”
The skydiver replies, “No, not yet! This is great! I’ve got plenty of time.”
A few seconds later, the instructor says, more urgently: “You’re at 3,000 feet. You need to open your parachute.”
“A little longer!”
“You’re at 1,000 feet! Open your parachute!”
“Not yet!”
“Damn it! You’re at 500 feet! Open your parachute!” Not yet. “You’re about to hit the ground! Open your f*cking parachute!”
“That’s OK! I can jump from here.”
In 1990, climate scientists said, “There are reasons to believe humans may be changing the climate. To be safe, we should begin the transition to a low-carbon economy.”
Politicians said, “That’s nice. There’s not enough evidence. Let’s study it some more.”
“It’s the year 2000,” we said. “Now we’re confident humans are changing the climate. We should cut fossil fuels while there’s still time to do so gradually.”
“That would be economically ruinous. Let’s wait.”
“It’s 2010. Climate change is increasingly urgent, and if we don’t act now, there will be grave damage to humans and the natural world.”
“What are you, some kind of socialist? Let’s wait.”
“It’s 2020! Cut the f*cking greenhouse gases!”
“Come now, you’re being alarmist.”
With that in mind, let’s consider this question from contributor WigWag:
John Kerry, President Biden’s climate czar, recently said, “Well, the scientists told us three years ago we had 12 years to avert the worst consequences of the climate crisis. We are now three years gone, so we have nine years left … ”
Kerry made this claim in a CBS interview on February 19. Climate scientists cringe when politicians say things like this. I don’t know any scientist who would say we have exactly nine years left to save the planet. WigWag is right to question Mr. Kerry’s precision.
Lack of precision in climate science is not, however, a good reason to delay reducing greenhouse gas emissions—no more than lack of precision in assessing a skydiver’s terminal velocity would be cause to delay opening the parachute.[1]Lest I be misunderstood: There is no climate analogue to the moment the jumper goes splat.
Here’s where the “nine years left” claim probably comes from. Article 2(a) of the Paris Agreement, adopted in 2015, specifies a goal:[2]Claire remarks: An original version contained a sentence suggesting the Paris Agreement was, somehow, signed in the future. This was obviously a typo.
Holding the increase in the global average temperature to well below 2 °C above pre-industrial levels and pursuing efforts to limit the temperature increase to 1.5 °C above pre-industrial levels, recognizing that this would significantly reduce the risks and impacts of climate change;
My question, Dr. X, is whether you think the data generated by climate scientists is so overwhelming and so amenable to precise analysis that scientists can determine the exact year when, absent dramatic reduction of greenhouse gas emissions, “the worst consequences” (whatever that means) will result?
To put it another way, is there now or has there ever been, a consensus of climate scientists that we are currently in a short window of now nine years where if we don’t take severe action calamity becomes inevitable?
Since that year, we’ve been trying to determine what constitutes dangerous human interference. But we can’t specify this precisely, because it depends on uncertain climate projections and your definition of “dangerous.”
The global average temperature has risen, again, by about 1.2 degrees C since 1850, and most of this warming is the result of human emissions of greenhouse gasses. CO2 levels have risen from 280 ppm to about 420 ppm; the concentration of methane, the second most important GHG, has increased from about 700 ppb (parts per billion) to 1900 ppb. Since we can see harmful impacts of climate change today—ice loss, rising sea levels, an increase in droughts and floods, among other things—some would say we’ve already passed the threshold for dangerous human interference. Others would argue people can adapt to this, so it isn’t yet dangerous. Still others would say, “Dangerous compared to what?” After all, it is dangerous, too, suddenly to stop farming your crops, heating your homes, and running your hospitals.
One way (though not the only way) to draw the line is to say it’s dangerous to pass certain tipping points. A climate tipping point is said to occur when a system transitions to a new state, one from which it can’t quickly recover—even if the extra greenhouse gasses could magically be removed.[3]I trust readers know that by “quickly,” I mean “as these things go.” Systems with abrupt transitions are said to display nonlinear behavior, or hysteresis.
It’s a common misconception that the climate system has a tipping point such that if we stay on the near side of that point, we’ll be fine, but past that, we’re doomed. In fact, many parts of the Earth system are approximately linear, as are many impacts. Raise the temperature 1 degree, and things get bad; 2 degrees, and they get worse; 3 degrees, and they are profoundly worse. But there’s no climatological red line.
So when people ask me if it’s already too late, I always say no. Any steps we take today to cut greenhouse gases will give us a nicer climate in the future than we’ll have if we don’t.
Some natural systems, however, are strongly nonlinear, such as the West Antarctic Ice Sheet. If temperatures in the Antarctic rise by 1 degree C, we might see only modest ice loss. But if temperatures rise by 2 degrees, parts of the ice sheet might destabilize, raising the global average sea level by 3 meters or more in the next few centuries. Once this process starts, it is probably irreversible, so we don’t want to cross this threshold. Unfortunately, we can’t yet say where precisely the threshold is, just “about 2 degrees, give or take a degree.”
With these complexities in mind, the Paris Agreement negotiators tried to set targets that are politically and technologically feasible yet wouldn’t leave the world on a dire trajectory. Small island nations played a decisive role in adding the 1.5 degree goal to the final agreement.
In 2018, the IPCC published its Special Report on Global Warming of 1.5 degrees C, laying out what we can say with various levels of confidence about the difference between 1.5 degrees of global average warming and larger amounts. As a result, 1.5 became an iconic number. Would 1.5 degrees of warming be much worse than 1.4 or much better than 1.6? Probably not, but people like to set goals using round numbers. Roger Bannister would not have become famous for running a mile in 4:03.
Many think the 1.5 degree target is unachievable, but I prefer it to the more vague target of “well below 2 degrees.” I’m risk-averse. I know, from personal experience, that catastrophic things do happen, so I’d rather build in margin for error than count on being lucky. Recent advances in renewable energy have given me hope that 1.5 degrees might be technologically feasible.
Reasonable people may differ about the right target—1.5 degrees versus 1.7 degrees, say—because climate science and economics are imprecise. My sense of the evidence, however, is that warming above 2 degrees would be very dangerous. Some economists argue that the cost of staying below 2 degrees exceeds the benefits, but their models strike me as undervaluing things that are hard to value and too severely discounting the future. I agree with Noah Smith that climate economics has failed usefully to inform policy discourse.
If our goal is 1.5 degrees, how fast do we need to cut CO2 and other greenhouse gasses to avoid exceeding the target? What, in other words, is the remaining carbon budget? Computing this budget is one way to answer the question, “How many years do we have left?”
Humans now emit about 40 Gt (40 billion metric tons) of CO2 each year, a bit less during 2020 because of the pandemic. Emissions haven’t yet peaked. Since the late 1800s, we’ve emitted about 2200 Gt, bringing us 80 percent of the way to 1.5 degrees warming. Assuming a linear relationship between CO2 and warming, a back-of-the-envelope calculation suggests that if we emit another 500 or 600 Gt of CO2 , we’ll get to 1.5 degrees. At the current rate, that’s between 12 and 15 years.
The IPCC authors don’t rely on such a simple calculation; they assess many climate observations and models. But they get a similar answer: if we’re to have a 50 percent chance of meeting the 1.5 degree target, our total CO2 emissions, starting from 2018, must not exceed 580 Gt.
With 420 Gt, the odds rise to 67 percent; with 840 Gt, they drop to 33 percent. The report is clear about how they arrived at these numbers.
The remaining carbon budget is sensitive to the temperature target. If the target is raised to 2.0 degrees, the carbon budget increases to 1170 Gt, 1500 Gt, and 2030 Gt, respectively, for 67 percent, 50 percent, and 33 percent odds of success. Compared to 1.5 degrees, the horizon for emissions cuts more than doubles—from under 15 years to three or four decades.
The IPCC assigns medium confidence to these estimates. Sources of uncertainty include the historical temperature record and the climate response to future emissions of GHGs other than CO2. Long-term feedbacks of greenhouse gas emissions, such as the release of carbon and methane from thawing permafrost, may cause more warming. So the 12-year figure cited by Kerry and others is linked to a 1.5 degree temperature target, and to IPCC statements like this one:
Without increased and urgent mitigation ambition in the coming years, leading to a sharp decline in greenhouse gas emissions by 2030, global warming will surpass 1.5 degrees C in the following decades, leading to irreversible loss of the most fragile ecosystems, and crisis after crisis for the most vulnerable people and societies.
The IPCC often uses round-number years like 2030, 2050, and 2100 in its projections. The statement above, made in 2018, suggests a window of about 12 years for deep cuts in emissions. Obviously, though, scientists don’t believe there’s some bad climate juju in years that end in zero.
Kerry’s statement is confusing and doesn’t reflect the science. Maybe he means well and is trying to convey a sense of urgency, but I think it’s a mistake to make misleading arguments, even for worthy goals. Suffice to say my kids are not allowed to beg off homework because some say the world will end in fire.
Does this mean we can safely delay cutting greenhouse emissions? It does not. The true budget is as likely to be below the IPCC’s best estimate as above it. And any GHG cuts made today will reduce harmful climate change in the long run.
Given a risk-averse 1.5 degree goal, my carbon budget preference would be about 400 Gt—roughly ten years of emissions at the current rate. I’d aim to halve emissions in the next decade, at least in countries with high emissions like the US. In the following decade, I’d try to get as near zero as possible, anticipating that some sectors will be hard to decarbonize and take longer. I’d also aggressively cut emissions of other GHGs. This recent study suggests relatively low-cost methane reductions could spare us a quarter of a degree of warming by mid-century, buying us more time to cut CO2. So my timeframe would be similar to Kerry’s, but I’d be less numerically precise. And I’d justify it differently.
IS IT ALL THAT BAD? A READER ASKS
In my last piece for the Cosmopolitan Globalist, Claire asked me to answer a series of interesting questions from subscriber Eric Dyke.
I’m greatly touched by Mr. Dyke’s kind words. Let me try to answer two more of his questions:
Critics say that research funds are only being directed to those who support global warming, and those who do not are rejected. Do you see that happening?
This is hard to answer with a simple yes or no. Let’s define “support for global warming” as accepting the claim I’ve made here previously: The Earth’s climate is warming, and most of the warming is caused by humans.
This claim is uncontroversial among climate scientists, and it’s true that nearly all government funding goes to researchers who support it. To say in 2021 that the Earth isn’t warming, or that it’s warming for exotic reasons for which there’s no evidence, is at this point so far away from the scientific conversation that it’s like claiming the Earth is 6,000 years old. Sure, many people believe in a young Earth, but that’s not due to arguments from geology, biology, or astrophysics.
Nonetheless, there’s room to wiggle with a word like “most.” Are greenhouse gasses responsible for virtually all the warming since 1950, or only, say, two-thirds? Although natural variability can’t by itself explain the observed warming, it could account for part of it. If so, then the climate’s sensitivity to greenhouse gasses would be at the low end of the predicted range.
We use models and evidence from past climates to estimate the global, long-term average warming from doubling atmospheric CO2. This figure is known as the Equilibrium Climate Sensitivity. According to the IPCC Fifth Assessment Report,
Estimates of the Equilibrium Climate Sensitivity (ECS) based on multiple and partly independent lines of evidence from observed climate change indicate that there is high confidence that ECS is extremely unlikely to be less than 1 degree C and medium confidence that the ECS is likely to be between 1.5 degrees C and 4.5 degrees C and very unlikely greater than 6 degrees C.
That’s a large range, and we’re still trying to narrow it. (Note the difference between ECS and transient climate sensitivity; the latter indicates changes in temperature at the time of CO2 doubling. The difference is owed to warming that takes place decades after greenhouse gasses are introduced to the atmosphere.)
Suppose that after analyzing a new source of paleoclimate data—ancient lake sediments, for instance—I have reason to suspect ECS is only 2 degrees, or perhaps even lower. Yet I need more observations to strengthen my case. I think I could write a compelling grant proposal; my chances of getting research funding would be just as good as they’d be if my new data pointed the other direction.
Now let’s say I get funding and gather more observations, but find that alas, the new data suggest an ECS of 3 degrees—in the middle of the consensus range. My professional and ethical responsibility would be to publish what I’ve learned. Conversely, if I expect to find medium or high ECS, but instead find that it seems to be lower, I need to publish that. If I have an ideological commitment to a high or a low ECS such that I refuse to publish results in conflict with that commitment, funding bodies will notice that I’ve taken their money and published nothing. So will quite a few people. I’ll be less likely to get funding in the future.
This doesn’t mean there’s no such thing as scientific fraud, fudged results, or observer bias; of course all these phenomena exist in science, as they do in any human endeavor. But scientists are in competition for the same jobs and grant money, so we do check each other’s work carefully. It’s very hard—as it should be—to get peer reviewers to sign off on a weak argument. Remember: my fudged results are my rival’s straight shot to tenure and the corner office.
The harmful effects of global warming are stated everywhere in great detail. Are there no countervailing benefits?
Good question. On average, people are better adapted to the steady climate of the past 1,000 years than to the warmer climate we’re creating. But temperature and rainfall patterns could shift, for example, making the US Great Plains less conducive to growing wheat and Manitoba more. That’s not to say that climate change will be good for everyone in Canada, but it would be going too far to say there will be no benefits.
I’d caution, though, that it’s too simplistic to imagine a warmer climate will translate to more bountiful harvests. You can’t make infertile soil fertile by warming it. A higher evaporation rate could dry out the soil, too. Too much CO2 might make crops less nutritious. There may be no net gain. Nature is full of surprises. (Although there are not so many that we’re unable to model the fundamentals.)
I thank Mr. Dyke for following up on Bill Gates and the polar bears. If Bill Gates questions whether solar energy can meet the power demands of Tokyo, I’m inclined to agree. Japan has ten times the population density of the US and much less land available. Solar energy will work well for the American West, but not for everyone. I also agree about innovating in many directions. Who wouldn’t?
It’s interesting that neither of us found peer-reviewed evidence for significant changes in the total number of polar bears. Maybe they’re not declining. Maybe they are, but there’s no clear relationship between the decline of sea ice and the decline of polar bears. Maybe it’s hard to measure.[4]From Claire: Who’d be crazy enough, I asked myself, to try to put a GPS collar on a polar bear? But how else would you know if their population is declining? Overcome by curiosity, I decided to … Continue reading Whatever the case, I’m sure we all wish the polar bears well.
SCIENCE HAS DELIVERED: NOW WHAT?
I became a scientist, in part, because I wanted to help expand the store of human knowledge in a useful way. In a broad sense, scientists have done our job. We’ve shown that human-emitted GHGs are changing the climate. Since a 1.5 degree mitigation pathway is much more challenging than a 2 degree pathway, there’s still scientific work to do; we have yet to figure out which pathway is optimal. But broadly, we’ve delivered the goods. We’re confident that humans are changing the climate.
Now it’s up to citizens and their governments to act on this knowledge. Whether to do so, and how fast, are moral and political questions, not scientific ones. How do we weigh the well-being of future generations against our own? How could we make this transition less painful? Above all: How much risk do we want to take?
I know what you’re thinking. “Dr. X., do we have nine years to save the planet or not?” Well to tell you the truth, in all this excitement, I’ve kind of lost track myself. But suppose there is no mitigation at all, GHG emissions track the IPCC’s ssp5-8.5 high-emission scenario, and by 2100, CO2 reaches 1100 ppm, which is close to quadrupling. Assume ECS of 3 degrees C, a median estimate. By 2100 or soon after, we would have 6 degrees C of global mean warming—about 11 degrees F. With massive release of CO2 and methane from thawing permafrost, it may be too late to mitigate. Global sea level could easily rise 10 to 20 m, but that might take a few centuries. The collapse of agriculture would be the more immediate nightmare, along with floods of refugees from places that are no longer habitable. A majority of the world’s species would probably go extinct.
Being as I’ve chosen a mid-range ECS, I’d rate the odds of global catastrophe under this no-mitigation scenario around fifty-fifty. So we’ve got to ask ourselves one question:
Do we feel lucky?
Dr. X is a distinguished American climate scientist. To protect his family from the viciousness of social media and because there are “too many crazy people out there,” he prefers to remain anonymous.
References
| ↑1 | Lest I be misunderstood: There is no climate analogue to the moment the jumper goes splat. |
|---|---|
| ↑2 | Claire remarks: An original version contained a sentence suggesting the Paris Agreement was, somehow, signed in the future. This was obviously a typo. |
| ↑3 | I trust readers know that by “quickly,” I mean “as these things go.” |
| ↑4 | From Claire: Who’d be crazy enough, I asked myself, to try to put a GPS collar on a polar bear? But how else would you know if their population is declining? Overcome by curiosity, I decided to find out. Wouldn’t you know it, there are people out there who are crazy enough to try to put GPS collars on polar bears. The problem is— surprise—the bears don’t like it. So the data is “deficient” because the vexed bears keep tearing off their collars and tossing them into the ice. Still, the effort to collar polar bears hasn’t been wasted, because it turns out tracking the discarded collars is a handy way to track the way the ice moves. The collars showed that ice-drift modeling data from the US National Snow and Ice Data Center underestimated the speed at which ice moves around in Hudson Bay. So we got something more useful out of that research grant than a bunch of poked bears. |
Since we’re rearranging baggage, I’ll close my participation in this series (which, counting this comment, amounts to roughly two remarks) with this:
“I will leave others to debate the merits of your [i.e., my] comments on long-term climate change. But from an economic perspective, I should think that the answer to “Why do we care about atmospheric CO2 as a greenhouse gas in the first place?” is the risk to the huge investments that have been made, to populations vulnerable to extreme weather, and to the natural world.”
That’s from our moderator.
Since the question of why we should care has been, by design, explicitly excluded from the conversation of the greenhouse gas and planetary warming aspect of energy provision, this entire discussion has been a long exercise in irrelevance, for all that the details of how to generate energy and provide it to folks have been enormously informative.
Without that historical context, though, we don’t even have any idea of what “extreme weather” is, much less whether it’s significantly different from other eras. Nor do we have any understanding of risks “to the natural world” absent that history.
And so the risk from political overreaction to a situation whose history is carefully ignored is far more than merely “huge investments,” it’s the destruction of the quality of lives of billions of people, and the destruction of lives themselves, from the economic dislocation of shifting to a particular form of energy generation, or a bar against generation from burning hydrocarbons.
Along those lines, the IEA doesn’t think a shift to renewables only is feasible at any time soon: https://www.iea.org/reports/the-role-of-critical-minerals-in-clean-energy-transitions
One problem: “demand for key minerals such as lithium, graphite, nickel and rare-earth metals would explode, rising by 4,200%, 2,500%, 1,900% and 700%, respectively, by 2040.” That’s as cited by the WSJ in their summary of the IEA report, and that’s the level of economic and environmental destruction that would result from just our Progressive-Democratic President Joe Biden’s panicky plan.
That’s part of the cost of ignoring history.
Eric Hines
Indeed.
I think that history, in its many facets, should be much more prominent a presence in discussions of this issue. Just now I’m reading Barbara Tuchman’s “The Proud Tower: A Portrait of the World Before the War 1890-1914.” As an antidote to optimism and wishful thinking it’s hard to beat.
I’m actually concerned with a longer term history than that that’s being ignored..
Eric Hines
Understood. But as I intimated, history embodies many lessons relevant to this issue. The era Tuchman portrayed was a time of tumult and optimism. The former proved to be an omen, the latter a delusion. In the large, optimism is not only unwarranted but dangerous.
Optimism is no more unwarranted in the large than is pessimism. I am spring-loaded to the optimism side of center, though, because facts let us overcome adversity far more so than blind luck (which is wholly agnostic), and we are capable of learning facts and acting rationally on them.
Human history is replete with progress and disastrous stupidity, but in the (human) large, we make net progress.
Eric Hines
History refutes your assertion. Progress is an illusion. Upon examination, it’s the byproduct of material prosperity, nothing more. People who are comfortable and well fed can afford optimism. But take away their comfort, their good dinners, and what do you think would happen?
The problem is that while scientists like Dr. X are pulling the fire alarm, it’s the politicians like John Kerry who are dispatching the hook and ladder. To me this suggests that either rapid technological advances will need to make it so overwhelmingly economically advantageous to limit greenhouse gas emissions or we’re doomed to the global warming scenario that gives Dr. X nightmares. Effective governmental intervention either in the form of mandates or incentives are unlikely to be impactful.
Just last month in New York we saw a perfect example of the the hypocrisy and incompetence of environmental activists and the politicians who genuflect to them. For decades, New York City got 25 percent of its base load power from three reactors located at the Indian Point Power facility in suburban New York (about 30 miles north of the City). Obviously, the power generated was carbon-free and the plant had a spotless safety record.
Despite this, environmental activists have spent the better part of 30 years bitterly complaining that the plant was allowed to operate. Of course it’s these same environmental activists who whine continuously about the threat posed by carbon emissions. A major champion of the activist community is New York’s Governor, Andrew Cuomo (currently under an impeachment threat for alleged serial groping). Governor Cuomo has banned fracking in New York State, despite an ample supply of natural gas deposits and he has been a mortal enemy of those who want to build pipelines in New York. As a result of his Jihad against all things with the prefix “fossil,” there are parts of the State where it is impossible to hook up new natural gas lines, which dramatically increases the cost of heating homes and making hot water because New York has amongst the highest electric rates in our nation. The excess cost, which can be onerous for working and middle class families could not matter less to the Governor, the state legislature or the latte-loving activist community.
Despite the fact that he allegedly worships at the altar of “clean energy” Governor Cuomo badgered Entergy (the owner of Indian Point) to close all three reactors located at the site. The final reactor was decommissioned in April.
As the reactors closed one by one, the electricity produced by Indian Point was replaced almost exclusively by electricity generated by natural gas. After the first reactor closed a few years back, the share of the State’s power that came from gas generators jumped from 36 to 40 percent. With the closure of the other two reactors, New York State will probably get somewhere around 50 percent of its electricity from gas-powered plants during the winter. During the summer, when electricity use spikes, the share of gas generated electricity will surely jump to at least 55 percent and maybe 60 percent. If we have a particularly hot summer, there’s plenty of peak-load capacity at the ready, but most of this generating capacity relies on oil.
Perhaps Dr. X will forgive skeptics from wondering why they should believe global warming activists and politicians who claim we face an extinction event when those same activists and politicians are not alarmed at the prospect of closing down a perfectly functional nuclear facility even at the cost of increasing green house gas emissions. The conclusion is inevitable, even the activists don’t believe that reducing green house gasses is all that urgent; after all, they’ve successfully lobbied for a policy that significantly increases these emissions.
Although he wasn’t the climate czar when the decision to close Indian Point was made, John Kerry was a well-known environmental activists who had fashioned himself as the Democratic Party’s kibitzer-in-chief. We never heard him begging Governor Cuomo to keep Indian Point open. I don’t remember hearing much from Bill McKibben, Greta Thunberg or any other well-know global warming activist either. Obviously, they must have felt that the large increase in green house gas emissions that inevitably arose from closing Indian Point was simply no big deal. If that’s what leading climate change activists think, why should the rest of us believe anything else?
But here’s the real irony; the environmentalists who lobbied for the shut down of Indian Point assure us that there’s nothing to worry about. New York has great big plans to generate renewable energy. Off-shore wind farms and thousands of acres of solar arrays are on the way, we’re told. Just a few years back, the State legislature mandated that by 2030, 50 percent of the State’s electricity had to come from renewable sources. Last year our legislators decided that their goal wasn’t ambitious enough and they raised the mandate to 70 percent.
Very little of this infrastructure has been built and anyone who believes that a State as overburdened by governmental bureaucracy as New York can pull it off by 2030 must be smoking some of the newly legal cannabis now for sale on almost every corner. If the fastidious Germans couldn’t do it, New York doesn’t have a chance.
But suppose by some miracle that we can. Suspend disbelief and contemplate the possibility that by 2030, New Yorkers will get 70 percent of their electricity from renewable sources. Does this mean that all the increased carbon emissions we contributed to the atmosphere in the intervening years as a result of the closing of Indian Point simply don’t matter? Not if Dr. X is right. His argument suggests that those emissions are part and parcel of a looming disaster or, at least, a potential disaster.
Of course, 2030 is exactly 9 years away. That’s exactly the point where John Kerry said we reach the point of no return. If we finally start making up for the emissions spewed into the atmosphere by the fossil-fuel burning generators that replaced Indian Point nine years from now, doesn’t John Kerry think its too late? If we wait that long, and John Kerry is right, why bother trying?
With friends like environmental activists, do climate scientists really need enemies?
It seems highly unlikely that any of the goals proclaimed by climate scientists will be met. Shouldn’t we start planning for the inevitable consequences?
I agree with almost every single point you make. As I said above, yes, I agree that either “rapid technological advances will … make it so overwhelmingly economically advantageous to limit greenhouse gas emissions” or “we’re doomed to the global warming scenario that gives Dr. X nightmares,” although note, that scenario is, even in the event of *no* mitigation, not a certainty. The consensus, if I rightly understand it, is that RCP8.5 is an unlikely future; if I understand rightly, the odds of it are about five percent. The consensus now is that a zero-mitigation scenario is unlikely; it’s unlikely we’ll keep burning coal, for example, at previous high rates.
I *strongly* agree with you about so-called environmental activists who shriek at the idea of a nuclear power plant. They’re stupid. But I don’t agree that with your reasoning–if I’m understanding it correctly–that “the rest of us” should be guided in our beliefs by the most irrational of climate change activists. Anyone who allows Greta Thunberg to shape his beliefs, either in favor *or against* any given environmental policy, is giving himself, or herself, over to hysteria.
Good morning from New York, Claire. The last few days it’s been sunny and getting warmer. It’s already been a bad spring allergy season so air conditioners are awakening from their long hibernation and cranking on all over the City. Surely this means the need for more electricity that will have to be generated by burning natural gas now that the perfectly serviceable number 3 reactor at Indian Point is being decommissioned.
It’s not that I think that we should allow the lunacy of climate activists to distract us from what the science teaches us. Dr X and others make a compelling case. But I can’t see how we can expect millions of citizens beyond the activist community to take climate change seriously when the activists themselves only pretend to take it seriously. If the activists were truly worried about increasing greenhouse gas emissions they would have been demonstrating in front of the Governors mansion demanding that Indian Point remain open. They were demonstrating all right; but their demand was that Indian Point be shuttered, the climate consequences be damned.
I doubt that the climate problem will ultimately be fixed because I don’t believe our politics can sustain the comity needed to arrive at consensus solutions.
Claire, if you think it’s bad now; just wait. Who would have ever guessed that the abortion debate and the climate change debate are related? They are, you’ll see.
Just yesterday, the United States Supreme Court granted certiorari to a case from Mississippi which will undoubtedly pare back or overrule Roe v Wade. Once the decision is announced about a year from now, all hell is going to break loose in the United States. The resulting political warfare will make it even more difficult to arrive at political consensus about anything. The issue of climate change will be collateral damage.
Doing big, difficult things requires political consensus. The actions needed to ameliorate climate change are both big and difficult. An increasingly angry political climate is simply not conducive to meeting the goals that the erudite Dr. X has recommended.
Who to blame for all of this is (in the United States) another question. I think both Democrats and Republicans are to blame with the Democrats more complicit than their political rivals. But it probably goes deeper than that.
Something must underlie the crack-up of the Western world. One of the reasons I like to read the essays at the Cosmopolitan Globalist is because these issues are addressed in a serious and thoughtful fashion.
I think the cat is out of the bag. The world will not take the actions needed to ameliorate climate change in a manner sufficient to prevent serious consequences. The more logical approach is to plan for the consequences.
The fact that it’s too late to do what is best, doesn’t mean it’s too late to do something good now. What if we try and work on this problem in by both reduction and addressing the consequences? (Guided by scientific projections, not John Kerry. In case that needed to be said.)
I think that would be a great approach. Maybe not perfect in the best of all worlds but perfect in the real world.
First I do think it is unfair to say that ALL Democrats and in ALL areas of the country oppose nuclear power. There are many instances in many purple to even blue-ish states of Democrats being supportive of nuclear power say New Hampshire(There are also rare instances of the GOP opposing nuclear power). I would even go as far as to say Democrats in Illinois, New Jersey, and Connecticut have pretty explicitly supported keeping existing nuclear power plants running over the past few years. Where I do think WigWam IS right is that there is deep opposition to nuclear power in both New York and California which do play a huge disproportionate role in the national media narrative and very few of the so-called reasonable and rational activists including some of the authors right here at the Cosmopolitan Globalist seem to be unwilling to call out what is going in California and New York instead referring to the decisions like with Indian Point as being “local” in nature.
I will make another comment later but along these lines I find the conflict between New Hampshire and Massachusetts over Seabrook Nuclear Power Plant in New Hampshire when both states have all Democratic congressional delegations to again be reflective of these cultural and political splits.
I feel a lot of similar frustration with the Republicans. New England Republicans are scarcely the same party as Bible Belt Republicans and it’s part of the reason that I HATE the national primaries.
One thing I will add is that even a single nuclear power plant in a small state like New Hampshire has a big impact economically. Seabrook generates more power than New Hampshire consumes and a employer that has lets say 1000 well paid workers in NH is not insignificant in the same way it might be treated in California lets say. This again I think is probably part of the explanation for the support of nuclear in New Jersey and Connecticut also factoring in the that Salem, NH and Millstone, CT are in the lesser populated and poorer parts of their state thus Cory Booker saying the Salem Nuclear Plant in the far Southern end of NJ far from Booker’s political base in North NJ has less political salience to anti nuke Dems than if the plants in question were in a more populated region like Westchester County, NY. There are exceptions to this theory of mine, the closure of Vermont Yankee I think was just reflective of out of bounds woke-ism of Vermont generally. Also the Diablo Canyon plant in California isn’t really near the two big population centers of the state either but still stirs the eir of big city anti nuke people.
Tim, I enjoyed the comments that you added on one of the related threads about your recent visit to the venue in New Hampshire where the Seabrook Nuclear Plant is located.
In the mid 1970s, I lived in Worcester, Massachusetts which, as you know, is only a hop, skip and a jump from the nuclear plant as the crow flies. Many of my friends at the time we’re members of the Clam Shell Alliance and several were arrested (I think it was in the Spring of 1977) at the demonstrations that took place there.
At the time, they all self identified as socialists and some self identified as Marxists. A surprising number went on to become venture capitalists, money managers or hedge-fund types. Today, the old friends I’ve stayed in touch with run the political gamut from Trump Republicans to Bernie Sanders democratic socialists.
I didn’t suggest that Democrats don’t support nuclear power; I’m sure many do. But I do think that Democrats are more responsible for fostering a climate of political intolerance than Republicans are though the GOP is far from blameless.
Democrats are centralizers and their philosophy inspires political discord. Democrats believe abortion is a right that has to be available everywhere. They believe that gun control standards should be nationwide. They insist that trans girls must be allowed to compete with biological girls on high school teams everywhere-always. The list goes on.
The Supreme Court has abetted this centralizing tendency by forgetting the meaning of federalism. Both “liberal” and “conservative” justices are complicit.
The inevitable result is anger and often fury, as values that may be very different in one place versus another are shoved down the throats of people who don’t approve.
This centralizing tendency breeds anger that makes it impossible to form a national consensus about anything, including climate change.
There are a few areas where a national policy does make sense, bathroom-use policy in public schools isn’t one of them but national defense and climate issues truly are.
Sadly, the centralizing fixation of Democrats shapes an environment that spoils any attempt to forge policy that all of us should be able to sign on to.
I don’t know much about Europe, but I suspect the same challenge is problematic in the EU; many European nationals may be sick and tired of faraway bureaucrats telling them what to think and do. Claire and colleagues would know much more about this than I do.
Anyway, that’s why I blame Democrats more than Republicans for our nation’s failure to adopt a reasonable policy to fight climate change. Their insistence on a national policy for literally everything insures it isn’t feasible to adopt a national policy on anything that matters.
Democrats seem to have the reverse Midas touch. Everything they lay their hands on turns into you know what.
I probably shouldn’t say this publicly but my current residence is Andover, MA so even closer to the Seacoast than Worcester but not per say along the coast. I have been pretty familiar with the MA and NH Seacoast since I was a child(and BTW Central MA too. I learned to ski at Mt Wachusett). One reason in part I was thinking about this issue so much is am not really a fan of fast food but during the pandemic I heard by word of mouth that the McDonalds across the street from the Seabrook Nuclear Power Plant had an exceptional good drive thru window by McDonalds standards delivering really hot food(perhaps they have a secret steam pipe running from the nuclear reactor across the street to the french fry machine). Anyways for a lot of Covid lockdown one of my few outings to keep myself from going insane was to drive the 25 from my house to the Seabrook, NH McDonalds Drive- Thru of which several times I noticed nuke plant employees waiting in line front of me.
Below is to show how close I was to the nuclear plant every time I went there and how the average local I think barely notices the plants existence(You get a better view from Route 1A right along the ocean)
https://www.google.com/maps/dir/NextEra+Energy+Seabrook+Station,+Lafayette+Rd,+Seabrook,+NH/McDonald's,+710+Lafayette+Rd,+Seabrook,+NH+03874/@42.8960405,-70.8652695,1540m/data=!3m1!1e3!4m14!4m13!1m5!1m1!1s0x89e2e6f97167a31d:0x4b959d5bbf398463!2m2!1d-70.852847!2d42.8988616!1m5!1m1!1s0x89e2e65a1e090fa9:0x15bcdf0c472bfa47!2m2!1d-70.870427!2d42.8949755!3e0
On a further Central MA and climate related note the Wachusett Mountain ski area did an interesting podcast series over the last year. One interesting episode was with part-owner Carolyn Stimpson Crowley of the Worcester, MA Crowley family that also owns Polar Beverages about some of the insane fighting in the 1990s over expanding the ski area.
https://podcasts.apple.com/us/podcast/carolyn-stimpson-history-of-wachusett-pt-2/id1525019169?i=1000490513627
The second I thought was kind of interesting in terms of some of the success of weather/climate technological adaptation in particular how important snowmaking has been to the ski industry from the early 1990s starting the in Northeast US but now expanding to other parts of the world(One of the largest manufacturers of snow-makers is based in Natick, MA).
https://podcasts.apple.com/us/podcast/charles-santry-hkd-snowmakers/id1525019169?i=1000500915985
But Claire, it was precisely those irrational climate change activists who were responsible for the closure of the Indian Point reactors. The rational ones (if such exist) were nowhere to be found.
I suspect they’re around (unless you consider Dr X irrational), but pundits can make a LOT more money by flashing the worst of them across your screen. Hence, harder to find, but not impossible.
I only meant: Where were they when the irrational extremists were busy closing down the reactors? Did any of the rational climate change activists raise an objection? If not, or if no one pays attention to them, what good are they? In any case it seems pretty obvious that the irrational extremists are the ones in charge of the Green movement.
There have been environmentally conscious people speaking in favor of nuclear energy for decades. I can’t find a source, but I remember hearing several arguments as far back as the 90s. Sometimes they change minds. Sometimes they fail. I’d rather they keep trying than give up in the face of those failures. Perhaps it’s up to us to learn how to present a case better, rather than throw up our hands and point fingers, because that won’t get us anywhere.
Good for them. But as far as I can tell, they have no influence in the environmental/Green movement.
Throughout Energy Week/s I have probably been more closely aligned with Claire’s view ideologically than anyone else here however, I do have to pushbank Claire’s assertion and propose my own counterfactual that if shared Claire’s more idelogical and what I consider statist Atlanticism(which I don’t but more on that later) that RNA technology is solely an American invention. While I don’t want to get into percentages of work it clearly is lot as the most sucessful vaccine manufactured and distributed from Pfizer was actually developed and researched by a German company based in Germany called BioNTech. You are in fact seeing an assertion of the German role in it’s development by Angela Merkel’s refusal to go along with an international intellectual property waiver of the underlying RNA technology in the vaccine. I suspect if the vaccine was really 100% American made I don’t think Merkel would be particularly interested in protecting it’s intellectual property.
The counterfactual if I was more Atlanticist like Claire is I would actually suggest that if you believe that a vaccine patent waiver is the “right” policy from the standpoint of a global benevolent superpower like the US the fact the US wasn’t leaps and bound ahead of Germany from a R&D standpoint so much that RNA technology was a literally a 100% American field that the US can freely give to the world simply on it’s own say so without asking permission of Germany than America not having that 100% R&D dominance was actually a bad thing.
Another example of this I might suggest that if France’s had not fought as tenaciously and be proudful for hosting the ITER Fusion which America does still play a very big role but instead suggested it by hosted in the US instead and allowed America as global leader to take a very explicit emotional and practical ownership over the ITER project perhaps it might be significantly further along. At least Americans might have paid more attention to it if it was being built in there own country.
Now the reason I fgind Claire’s view of Atlantiticism(and people like Toomas Ilves’ view too) as “statist” as I think as a more survival of the fittest libertarian minded person that the US and Germany is also aspects of culture, economy, science, and business etc should be cooperating but also day in and day out dog eat dog competing with each other in the most competitive manner possible. It is this dog eat dog competition that my opinion leads to the advancement and flourishing of the human race and the western liberal democratic world. I also acknowledge this model is quite bad for a country like Estonia or even more so the Ukraine which is still very much in the minor leagues of the democratic liberal world and not able to compete at the level of Germany and the US up in the major leagues. Anyways enough for now. Say Merkel trades vaccine patent waivers for Nordstream 2 with Biden.
Does anyone really believe that India, China, Africa, Russia, etc are going to accept a 1.5 degree C target? I have a hard time seeing that happen.
It will depend on the cost of alternatives. It `*will* happen, I think we can be confident of this, if other sources of energy become significantly less expensive (in every sense, including the economics of the transition). I’m just as confident that it won’t happen if alternatives are more costly.
I’d guess that the only hope we have of making China, India, Africa, and Russia reach this target is this way: The US pours money into R&D, quickly figures out how to power the world cheaply without emissions, and shares the technology. It’s a narrow path, but it’s imaginable. I don’t think it’s imaginable that absent this, the world will willingly immiserate itself, return to the pre-Industrial era, and remain there. I don’t think any country but the US is apt to make this kind of technological breakthrough, but owing to our highly exceptional science, research, and investment culture, we’re great at breakthrough inventions (like mRNA vaccines), especially when we pour public money into a problem, too.
Markets can be distorted in many ways, and through many policies. But energy is so fundamental to the economy–the price of *everything,* literally everything, reflects the cost of the energy used to make it*–that I see no way at all that the market will fail to dictate the broad contours of the outcome, no matter what targets we set in the abstract. Vivek made this point in the Cosmopolicast, and I agree with him. All of the discussion is in some sense moot in light of this–although not entirely moot, because policy preferences will dictate the pace and scale of public funding for R&D.
*I asked myself if this was true. Does the price of my love, say, reflect the price of energy? Yes, it does. It’s less costly for me to love, say, an extra cat if the price of cat food, cat litter, and veterinary care goes down. If object X has a price, then that price will reflect the cost of energy. Can anyone think of a counterexample?
This is more like it. I wish people who opine about climate change & etc. would pay some attention to economics. Maybe then they’d stop thinking in terms of big, disruptive, absurdly expensive GND-style solutions and come to terms with the reality of trade-offs. Absent some major scientific or technological breakthrough (which is of course possible) there is absolutely no way that a shift from fossil fuels on a short timeline can be accomplished without major disruptions—which is another way of saying that radically slashing carbon emissions will require many other desirable things things to be traded away. And that’s the real hurdle. How do you market economic and social disruption to the masses?
Almost certainly not. Despotic and authoritarian regimes are not only contemptuous of human rights, they’re poor stewards of the environment. When the USSR and its European satellite states collapsed, the environmental devastation caused by 70 years of “scientific socialism” became horribly apparent. I can’t think of a reason to suppose that V. Putin, the Chinese oligarchs, etc. would behave differently.
Dear Dr. X,
During the past week, thoughtful writers described key components of climate change that somehow you didn’t include in your latest essay. The word “China” doesn’t appear in your piece, despite China being the #1 greenhouse gas emitter, and increasing. You didn’t mention the energy needs nor economic realities of 4 billion people living in China, India, and Southeast Asia. You didn’t mention their realistic trade-off between energy needs and fossil fuel burning. You didn’t mention “nuclear”, neither fission nor fusion, nor that they are carbon-free. You didn’t use the word “adaptation”, while every coastal mayor and city council in the world must consider actual adaptation measures, such as sea walls. You also didn’t articulate the nuanced policy navigation between the political, the engineering, and the financial (and social media hysteria). You didn’t mention global population, and its coming maximum. You admit that limiting the global average rise to less than 1.5 C is unlikely. But your piece hardly mentions practical decisions about sea walls, purchasing and developing batteries, diminishing forest fires, and adapting to drought or floods. Did you write your essay before reading the prior Energy essays in GC?
These two sentences struck me as unscientific: “Given a risk-averse 1.5 degree goal, my carbon budget preference would be about 400 Gt—roughly ten years of emissions at the current rate. I’d aim to halve emissions in the next decade, at least in countries with high emissions like the US.” Unfortunately, there is no global energy “czar”. One’s ideal “aims” are academic. Further, if the U.S. vanished, the concentration of atmospheric carbon would continue to increase at 90% of its present rate of increase. We all known that the U.S. and Europe are decreasing their GHG emissions.
Finally, your last sentence, “Do we feel lucky”, is disrespectful. You could add Clint Eastwood’s “punk”, as if we are climate imbeciles. In contrast, we are trying to find a thoughtful balance of mitigation and adaption for both developing and the developed countries. We’re trying to navigate a global challenge, with due respect for the complexity of this challenge.
Dr. M.
Geoff–seems to me Dr. X has been scrupulous, throughout this discussion, to draw the distinction between what he can say as a climate scientist and what he can say as a citizen. All of the points you raise are, essentially, political points. They concern what Bismarck would have called “the art of the possible.” The Cosmopolitan Globalist isn’t an American policy journal but a global one; if Chinese readers wish better to understand the how climate scientists arrive at their understanding of the impact of GHG emissions on the climate, they’re welcome here. If any Chinese reader would like to contribute an essay on China’s perspective on this issue, we’d find that fascinating, and so long as it was well written, and stood up to fact-checking, we’d publish it. But Dr. X clearly wasn’t seeking to address the sources of Chinese policymaking: He was asked very specific questions by our readers, and sought to answer them in good faith. So I don’t understand your complaint.
Nor do I quite understand the complaint that the sentence you highlight is “unscientific.” Of course it isn’t scientific; no sentence that begins “my preference is” could be scientific. He’s offering his opinion, and this in the clear context of saying, “These are moral and political judgements, not scientific ones.” As he says, even if there’s basic agreement on the scientific facts, it does not imply a particular policy: How you answer this question will generally be determined by the level of risk you’re willing to tolerate, the way you assess the value of future versus present well-being, what you think a world in which we’re not emitting this much CO2 would look like–e.g., do you think we can succeed in quickly providing abundant nuclear power to the developing world? Or do you think these targets would mean, in effect, just starving it of energy?
Finally, I don’t understand your complaint about the last sentence, which I suggested. I thought it was a short, clear way to summarize his argument by means of a reference everyone understood. He *didn’t* add the word “punk.” His argument: Yes, there is scientific uncertainty about the precise relationship between emissions and the future climate. However, we’re confident in specifying probability ranges for certain outcomes. The worst-case scenario with which he concludes is considered low-probability, but not impossible. Whether you’re willing to tolerate this risk comes down to your ability to tolerate risk. Whether, in other words, you feel lucky. (No one would tolerate that risk if it were a certainty, after all.)
This reminds me of an old Steve Martin joke. It goes something like this:
YOU can be a MILLIONAIRE and NEVER PAY TAXES! Here’s how. First, get a million dollars…
If only the scientists could produce a realistic plan for a sharp decline in carbon emissions by 2030—problem solved! But they won’t because they can’t. No one can. The complexities involved are beyond analysis, much less solution. Clausewitz wrote that “In war everything is very simple, but the simplest thing is difficult”—an observation that’s equally applicable to the issue under discussion here. “We must sharply reduce carbon emissions by 2030 (or 2040 or 2050),” etc., etc. are deceptively simple statements that skate past the “frictions” as Clausewitz called them—all those unforeseeable factors, major and minor, that accumulate to seize up the machinery of the plan. And we might usefully apply his conception of war as a “fascinating trinity” to climate/energy policy: (1) a political, social and cultural question involving partisan interests and primordial instincts; (2) a landscape of uncertainty and chance inviting creativity; and (3) a scientific issue amenable to pure reason. That, I believe, is an apt characterization of the matter at hand.
The trouble with scientists is that they make bad politicians and economists; they tend to lack vision, except through a microscope. I found Dr. X’s exposition most interesting. Do I think it moves the ball? Not really. To be fair, he touches on the non-scientific factors involved. But he doesn’t grapple with them. “I’d aim to halve emissions in the next decade, at least in countries with high emissions like the US. In the following decade, I’d try to get as near zero as possible, anticipating that some sectors will be hard to decarbonize and take longer. I’d also aggressively cut emissions of other GHGs.” How is all that supposed to happen?
Dr. X and others assume that since human activity is largely responsible for climate change, humanity can fix the problem. But maybe that’s not true at all. History doesn’t encourage optimism, that’s for sure.
Here’s a headline from today’s New York Times;
“Nations Must Drop Fossil Fuels, Fast, World Energy Body Warns”
Here’s the article (paywall warning)
https://www.nytimes.com/2021/05/18/climate/climate-change-emissions-IEA.html?action=click&module=Top%20Stories&pgtype=Homepage
Here’s the take home message from the article,
“Several major economies, including the United States and the European Union, have recently pledged to zero out their emissions responsible for global warming by midcentury. But many world leaders have not yet come to grips with the extraordinary transformation of the global energy system that is required to do so, the agency warned… [T]he annual pace of installations for solar panels and wind turbines worldwide would have to quadruple by 2030, the agency said. For the solar industry, that would mean building the equivalent of what is currently the world’s largest solar farm every day for the next decade.”
I wonder what Dr. X thinks about the practicality of building solar farms as large as any yet built every day for the next 3,650 days. If this is really what’s required, wouldn’t the more logical approach be to just throw in the towel and mitigate to the extent possible?
Or does Dr. X believe that the International Energy Agency is emulating chicken little?
Assumptions that are as likely wrong as correct:
1. A world 2 or 3C warmer would be worse off than now.
2. The are no natural negative feed backs that would reduce any warming from CO2 increases.
3. History: People were worse off in the Roman and Medieval Warming periods that were warmer than now.
4. History: People were better off during the Dark Ages and Little Ice Age that were colder than now.
5. Most of the warming since 1850 is the result of human emissions. History: Most of this warming occurred before humans began large scale emissions.
6. Sea rise is faster now than it was before CO2 emission rose. Actually, the gradual sea level rise that began when the Little Ice Age ended is proceeding at about the same pace as was naturally occurring before CO2 emissions rose. The variations are within the error margins of the measuring devices.
7. Droughts and flood are increasing. The data does not show an increase.
8. Tipping points exist. They did not happen when the climate was several degrees warmer earlier in this interglacial. Modelers can program their models to create them, but there is no evidence they exist in the real climate. They are a hypothesis without evidence.
9. Doubling CO2 to 800ppm would make a significant difference. The physics says that since warming effect of CO2 at 400ppm is saturated above 98.5%, Doubling to 800ppm would only increase the warming effect to around 99.5% in a very gradual rise by 2100. This small amount of potential warming by 2100 is not an emergency. A prosperous world will easily adjust to this slow motion change.
10. A few degrees C will destroy the West Antarctic Ice Sheet. The real danger to the ice is the dozens of active volcanic vents melting it from below. Reducing CO2 will have no effect on the volcanos.
11. The assumption of a linear relationship between CO2 levels and global temperature is unverified because it can’t be isolated from all the other factors. It is more likely, if you believe the physics experiments, an inverse logarithmic relationship. Every doubling has a much smaller effect than the prior doubling. Once saturation is reached, there is no more increase.
12. Methane is a strong greenhouse gas. Yes, but since water vapor has already saturated the IR frequencies methane absorbs, more methane cannot increase atmospheric temperature in any measurable way.
13. The climate has not been “steady” over the last 1000 years. The Medieval Warming Period was several degrees C warmer and the Little Ice Age was several degrees C cooler.
14. Climate models can successfully predict future climate. No way to know. They haven’t been very good at predicting the last 40 years.
15. The best mitigation might be to provide everyone with all the inexpensive electricity they need and increase the prosperity of all people as much as possible. A prosperous world can easily adjust any of the projected climate changes. Even the worst case IPCC guesses.
That is a lot of assuming by Dr X and others. I would prefer, at the government level, that decisions be based on data and the results of experiments, admitting that we don’t know when we don’t. Making these decisions based on the educated guesses of one set of experts (with or without a complicated computer program) is a formula for bad policy and misallocated resources.
By the way, I greatly appreciate Dr X putting himself out there for us to pick at and get the discussion going.
There are so many unknowns that people will be on all sides of this.
Being certain with few facts was a good strategy for survival in prehistoric times. That our brains are still instinctively wired this way makes us hard to get along with at times.