From fires in the Amazon and in Australia, to flash flooding in Europe, right across the globe we are witnessing the impact of climate change on the environment. But how does a changing climate affect key infrastructure? Engineering experts explain.
How does climate change affect transport infrastructure?
School of Civil Engineering academic, Professor David Levinson is a transport engineering expert who says transport infrastructure both contributes to climate change, but can also be affected by it.
“The issue goes two ways in transport. Typically, road and air transport are considered major contributors to climate change, making up 23 percent of CO2 emissions,” said Professor Levinson.
“But transport is also vulnerable, particularly due to so many facilities like roads and bus terminals being in flood zones, for instance New Jersey Transit lost $US120 million in damage to buses after Hurricane Sandy.
“Many transport facilities are also below grade, tunnels like those in the New York Subway were severely damaged from flooding during Sandy. Airports being at low elevations along the coast are at risk of sea-level rise. Extreme heat can cause road buckling, freeze-thaw cycles cause pavement cracking and potholes.
“Extreme weather increases the variability of weather, and roads designed for a particular climate range may fail more quickly. All of these add costs to design and retrofit, as well as decreasing reliability for users.”
This paper develops a link-based full cost model, which identifies the key cost components of travel, including both internal and external versions of cost, and gives a link-based cost estimate. The key cost components for travelers are categorized as time cost, emission cost, crash cost, user monetary cost, and infrastructure cost. Selecting the Minneapolis – St. Paul (Twin Cities) Metropolitan region as the study area, the estimates show that the average full cost of travel is $0.68/veh-km, in which the time and user monetary costs account for approximately 85% of the total. Except for the infrastructure cost, highways are more cost-effective than other surface roadways considering all the other cost components, as well as the internal and full costs.
So your planet has global warming.[1] Venus says “Welcome to the club!” CO2 pollution [2] not only destroys the environment and adds to remediation costs, the traditional air pollution that comes with it shortens your life. While this undoubtedly annoys you as a human being, it could be worse; your planet might not have excess carbon dioxide emissions or pollution because no one wants to be there (hello Mars). Still, it would be great to have a thriving planet without pollution. People could do more things over their longer life.
Pollution like congestion can be thought of as a queueing problem. There is a demand side (production of pollution) and a supply side (the ability (capacity) of the environment to process pollutants). When the production of a pollutant exceeds the ability of the environment to process, the pollutant builds up, e.g. there is more CO2 in the atmosphere because humans produce more CO2 than nature can absorb in the short run. So like traffic in a queue, CO2 in the atmosphere rises. This is a straight-forward physical process.
From Wikipedia. Description: This figure shows the history of atmospheric carbon dioxide concentrations as directly measured at Mauna Loa, Hawaii since 1958. This curve is known as the Keeling curve, and is an essential piece of evidence of the man-made increases in greenhouse gases that are believed to be the cause of global warming. The longest such record exists at Mauna Loa, but these measurements have been independently confirmed at many other sites around the world. The annual fluctuation in carbon dioxide is caused by seasonal variations in carbon dioxide uptake by land plants. Since many more forests are concentrated in the Northern Hemisphere, more carbon dioxide is removed from the atmosphere during Northern Hemisphere summer than Southern Hemisphere summer. This annual cycle is shown in the inset figure by taking the average concentration for each month across all measured years. The red curve shows the average monthly concentrations, and blue curve is a smoothed trend. The carbon dioxide data is measured as the mole fraction in dry air. This dataset constitutes the longest record of direct measurements of CO2 in the atmosphere (data for 2016 are preliminary). Date 11 January 2017 Source Own work. Data from Dr. Pieter Tans, NOAA/ESRL and Dr. Ralph Keeling, Scripps Institution of Oceanography.When the CO2 in the atmosphere rises, the heat of the planet rises with it. This is also a straight-forward physical process, noted by Arrhenius in the 19th century. Now like transport and behavioral systems, environmental systems are complex, so even though the direction is clear, the rate of change is hard to ascertain, and there are many mitigating or exacerbating feedbacks. Still more CO2 emissions means more heat.
Some of that gets absorbed in trees or the ocean, or is not measured, but the temperature will rise. If the rate of human production of excess CO2 falls to zero, the excess CO2 in the atmosphere will eventually be absorbed by nature, the queue will be discharged. But nature will have been changed by the whole process. For as long as we don’t have net zero or net negative carbon emissions, the queue of unabsorbed pollution will continue to lengthen.
There are a number of proffered solutions out there. Pollution is, in principle, a mostly solvable problem, even if no fast-growing planet has, to the best of our knowledge, fully solved it.
This article outlines ways that pollution could be solved. Some of these are dumb, many are good, one is great.
Capacity [Bio-Engineering] – Perhaps the most obvious, ‘common sense’, solution when demand (pollution) is in excess of supply is to expand capacity. This is what we do with most things if we can. If our house is too small, we make it bigger. If our wallet can’t hold all of our cash and ID cards, we get a bigger one. If the internet is too slow, we add capacity. In roads, this usually means adding lanes to existing roads. Perhaps we could plant more trees to absorb more carbon pollution. Unfortunately, there is not enough space for enough trees to offset the problem. Maybe algae in the oceans, but that sure seems like that would have adverse consequences.
Capacity [Geo-Engineering] – Besides planting trees, perhaps we could do something faster, typically called geo-engineering, using the power of chemistry to capture CO2 gas or change CO2 gas into something more benign. Wikipedia lists a bunch of inter-related topics:
The first problem with this set of solutions is that it is potentially expensive. Adding to the ability of the planet to absorb pollution is difficult. Unlike transport, people have only done this kind of geo-engineering speculatively. So there is a huge risk associated with some of these techniques, especially the more speculative ocean fertilization. But you know, “what could go wrong?” For the less expensive methods, the question is whether they can scale to be significant contributors.
Solar Radiation Management. Just deal with the heat, ignore the carbon. As Wikipedia says: “Solar radiation management (SRM)[4][34] techniques would seek to reduce sunlight absorbed (ultra-violet, near infra-red and visible). This would be achieved by deflecting sunlight away from the Earth, or by increasing the reflectivity (albedo) of the atmosphere or the Earth’s surface.” This sounds like a terrible idea to me, but if the CO2 is bad only because of the rising heat, it could be an interim solution. Volcanoes have similar effects. The problem is cold summers, and one could easily imagine this going badly for crops (and thus humans). Wikipedia has a series of articles …
The first set of strategies are basically supply side. But pollution problems are caused by a mismatch of supply (ability to absorb) and demand (production). So let’s turn to demand. The main sources of demand are transport, industry, agriculture, and residential, with the electric power sector serving these indirectly.
The basic equation for emissions in the transport sector is given by:
Emissions = Liters/KM x Carbon/Liter x Vehicle KM Traveled.
If cars had better fuel consumption, less emissions per fuel consumed, or traveled less, there would be less emissions. All three of these things can be worked on together.
The first few are technological shifts, the latter will require behavioral change.
Bio-fuels – If all of our fuel was from recently deceased plant matter, rather than oil (long deceased plant matter), and those plants were replanted, net CO2 from burning fuels would be about zero (assuming the equipment used to harvest and transport the bio-fuels also used bio-fuels, (like turtles, all the way down)). The advantage is that the energy density of liquid fuels is generally better than batteries. The disadvantage is the large amount of area needed for bio-fuels, which will compete with food agriculture for the best farmland. This is likely to be especially important for aviation.
Controls Better pollution control devices like the catalytic converter for Internal Combustion Engine vehicles have significantly reduced tailpipe emissions of EPA criteria pollutants. Something similar could be done for CO2 emissions. So the same amount of liters would somehow produce fewer tons of carbon. The difficulty here is chemistry. The gasoline is ultimately burned, producing CO2. Perhaps it can be captured and stored, or catalyzed into some other what we know believe to be innocuous byproduct. Arguably this is a supply side method, but I class it as demand side here as the aim is to reduce the amount of CO2 emitted, not improve the capacity to deal with emitted CO2.
Improve fuel economy in transport. Better fuel economy for Internal Combustion Engine vehicles has significantly reduced fuel use, and thus CO2, and has plenty of generally good side effects for society, like reduced air pollution and less dependence of oil more generally. Increased energy efficiency overall throughout the economy is feasible.
Electrify the automobile fleet, switch the energy source for automobiles from fossil fuels to electricity powered by renewable sources (e.g. solar and wind and hydro and nuclear) or use fuel cells to transform the number of Liters/KM to zero.
Reduce (or end) automobile use. This works on the third part of the equation. Transport is about 1/3 of CO2 pollution, plus or minus. My earlier post “21 Strategies to Solve Congestion“, (which this not-coincidentally resembles), outlines how to reduce automobile demand, which is a large or the largest source of CO2 pollution. So long as cars continue to rely on the Internal Combustion Engine (in some form for a few more decades yet), reducing automobile demand and gasoline consumption will be critical to reducing CO2. There are many reasons to reduce automobile use, pollution among them. It turns out that biking is more efficient than driving. It turns out, more surprisingly, that eBikes are more efficient than bikes (after netting out the extra energy for the extra food for the extra calories burned biking).
Non-transport
The same basic logic applies outside the transport sector. Emissions depends on energy consumption, carbon content, and activity.
Conserve. Reduce electricity and natural gas consumption at home and work. Use LED light bulbs. Insulate your buildings. As Jimmy Carter suggested, put on a sweater and set the thermostat cooler in the winter. Strip naked and set the thermostat higher in the summer (though he didn’t say it, he may have thought it). Recycle. There are a thousand or more ways to reduce energy consumption.
Make production processes more energy efficient. This is related to conservation, in that it reduces consumption, but at a much bigger and holistic scale, and examines the process by which outcomes are achieved.
Use Renewable Energy in the Electricity Sector. Electricity is about 1/3 of greenhouse gas emissions in the US. Transformation from burning coal is well underway, and adoption of renewable energy sources like solar, wind, and hydro power, among others, are the best way to get this sector down to zero net CO2 emissions over the coming decades. There is a large amount of fixed capacity (sunk costs) out there now, so the transition will take some time.
Reduce industrial energy demand by closing industry – Industry is about 1/5 of CO2 pollution. Perhaps intuitively, if we shut down polluting industries, we reduce pollution. To the extent we want the thing the industry intends to pollute (aside from the pollution), this might be problematic. If we want it closed, but want the goods, the factory will pop up elsewhere with fewer environmental strictures.
Social Solutions
Exhortion – Tell people they shouldn’t pollute because it is bad for themselves, or society, or will condemn them in perpetuity to an unpleasant afterlife. Guilt can get you a little bit of benefit, but as evidenced by the state of the world, can only go so far. This is really a means to one of the other ways of actually reducing pollution.
Rationing – Give people and firms pollution credits, the right to emit a certain amount of CO2 per year. Reduce that credit annually. Allow them to trade credits for money. If it were cost effective to reduce pollution, they would do so to sell credits. If it were not, they could buy credits. When people talk about cap and trade, that is a form of rationing.
Pricing – Charge people and firms for the amount of pollution they generate and they will generate less pollution.
How do polluters reduce pollution?This is the best part. Each individual or firm decides for themselves whether or how to consume or pollute less, what production processes to change, when to substitute clean power for dirty. With pricing, polluters will see the air, which is now treated as an unregulated commons as a valuable resource, and if they increase throughput per unit of carbon, they will save money. They will try to be more efficient about managing the use of the existing clean air.
Isn’t this another tax?This is the second best part. It raises money by discouraging people from doing something that we don’t want them to do. Other high taxes on things that we do want them to do (like work) can be lowered. Done properly, this is revenue neutral.
Can this work?This is the third best part. There are many proposed strategies to implement pricing. Obviously this has been politically difficult, or it would already be widespread. Carbon taxes are the simplest intervention, and we already do this in some places (12% of the world’s Carbon is already taxed). Since it is assessed for industries rather than on individuals, it has a low cost of collection. For instance rather than metering each car, petroleum from refineries or fuel wholesalers can be taxed. This accelerates the uptake of electric vehicles, which should on the net be a good thing.
There are undoubtedly some other solutions out there not discussed here, and lots of details overlooked.
Pricing is the answer and you know that for sure
Pricing is a flower
You got to let it, you gotta let it grow
This post is basically a rewrite of my popular post about a different externality: congestion: “21 Strategies to Solve Congestion“. Perhaps we might call this `CO2gestion’.
Yes, I know some people don’t accept CO2 as “pollution” and prefer “emissions.” Since it is above the ability of the environment to process in the short term, it imposes harmful or dangerous effects, and so it is pollution, even if it is a natural product. All pollutants are fine in small enough amounts, and everything is horrible in too great amounts.
Catholics have a notion called “Indulgences”. Wikipedia summarizes it as “a way to reduce the amount of punishment one has to undergo for sins.” In the Middle Ages, indulgences were commercialized, so wealthy people could buy themselves out of punishment (or the loss of wealth might be considered the punishment, if you want to be charitable).
Pedro
In the modern world, carbon emission is a great sin. Those traveling by air sin the most. Prominent environmentalists are often targeted for hypocrisy, and those hoping to avoid hypocrisy might purchase “Carbon Offsets“. These are the more equivalent of commercial indulgences. The airlines offer them to guilt-ridden passengers.
Perhaps the most obvious, ‘common sense’, solution when demand (pollution) is in excess of supply is to expand capacity. This is what we do with most things if we can. If our house is too small, we make it bigger. If our wallet can’t hold all of our cash and ID cards, we get a bigger one. If the internet is too slow, we add capacity. In roads, this usually means adding lanes to existing roads. Perhaps we could plant more trees to absorb more carbon pollution.
Consider for instance the Boston to London round trip. It is 3255 miles each way (5237 km) and 1.1799 metric tons of Carbon roundtrip. For $14.16 or 1,888 Award Miles a United Airlines passenger can support the Alto Mayo Conservation Initiative. Objectively this is not a lot of money in the scheme of things, and maybe it will offset your trip. I don’t have the impression most travelers purchase these indulgences.
More importantly, I don’t think this scales. Some estimates below:
A Trans-atlantic flight might require 11 trees per person per flight to do a full offset. There are about 100 million international enplanements from the US per year. Not all are Transatlantic of course, many are Trans-Pacific or to South America, and so longer. I will leave it to a research paper to figure out total distance. So that is on the order of 1100 million trees per year (probably more) to be planted to guiltlessly offset US international air travel. Let’s assume 5m x 5m per tree (25 m^2). 25*1100M = 27,500 million square meters to offset international aviation from the US (excluding US domestic aviation and travel in other countries. That is 27,500 km^2, or an area of about 165 x 165 km on edge per year (for say 50 years until aviation switches to biofuels). This is the size of Massachusetts.
While that is technically feasible, since the US has lots of land (and is more than 50x the size of Massachusetts, as Massachusetts is a smaller than average state), no-one is actually doing this, and the offset is over the life of the tree, not immediate, so we would need one Massachusetts per year until the end of carbon-emitting aviation to make offsets work.
I like to think in terms of queues. The environment can clear (absorb) a certain amount of CO2 per year, basically the equivalent of net zero carbon emissions. If there is a positive amount of emissions, the CO2 queues in the atmosphere, waiting to be absorbed. (And probably doing things to the environment we wish were otherwise.)
If offsets are not employed, the alternative is that the accumulated CO2 queue from US Transatlantic enplanements will continue to grow. We could pull out Kant’s categorical imperative “Act only according to that maxim whereby you can, at the same time, will that it should become a universal law.” and argue since this doesn’t scale (can’t become a universal law), you shouldn’t do it. But that’s the sort of philosophical nonsense that we hope philosophers have recovered from.
Just because it can’t solve the entire problem and can’t become universal doesn’t mean it can’t be useful to plant more trees. Trees are good. However, while a carbon offset indulgence may absolve you from guilt on a particular trip, it cannot absolve the industry, since it cannot scale. Imagine the number of trees required for all aviation, not just international, and for auto travel (about 10x aviation). A more serious solution is required, one which either takes CO2 out of the air more efficiently, produces less CO2 per flight (through say biofuels or electric power), or reduces the number of CO2 emitting activities like flights (and internal combustion engine car trips) (by reducing travel).
Now to be clear, if you expand the capacity of the planet to absorb pollution (i.e. plant more trees), and people pay for their pollution, the reduced cost of per unit of pollution means that people will pollute more. Drivers will travel longer, industry will use less socially efficient means for energy generation. There might be a small amount of GDP growth associated with both the geo-engineering and resource extraction, so it is not entirely a bad thing, but it may not solve your pollution problem.
We should reframe America’s approach to pollution. Instead of addressing pollution through a regulatory regime, we should use pollution charges to allow the market to allocate the scarce resource of clean air, water, and land. A levy would be imposed on polluters proportionate to their pollution.[1] Fines above and beyond the base rate would be collected on those who exceed permitted levels with especially dangerous pollution levels.
That revenue would be dedicated to support the US Federal Government’s broad collection of agencies that monitor, regulate, protect, and restore the environment, reduce the impacts of humans on the environment, and address the problems that arise when we face environmental emergencies or just dealing with the costs of day-to-day pollution. These agencies include the Environmental Protection Agency, the National Oceanic and Atmospheric Administration, the Federal Emergency Management Agency, and large swaths of the Departments of Agriculture, Interior, and Energy among other environmental programs, as well as the Health sector. Estimates of damages from pollution[2] are similar in magnitude to the budgets of the listed government agencies.[3]
As pollution diminishes, funding declines, pollution control and remediation programs would shrink naturally, since they are not needed as much. If pollution rises, the revenue increases, giving the government agencies the resources needed to address the problem and compensate those polluted upon.
A bipartisan Blue Ribbon Commission appointed by the National Academies would be appointed to recommend rates annually based on the best science and economics of the damages that pollution causes (so if avoidance is cheaper than accepting damages it will be undertaken). Any polluter could reduce their taxes by limiting their emissions. Polluters that find that cost-effective will do so. The rates would be phased in over 5 years to allow smooth and economically efficient transitions.
This proposal lowers expenditures on the discretionary budget from general revenue by pulling the listed agencies off the unified budget. This frees up budget resources that could be used for income tax reform, negative income taxes for people with low incomes, or lowering the budget deficit.
The Environmental Trust Fund, supported by a pollution tax, would incentivize the market to determine the best ways to reduce pollution, rather than relying on government regulations and industrial policies ranging from subsidies and loans to tax credits for favored sectors. Internalizing these negative externalities would reward what we want (pollution reduction) and discourage what we don’t (pollution). This would let individuals and organizations figure out best ways to reduce pollution. It would also provide opportunities for significant tax reforms on the general revenue ledger.
[1] For the purposes here pollutants are those that contaminate an environment with manmade wastes. Air pollutants include (but are not limited to) EPA criteria pollutants Pb, SOx, NOx, Hydrocarbons, CO, PM10, PM2.5, as well as ultra fine particulates, and CO2 and other greenhouse gases. Water and land pollution rules would also be established. Other pollutants as defined by the Blue Ribbon Commission would also be appropriate for taxation.
[2] Knittel, Christopher (2012) “Cleaning the Bathwater with the Baby: The Health Co-Benefits of Carbon Pricing in Transportation” estimates a gas tax on the order $1/gallon would cover the social costs of carbon from cars, and “reduced air pollution would substantially ameliorate the costs of an increased gasoline tax”. This is substantially lower than fuel taxes in many countries. In the US, current gas taxes vary by state but are on the order of $0.40-0.50/gallon (state + federal)
[3] According to the US Energy Information Administration, the US currently consumes about 134b gallons of gasoline annually. http://www.eia.gov/tools/faqs/faq.cfm?id=23&t=10. At $1/gallon dedicated to the ETF, this would raise about $134b (ignoring short run demand response, which is likely on the order of 10%). The actual rates should be determined by the Blue Ribbon Commission. Similar magnitudes of revenue could be raised from pollution taxes on from other economic sectors besides transportation, particularly electricity generation. These funds would be distinct from highway user fees dedicated to road infrastructure.
Current budgets of selected agencies (not all of which are pollution related):
I recently had dinner with Fred Salvucci in Santiago Chile, among other topics, he talked about complaints about environmental regulation. He made a point any queueing theorist could appreciate. He argued that environment regulations are not slowing down transportation projects as a whole. There is only so much federal (and state) funding, and that is the real bottleneck. Loosening environmental regulations will not make any more projects get built in any given year.
He adds ” A further concern that I have is that many DOTs are most concerned with maximizing construction volume, so are likely tempted to skew their candidate projects towards the simpler to get through the environmental process. These projects may actually be the least important ones to actually implement, so there is likely a perverse outcome in terms of project portfolio.”
Of course it may affect the sequence of projects, projects with more environmental problems, or more social impacts which induce well-heeled people to use environmental regulations as a roadblock, may get deferred for simpler projects without such problems. But shouldn’t they in a functioning democracy?
If environmental costs are real, and we think they are, that should make projects more expensive in order to ameliorate such costs, either through avoidance of creating the damages in the first place, or compensating the losers. This higher costs reduces the number of projects that can be done with the money. So it goes. All the low hanging fruit was eaten years ago.
If those projects still pass a Benefit / Cost test after amelioration, then sure, build them. That is of course less likely than if transport investments export environmental costs to the health sector or agriculture, or property values, or anywhere else that it is not properly accounted for.
Consult most news sources these days – this one included – when it comes to poor air quality, and what you’re likely to uncover is that more often than not in the blame-game, traffic – more specifically, tailpipe emissions – is named. Obviously, not the only source of pollutants, nevertheless, the portion of pollutants coming from traffic – and transportation, more universally – is sizable.
Falling gasoline prices: What effect is this having on both motor vehicle and public transit use and, by extension, what, if any, impact has the decline had and having on the quality of our air.
He cites my earlier post
David Levinson in “Mount Transit, Mount Auto, Mount Next,” at the Transportationist Blog, clues us in.
“In the US, we have seen a great struggle play out in the twentieth century between what David Jones calls Mass Motorization and Mass Transit. The conflict between the modes continues to this day, and has become a morality play in the culture wars. While they mostly serve different markets, they compete for users, and roadspace, and funding, and the hearts and minds of travelers. They are competing on old turf though, …, both modes appear to be in decline, transit for decades, the decline of the auto-highway-system is just beginning.”
This is an interesting revelation, because what this tells me is pollution from both sources should be becoming less and less, that is, as long as the mode-split-relationship (and other influencing factors) has not significantly varied.
He doesn’t outright state a final conclusion to the question, though he says:
But, then I noticed something interesting. The overall trend was positive between 1961 and 2007, taxed gallons going from 60.006 billion in 1961 to 177.394 billion in 2007. After the Great Recession hit just subsequent to this, the number of gallons of gasoline taxed dropped to 171.229 billion in 2008, dropping even more to 168.551 billion in 2009, rose again in 2010 to 171.101 billion, falling to 168.722 billion in 2011. Only if there are fewer less-fuel-efficient vehicles on the road coupled with greater use of cleaner-burning fuels and/or less traffic on the roads coupled with greater use of cleaner-burning fuels – along with the dip in the amount of gallons of gasoline taxed, am I able to conclude that emissions emanating from motor vehicles are also fewer. That’s a good sign even if the number of motor vehicles on America’s roadways experiences level or upward growth.
I subscribe and listen to the Seminars About Long Term Thinking Podcast by the Long Now Foundation.
So I was surprised and pleased to find the most recent episode featured Jesse Ausubel, (previously mentioned on this blog, and who has a lobster named for him) discussing fascinating trends in dematerialization, and how the environment is recovering (mostly) even without concerted public policy.
The blurb says:
In the field of environmental progress the conflict between anecdote and statistics is so flagrant that most public understanding on the subject is upside down. We worry about the wrong things, fail to worry about the right things, and fail to acknowledge and expand the things that are going well.
For decades at Rockefeller University Jesse Ausubel has assembled global data and trends showing that humanity may be entering an exceptionally Green century. The most important trend is “land-sparing”—freeing up ever more land for nature thanks to agricultural efficiency and urbanization. Ausubel notes that we are now probably at “peak farmland“ (so long as we don’t pursue the folly of biofuels). Forests are coming back everywhere in the temperate zones and in many tropical areas, helped by replacing wild logging with tree plantations. Human population is leveling rapidly and we are now probably at “peak children.” Our energy sources continue to “decarbonize,” and a long-term “dematerialization” trend is reducing the physical load of civilization’s metabolism.
In the ocean, however, market hunting for fish remains highly destructive, even though aquaculture and mariculture are taking off some of the pressure. In this area, as in the others, rigorous science and inventive technology are leading the way to the mutual flourishing of humanity and nature.
At my conference on the future of methane in Fort Worth last November, I found out about a documentary called Switch, about the future of energy in the US. I finally got around to getting and watching. It is highly recommended for those interested in the subject.
It is largely non-partisan (though the protagonist is a geologist) and covers all of the important energy types in a serious and engaging way, with a bit more meat and less chrome than the typical PBS science show. You have to request a copy from the website, it is not available on iTunes or Netflix yet.
I don’t agree with everything. I think it overestimates how long the switchover to renewables + nuclear being the largest share of energy will take. It does this because it underestimates future technology advances — looking more linearly and less exponentially/logistically in terms of technology development and deployment. Similarly it underestimates the ability of larger inter-connected networks to mitigate reliability/availability problems from solar and wind, and advances in storage of various types. I don’t think this change will be overnight, but I hope it will be sooner than the 50 years the film estimates. The cost curves on solar and wind are getting very competitive, and the more interest they have, the more investment they will get.
![Description English: This figure shows the history of atmospheric carbon dioxide concentrations as directly measured at Mauna Loa, Hawaii since 1958. This curve is known as the Keeling curve, and is an essential piece of evidence of the man-made increases in greenhouse gases that are believed to be the cause of global warming. The longest such record exists at Mauna Loa, but these measurements have been independently confirmed at many other sites around the world [1]. The annual fluctuation in carbon dioxide is caused by seasonal variations in carbon dioxide uptake by land plants. Since many more forests are concentrated in the Northern Hemisphere, more carbon dioxide is removed from the atmosphere during Northern Hemisphere summer than Southern Hemisphere summer. This annual cycle is shown in the inset figure by taking the average concentration for each month across all measured years. The red curve shows the average monthly concentrations, and blue curve is a smoothed trend. The carbon dioxide data is measured as the mole fraction in dry air. This dataset constitutes the longest record of direct measurements of CO2 in the atmosphere (data for 2016 are preliminary). Date 11 January 2017 Source Own work. Data from Dr. Pieter Tans, NOAA/ESRL and Dr. Ralph Keeling, Scripps Institution of Oceanography.](https://transportationist.files.wordpress.com/2017/12/1200px-mauna_loa_co2_monthly_mean_concentration-svg.png?w=300&h=300)
David Levinson, Transportist 
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