The census is a vital data source for all sorts of transportation and land use planning.  A voluntary census is nearly useless, since the sample will suffer from voluntary response bias.  This will do nothing to reduce the number of analysts and bureaucrats – provincial governments will be forced to step in and collect the same data themselves, but this will inevitably result in the loss of province-to-province comparisons.

As for privacy, the alleged basis for this decision: Statistics Canada jumps through all sorts of hoops to ensure the privacy of respondents.  It would be difficult if not impossible to connect any of the published census data back to an individual.  Yes, the questions are detailed and probing; but the anonymization process used by Stats Can is tougher  than anywhere else in the world that I’ve seen.

No related posts.

The judicial verdict is in on the sensational case of Michael Bryant. It sounds like a tragic case of a driver whose car’s stop/stall/roll action accidentally provoked an unstable bicycle courier, with tragic and ultimately fatal consequences. The driver appears to have behaved completely reasonably under the circumstances. The cyclist had a long history of aggressive confrontations and appears to have behaved in a threatening manner.

I take no issue with the facts of the case or the judgment. However, the incident has taken on large proportions in the media and the cycling community, and I find the official legal summary wanting in this regard.  The crisp, neutral judicial language gives the document the air of Truth and Justice, when in fact it only represents The Law.

The document answers the legal problem at hand, a judgment on dangerous driving, and therefore focuses entirely on what constitutes “reasonable driver behaviour” under the circumstances.  Lost in the context is what constitutes a reasonable cyclist’s reaction – and while the cyclist was not reasonable, an emotional reaction to having your rear wheel bumped is legitimate, and a subsequent furious reaction to being sent flying over the hood of the car is also fair.  Because the document is necessarily focused on the Law, all such points on the public debate of cyclist/driver perspectives and emotions are out of the picture.  Also lost in the discussion is any mention of the differences between car/car collisions from car/bike collisions – what may be a fender-bender in one context is an unnerving experience in the other, even if the vehicle doesn’t touch the cyclist’s skin, or if the vehicle is only going 13 km/h when it sends the cyclist flying over the hood.

The cycling community’s discontented reaction to the case stems from a desire for the driver world to “please understand our feelings!”  Unfortunately, this particular cyclist’s aggressiveness makes it an unlikely to elicit any soul-searching.  Note however the pattern: whether the cyclist is in the wrong (this case) or in the right (2008 story with a cyclist’s amputated leg), the cyclist will always be the one who gets injured or killed.

The morals: cyclists must hold their tempers, no matter the incident. And, there’s a profound lack of mutual understanding and respect still out there on the streets.

Related posts:

1. Road rage
2. Bad bicycle routes

Growing up in Toronto, I was a six-month cyclist and six-month pedestrian/transit rider. Since moving back a few years ago, I’ve been shifting to closer to ten months of cycling. I realized that I feel much better when I get that daily exercise and sunshine, and it’s considerably faster for getting around, chaining trips and running errands.

In the process, I’ve been trying to find the right bike for the job, and have just bought a pricy Dutch bike for the coming winter. My summer bike is out of the question; it’s a nice bike, and far too vulnerable to the winter salt, grit and filth.

Bicycle #1. I bought this road bike at the nadir of my student bank balance for $100. It’s as old as I am and a little too small. It handled reasonably well on the winter streets, the narrow tires were good at punching through the snow to find pavement, and the vintage handlebar-end shifters were easy to use with big mitts. The caliper brakes are the deal-breaker though: quite weak in wet conditions, and so tight around the wheel that I can’t have both fenders and knobbly tires. I rode it over the two winters of 2006-2008, when I lived in an apartment building. In that building, I could use the underground parking garage for cleaning and regular maintenance, and the bike thawed overnight in slightly-above-zero conditions. Rusting was a major problem: a new chain and rear cluster every spring, often cables as well, and a lot of surface oxidization wherever the paint had chipped off.

Bicycle #2: I won this ultracheapo “mountain” bike in a draw at work. It only came in one far-too-small size, but I had hopes that a trashy department store “mountain” bike with better brakes would be okay in the winter. I sank some cash in fenders, rack and lighting and waited for winter, when my hopes were quickly dashed. The brakes were strong, but the size was painful and the cheapo shifters and drivetrain were unreliable. Plus, I moved to a house without a garage, and the bike was sitting outside in rain, snow and freezing rain, taking a real toll. The bike couldn’t thaw overnight, and maintenance was impossible since I had no indoor space where I could work. I used it for one season, and was forced to ride transit much of the time. With a new chain it’s still rideable, but it’s pretty clear that another winter will destroy the drivetrain.

Bicycle #3: after doing my research, I learned that Dutch-style city bikes are often recommended for winter cycling. The internal gearing reduces derailleur maintenance, the fully enclosed chain keeps out dirt and ice, and internal drum or coaster brakes work better in wet conditions and need considerably less maintenance. The longer wheelbase and heavier weight make it more stable, and the built-in heavy-duty metal fenders keep the rider clean. In Amsterdam, most apartments don’t have indoor parking space, so they’re designed for parking outside on the street in the rain: low-rust stainless steel all over. The Netherlands gets a lot of rain and some snow, and uses salt on the roads; but I imagine that Toronto will be a more demanding environment.

After doing test rides up a major hill from Bloor to St. Clair, I decided that a five-speed model was necessary here, and I settled on a Batavus Fryslan from Curbside Cycle. The rear coaster brake is quite responsive, the front drum brakes less so, but both work just as well in wet weather. The big question: after dropping cash for an expensive low-maintenance bike, will it get destroyed over the winter? Stay tuned.

A final note on tires and winter: from what I’ve read, my intuition on the subject may be wrong. You’d think that big, knobbly tires would be good, possibly with metal studs for ice. But from what I’ve read:

• Most of the time, you’re on bare pavement. The main streets in Toronto are bare 90% of the winter, and I’m willing to walk the last few blocks to my house if necessary. I don’t ride in a heavy snowfall or extreme weather, particularly ice.
• Wide tires tend to “float” on the snow while narrow tires concentrate the bike’s weight and punch through snow to touch pavement. Tire-to-pavement contact is much better than trying to move on snow, especially if you’re on a street with traffic and you can’t afford to skid.
• Knobby tires may not help in snow; the tread pattern is more important.
• Studded tires may be good on ice, but they’re a pain on pavement. There are tires that just have studs on the tire corners, to give traction when turning.
• Low tire pressure seems to be a common solution for improving traction, although I haven’t tried it yet.

Be careful with information on the web – a lot of it is for people who are riding winter trails on mountain bikes, not city streets. On a narrow four-lane arterial with streetcars, controlled skids are not an option.

Related posts:

1. Dutch bike culture
2. Planning for Cycling
3. New bike

Related posts:

1. Planning for Cycling

In the interim, though, Google has made some big advances in its handling of transit. They have a full database of rapid transit stops in Toronto (GO and TTC subway), and a layer that shows the TTC subway lines as well. York Region has provided Google with full local bus data, including schedules, and Google Maps does a fairly nice job of showing that information. That said, the visuals for the transit system aren’t the most attractive, the lines showing the GO rail network are hard to see, and other major transit facilities don’t jump out at the viewer (like the York VIVA BRT Light system or the Spadina streetcar). And in Vancouver, Google still has zero data.

So, my maps still serve a purpose. The changes in this edition are:

Greater Toronto Hamilton Area

• Added York VIVA Blue and Purple lines
• Changed Toronto colour scheme to colour code by operator (TTC, GO, VIVA) rather than by line. Changed line thickness to represent “all-day” vs. “peak only” service
• Added links to TTC and GO station websites
• The debate over “what to include on the map” is growing in my mind. Should St. Clair and Spadina be in, since they have partial segregation from traffic? Should the north half of VIVA Blue really be in, when it has 15 minute frequencies in the peak hour and operates in mixed traffic?

Metro Vancouver

• Removed 98 B-Line and moved Canada Line to the “present day” map. Updated Canada Line alignment, added numbers of connecting buses.
• Changed colours to match latest TransLink map, and changed line thickness to represent “all-day” vs. “peak only” service

Codebase

• Moved to more modern Google APIs now that they exist (e.g., GMarkerManager)
• Removed labels from map – the Toronto map in particular was far to cluttered, and the speed penalty for showing the labels was too high. They’re still there, but only if you move the mouse over a station icon.

Related posts:

1. Toronto Transit Map
2. Google Transit Map
3. GO Transit

MacKay’s great strength lies in communicating numbers: using these simple, visual representations, a single consistent set of units throughout the book, and back-of-the-envelope calculations that are designed to illustrate the cases at hand, he’s assembled a solid book. MacKay doesn’t cover the politics or economics, and he doesn’t frame the book in terms of climate change, although that’s clearly the key underlying motivation.

Here’s the background: an example of a simple visual story, showing why burning fossil fuel reserves represents a massive change to the climate system. I’m going to paraphrase MacKay to cut to the chase, but if you prefer, please read MacKay’s original text, pages 241-243.

Throughout the book, MacKay uses a type of figure where the area of a box represents its size. The bigger the box, the bigger the number, and it’s really easy to visually compare different boxes.

Figure 1: Estimated amounts of carbon, in gigatons, in accessible places on the earth.

“Until recently, all these pools of carbon [shown in the above figure] were roughly in balance: all flows of carbon out of a pool (say, soils, vegetation, or atmosphere) were balanced by equal flows into that pool. The flows into and out of the fossil fuel pool were both negligible. Then humans started burning fossil fuels. This added two extra unbalanced flows, as shown [in Figure 2].”

Figure 2: The arrows show two extra carbon flows produced by burning fossil fuels. This cartoon omits the less-well quantified flows between atmosphere, soil, vegetation, and so forth.

The flows shown in Figure 2 (right) are from fossil fuels to the atmosphere, and from the atmosphere to the surface waters. As shown, roughly one quarter of the fossil carbon winds up in the oceans on a short timescale of 5-10 years; recent research indicates that this may be reducing as the surface waters saturate, however. Some carbon is moving into vegetation and soil, perhaps 1.5 GtC/y, but this is less well measured. What is observed today is that roughly half of the fossil carbon stays in the atmosphere.

Now, throw one more number into the mix: if fossil fuels remain our dominant energy source, then carbon pollution under “business as usual” is expected to emit 500Gt of carbon over the next 50 years, with roughly 100Gt expected to be stored in the surface waters of the ocean (at 2Gt/year). By looking at the figure, it is clear that the amount of carbon in the fossil fuel supply dwarfs the carbon in the atmosphere.

The figure shows quite clearly that if we’re talking about burning a large fraction of the remaining fossil fuels, we’re talking about major disruptions in the carbon balance. Something has to take up the carbon—either the atmosphere, surface waters, soils or vegetation, and all data to date suggests that the atmosphere is where the majority of the carbon winds up. Given the size of the fossil fuel slice, it’s easy to see how a doubling or tripling of atmospheric CO₂ could happen within 50-100 years.

And yes, there’s a lot of carbon stored in the deep ocean—but as MacKay makes plainly clear in his discussion, the timescale for ocean mixing is thousands of years. “On a time-scale of 50 years, the boundary [between the surface waters and the rest of the ocean] is virtually a solid wall.”

Plus, the figure shows two risk areas: vegetation and soils from vicious cycles. If the high temperatures (caused by high atmospheric carbon) kill off vegetation or melt the tundra and release methane, large stores of carbon from the vegetation and soils categories could wind up in the atomsphere easily—and from the size of those boxes, it’s clear that could be a catastrophe. (As it happens, the IPCC A1FI scenario expects emissions of 1800-2500 GtC by 2100—I’d guess that means that much of the easily accessible fuels are burned, plus a substantial net release of carbon from vegetation and soils.)

At any rate, I like these figures because they clearly show this concept. By using a simple visual representation of quantity, and separating the steady state out from human-driven changes, MacKay cuts to the heart of the matter. Now, for comparison, here’s an IPCC figure (from their technical reports) showing carbon stores and fluxes (source is AR4 figure 7.3):

Confused yet? Black is preindustrial, red is human-caused. The IPCC figure can certainly be understood if you spend the effort, but it doesn’t leap off the page. Admittedly, it’s from a technical chapter that’s trying to communicate carbon fluxes rather than carbon stores; the comparison isn’t entirely fair. The IPCC has produced simpler figures (for other topics) in their policy-oriented chapters, but they could still borrow a few pages from MacKay’s book.

Related posts:

1. 5 degrees warmer by 2100 and rising, unless we take action
2. Emissions and the Tar Sands

Photo by Rodrigo Sala

I’ve been a little baffled by the tar sands’ villainization in the climate literature for some time. While a few photographs can clearly show that the tar sands have dire impacts on the local environment (as a recent National Geographic special showed), I haven’t really understood why the tar sands have been singled out for so much venom in the climate literature. About two years ago, I first saw the stats: if you measure all emissions from extraction to the tailpipe (a “well-to-wheel” basis), the tar sands are between 15–40% worse than conventional oil. Why, then, is tar sands oil so much worse than—say—a vehicle with 15–40% poorer fuel efficiency? Here in Canada, the tar sands represent a lot of potential wealth and jobs; why should our oil get singled out relative to Saudi crude?

My reading recently took me past a figure that illuminated the problem for me in many ways. The figure below is adapted slightly from Farrell and Brandt, “Risks of the Oil Transition,” Environmental Research Letters 1(1), 2006, although I’m sure it can be found in many places in the literature.

Global supply of liquid hydrocarbons from all fossil resources and greenhouse gas emissions. EOR is enhanced oil recovery, GTL and CTL are gas- and coal-derived synthetic liquid fuels. The CTL and GTL quantities are theoretical maxima because they assume all gas and coal are used as feedstock for fuels and none for other purposes. The lightly shaded portions of the graph represent less certain resources. GHG emissions in the lower figure are separated into fuel combustion (downstream) and production and processing (upstream) emissions by a dashed line. [Original figure included only the darker top of each bar, indicating the range in emissions estimates; modified to extend the bar down to zero, to emphasize the total area.

The horizontal axis here represents the number of barrels of oil possible with each source, the vertical axis represents the greenhouse gas emissions per barrel, and the area of each bar is therefore the total emissions if all possible fuel of that type is extracted and used.

The black bar to the left of the axis represents the emissions from all oil burned to date. Everything to the right of the axis represents the potential emissions from conventional and unconventional oil, in order of price per barrel. The oil used to date is dwarfed but what remains in the ground and could be emitted in the future.

Coming back to the tar sands, a few points can be drawn from the figure:

• It’s total CO₂ that matters—not just CO₂-per-barrel alone. The tar sands may be only 15–40% worse per barrel than regular oil, but regular oil is already a major problem. The “dirtiness” of the tar sands comes from the total area of the bar (total GHGs), not just from the vertical axis alone (GHGs-per-barrel).
• Carbon capture and sequestration (CCS) can only deal with extraction emissions (well-to-tank, above the horizontal line) and not the emissions when the oil is burned in a car (tank-to-wheel). CCS can therefore only bring tar sands emissions down to the same level as conventional oil, leaving a massive amount of emissions unaddressed.
• We have to draw the line somewhere if we’re going to stop climate change. If all emissions shown occur, we face dire consequences. From a carbon perspective, the wisest approach is to exploit the resources that have the lowest emissions and lowest price while we make the transition to a low-carbon economy. The threshold that determines where the line is drawn would ideally be set based on the maximum amount of emissions and temperature rise that we can tolerate. According to Joe Romm’s analysis, for a 2°C temperature rise, the line needs be drawn at conventional oil: enhanced oil recovery, tar sands, synfuels and oil shale would all be out.
• The Canadian perspective is not the global, rational perspective. The above analysis was the 10,000-foot perspective on the issue. If adopted, if would mean that Canada would have to forego the valuable tar sands and allowing others (particularly in the Middle East) to take massive profits from selling conventional oil—which is, as already noted, a dirty and dangerous resource. There is undoubtedly an element of unequal treatment involved, although it clearly makes sense in terms of optimizing the energy/emissions ratio.

The regulatory tool that is currently being mooted to address this issue is carbon fuel content regulation. California’s ambitious Low Carbon Fuel Standard (LCFS) aims to progressively reduce the lifecycle carbon emissions emitted for each barrel of fuel burned, with an initial target of a 10% reduction in sales-weighted fuel carbon intensity by 2020. This avoids the rancorous process of picking winners and explicitly declaring the tar sands off-limits—instead, it simply requires that any sales of high-carbon fuels be balanced by low-carbon fuels (such as yet-to-be-commercialized cellulosic biofuels). If it works, it would effectively impose a disincentive on the use of high-carbon fuels, without explicitly banning them.

The Alberta government is pursuing CCS for the tar sands (with lackluster enthusiasm from the oil companies themselves). Given the Alberta government’s tepid and ineffective climate policies, many argue that this is simply a distraction or greenwashing. However, it could possibly be interpreted as a strategy to level the playing field for the tar sands relative to conventional oil. If many governments worldwide adopt some LCFS-like regulation to tackle climate change, regular tar sands oil will be more challenging to sell because it will have to be balanced by a large amount of low-carbon fuel sales. However, if CCS is implemented for the tar sands, then tar sands production would be GHG-equivalent to conventional oil, and equally attractive on the global market—except for the price of its inputs (natural gas) and the CCS costs.

Skepticism is still warranted. Carbon sequestration in the tar sands faces some huge obstacles:

• It is unlikely to be mature enough for commercial deployment before 2030, and will be expensive even then. (See a recent Economist editorial, article and related coverage.)
• To be effective, sequestration would need to be 100% reliable with no leakages of carbon dioxide. Even a small annual leakage rate from a sequestration site could unravel the sequestration effort, with enough time. It will also need to be auditable and verifiable.
• The most cost-effective place to deploy CCS will be in coal plants. Using it for natural gas would likely be a waste of capital, since natural gas is already one of the cleanest-burning fuels. In a future with real constraints on carbon, the opportunity cost of using scarce clean natural gas to extract oil (instead of using it to replace coal plants) would also make tar sands CCS a poor choice.
• Suppose that we cannot allow the total emissions from oil to exceed the area of the “conventional oil” box in the graph above. Even if each barrel of CCS-equipped tar sands is GHG-equivalent to conventional oil, this doesn’t change the total emissions allowed—for each barrel of tar sands oil extracted, a barrel of (much cheaper) conventional oil would have to be left in the ground.

Ultimately, this is why authors like Joe Romm are so scathing about the tar sands. North of the 49th, we have trouble seeing anything beyond our economy’s dependence on the tar sands and associated jobs and windfall of wealth.

Related posts:

1. Visualizing Carbon Stores
2. 5 degrees warmer by 2100 and rising, unless we take action
3. Canada in last place

However, TRB doesn’t provide any LaTeX templates, so I took a shot at rolling my own based on the TRB Style Manual. It’s very primitive in its present state, but it’ll handle the page layout, headings, captions, fonts, and bibliography style.

Unfortunately, they still require a Word document if you plan to publish in their journal, Transportation Research Record. I’m submitting my paper to a different journal for publication, and that journal accepts LaTeX submissions. But if the ultimate destination for your paper doesn’t accept LaTeX or PDFs, take care.

• trb_example.tex: the template and an example document
• trb.bst: the bibliography style
• trb_latex.zip: all files, including a demo bibliography

For the record, a little discussion of my adventures in creating all of this. Most of it is fairly straightforward stuff—find the right packages to adjust margins, heading styles, fonts and so on. (Largely, this makes the document more ugly. The TRB journal format is quite unattractive, Word-like and dense, if you ask me.)

The one tricky part was the bibliography style. The recommended TRB citation style is different from any of the built-in LaTeX and BibTeX styles, and I wanted to replicate it correctly. Thankfully, I found the excellent custom-bib program (a.k.a. makebst), which walks through a series of questions to produce a tailor-made Bibliography Style file (bst). I still had to make a few final edits to the resulting bst file (to adjust the volume/number citation style, and technical reports) but thankfully didn’t need to learn much about the cryptic and obscure language they use.

At any rate, it was a surprisingly painless procedure, requiring under a day to get everything working. Now hopefully some other transportation researchers will find this useful and reuse the template.

Related posts:

1. Thesis: Synthesizing Agents and Relationships for Land Use / Transportation Modelling
2. AutoDesk Mapguide setup

“In a worst-case scenario, where no action is taken to check the rise in greenhouse gas emissions, temperatures would most likely rise by more than 5°C by the end of the century.”
—Dr. Vicky Pope, head of climate change predictions at the UK’s Hadley Centre, Dec. 2008

“Without a change in policy, the world is on a path for a rise in global temperature of up to 6°C.”
—International Energy Agency, World Energy Outlook, Nov. 2008 [traditionally a very conservative agency]

“We are on the precipice of climate system tipping points beyond which there is no redemption.”
—James Hansen, director, Goddard Institute for Space Studies (NASA), December 2005

The IPCC Numbers

Is there a definitive scientific source for these projections, however? With a little digging, I’ve found similar estimates from the Intergovernmental Panel on Climate Change (IPCC) itself, a source that I consider authoritative. The figure below shows annual emission scenarios (left) and temperature effects (right) for six different scenarios. For reasons I’ll explain later, I believe A1FI and A2 are the two scenarios that correspond most closely with a “business-as-usual” approach to carbon emissions. A1B is also worth considering, as a scenario “business-as-usual” is not possible due to limited fossil fuel supplies. (While the peak of conventional oil production is almost certainly around the corner, this scenario could well require constrained supplies of all fossil fuels—including coal, tar sands oil, shale oil and natural gas.)

Source: Climate Change 2007: Synthesis Report, Summary for Policymakers, Figure SPM.5

The temperatures shown in the right panel are relative to 1980-1999 average temperatures, which were already 0.5°C warmer than preindustrial levels (1850-1899). The curves are the “best estimates,” and the bars on the right show the range in 2100 temperature estimates. As you can see from the right panel, the “business-as-usual” estimates for 2100 temperature rise are between 3.9°C (A2) and 4.5°C (A1FI) relative to preindustrial levels. The constrained-fossil-fuel scenario gives a 3.3°C rise (A1B). Furthermore, all three of these scenarios show temperature continuing to go rapidly upwards past 2100. Note also that while emissions in the A1B scenario peaked in 2050, the temperature continues to rise to 2100, although the rate of increase has slowed.

IPCC may be an underestimate

In his book (which I highly recommend), Joe Romm argues that the IPCC has underestimated the actual temperature impacts of “business-as-usual” emissions. The basis of his argument is that almost all models currently omit four key vicious cycles (positive feedback effects) that are likely to occur for large atmospheric and temperature changes: reduced ocean absorption of CO₂, reduced soil/tropical forest absorption of CO₂ (and possible reversal, turning into CO₂ sources rather than sinks), and massive release of CO₂ from thawed tundra, permafrost and frozen peat.

Romm has lays out his reasons for believing that the IPCC has underestimated the temperature rise on his blog in a three part series (part 1, 2 and 3). If you buy his arguments—and from a cursory reading of RealClimate and other sites, they seem to make some sense—then you can add an additional 1-2°C.

So in conclusion—this is why, I believe, the Hadley Centre and many other scientists believe that “business-as-usual” will take us above 5°C warming relative to preindustrial levels. The IPCC has not yet endorsed such a drastic temperature rise, but has indicated that a minimum 3.9°C – 4.5°C warming are entirely plausible by 2100—with temperatures continuing to rise steadily into the following century.

All of these reflect “business-as-usual”: no change in the use of fossil fuels, and no change in personal attitudes towards the environment. We have the power to stop these dire scenarios from occurring; we just need the political will to make it happen.

I’ll close with a recent graphic from MIT depicting their interpretation of the greenhouse gamble: a roulette wheel showing what sorts of temperatures we can expect if we do not act, and another showing what we can expect if governments adopt suitably aggressive policies. These are relative to the 1980-1999 average temperature, so add 0.5°C to get the temperature change relative to preindustrial levels; they are also based on a recent post-IPCC AR4 update to the MIT model.

The "Greenhouse Gamble" (MIT)

Aside: My Assumptions

Warmer than what? Many projections are relative to today’s temperatures; but today’s temperatures are already roughly 0.7°C warmer than 1900 temperatures, due to human fossil fuel emissions over the last century. I will stick with a warming level relative to the 1850-1899 average, to emphasize the magnitude of the shock we’re introducing to the environment where human civilizations developed.

Under what emissions scenario? The level of warming depends on how much carbon is emitted in the future. My first question is to see what the warming would be under the assumption that we continue with our current energy strategy and values. That is, exploiting the cheapest available energy sources (which for the foreseeable future will remain some mixture of fossil fuels), and a high level of materialism and low level of environmental conscientiousness.

• The IPCC defines four primary emissions scenarios, labelled A1, A2, B1 and B2; A1 has been refined into three variants, A1FI, A1B and A1T. From the IPCC’s perspective, no single one of these represents “business-as-usual.” All are possible, and explore a wide range of visions of what the future looks like. Each comes with a narrative describing the vision of the future.
• The A-series scenarios focus on economic growth, while the B-series scenarios involve a citizen-driven shift towards sustainability (“a high level of environmental and social consciousness”). To my mind, the A-series is where we are today, and the B-series would represent a departure from today’s attitudes and would require a profound acceptance of the causes of climate change.
• The 1-series scenarios involve global convergence (1) while the 2-series scenarios anticipate more regional heterogeneity (2) in the future. I view both of these as possibilities from where we stand today.

I would consider A1FI, A2 and A1B as the best scenarios for thinking about temperatures in the future assuming no change in attitudes or policies. Just keep in mind that the IPCC uses a broader perspective and treats all scenarios as equally likely.

• A1: rapid GDP growth, rapid introduction of technology; global population peaks mid-century and declines
  • A1FI: fossil fuel-intensive scenario
  • A1T: non-fossil fuel scenario with a very different energy mix from today, with rapid development of solar, nuclear, wind, etc. power
  • A1B: a “balanced” energy mix combining fossil fuels and renewables, possibly due to limited resource availability
• A2: large population growth (13 billion), medium GDP growth, high fossil fuel use

Related posts:

1. Visualizing Carbon Stores
2. Backcasting: From Climate to Transportation
3. Emissions and the Tar Sands