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Two Studies on Regional Options for Reducing GHG Highlight Need for Reduction in Travel Intensity

Projected GHG emissions in Minnesota with different reduction wedges and wedge portfolios, in million metric tons of CO2 equivalent. The uppermost line in each graph represents emissions under the business as usual (BAU) scenario. Each patterned wedge depicts the reduction below BAU emission levels attributed to a given technology or practice. Olabisi et al. (2009) Click to enlarge.

Achieving targeted regional reduction in greenhouse gas (GHG) emissions from the transportation sector will require concentrated efforts to change travel behavior and reduce vehicle miles travelled in addition to advances in vehicle technology and fuels, according to two recent studies.

A paper by researchers at the University of Minnesota, published in the ACS journal Environmental Science & Technology, projects GHG mitigation strategies for Minnesota, which has adopted a strategic goal of 80% emissions reductions below 2005 levels by 2050. A paper by researchers at the Institute of Transportation Studies (ITS), University of California–Davis, to be published in the journal Transportation Research Part D: Transport and Environment, examines how California may reduce transportation greenhouse gas emissions 80% below 1990 levels by 2050 (“80in50”). (Earlier version of study, earlier post.)

Minnesota. The team from the Ecosystem Science and Sustainability Initiative, University of Minnesota examined the potential for policies and technologies to effect GHG reductions across all sectors in the state. The researchers used GHG mitigation categories developed by Pacala and Socolow in a variant of the Pacala and Socolow wedge framework, but took a very different approach to analyzing the strategies’ contributions to GHG mitigation.

[Pacala and Socolow] selected diverse strategies that could each contribute a set reduction of 1 Gt carbon emissions over 50 years, whereas we examined the maximum emissions reduction possible within Minnesota for the strategies considered and did not limit these wedges in terms of a contribution to a pre-determined amount of emissions reduction. In our study, wedge refers to the size of the GHG reduction that a specific technology or strategy could contribute by 2050 compared to a trajectory of emissions representing currently implemented reduction actions and historically observed economic impacts on energy consumption (we call this trajectory “business as usual” or BAU).

—Olabisi et al. (2009)

The researchers used scenarios to evaluate potential GHG reductions from technologies determined to be feasible and available in Minnesota within 10-20 years, primarily in the transportation and electricity production sectors.

Under the business as usual (BAU) scenario, GHG emissions in Minnesota would rise to approximately 223 million metric tons of CO2 equivalent by 2050—an increase of 49% over 2005 emissions levels. Minnesota’s population is expected to grow by 30% during this time period, and real gross state product by 253%.

Transportation wedges (and resulting reductions from projected BAU 2050 emissions) include:

  • Vehicle miles driven cut to 50% of 2005 levels by 2050, with ethanol blending mandates (20% reduction from 2050 BAU levels);

  • Fleet vehicle efficiency increased to 55 miles per gallon (mpg) average by 2030, with current ethanol blending mandates (19% reduction);

  • Complete transition to switchgrass-based ethanol (18% reduction);

  • Complete fleet transition to PHEVs while retaining conventional electricity mix (9% reduction); and

  • Complete transition to corn-based ethanol for personal vehicles (7% reduction).

The wedges from all sectors could be combined in several ways (portfolios) to enable the state to meet the goal of reducing GHG emissions 80% below 2005 levels. One example given combined generating all of Minnesota’s electricity from poplar biomass and sequestering the carbon emitted at the generation plants; reducing vehicle miles driven by half; improving vehicle fleet fuel efficiency to 55 mpg; and reforesting 5% of Minnesota’s land area. This resulted in the “maximum reduction” portfolio of 95% below 2005 GHG emission levels.

The trajectory of GHG emissions in Minnesota is more sensitive to the number of miles Minnesotans drive than it is to the amount of electricity they use. This makes intuitive sense, as driving is a more carbon-intensive activity than electricity consumption in terms of daily emissions. By reducing vehicle miles traveled in the state to 1999 levels by 2050, Minnesota could restrict its GHG emissions growth to only 23% above 2005 levels, rather than 49% as predicted under the BAU projection. This would mitigate the need for Minnesota to adopt as many other carbon-saving technologies.

...Public acceptance to deploy the wedges will be related to cost and the degree to which they fit within embedded political interests and require a transformation of existing infrastructures—significant for switching to renewable electricity production or reducing vehicle miles driven; less significant for producing motor fuels from corn or improving the efficiency of electricity use. Reducing vehicle miles driven in Minnesota would likely induce spillover effects, such as increased bus traffic, which were not analyzed in this study.

—Olabisi et al. (2009)
Greenhouse gas emission reductions for Silver Bullet scenarios relative to Reference scenario for Instate emissions. Yang et al. (2009) Click to enlarge.

California. The ITS study used a scenario approach looking across all transportation subsectors (light-duty vehicles, heavy-duty vehicles (buses and trucks), rail, aviation, marine, agriculture, and off-road) to explore options for reducing emissions in the transportation sector by 80%. Scenarios included strategies for reducing travel demand, improving efficiency and using advanced technologies with alternative fuels.

The researchers used a spreadsheet model, the Long-term Evaluation of Vehicle Emission Reduction Strategies (LEVERS) model, which is built around a transportation-variant of the Kaya identity, to analyze GHG emissions. The Kaya identity decomposes CO2 emissions into the product of several important parameters. While the original Kaya identity defines activity in terms of GDP, the ITS variation of the Kaya equation focuses on transport intensity as the main activity driver in the transportation sector. Transportation CO2 emissions are decomposed into four main drivers: population, travel demand, vehicle fuel consumption, and fuel carbon intensity.

Three of the Kaya parameters correspond with three main “levers” for reducing emissions: reducing transport intensity (T), energy intensity (E) and fuel carbon intensity (C). Population is not considered in this analysis as a means of reducing emissions; California’s population is expected to double between 1990 and 2050. Important considerations for determining how effective a strategy will be in reducing emissions include the following: what mitigation options are used, how broadly they are applied, and the degree of improvement they provide. Some mitigation options cannot be implemented in all subsectors.

...Transport intensity may be reduced by several means. Better land-use planning, higher-density developments, telecommuting and increased co-location of jobs and housing can reduce travel demand even while maintaining or improving the ability of people to access their desired destinations. Another method is mode-switching from private cars to mass transit (buses, trains, etc.), which has the capacity to carry a large number of people at a given time. Changes in consumer and industrial purchasing behavior can reduce activity in the freight sector.

—Yang et al. (2009)

The ITS researchers examined seven scenarios: one reference and six “Silver Bullet” scenarios. Silver Bullet (SB) scenarios describe futures in which one mitigation option, such as an advanced vehicle technology or alternative fuel, is employed to the maximum feasible extent from a technology perspective in 2050.

  • Reference scenario. Doubling of population, modest increase (21%) in transport intensity, slight efficiency improvement (35%) and similar carbon intensity relative to 1990.

  • Moderate efficiency SB. No breakthrough technological advances, but applies all advances in conventional technologies towards improving vehicle efficiency to achieve doubling of average vehicle efficiency from 1990. Same carbon intensity as Reference, except for some electrified rail.

  • High efficiency SB. Significant breakthroughs in conventional technologies to achieve nearly triple (265%) vehicle efficiency from 1990. Same carbon intensity as Reference, except for some electrified rail.

  • Hydrogen-intensive SB. Applies FCV and low-carbon hydrogen fuels (9.5 gCO2e/MJ) aggressively across most subsectors, except aviation, and provides 58% of all transport miles. Fleet market share of on-road H2 vehicles is limited to 60% in 2050. Assumes that the obstacles to use of hydrogen in heavy-duty trucks are overcome.

  • Electricity-intensive SB. Electric vehicles (BEVs and PHEVs) and very low-carbon electricity are applied across many subsectors except marine and aviation, providing 77% of all transport miles. Electricity carbon intensity (6.5 gCO2e/MJ) is 94% below the 1990 value.

  • Biofuel-intensive SB. Low-carbon biofuels (16.3 gCO2e/MJ) are the primary fuels used in conventional vehicles (low efficiency) in all transport subsectors, providing 59% of all transport miles. Biofuels are limited to 15–20% of future US supply.

  • Passenger Miles Travelled (PMT) SB. About 25–50% reductions in passenger travel demand for LDVs and aviation relative to Reference scenario, through better land use, smart growth, transit and high-speed rail. No alternative fuels; same carbon intensity as Reference. Improved energy intensities due to increased vehicle load factors.

The Silver Bullet scenarios show that no mitigation option can singlehandedly meet the target goal because travel demand is expected to increase significantly by 2050 and advanced technologies and fuels may not be suitable for use in all subsectors or may be limited in availability. The 80in50 scenarios illustrate that the 80% reduction goal could potentially be met in multiple ways. The Efficient Biofuels 80in50 and Electric-drive 80in50 scenarios show that if vehicle and fuels technologies become clean enough, California can preserve its current levels of mobility. The former requires more primary energy and relies heavily on biomass, while the latter uses fuel more efficiently and has the potential for a significantly more diverse resource mix. The Actor-based 80in50 scenario shows that large shifts in social and travel behavior are valuable mitigation options, especially if technology is not as successful. This scenario has the lowest energy resource requirements.

—Yang et al. (2009)



Will S

A mindset change is clearly in the works for some, and as peak oil will show, will be non-negotiable. Indeed, peak oil may have far-reaching consequences that will result in 80% reduction in fossil fuels through widespread demand destruction and continued economic decline.


Quite a long article but I agree that reducing the number of miles travelled should a large part of the solution along with new carbon free or low carbon technologies.

Most of the miles we travel are not miles we enjoy to travel, so that's rather a good new if we could be less dependent on cars. Almost 50% of miles we travel could be done biking with all the potential benefits on air quality, public health, life quality in cities etc, if biking is bad for your bike, buy a recumbent you will be faster and more confortable


"if biking is bad for your bike, buy a recumbent you will be faster and more confortable (sic)"

Interesting to note the disregard and by inference disrespect that some hold for our retired, elderly and impaired populations. This is a disturbing trend noted from previous posts re: elderly and retired people as having little or no significance. You tread on very thin ground. Who is to say that a renewably charged electric vehicle should not drive 500 miles/day if they so choose? WillS? Treehugger? AGW cultists?

Many retired and elderly choose to live out their lives traveling to see the world they never saw while working 40-60+ hours per week. The lack of care or compassion for our seniors and the sacrifices they've made, again betrays the underlying agenda of the cultists. It is misanthropic at minimum. Violent at extremes.

Will S

sulleny attempts to make the case that unless we support the elderly driving 500 miles per day, we are somehow bereft of "care and compassion", indeed "misanthropic" or even "violent cultists".

I've never heard such extreme distortions (outside of a Rush Limbaugh broadcast, that is). Those who advocate limitless energy consumption presumably "because it is American" completely miss the point that we are "addicted to oil" and are growing in our energy dependence. Trying to use the elderly as human shields in your debate bombast is shameful.



thanks for your contribution, the point of Sulleny is a gross distortion of my own point. First of all retired people can drive bikes too in most of cases, and they can use public transportation as well there is no descrimination here. And also I said that most of miles we drive are not fun at all without disrespect for elderly or whoever and consequently it would be beneficial for our life quality if we had to drive less.

I am not insinuating that we should restrict our driving when we fancy to drive, not at all

sorry for the typo, I meant if biking is bad for your back take a recumbent.


The needs of the elderly are an important issue, particularly with the aging populations in all developed countries. The real need is for a good public transportation infrastructure so retirees who are capable CAN ride a bike to the station.

I am not yet retired, but I can tell you that riding on current roads with little provision for bikes is hazardous and riding 5 miles to work with 3 major hills is a challenge, even in good weather. It is not an option in the snow.

Bikes are good, but not a solution without the rest of the system in support (and not an option for my 88 year old mother).


Perhaps worse than the misanthropy is the unctuous attempt to deny it:

"Only retired people will still accept to live there [Arizona], so it doesn't matter at all"

Treehugger, February 13, 2009 at 10:21 PM


What does "addicted to oil" have to do with someone driving an EV charged by renewable energy? Apparently your group's real gripe is not with energy - because even when it is fully sustainable (e.g. solar-derived) you still wish to restrict peoples' lifestyle choices. Good luck.



It is not because retired people accept to live in arizona because of water restriction moving forward that I mean any disrespect agaisnt elederly people

for your question, it has to do with what is explained in this arcticle, that new technologies won't fill the gap anytime soon.

Stan Peterson

The questiion arises why is all this necessary? Because some cultist AGW warmists want it? If they do, let them do it.

Unlike Eurasia, California and the rest of North America already sequester all the CO2 they make by Man or Nature. CO2 is turning out to not be a primary warming component nor even a secondar nor a tertiary one. There is accumulating recent scientific evidence that a CO2 doubling would effect the climate by not tens or single degrees; nor even tenths of a degree but some few hundreths of a single degree.

Meanwhile the beneficial affect of a slightrecovery from the Little Ice Age is benign to flora and fauna.

Certainly, there will be a change in the source of the eneergy to be consumed, but little need to make do with less. Even as we will do so auotmatically by improved vehicles and motive sources.

This is just a government study waste of paper. I suggest just burning the money, it would be more direct and wastle less resources. After all somebody had to write this goo; and then make the paper and ink to be wasted on it's publication.


Quite a long article. Or maybe the mind numbing composition only made it seem so.

Doesn't this really just say that driving half as far will use half the fuel, unless cars get twice the mileage - then it will be one forth the fuel?
Peak oil is indeed in our future, and may always be.
We have a similar situation here in good ol' Aridzona - except our concern is "Peak Water".
Our water bill is ~$40/mo - that includes drinking some, showering sometimes, flushing, topping up the pool and watering the lawn. I think the lawn watering makes up about $39 of the bill. The same science works for the retired people that come mostly from the rust belt (if it matters at all).
The idea of packing people together to protect nature from them has been around since the 1950’s. It’s a fine idea but usually implies forced migration, since most people do not want to live in a hive. I think the idea of making people conform to their vision appeals, more than it should, to some.
This article does not seem to shed much light on how our energy crises must be dealt with.


According to the robot that opperates under the nam of Stan Peterson

- there is no such thing as climate change or AWG
- there is no such thing as peak oil
- all the "green" oriented people should be crucified alive especially if they are from California
- all attempt to regulate polluting emissions is just a conspiracy of California agaisnt the rest of US

So why he is spending so much of his time on this site ?

I am still trying to find out

After all why do we need green cars after since everything is fine, why do we need green car congress?


Or... Why do we need religious minimalists masquerading as environmentalists??

There IS a need for green cars. There is NOT a need for totalitarian attacks on the poor, the infirm and the elderly. This disregard for human rights and unyielding attack on the weak will result only in heightened antagonism directed at the minimalists. Not a pretty picture.


Actualy touring cars wich are the type of cars elderly drive as well as rvs will all likely be biofuel/fuel cell powered as soon as possible.

Because a touring car is made for long trips bev is out of the question and so is erev realy. Same with rvs they travel VERY long distances then sit around for days or weeks at a time at each location.

A good 50 kg tank will support a very long drive time AND a very long load time on self power. And a side benfit of h2 production from water is of course a ton of high quality oxygen.... very useful for people on sup ox.

Interesting stepping stone for fuel cells is of course the apu on an rv.

The Goracle


"Two Studies..." yada, yada, yada...

"Research" grant GREED! Follow the money. This time it's $$$$$ for two (dos, 2) "studies."

Fortunately, the indisputable scientific consensus is that the Globalwarmist's predictions of doom are false.

Now lets focus our precious time and resources on actual problems such as energy independence and pollution. Regulating breathing (CO2) is shameful.


richard schumacher

Note that the Minnesota study again confirms a much larger bang for the carbon-reduction buck by addressing electricity generation. If we replace all of our coal-fired power plants with nuclear, wind, Solar and geothermal we will still be able to go for Sunday jaunts in our Prius jalopies when we're 64.

Also, it is possible to manufacture artificial carbon-neutral liquid hydrocarbon vehicle fuels from atmospheric CO2 using carbon-neutral energy sources. This will allow aviation to continue and even grow with no increase in AGW, although at greater cost than today.

The Goracle


Wow... Will S admits to being a Rush Limbaugh listener: "I've never heard such extreme distortions (outside of a Rush Limbaugh broadcast, that is)". No wonder so many of his/her posts are extreme.

Will S, please stop listening to such extreme views.



Mister Goracle

Please bring your sources to support your ridiculous statement that "the indisputable scientific consensus that global warming is false" I don't find any trace of this presumable scientific consensus anywhere on the web


if you care so much about the poor, the infirm and the elderly you should then blame all the Reagan and post Reagan american policy until now, when never before the gap between poors an richs has grown so fast. These 7 past years have seen a stagnation of the income for the middle class when the GDP has grown 20%. The green are not to blame for this I think.

And about totalitarism attack, you should ask Stan Peterson to stop his attack against California.

California has been the first place in the world where we started to regulate emissions, and in the same time California had innovated more than any place in the world, so who is the totalitarist in that matter ?


Well this is going nowhere but there is an answer - especially for Tree and friends:

Real science with real answers. But Trolls and trollish disrespect are immediately nixed. Enjoy!



The link you provide doesn't discard man made CO2 induced climate change. It points out at some exagerations of some alarmist. Sure the CO2 level was much higher 500 milillions ago but the earth was also much much different as well as the geography, there were only one continent at the time and no land on poles, the fact that there land on poles (in south) and around poles in north makes a big difference for the climate. Climate fluctuations due to influence of other planets and earth precession are only observed in the north emisphere not in the south, because most land are in the nort emispher allowing the ice sea to extends mch more than in the south emisphere.


We should let GM go bankrupt. Chevrolet, Buick, Pontiac, Cadillac and GMC Trucks can continue making cars in competition with other domestic and foreign car makers.

The automobile technology carmakers need to produce are hybrids. GM claims they have to wait for Lithium-ion batteries. This is a lie. And the hybrid models GM plans to produce are aimed for the luxury car market.

Reducing VMT (vehicle miles travelled) has more to do with the daily commute than weekend touring and vacation travel. No amount of freeway widening to add HOV lanes can reduce VMT. For that we have to change the way we build our cities and suburbs, so that we may achieve more goals by driving less and walking, bicycling and taking mass transit more.

Sorry pops. You done lost your driving priviledge. You're too old to drive. Put your teeth back in. You flapped your jaws once too many and now you got nuthin to say.


Treehugger, Will, Sirkulat demonstrate their now uncovered hatred for the elderly. Theirs is the reel bleak agenda of the AGW cult:

1) Revoke elderly/retired folks driving privileges

2) Control the number of miles elderly drive

3) Force them to ride bicycles - if they cannot - make em walk to public transit

4) Tear down suburbs and replace with high density living hives

5) Confiscate cars (including EVs) & income privileges from those who don't conform to high density living

6) Force non-conformists into re-education through labor camps like those operating in China.

Disguise all the above as programs to combat "Climate Change." Hmmm. Is that the Twilight Zone theme I hear playing?



That's fine for me, being almost 50s I don't feel like I am a slave of my car and have much more fun riding my low racer recumbent. Each time I take vacation I try to find a place where I don't have to drive a single day, what a joy not to have to loose time in this piece of metal

Will S

Reel said;

Treehugger, Will, Sirkulat demonstrate their now uncovered hatred for the elderly.

You are really going off the deep end. Seek help.

sulleny said;

Real science with real answers. But Trolls and trollish disrespect are immediately nixed.

In other words, the site is censored. I've seen other conservative sites do the same think, so this is no surprise. So expect a completely unbalanced attack on science at this site without the ability of others to refute.

If you want to see a GW site that does allow full discussion (and it almost always tends to be at an academic level of discourse), see Real Climate, where actual paleoclimatologists (not just some crank with a keyboard) provide the content.

Will S

Real Climate link noted above.

Nat Pearre


Are you arguing that people who claim to be concerned about climate change are only doing so so that they can abuse the elderly? Really? Such screeching hysterics do nothing to further what I assume is your real argument that climate change is not real, or does not pose a real threat.

Elderly -as a group- are pretty irrelevant to the problem. On average they tend to live in smaller spaces and drive less.

Eliminating ALL personal transportation is not anyone's objective... just reducing the carbon intensity of trips taken, and reducing the amount of unnecessary travel.

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