The science-policy disconnect on carbon offsets

Caroline Alden, BURN Contributor

Carbon credits are a hot commodity these days, but reliance on this system as a permanent offset of fossil fuel emissions may be dangerous. By nature, the land carbon stock is vulnerable and volatile, and policy makers and offset traders might need to reign in their expectations a bit. 

A recent article in Nature Climate Change clears up some common misconceptions about the land carbon sink, with the goal of making clear to those involved in climate policy and carbon offset markets that reducing emissions – not trading emissions credits – is the only way to stop global warming.

Land management is key to carbon markets, because protecting and rebuilding forests facilitates sequestration – the capturing of a tradeable commodity. But land management – and the offsets it achieves – while good for the environment (and, at least temporarily, for climate), can not stop climate change.

Here are the main points made in the article:

  • NEWSFLASH: Carbon offset policies and markets typically rely on the promise of carbon storage in land reservoirs of 100 years as sufficient for issuing a carbon credit. However, the lifetime of CO2 in the atmosphere is far, far longer than 100 years. Many think that lifetime is 100 years, and for good reason; even the Intergovernmental Panel on Climate Change botched this one in its first assessment report. This misunderstanding is literally an issue of semantics: an individual CO2 molecule will move from the atmosphere into another reservoir in about 100 years. But that’s not the point for global warming. What matters is how long high CO2 conditions (due to fossil fuel burning) will last, and that CO2 lifetime is many thousands of years.
  • PUT IT IN PERSPECTIVE: Reforestation offers some, but not a lot of leverage on the climate system compared with what we’re about to add to the atmosphere by burning fossil fuels, not to mention what more could be added if deforestation continues or if climate change degrades existing forests. Say humans managed to put back all of the carbon that we’ve released through deforestation and land use over the years… how much fossil fuel emissions would that ‘offset’? Such a colossal task would account for only a 40-70 ppm reduction in the 2100 CO2 concentration. Consider that conservative emission scenarios predict an increase in atmospheric CO2 of 170-600 ppm by 2100 (over 2000 levels), and that total global deforestation would increase CO2 levels by 130-290 ppm.
  • PUT IT IN GIGABYTES: “The land carbon stock can be described as a ‘buffer,'” the authors write, “by analogy with the term used in computer science to describe a device which temporarily stores data.” The image is excellent: we can fill the land carbon hard drive with a little extra carbon by planting trees, or release some to the atmosphere through deforestation, degradation, or burning. At the end of the day, though, a 500 gigabyte drive maxes out at 500 gigabytes of data. As for potential carbon storage in plants, scientists don’t know exactly what this maxing out point is. But they do know that there isn’t nearly enough storage on Earth to provide any real silver bullet place to put climate-warming excess CO2.
  • HARD DRIVES CRASH: Land carbon stocks are also not particularly reliable places to permanently store carbon. Fires and droughts can release massive amounts carbon back to the atmosphere within a season. Furthermore, climate change is shifting the landscapes for growth: some areas will increase biomass thanks to more rainfall and decreased evaporation. But other places will lose biomass due to increased drought and heat stress. A compilation of results from 13 climate-carbon cycle models shows that the net effect of climate change is likely to be destabilization and weakening of land carbon stocks, and a resultant boost in atmospheric CO2 concentrations. 
  •  EXTRA CREDIT: In the words of the authors, it must be recognized that forest conservation can avoid or reduce future carbon emissions, but does not in any meaningful sense offset continuing emissions from other sources. It must also be recognized that the capacity of the land buffer to remove and store CO2 from the atmosphere is strictly limited. However vigorous the measures taken to increase land carbon stocks, their total potential for carbon storage is minuscule compared with the stock of fossil fuels that could yet be burnt.

This is not to say that protecting forests is not vitally important for the health of the planet for many reasons, including climate change. But the language and metrics in carbon markets and policy forums should be both scientifically sound and self-consistent. Again, the authors:

As long as the right kinds of land management responses are implemented, the land carbon buffer can provide a valuable, cost-effective, short-term service in helping to reduce atmCO2, and slow the rate of anthropogenic climate change, bringing co-benefits for biodiversity and sustainable livelihoods, and giving us some time to develop a low carbon economy….

Consistent with our understanding of the lifetime of the airborne fraction of a pulse of CO2, the most effective form of climate change mitigation is to avoid carbon emissions from all sources.


Caroline Alden is a graduate student at the Institute of Arctic and Alpine Research in the Department of Geology at the University of Colorado at Boulder.

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Global warming discount expires soon

Caroline Alden, BURN Contributor

A recent BURN Journal post on the global carbon cycle and the fate of fossil fuel CO2 emissions – Carbon Cycle 101 – discussed how land plants and the world’s oceans slurp about half of fossil fuel CO2 emissions out of the atmosphere each year.

In other words, 50% of fossil fuel CO2 emissions are naturally sequestered by nature in land plants and ocean waters. The important corollary is that only half of the CO2 we emit each year remains in the atmosphere to trap heat and warm the globe.

Scientists have been waiting worriedly for these sinks to “saturate,” or quit taking so much extra CO2 out of the atmosphere. Models predict that land plants will soon become satisfied with the level of fertilization that extra atmospheric CO2 provides, and that ocean chemistry will soon lose its capacity to accommodate extra CO2.

A paper published last summer in Nature by researchers in Boulder, Colorado compared the growth rate of the concentration of CO2 in the atmosphere each year with the amount of CO2 put in the atmosphere by fossil fuel combustion each year since 1959.

What they found was that not only are land and ocean sinks still taking up excess CO2 from the atmosphere, but that the rate of uptake has grown steadily stronger for the last 5 decades!

sinks for caroline

Panel a shows the annual growth rate of CO2 in the atmosphere. Panel b shows emissions from fossil fuel combustion (in red) as well as land-use changes (gold). Panel c shows the difference between panels a and b, or the annual global net uptake of carbon by land and ocean sinks. The dark shaded areas represent 1-sigma uncertainties, and the light shaded areas represent 2-sigma uncertainties. (Source: Ballantyne and others, published in the journal Nature in August 2012)

This finding is both good news and bad news.

The good news is that, to date, climate change has probably been attenuated by strong natural sinks; if more of our emissions had remained in the atmosphere, the globe would have warmed more than it already has.

The bad news is that climate change is already happening, in spite of the 50% climate discount on emissions that the Earth’s natural sinks currently offer us.

That is troubling. What happens when natural sinks stop and that discount disappears?

Furthermore, these natural carbon sinks – the land sink in particular – are not permanent storage places for COand are vulnerable to extreme weather events and to climate change itself. Droughts and fires can release land carbon stores back to the atmosphere within a season.

When the land and ocean sinks saturate – and all signs say they very will soon – the impacts of each watt of electricity produced by a coal-fired power plant, of each mile driven by a gasoline-powered vehicle, and of each lawn mower lap around the back yard will be felt in full by greenhouse gas warming of the planet.

Caroline Alden is a graduate student at the Institute of Arctic and Alpine Research in the Department of Geology at the University of Colorado at Boulder.

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Bill McKibben’s lights-out plan for big oil & gas

Caroline Alden, BURN Contributor

Bill McKibben is a big name in the climate movement, and he’s got a game changing idea.

McKibben is the founder of, a grassroots organization aimed at stopping fossil fuel extraction (350 is the atmospheric concentration of CO2, in parts per million, above which leading scientists predict global warming may seriously threaten civilization).

 Since 2007, activists have been going big with their campaigns on behalf of the environment, from forming human chains around the White House, to promoting a global solar panel installation day (for the record, “PutSolarOnIt” predated “put a bird on it”).

Despite the aggressive work of 350 and other organizations, 230 billion more tons of CO2 have been dumped into the atmosphere over the last 6 years, putting us at  397 ppm today.

 McKibben recently teamed up with Naomi Klein to draft a new focus for 350: a campaign for divestment from the top 200 fossil fuel companies. So far, four colleges, one public university, one major city, and potentially one mega church have committed to freezing and ultimately withdrawing investments. The narrative driving this campaign is that investing in the fossil fuel industry promotes global warming.

 McKibben’s rhetoric – including a Rolling Stone piece he wrote last year – suggests he may be attempting to reframe global warming entirely, as a “good vs evil” fight against the fossil fuel industry.

 …[T]he planet does indeed have an enemy – one far more committed to action than governments or individuals. Given this hard math, we need to view the fossil-fuel industry in a new light. It has become a rogue industry, reckless like no other force on Earth. It is Public Enemy Number One to the survival of our planetary civilization. “Lots of companies do rotten things in the course of their business – pay terrible wages, make people work in sweatshops – and we pressure them to change those practices,” says veteran anti-corporate leader Naomi Klein, who is at work on a book about the climate crisis. “But these numbers make clear that with the fossil-fuel industry, wrecking the planet is their business model. It’s what they do.”

I got to hear the new McKibben pitch on his “Do The Math” tour in December. He painted a picture of a global society that wants electricity to come out of wall sockets, but doesn’t want to destroy the planet in the process. Standing in the way, to use McKibben’s rhetoric, are fossil fuel industry execs more interested in profit and far less concerned with the environment.

Also on tour were Ira Glass and Josh Fox (the banjo-wielding creator of Gasland), and an elaborate demonstration involving multiple cases of beer and Winona LaDuke drinking them: a witty metaphor for… wait… what was the point of that again? Largely, it seemed, to attract the college-aged demographic.

 But, back to McKibben. By his calculus, framing this global issue as an actionable fight against an antagonistic tyrant may mobilize people – especially young people, who will be most affected by climate change – to demand change from their universities, colleges, churches, and local governments.

 The question of whether the divestment campaign will succeed as a purely economic tool might be secondary to McKibben’s ability to rouse a new generation to take positions – and take action – in the climate debate.

In an interview with Gothamist last summer, McKibben frequently cited the economic success of divestment in ending South Africa’s system of Apartheid. That point is spelled out at – a base for McKibben’s investment freeze campaign.

There have been a handful of successful divestment campaigns in recent history, including Darfur, Tobacco and others, but the largest and most impactful one came to a head around the issue of South African Apartheid. By the mid-1980s, 155 campuses — including some of the most famous in the country — had divested from companies doing business in South Africa. 26 state governments, 22 counties, and 90 cities, including some of the nation’s biggest, took their money from multinationals that did business in the country. The South African divestment campaign helped break the back of the Apartheid government, and usher in an era of democracy and equality.

Economists point out that it wasn’t the direct economic instrument of divestment that ended Apartheid, but the combined social and economic pressures that mounted and prevailed, as the global community identified and rejected a moral wrong.

If the rabble gets roused, then we may find that McKibben is indeed onto something.

Caroline Alden is a graduate student at the Institute of Arctic and Alpine Research in the Department of Geology at the University of Colorado at Boulder.

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Why you can’t attend a rising seas conference in NY

Alex Chadwick, BURN Host

This week, in New York City, the Union of Concerned Scientists is convening a meeting of dozens of public officials from New York, New Jersey, Virginia, North Carolina and Florida to talk about one of the most serious issues these officials are facing: rising sea levels brought about by global warming, the product of greenhouse gases. Some of these officials dealt with Hurricane Sandy – the one that left parts of Manhattan without power for five days and battered the New Jersey coast. Others, especially in Florida, already see evidence of climate change – not from storms, but simply in the tides. The officials are meeting with one another for conversations, with a few scientists on hand to offer guidance.

They will be there – but the public will not. UCS, which describes itself as a coalition of citizens and scientists working to better public policy and corporate practices, has closed the meeting.

I learned of the event a month ago through one of the participants. I sent UCS a note asking to go, and dropped what I thought would be our best card with this group – we were just recognized by the American Association for the Advancement of Science for best radio science reporting. I though of this as an opportunity to meet and listen to the people who are going to be creating the policies and practices that will be of ever greater significance in this country, as more and more lives and enormous swathes of property are at increasing risk.

The response from UCS was that it would be ‘unwieldy’ to allow reporters to observe. And no one from the public, either.

A citizen who might think s/he would like to know more about rising sea levels? No, not this time, they said. Unwieldy.

I’ve known the Union of Concerned Scientists to be public-minded advocates of science-based solutions to all sorts of issues. They’re tough-minded and fearless in their frequent papers and testimony. But when I protested the exclusion of reporters and others from this meeting, a UCS press person said that climate has become so controversial that they worried about hecklers, or trouble-makers – people who would show up for theatrical opposition.

If UCS is going to close a meeting because some nut-job – or even a true skeptic, though many believers doubt there is such a thing – might show up and try to disrupt things, then we are in worse shape than I thought. These are public officials, at a meeting convened by a science organization that boasts of its citizen involvement. And they want to talk just among themselves because an outsider might be argumentative – even disruptive?

A spokeswoman told me a week ago that they’d think about opening the meeting. She’d tested the idea on one official already, and the response was that UCS would be changing ‘the rules’, and thus the official might not attend. Wonderful. If UCS and public officials are doing such a great job getting out the climate message, where is the public consensus about the urgency of doing something?

UCS and public officials have done such a great job getting out the climate message that there is noted consensus about the urgency of doing something. So, okay, maybe we should just leave them alone in a room, talking to each other. But when they close the doors, I hope there’s a flicker of shame somewhere inside there.

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Global warming’s day at the beach

Alex Chadwick, BURN Host

If energy-induced global warming truly is global, how come it’s not showing up in my neighborhood?

Actually, it is in my neighborhood. I live around Venice Beach in Los Angeles. A couple of months ago, I noticed new flood gates on the Venice canals. The agency putting them in called them tidal gates – but the canals have been here for more than 100 years, and they never had gates until fairly recently.

Here’s another sign: you can get in the water. Without wet suits. And it’s barely April.

I grew up near New England beaches. I’m used to water that’s too cold for most people. I usually start swimming here in late April or May. There’s a big difference in water that’s 58º or 60º. Late March/early April is a little too cold.

Except now, it’s not. It’s tolerable, at least wading out knee-deep. And I saw little kids getting in in the last week. I would guess the ocean is about a month ahead of itself in terms of water temperature. It should be 57º right now.

But I checked with two lifeguards. They have boats out everyday, and they sample water temperature daily just off from where I go in. Their readings these days are running at least 60º. Yes, they said. Warmer than normal.

It’s been overcast here. The subject of another posting to come. But if we get a warm day, I’m going in for further data collection. And a good wave or two.

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The Connections Between Greenhouse Gas Emissions and Energy

Most of the greenhouse gas emitted through human activity comes from the production of energy.

This group of gases is thought to contribute to global climate change, long-term shifts in weather partly due to the tendency of these gases to trap energy, in the form of electromagnetic radiation from the sun, that would otherwise have been reflected back out into space. For more about the relationship between the climate and greenhouse gases, go here.

Noteworthy greenhouse gases  are carbon dioxide, nitrous oxide, methane, hydrofluorocarbons (HFCs), perfluorocarbons (PFCs), and sulfur hexafluoride (SF6).

Energy creation results in such a high level of greenhouse gas because the vast majority of energy we use — regardless of what country we live in — comes from burning something, usually coal, petroleum fuels, natural gas, or wood. More than 80 percent of U.S. energy in 2009 came from the combustion of fossil fuels.  Go here for more information about how combustion works.


Plants and some types of microscopic organisms take carbon dioxide gas out of the air and turn it back into solid, carbon-based materials like plant fibers, using the energy of sunlight. The basis for all of our fuels, even the fossil fuels, comes from exploiting the fact that organisms convert  light energy into chemical energy, a potential energy source inside the plant or organism’s cells, whether the energy was converted in the last few decades (wood, biodiesel, ethanol) or millions of years ago (fossil fuels). Today, however, organisms don’t have the capacity to capture anywhere near as much of the greenhouse gas carbon dioxide as we produce, partly because we are burning fuels produced over millions of years.


The United States produces more greenhouse gas each year per person than most other countries. However, even if we stopped producing any carbon dioxide at all, which is unlikely, the world would still keep producing 80 percent of its former output. Other regions produce just as much as we do, particularly Europe and China.

Furthermore, instead of holding steady at a particular emission rate, every year we use more energy and therefore emit more greenhouse gas. For a graph of atmospheric carbon dioxide by year, go here.

When we talk about energy-related emissions, we don’t only mean electricity. Energy involves burning oil and natural gas for heating, burning gasoline, diesel, and jet fuels for transportation. Transportation accounted for just over a third of all carbon dioxide emissions in 2009, electricity was almost 40 percent and residential, commercial, and industrial production, excluding electricity, made up roughly 26 percent.

Some greenhouse gases are thought to alter the climate more than others. Nitrous oxide is a much smaller percent of the gas mix than carbon dioxide, but for its weight it has a much stronger heat-trapping capability.

For more information go to The connection between greenhouse gases, climate change, and global warming.

Each year what proportion of emissions are man-made are carefully tracked by several agencies nationally and internationally, including the National Oceanic and Atmospheric Administration, the National Weather Service, and the National Aeronautics and Space Administration.


U.S. Geological Survey
U.S. Energy Information Administration

U.S. Environmental Protection Agency
U.S. National Oceanic and Atmospheric Administration
CIA World Fact Book
World Energy Council
National Renewable Energy Laboratory
Emissions of Greenhouse Gases in the United States 2009: Independent Statistics & Analysis. U.S. Energy Information Administration, Department of Energy. March 2011.

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The Connection Between Greenhouse Gases, Climate Change & Global Warming



Climate change is the shift in long-term, global weather patterns due to human action; it’s not exclusive to warming or cooling.

Climate change includes any change resulting from different factors, like deforestation or an increase in greenhouse gases. Global warming is one type of climate change, and it refers to the increasing temperature of the surface of Earth. According to NASA, the term global warming gained popular use after geochemist Wallace Broecker published a 1975 paper titled Climatic Change: Are We on the Brink of a Pronounced Global Warming?

Since 1880, the average surface temperature of the Earth has increased by roughly 0.9 degrees Fahrenheit, but the rate it’s increasing is faster than that, depending on which region you live in. If you’re closer to the equator, temperatures are increasing more slowly. The fastest increase in temperatures in the United States is in Alaska, where average temperatures have been increases by more than 3 degrees Fahrenheit per century. For a graph of average global temperatures by year, see the NASA website here.



Greenhouse gases are those thought to contribute to the greenhouse effect, an overall warming of the Earth as atmospheric gases trap electromagnetic radiation from the sun that would otherwise have been reflected back out into space.

Noteworthy greenhouse gases are methane, nitrous oxide, carbon dioxide, hydrofluorocarbons (HFCs), perfluorocarbons (PFCs), and sulfur hexafluoride (SF6). These gases are thought to affect the climate directly and indirectly, even though they constitute only a small fraction of the blanket of gases that make up the atmosphere.

Currently, the composition of the atmosphere is mostly nitrogen and oxygen, with just 0.033 percent carbon dioxide and all other gases accounting for even less.



According to 2010 models cited by NASA, 20 percent of the greenhouse effect is attributed directly to carbon dioxide and 5 percent to all other greenhouse gases. The remaining 75 percent of the greenhouse effect is thought to be due to water vapor and clouds, which are naturally-occurring. However, even though carbon dioxide and the other greenhouse gases are such a small percentage of the total gas in the atmosphere, they affect when, where and how clouds form, so greenhouse gases have some relevance when it comes to 100 percent of the greenhouse effect. Carbon dioxide is thought to modulate the overall climate, like a atmospheric thermostat.

Some greenhouse gases are produced in natural processes, like forest fires, animal manure and respiration, or volcanic eruptions. However, the majority of new greenhouse gases are produced from industrial processes and energy production.

The four largest human sources of U.S. greenhouse gases in 2009 were energy, non-fuel use of fossil fuels, natural gas production, and cement manufacture, in descending order. Non-fuel, greenhouse gas-producing applications of fuels include industrial production like asphalt, lubricants, waxes and other . Emissions related to cement manufacture happen when limestone (calcium carbonate) is reacted with silica to make clinker, the lumps ground to make cement. ( Emissions of Greenhouse Gases in the United States 2009: Independent Statistics & Analysis.)

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Petroleum, Natural Gas, and Coal

The world depends on fossil fuels for its energy, and the United States is no exception. The vast majority of U.S. energy — more than 80 percent in 2009 — comes from burning fossil fuels. (more…)

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“Cap-and-Trade” and Carbon Tax Proposals


Phosphorus factory smokestack in Muscle Shoals, Alabama.Source: U.S. Library of Congress.

The idea of “cap-and-trade” first emerged in the United States in the 1960s as a device to get the free economy to control pollution, folding in the cost of pollution instead of telling industry how to stop polluting. Often called emission trading, in a working cap-and-trade system, industries that release undesirable compounds into the air, water, or soil have limits of how much they can emit based upon pollution permits. Depending on the system, polluters either are given or have to buy their permits. The government establishes how much total pollution that the permits will grant, an umbrella cap on the economy. If an industry participant wants to release more than the permit allows, they buy the right from another industry player, if available, or perhaps face penalties, depending on the details.

Cap-and-trade can be used to regulate any pollutant, not only carbon dioxide or other greenhouse gases. The U.S. Environmental Protection Agency has three cap-and-trade programs, none of which apply to greenhouse gases. They aim to combat acid rain by reducing sulfur dioxide and nitrous oxide compounds, mostly an issue with coal power.

There is no U.S. cap-and-trade for carbon dioxide, though proposals have been raised regularly, and the U.S. House of Representatives passed an emissions trading program  in an energy bill in 2009, but the bill hasn’t been approved by the U.S. Senate, as of June 2011.

Australia has been considering a cap-and-trade program for carbon dioxide, but that too hasn’t been implemented as of June 2011. The European Union has had a carbon emissions trading program since 2005.

For more about greenhouse gases, climate change, and their relationship to energy go here.



In the United States, the Acid Rain Program‘s cap-and-trade system has successfully reduced pollution and cost industry far less than expected, at $3 billion per year instead of the feared $25 billion per year, according to a study [that I haven’t found yet] in the Journal of Environmental Management. Savings from cleaner air and water and avoided death and illness are estimated in the range of $100 billion per year, according to the EPA.

However, acid rain chemicals are easier to tame than carbon dioxide. The goal for the subjects of U.S. regulations today – nitrous oxide and sulfur dioxide – is as little as possible. Everyone agrees that these pollutants are bad for the environment and people, and there was a commercially-available solution for nitrous oxides and sulfur dioxide emissions when the cap-and-trade system began in 1990: scrubbers on the smokestacks. Even though the U.S. Congress could have ordered industry to buy the scrubbers, it was easier to pass cap-and-trade politically, and only a certain sector of energy production emits a significant volume of these chemicals. Today, there isn’t consensus about the effects of carbon dioxide gas, which isn’t toxic to humans. There isn’t consensus about how much carbon emissions is acceptable, and there is no viable carbon capture technology. And more than 80 percent (by volume) of energy production methods still produce carbon dioxide, whether that’s from biofuels or coal.

A dynamic map of U.S. carbon dioxide emissions.



In 2005, the European Union passed its own cap-and-trade program to limit carbon dioxide emissions, applied to more than 12,000 factories and power plants in 29 countries. The program includes some limits to nitrous oxide, and airlines will be obliged to participate by 2012. The carbon “cap” on total emissions decreases 1.74% per year.

Some regulators have already claimed success, as the carbon dioxide emissions were reduced in 2009; they increased again a little in 2010. However, the EU admits it gave out too many permits and that future permits will need to be tighter. Furthermore, the recession has acted as a major factor in lowered emissions, and European industries haven’t needed to make any technological changes because of lower demand.

“Power companies were given free carbon permits, but they raised electricity fees anyway — as if they had paid the market price for their permits — and pocketed the markup. Many companies were allocated too many allowances, often the result of powerful industries lobbying the governments that give the permits,”  Arthur Max of The Associated Press wrote from Belgium in a 2011 story about the Europeans’ progress.

If the EU’s carbon dioxide emissions will be reduced in coming years has yet to be determined since the real effects of the cap haven’t truly set in.

For more information about the EU’s program see the EU FAQ here.



Ten states in the Northeast have applied a cap-and-trade system to carbon dioxide as of 2008, in the Regional Greenhouse Gas Initiative, with the goal of reducing greenhouse gas 10 percent by 2018.

California is planning its own cap-and-trade program, slated to begin December 2011. Ten Canadian provinces and Western U.S. states and have joined California in the Western Climate Initiative, with the hope that there will be a regional cap-and-trade program too.



Carbon taxes are another way to integrate emissions reductions into the economy. The taxes makes a beeline for fossil fuels, which are far and away the main source of carbon dioxide emissions, whether they’re burned in vehicles or for electricity. A carbon tax on fuels raises the overall price, in theory reducing our ability to buy too much.  That means that industries or individuals can still produce as much carbon dioxide as they please, but they’ll have to pay for it.

Some economists prefer carbon taxes, as they are simpler to enforce, particularly internationally, and there’s likely to be less dramatic shifts in pricing. Others prefer cap-and-trade because there’s a finite ceiling to emissions. Many other arguments support either measure.

From a carbon tax perspective, diesel fuel and natural gas have an advantage over gasoline and coal, respectively, since they produce less carbon dioxide for the energy they generate. Of course, solar and wind produce none, but biofuels are more complex. Many carbon taxes in effect exclude biofuels like wood waste, even though they produce carbon dioxide.

Several European countries and individual U.S. states have various carbon taxes, applied from anywhere in the range of cents to close to $100 per ton, about as much carbon dioxide as would be emitted from using roughly 103 gallons of gasoline. These taxes are still low enough that they aren’t halting emissions. (For more details about calculating carbon emissions, see The Intergovernmental Panel on Climate Change.)

In the United States, carbon taxes in individual states are currently insignificant compared to other market pressures on the price of fuels, particularly in the case of petroleum.


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