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New Report Outlines ‘Pathways’ to Cut CO2 Emissions

Carbon emissions have been rising since the start of the Industrial Revolution. But they’ll have to be curbed soon, and sharply, to keep the globe from warming above “safe” levels. A new report lays out avenues to get there and shows that while it’s possible, it’ll take a little human ingenuity and a lot of global cooperation.

A coal fired power plant in Wyoming. Sites like this would have to become scarce for the world meet a warming threshold of 2°C.
Credit: Greg Goebel/flickr

A draft of the report, called the “Deep Decarbonization Pathways Project,” was delivered to the United Nations on Tuesday. It was developed by researchers working in the 15 countries that have the highest CO2 emissions and shows how each of those countries could rapidly reduce its emissions by 2050.

International negotiators looking to strike a climate deal have agreed to try to limit warming to 2°C. And scientists have outlined how much more carbon we can emit to likely keep warming below 2°C, calling it a carbon budget. It’s just like a household budget except going over it could increase the likelihood of major sea level rise, an increase in the frequency and intensity of extreme heat events, and a rapid decline in Arctic sea ice.

“We’ve just about exhausted the carbon budget. The world is unfortunately engaged in a massive gamble,” said Jeff Sachs, director of Columbia University’s Earth Institute and one of the leaders of the new report.

According to the new report, annual CO2 emissions would have to be slashed to 11 gigatons from our current level of about 36 gigatons by 2050. Put another way, each of the world’s 7 billion people is responsible for 5.2 tons of CO2 emissions each year (though much of that comes from developed countries). By 2050, there will be another 2.5 billion people, and annual per capita CO2 emissions will likely have to be reduced to 1.6 tons to keep warming within the 2°C range.

If that sounds daunting, it is. The world’s governments have failed to take meaningful action to get to those levels, in part because it means leaving a lot of fossil fuels, and the riches that go with them, in the ground. But it doesn’t mean it can’t be achieved.

“The basic conclusion of this report is the 2°C limit is achievable, but just barely. We’ve gone on so far with rising CO2 emissions, and greenhouse gas emissions more generally, that we’re just about out of time to meet this crucial limit,” Sachs said.

A graphic showing how much energy-related CO2 emissions would have to fall by 2050 to stay within "safe" levels.
Credit: Deep Decarbonization Pathways Project

Rapidly cutting emissions will require efforts from individual countries and the global community and the use of both proven and emerging technologies. The report outlines rough pathways for 12 of the 15 countries to reduce their CO2 emissions based on their economic and population profile, with the other 3 coming in the next year. Generally, combined emissions from energy generation would have to peak around 2020 and decline thereafter.

While each plan is different, Sachs said energy systems across the globe do have some “shared DNA” and will therefore see some shared, and somewhat obvious, solutions.

Those shared solutions include improving energy efficiency and switching from carbon-intensive energy sources like coal to renewables by 2050. But for developing countries like China, coal use can continue to rise for the next few decades before declining and being replaced by renewables like wind and solar. But in countries like the U.S., coal use would have to rapidly decline starting this decade. 

Current solar and wind technologies will play a role in meeting the low carbon pathways, but the report also assumes that more advanced versions of these will come online in the future. In particular, renewable energy systems that are able to efficiently store wind and solar power generated at off-peak hours and then feed it into the electric grid when it’s needed most will play an important role. These technologies exist but are currently costly and only available at select locations throughout the globe.

An interactive graphic showing a global pathway to reducing carbon emissions to meet the 3.6°C threshold. Credit: International Energy Agency

Similarly, the report proposes using carbon capture and sequestration technology at coal and natural gas plants to help reduce CO2 emissions by injecting carbon deep underground. There are currently only a handful of sites around the world that do this and questions remain about the best and safest way to sequester carbon.

Sachs said that to see if these and other technologies can be scaled to help meaningfully curb CO2 emissions, private and public investments are needed around the world. He cited the space race, the Manhattan project, and more recently, the human genome project as examples of projects where large investments produced relatively quick results. That’s something that’s been missing in the energy sector.

“The remarkable fact is we have not invested in an issue that is of existential importance for the planet,” he said.

There are still many unanswered questions about whether the world’s governments will be able to gather the political will to push these kinds of projects forward. Sachs said the goal of the current project was to show the feasibility of staying within a 2°C limit and that scientists working on the project specifically avoided discussing contentious issues of development, historical emissions and equality that have slowed international climate negotiations in recent years.

The report is timed to be available to world leaders who will attend a climate summit at the UN in September and a major round of climate negotiations in 2015. It could be guidance to show governments what a 2°C world would look like and why it matters, but not exactly how to get there.

“What would be an amazing breakthrough is to get governments to look at the carbon budget and to understand how tight it is,” Sachs said.

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By john harkness
on July 8th, 2014

Good to see that someone is putting some effort to think this through, but there are a number of major (if predictable) flaws:

First the article claims: “each of the world’s 7 billion people is responsible for 5.2 tons of CO2 emissions each year (though much of that comes from developed countries)”

The parenthetical piece is quite the understatement. The richest 20% (though not all of those are necessarily in ‘developed countries’) are responsible for about 80% of emissions; the poorest 60% for only about 6%.

So the statement should say: “The vast majority of people in the world are only responsible for less than .1 tons of CO2 each (most, much less than that). Meanwhile, the richest 20% emit over 20 tons each (many much, much more).”

That puts the proper perspective on where the biggest changes have to come. Add to that the the richest are mostly using these emissions for frivolous activities—driving obscenely big cars to obscenely big houses, eating obscenely large amounts of obscenely grown meat and dairy, and flying obscene amounts on, by any historic measure, obscenely extravagant vacations…

Second, setting goals for 2050 is essentially meaningless. We have to set goals for how much is going to be emitted over the coming year and the coming decade. The bigger the reductions there, the less draconian they have to be later. The more we stall and think about this as something we mostly have to do in a few decades, the more impossible we make it to actually do so, whenever we may actually decide to get around to it.

Finally (for now), many of your ‘wedges’ are pure fantasy. Carbon Capture and Sequestration has been shown nowhere to be a viable tool for doing much of anything, and is certainly no where near ready to scale up to economically extract even a fraction of a percentage of the carbon we are spewing into the air every day. Nuclear also cannot be scaled up in anything like the requisite time, even if it did not have enormous safety and economic hurdles of its own. “Fossil Fuel Switching” presumably means moving from coal to natural gas, but NG is coming more and more from extremely dirty and leaky ‘fracking’ operations that may be contributing a higher CO2 equivalent than conventional coal.

So since those are all essentially fantasies, that leaves all the heavy lifting to the last two—energy efficiency and renewables. But they just can’t make up for all those other wedges in anything like the time we have, and probably never could.

We need to radically and immediately reduce the amount of pretty much everything we’re doing—but especially driving, flying, eating meat and dairy, buying crap, over-heating and -cooling our buildings…

These curtailments we can start right now. And that’s when the world needs radical reductions in emissions—NOW!

But don’t take _my_ word for it. See, among many others, Kevin Anderson’s (of the Tyndall Center) excellent video:

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By Dave (Basking Ridge, NJ 07920)
on July 8th, 2014

Brian: In your definition, you are right about the 2C “limit” but somewhat light in your description.  The actual DNA of the 2C limit contains words like dangerous and interference in partial reference to predicted irreversible ecological impacts and their repercussions on society.  Regardless of that history, the 2 C ‘limit’ overall currently describes something very much more profound than what you briefly describe. In essence, yes, climate change will get that much worse at 2 C compared with now. But, more than that, there also comes a point, which is officially thought to be in the vicinity of 2 C but is possibly somewhat less than that, where the risk that we cannot turn some key nasty consequences around becomes a certainty than we can’t. This has been one of the central themes of what prominent climatologists have been virtually banging their heads against the wall trying to convey to the public and policy makers ever since Hansen first testified to Congress.

These days, the official and technical definition of danger in this climate context has evolved into a dry discussion of probabilities resulting in a blurring of that particular discrete 2 C global mean surface temperature from a black and white fine line of exactly 2.0 degrees C increase, into more of a smudged temperature increase region. That is a technically better description but it is also lengthy and complicated. So I still think that in everyday terms, the discussed limit is still useful as long as it is associated with the core of what the limit, and its intent, really stands for and that this is not watered down or ignored. It means that going beyond the limit is SERIOUSLY dangerous.

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By Patrick Mazza
on July 8th, 2014

Calling solar, wind and storage too costly when cost curves are pluging seems out of key.  It is time to set aside standard assumptions and invest the money to move 100% renewables asap.  Several global initiatives furthering this goal are linked from this piece.

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By Steve Elfelt (Altoona PA 16601)
on July 9th, 2014

Instead of “coal, oil, gas and the riches that go with them”

say “coal, oil, gas and the short-term profits for a few that go with them”.

It’s absurd to talk about “riches” based on equations that ignore the global climate cost that everyone in each of several generations will have to pay.

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By john harkness
on July 9th, 2014

Dave said: “there also comes a point, which is officially thought to be in the vicinity of 2 C but is possibly somewhat less than that, where the risk that we cannot turn some key nasty consequences around becomes a certainty than we can’t.”

Well, put. And we have already reached that point with regard to West Antarctic Ice Sheet instability: no matter what we do now, the whole thing is going to go, adding from this one course alone 10-13 feet of sea level rise, drowning the homes of hundreds of millions in coastal areas and cities around the world.

No one can say for sure when this will happen. Projections of it not happening for at least 200 years assume no increase from the current rate of melt and movement until then, which is clearly unrealistic.

Back to the report. The full report poses an equation for CO2 emissions:

CO2 emissions = Population x (GDP/Population) x (Energy/GDP) x (CO2/Energy)

The report focuses on reducing the second two elements to the right of the equals sign (essentially energy efficiency/renewables and energy intensity of the economy), and assumes growth in the first two. In fact, being economists (many of them, at least), they see growth of the second element (GDP/Population, in other words net economic growth), as a central goal.

Yet it is obvious that this is the one part of the equation that could in theory be lowered immediately and drastically. If we’re talking about the future viability of the planet, for X’s sake, why should any of the major elements be off the table for reduction. This is blind ideology over-running basic sanity and survival.

It is the least ‘real.’ And high GDP/Population ratios have been shown to not correspond to human happiness beyond a certain minimum, anyway. The blindness to this blindingly obvious fact (among other problems pointed out above) makes the rest of the study pretty useless, as far as I can see, even though there are a few good insights and some good science (not the economics, though).

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By john harkness
on July 9th, 2014

For more along the lines of what I just posted, please see this centrally important lecture by Kevin Anderson of the Tyndall Research Center:

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