Committed Emissions

This blog reported before that human activity from coal-fired power plants to car tailpipes is responsible for nearly 30 billion metric tons of carbon dioxide wafting into the atmosphere yearly, and roughly 15 billion metric tons remains in the atmosphere for a century or more.

Stanford’s Ken Caldeira is a climate modeller at the Carnegie Institution for Science’s Department of Global Ecology and participated in the study. He cautioned that “the study does not take into account all the enabling infrastructure—such as highways, gas stations and refineries—that contribute inertia that holds back significant changes to lower-emitting alternatives.”

Around the globe, we are adding more fossil-fuel infrastructure, so, the bad news, carbon trackers, is going to get a lot worse, says SciAmz David Biello. A team of scientists analyzed the existing fossil-fuel infrastructure to decide how much GHGs (Green House Gas emissions) to which we have committed. “The answer: an average of 496 billion metric tons more of carbon dioxide added to the atmosphere between now and 2060.”

That assumes life spans of roughly 40 years for a coal-fired power plant and 17 years for a typical car—potentially major under- and overestimates, respectively, given that some coal-fired power plants still in use in the U.S. first fired up in the 1950s. Plugging that roughly 500 gigatonne number into a computer-generated climate model predicted CO2 levels would then peak at less than 430 ppm with an attendant warming of 1.3 degrees C above preindustrial average temperature. That’s just 50 ppm higher than present levels and 150 ppm higher than preindustrial atmospheric concentrations.

And since 2000 the world has added 416 gigawatts of coal-fired power plants, 449 gigawatts of natural gas–fired power plants and even 47.5 gigawatts of oil-fired power plants, according to the study’s figures. China alone is already responsible for more than a third of the global "committed emissions," including adding 2,000 cars a week to the streets of Beijing as well as 322 gigawatts of coal-fired power plants built since 2000.

Countries that burn huge amounts of coal for power and the countries that supply them “over the next several decades will play a huge role in determining the ultimate degree of global climate change.” Cue the timpanist.

Coal-burning poses other threats as well, including the toxic coal ash that can spill from the impoundments where it is kept; other polluting emissions that cause acid rain and smog; and the soot that causes and estimated 13,200 extra deaths and nearly 218,000 asthma attacks per year, according to a report from the Clean Air Task Force, an environmental group. "Unfortunately, persistently elevated levels of fine particle pollution are common across wide swaths of the country," reveals the 2010 report, released September 9. "Most of these pollutants originate from combustion sources such as power plants, diesel trucks, buses and cars."

Of course, those are the same culprits contributing the bulk of greenhouse gas emissions. Yet "programs to scale up ‘carbon neutral’ energy are moving slowly at best," notes physicist Martin Hoffert of New York University in a perspective on the research also published in Science on September 10. "The difficulties posed by generating even [one terawatt] of carbon-neutral power led the late Nobel laureate Richard Smalley and colleagues to call it the ‘terawatt challenge’."

That is because all carbon-free sources of energy combined provide a little more than two of the 15 terawatts that power modern society—the bulk of that from nuclear and hydroelectric power plants. At least 10 terawatts each from nuclear; coal with carbon capture and storage; and renewables, such as solar and wind, would be required by mid-century to eliminate CO2 emissions from energy use. As Caldeira and his colleagues wrote: "Satisfying growing demand for energy without producing CO2 emissions will require truly extraordinary development and deployment of carbon-free sources of energy, perhaps 30 [terawatts] by 2050."

Other AG post on the topic of our increasing carbon footprint

This entry was written by jcwinnie, posted on 2010-9-9 at 7:55 pm, filed under atmosphere, climate, energy, forecast, model, tracking, world and tagged coal, emissions, petoleum. Bookmark the permalink. Follow any comments here with the RSS feed for this post. Both comments and trackbacks are currently closed.

2 Comments

jcwinnie

Posted 2010-10-10 at 6:50 pm | Permalink

Fire up those coal plants, we are going to need that dirty energy for our air conditioning and further climate denial efforts. Maybe bring back the singing coal lumps backed by the Stanford Chamber Choir.

The LA Times reports that Los Angeles hit an all-time record 113 degrees, breaking the record for electricity demand.
jcwinnie

Posted 2010-10-15 at 1:58 pm | Permalink

Everybody wants into the act, Professor Joe. Bryan Walsh patiently explains to his Time blog readers why carbon dioxide (CO2) is the main agent behind changes in the Earth’s climate—now and in the geologic past.

First a bit of background: one argument you might hear from skeptics of manmade climate change is that CO2 is much less important as an atmospheric warming agent than water vapor. Here’s how historical climatologist and skeptic Tim Ball summarizes the case for water vapor:

Water vapour is the most important greenhouse gas. If you get a fall evening and the sky is clear, heat will escape, the temperature will drop. If there’s cloud cover, the heat is trapped by water vapour and the temperature stays warm. If you go to In Salah in southern Algeria, they recorded at noon 52°C. By midnight, it’s -3.6°C. It’s caused because there is very little water vapour in the atmosphere and is a demonstration of water vapour as the most important greenhouse gas.

Makes sense—and in a sense, he’s right. Water vapor is the most important agent behind the greenhouse effect—it has more than twice the warming effect that CO2 does, and water vapor and clouds account for about 75% of the Earth’s greenhouse effect, with CO2 accounting for 20% and the other greenhouse gases and aerosol particulates accounting for the remaining 5%. But despite that, it is changes in CO2 concentrations in the atmosphere that is responsible for changing the climate—in other words, as the research team led by the physicist Andrew Lacis makes clear in the Science paper, CO2 is the principal “control knob” governing the Earth’s temperature.

Lacis and his colleagues note that water vapor, while much more common in the atmosphere than CO2, has a short atmospheric lifespan, eventually condensing and falling as precipitation as it responds to changes in temperature and air pressure. CO2, however, is a well-mixed gas that just builds up in the atmosphere over time, which is part of the reason why carbon dioxide emitted today can have a warming effect that lingers for hundreds of years. The amount of water vapor in the atmosphere is a function of temperature—the warmer it gets, the more water will evaporate and the more water the atmosphere can hold. And water vapor does have a warming effect, and it can act as a positive feedback—the warmer it gets, the more water vapor there is in the atmosphere, which makes it warmer, and so on.

But as the Science authors point out, it’s CO2 that provides the stable temperature structure for the climate, the skeleton on which climate is built. Here’s how they know: Lacis and his colleagues created a simple climate experiment where they removed all CO2, aerosols and other greenhouse gases from the model atmosphere, but left in the water vapor. They let the climate model run forward in time, and the results were startling. In just one year without any carbon, global annual mean temperature fell by 4.6 C. After 50 years, the global average temperature had fallen to -21 C, 34.8 C less than it is today. As the average global temperature fell, so did the water vapor in the atmosphere, while global sea ice cover increased from 4.6% to 46.7%, further increasing the planetary albedo effect and freezing the planet further. Without carbon and other greenhouse gases, we’d be living on Planet Hoth.

As the Science authors point out, there’s also ample evidence in our own geologic history that changes in CO2 levels in atmosphere—chiefly due to volcanic eruptions—have been a main driver in changes in Earth’s climate. Water vapor levels may amplify the effect of CO2, but it’s CO2 that is the main control knob—and as Lacis and his colleagues write, we’re turning that knob up to 11 thanks to rising manmade carbon emissions:

The anthropogenic radiative forcings that fuel the growing terrestrial greenhouse effect continue unabated. The continuing high rate of atmospheric CO2 increase is particularly worrisome, because the present CO2 level of 390 ppm is far in excess of the 280 ppm that is more typical for the interglacial maximum, and still the atmospheric CO2 control knob is now being turned faster than at any time in the geological record (20). The concern is that we are well past even the 300- to 350-ppm target level for atmospheric CO2, beyond which dangerous anthropogenic interference in the climate system would exceed the 25% risk tolerance for impending degradation of land and ocean ecosystems, sea-level rise, and inevitable disruption of socioeconomic and food producing infrastructure (21, 22). Furthermore, the atmospheric residence time of CO2 is exceedingly long, being measured in thousands of years (23). This makes the reduction and control of atmospheric CO2 a serious and pressing issue, worthy of real-time attention.

It’s important to note that while CO2 may be climate’s control knob, the metaphor only goes so far. CO2 isn’t the only knob on the climate controls (alterations in land use and deforestation can change the climate as well), and our understanding of exactly how different levels of atmospheric CO2 concentrations will change the climate in the future is still developing. But CO2 is the main show.

8 Trackbacks

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