Carbon dioxide (CO2) is a chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom. It is a gas at standard temperature and pressure and exists in Earth's atmosphere in this state. CO2 is a trace gas comprising 0.039% of the atmosphere.
As of January 2012, carbon dioxide in the Earth's atmosphere is at a concentration of 391 parts per million (ppm) by volume. Atmospheric concentrations of carbon dioxide fluctuate slightly with the change of the seasons, driven primarily by seasonal plant growth in the Northern Hemisphere. Concentrations of carbon dioxide fall during the northern spring and summer as plants consume the gas, and rise during the northern autumn and winter as plants go dormant, die and decay. Taking all this into account, the concentration of CO2 grew by about 2 ppm in 2009. You can watch the amount of CO2 in the atmosphere rise here.
Carbon dioxide is a greenhouse gas as it transmits visible light but absorbs strongly in the infrared and near-infrared. This process by which radiative energy leaving a planetary surface is absorbed by some atmospheric gases is called the greenhouse effect. Since the beginning of the Industrial revolution, the burning of fossil fuels has substantially increased the levels of carbon dioxide in the atmosphere, which the United Nations' Intergovernmental Panel on Climate Change has correlated to warming average temperatures.
Carbon dioxide is used by plants during photosynthesis to make sugars, and is emitted during respiration by plants, animals, fungi and microorganisms that depend either directly or indirectly on plants for food. Amounts of carbon dioxide are emitted from volcanoes and other geothermal processes such as hot springs and geysers and by the dissolution of carbonates in crustal rocks. Carbon dioxide is also generated as a by-product of the combustion of fossil fuels or the burning of vegetable matter like biofuels, among other chemical processes.
CO2, unlike other greenhouse gases, does not break down in the atmosphere. Its natural removal depends upon the absorption and eventual sequestration in the oceans or land as part of the earth's carbon cycle. Approximately 65% of emitted CO2 is removed from the atmosphere within a hundred years through the oceans and biosphere. The remainder stays until drawn down through much slower processes, with an additional 15-30% removed over the next 5,000 years, and the remaining ~10% after 400,000 to a million years.
Power plants largest source of GHGs in US
U.S. power plants released 72 percent of the greenhouse gases reported to the EPA for 2010, according to federal data that was the first catalog of global warming pollution by facility. The data include more than 6,700 of the largest industrial sources of greenhouse gases, or about 80 percent of total U.S. emissions.
While comprehensive, the EPA registry is not complete: it does not include carbon dioxide and other greenhouse pollution from motor vehicles or agribusiness. According to Think Progress, the exclusion of industrial agriculture pollution is due to a loophole inserted by the House of Representatives. However, the EPA will require emissions reporting from additional industry groups for 2011 data, including petroleum and natural gas systems, industrial wastewater treatment, electronic manufacturing, and industrial waste landfills.
2010 projected to be highest annual CO2 emissions since tracking began
Authored by a large team of scientists from the United States, the United Kingdom, Australia, and European countries, a Global Carbon Project report now predicts CO2 emissions from burning coal, oil and gas will reach their highest in history in 2010: “A new analysis of 2009 global greenhouse gas emissions shows increased coal use has boosted global greenhouse gas emissions to the second highest level on record.” The Independent explains the trend: “In the 1990s, annual average emissions of carbon dioxide rose by 1 per cent, and in the past decade they increased at an average annual rate of 2.5 per cent. This year they are on target to accelerate even faster.”
Scientists have revised their figures on global CO2 emissions, showing that levels fell by just 1.3 per cent in 2009 – less than half of what was expected. The study projects that if economic growth proceeds as expected, global fossil fuel emissions will increase by more than three percent in 2010, approaching the high emissions growth rates observed through 2000 to 2008.
In 2009 China lead the world in CO2 emissions. About 80 percent of China’s power plants run on coal. Due to “increased coal use in China and India” there was “a smaller-than-expected dip” in emissions. Because of the worldwide recession with a decline in production, researchers expected more of a decline in emissions; but, the recession has effected these countries’ economies less. China says foreign consumption of Chinese products is responsible for 30% of current GHG emissions.
In 2006, coal ranked second to petroleum in total energy use, accounting for 27.4 percent of world primary energy production. World coal production totaled 6.8 billion short tons, or 128 quadrillion Btu in 2006, and increased (XLS) by 32.7 percent from the 1996 level of 5.1 billion short tons.
2010 highest annual CO2 levels ever, mainly due to coal
In June 2011, it was reported by the U.S. International Energy Agency that global emissions of energy-related carbon dioxide in 2010 were the highest ever measured at 30.6 gigatonnes - a 5 percent jump over the previous record year of 2008. The majority of the energy-related CO2 emissions in 2010 -- 44 percent -- came from from coal, while 36 percent arose from from oil and 20 percent from natural gas, according to the IEA.
Carbon dioxide emissions in the United States rose 3.9 percent in 2010, which the Energy Information Administration attributed to increased economic activity. The country’s GDP grew 3 percent since the 2009 recession, pushing up CO2 emissions, particularly through a 6 percent increase in coal energy consumption. The 4 percent increase was the country’s largest increase in energy-related CO2 emissions since 1988.
In April 2007, the Supreme Court of the United States ruled in the case Massachusetts v. Environmental Protection Agency, 549 U.S. 497 (2007) that the EPA violated the Clean Air act by not regulating greenhouse gas emissions, the major contributer to climate change.
In the ruling, the Court said that the EPA Administrator must determine whether or not there was sufficient scientific evidence to support the statement "that emissions of greenhouse gases from new motor vehicles cause or contribute to air pollution which may reasonably be anticipated to endanger public health or welfare... The Supreme Court decision resulted from a petition for rulemaking under section 202(a) filed by more than a dozen environmental, renewable energy, and other organizations." (Section 202(a) of the Clean Air Act is titled "Emission standards for new motor vehicles or new motor vehicle engines.")
In May 2007, President George W. Bush issued an executive order, the Clear Skies Initiative, proposing regulations on greenhouse gases weaker than those proposed by the EPA itself following the court order. The American Clean Energy and Security Act in the form that it passed the US House of Representatives would strip the authority from EPA under the Clean Air Act to regulate green house gasses.
April 2009: EPA declares greenhouse gases a threat to public health and welfare
On April 17, 2009 the EPA issued a “proposed endangerment finding” and a related proposed “cause or contribute finding” regarding greenhouse gases under section 202(a) of the Clean Air Act (section dealing with “Emission standards for new motor vehicles or new motor vehicle engines”). The EPA held a 60-day public comment period for these proposed findings, and received over 380,000 public comments. On December 7, 2009, the EPA issued two final findings regarding greenhouse gases under section 202(a) of the Clean Air Act: Endangerment Finding – The Administrator finds that the current and projected concentrations of the six key well-mixed greenhouse gases--carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O), hydrofluorocarbons (HFCs), perfluorocarbons (PFCs), and sulfur hexafluoride (SF6)--in the atmosphere threaten the public health and welfare of current and future generations. Cause or Contribute Finding – The Administrator finds that the combined emissions of these well-mixed greenhouse gases from new motor vehicles and new motor vehicle engines contribute to the greenhouse gas pollution which threatens public health and welfare.
December 2009: EPA finalizes endangerment finding
On December 7, 2009, EPA finalized its endangerment finding that greenhouse gases including carbon dioxide are a threat to human health and welfare. The announcement was the final step in the April 2007 Supreme Court ruling in Massachusetts v. EPA, which found that under the Clean Air Act, the EPA must regulate greenhouse gas emissions if they endanger public health and welfare. The EPA's decision paves the way for new regulation of emissions from power plants, factories, and automobiles. Announced on the first day of international climate talks at COP15 in Copenhagen, the move gives President Obama new regulatory powers that could help gain consensus in efforts to curb global warming. Both Obama and EPA Administrator Lisa Jackson have said they prefer climate change legislation as a means of regulating global warming pollution, but the finding provides an alternative means of establishing emissions limits if the legislation fails. On December 15, 2009, the final findings were published in the Federal Register under docket ID [EPA-HQ-OAR-2009-0171; FRL-9091-8]. Further information on the findings may be found on the EPA website: http://epa.gov/climatechange/endangerment.html
March 2010: EPA Waits for 2013 to regulate carbon emissions from 50,000 to 75,000 tons a year
On March 3, 2010 EPA Administrator Lisa Jackson told the Senate Appropriations panel reviewing EPA's budget that the agency would focus on large polluters spewing more than 75,000 tons a year. “It will probably be at least two years before we would look at something like, say, a 50,000 threshold,” Jackson said. The initial phase of greenhouse-gas rules will go into effect in 2011 said Jackson.
Senator John D. Rockefeller IV (D) of West Virginia on March 4, 2010 introduced legislation that would delay the EPA's carbon rules. The bill calls for a "two-year suspension" that will give Congress “the time it needs to address an issue as complicated and expansive as our energy future." Two House Democrats, West Virginia’s Nick Rahall and Virginia’s Rick Boucher, also introduced legislation that would put EPA's greenhouse gas regulations for so-called “stationary sources” on hold for two years. Rep. Rahall was co-author of the cap-and-trade bill that passed the House in June 2009 and would replace EPA direct regulation on carbon emissions.
December 2010: EPA issues plan to regulate power plants and petroleum refineries
On December 23, 2010, the EPA issued its plan for establishing greenhouse gas (GHG) pollution standards under the Clean Air Act in 2011. The agency looked at a number of sectors and is moving forward on GHG standards for fossil fuel power plants and petroleum refineries—two of the largest industrial sources, representing nearly 40 percent of the GHG pollution in the United States. Under the plan, EPA will propose standards for power plants in July 2011 and for refineries in December 2011 and will issue final standards in May 2012 and November 2012, respectively. EPA will accept public comment on the plans for 30 days following publication of notice in the Federal Register.
The EPA regulation addresses existing sources, using the statutes of the Clean Air Act's New Source Performance Standards (NSPS) to impose limits in 2012 on the amount of CO2 the biggest polluters can emit. The EPA said it would cover 40 percent of U.S. emissions..
The EPA has also been developing a permitting program for new (or substantially upgraded) sources. In May 2010, the EPA issued its "Tailoring Rule," determining which sources will need to get permits (very large sources). In November 2010, it issued "PSD and Title V Permitting Guidance for Greenhouse Gases," which detailed that the permitting program would be run much like existing permitting programs: through the states.
Feb. 2011: House votes to block EPA regulation of GHGs
On Feb. 18, 2011, the Republican-controlled House voted to block the Environmental Protection Agency from regulating greenhouse gases. The 249-177 vote added the regulation ban to a spending bill that would fund the government through Sept. 30, 2011. Texas Republican Ted Poe pressed the anti-EPA measure. His Texas district is home to many oil refineries.
March 2011: Inhofe-Upton introduce bill to prevent any federal CO2 regulation
On March 3, 2011, Senator James Inhofe, Republican of Oklahoma, and Representative Fred Upton, Republican of Michigan, formally introduced the “Energy Tax Prevention Act,” a bill that they said would reverse the EPA’s finding that carbon dioxide and other heat-trapping greenhouse gases are a danger to human health and the environment. According to Inhofe: “The Energy Tax Prevention Act stops cap-and-trade regulations from taking effect once and for all." The bill has 42 co-sponsors in the Senate, all Republicans. In the House, three Democrats joined Upton and his Republican co-sponsors - Nick Rahall of West Virginia, Dan Boren of Oklahoma and Collin Peterson of Minnesota, reportedly to protect key industries in their states – coal, oil and agriculture – that would be affected by greenhouse gas regulations.
The Inhofe-Upton bill allows many Clean Air Act programs to continue, but takes away the agency’s authority to apply the landmark law to carbon dioxide. A deal negotiated with automakers to limit carbon dioxide emissions from cars and light trucks would be allowed to stand through 2016, but no further greenhouse gas emissions rules for vehicles would be permitted. State programs to try to address global warming and carbon emissions would be allowed to continue.
March 2012: Rule for new plants
On March 27, 2012, the EPA released its new rule limiting CO2 emissions from future electricity generating plants in the U.S. The EPA is proposing that new plants emit no more than about 454 kilograms of CO2 per megawatt‐hour, and would go into effect in 2013. It would have the biggest impact on coal-fired plants, but would not apply to existing plants or those already under construction. The EPA did leave the door open for companies that want to build new coal plants by allowing utilities to phase-in CO2 controls like carbon capture and storage over decades, as long as the plant's 30-year average of emissions met the new standard.
Science reported that the cap is unlikely to have much impact on current U.S. energy-industry practices, as utilities are favoring new power plants fueled by natural gas: "Nearly all gas-fired power plants built in the U.S. since 2005 would already meet the standard, according to EPA, as would typical gas plants on the drawing boards. So, in practice, analysts say the new standard will probably result in few—if any—immediate changes in how utilities build or operate new power plants." EPA is expected to finalize the rule later in 2012, after a public comment period.
September 2013: revised rule
On Sep 20, 2013, the EPA issued new CO2 rules separating coal and gas regulations. Newly built coal-fired power plants will have to keep carbon emissions below 1,100 pounds per megawatt hour—a level that will force new plants to have carbon capture and storage technology. Newly constructed natural-gas plants will be permitted to emit no more than 1,000 pounds of C02 per megawatt hour - essentially the level at which cleaner burning natural-gas plants currently perform.
2011 report on total cost of CO2
A 2011 peer-reviewed report by Economics for Equity and Environment - Climate Risks and Carbon Prices: Revising the Social Cost of Carbon - found that, taking into account the full effects of coal, one ton of CO2 in the atmosphere in 2010 did up to $893 in economic damage—more than 12 times the government's highest estimate.
2011 EIP report on highest U.S. CO2 emitters
A 2011 report by the Environmental Integrity Project, "Getting Warmer: US CO2 Emissions from Power Plants Emissions Rise 5.6% in 2010" shows that carbon dioxide (CO2) emissions from power plants in the U.S. rose 5.56 percent in 2010 over 2009, the biggest annual increase since the EPA began tracking emissions in 1995. In total, electricity generators released 2.423 billion tons of carbon dioxide in 2010, compared to 2.295 billion tons in 2009. The report is based on data from the EPA’s “Clean Air Markets” website, which tallies emission reports from electric generators.
The 10 worst states for CO2 pollution identified in the report are, in order, Texas, Florida, Ohio, Indiana, Pennsylvania, Illinois, Kentucky, Georgia, Alabama, and Missouri. Texas power plants released nearly 257 million tons of CO2, as much as the next two states - Florida and Ohio - combined, and more than seven times the total CO2 emissions from power plants in California. Texas opened three new coal plants toward the end of 2010, with a combined capacity of 2,156 megawatts.
Coal-fired boilers provided 45 percent of U.S. electricity in 2010, but were responsible for 81 percent of total CO2 emissions from electricity generation in 2010.
Other key report findings include the following:
- 50 coal-fired power plants accounted for 750 million tons of CO2 emissions in 2010, or about a third of the total. The two largest carbon polluters, the Scherer and Bowen power plants in Georgia, together released more than 48 million tons of CO2 in 2010. By comparison, emissions from all power plants in California were 37.1 million tons; in New York, 40 million tons; and in the six states of New England, 40.5 million tons.
- Coal-fired generation rose 5.2 percent in the 12 months ending November 30, 2010. Nearly 4.5 gigawatts of new coal-fired electric generation came online in 2010, about half of that in Texas. But power companies have also announced plans to retire almost 12 gigawatts of coal-fired capacity within the next few years, including the announcement in Jan. 2011 that Xcel would close nearly 900 megawatts of coal-fired capacity at four different power stations in Colorado.
Total CO2 emissions of Alberta's tar sands versus U.S. coal exports
In 2011, the group Sightline calculated the carbon dioxide emissions from U.S. coal exports versus Alberta's tar sands, and found projected emissions from coal exports to be substantially higher (the estimate did not count the emissions associated with mining, transport, construction, or any other related activities, nor any non-CO2 or fugitive emissions, to allow for a more simple, straightforward comparison.)
Coal exports: The calculation assumed that 110 million tons of Powder River Basin coal are exported each year, consistent with the 60 million tons planned for the Millennium Bulk Logistics Longview Terminal and the 50 million for Gateway Pacific Terminal at Cherry Point, Washington (this is probably a low estimate: Longview project sponsors have been found using an 80 million ton figure, and there are talks of other Coal exports from ports on the west coast of Canada and the United States, such as Grays Harbor, Washington; St. Helens, Oregon; and Coos Bay, Oregon.) The estimate assumed that Powder River Basin coal generates 8,500 BTUs per pound, and that one million BTUs would produce 212.7 pounds of CO2, consistent with U.S. Department of Energy figures. The final calculation was 199 million tons of CO2 per year in “direct” emissions from the coal exports
Tar sands: To calculate the CO2 emissions from the Keystone XL Pipeline, it was assumed that the pipeline moved 830,000 barrels of oil per day, in line with U.S. State Department figures, working out to about 303 million barrels per year. It was then assumed that each barrel of oil contains 0.43 metric tons of C02, which the U.S. EPA assigns for an “average” barrel of oil (direct emissions from burning are the same regardless if it's oil or tar sands), which works out to about 144 million short tons of CO2 per year for direct emissions from burning the oil. To account for the particular crudeness of tar sands oil, the emissions that are associated with extracting and processing it for use were factored using figures from David Strahan, Wikipedia, and other sources; it was assumed that extracting the oil and “upgrading” to make it suitable for refining results in somewhere around 18 to 26 percent more carbon emissions than the direct emissions from burning the fuel itself. A mid-point of that range, 21.7 percent, was used, and added up to 31 million tons of CO2, for a combined direct and indirect emissions total of 175 million short tons of CO2 per year for the pipeline oil.
CO2 and air pollution
2009 Environmental Science & Technology Study
A 2009 study, “Enhancement of Local Air Pollution by Urban CO2 Domes,” published in Environmental Science & Technology by Mark Z. Jacobson, found that domes of increased carbon dioxide concentrations – discovered to form above cities more than a decade ago – cause local temperature increases that in turn increase the amounts of local air pollutants, raising concentrations of health-damaging ground-level ozone as well as particulate matter in urban air.
According to Jacobson: "Warming increases water vapor, and both water vapor and higher temperatures increase ozone where the ozone is already high but have less effect where the ozone is low. Carbon dioxide domes over cities increase temperatures over the cities above and beyond the heat island effect, and these higher temperatures increase water vapor, and both higher water vapor and higher temperatures increase the rates of chemical air pollution production over cities relative to rural areas. The results suggest a causal nature of increased air pollution mortality due to increased carbon dioxide where the air pollution is already high. Thus, controlling CO2 emissions at the local level will reduce air pollution and the resulting air pollution mortality."
Jacobson’s estimates that “reducing local CO2 may reduce 300-1000 premature air pollution mortalities/yr in the U.S. and 50-100/yr in California, even if CO2 in adjacent regions is not controlled.”
2011 Union of Concerned Scientists Study
A 2011 study by the Union of Concerned Scientists "Climate Change and Your Health: Rising Temperatures, Worsening Ozone Pollution" projected future climate-induced temperature increases on the relationship between ozone concentrations and temperature to explore the potential “climate penalty on ozone pollution.”
Key findings included:
- In 2020, the continental United States could pay an average of $5.4 billion (2008$) in health impact costs associated with the climate penalty on ozone. California and states in the Midwest and the Mid-Atlantic could be hit especially hard.
- Higher ground-level ozone concentrations due to rising temperatures in 2020 could lead to an average of 2.8 million more occurrences of acute respiratory symptoms such as asthma attacks, shortness of breath, coughing, wheezing, and chest tightness. In 2050, that could rise to an average of 11.8 million additional occurrences.
- Higher ozone concentrations due to rising temperatures could lead to an average of 3,700 more seniors and 1,400 more infants hospitalized for respiratory-related problems in 2020. In 2050, that could rise to 24,000 more seniors and 5,700 more infants hospitalized.
Scientific Studies on historic CO2 levels
Study suggests CO2 levels may be highest in not just past 800,000 years, but 15 million years
In an Oct. 8, 2009 online edition of the journal Science, a study - “Coupling of CO2 and Ice Sheet Stability Over Major Climate Transitions of the Last 20 Million Years” - led by UCLA scientist Aradhna Tripati found that present carbon dioxide levels have not been this high since at least 15 million years ago, when global temperatures were 5 to 10 degrees Fahrenheit higher than they are today, the sea level was approximately 75 to 120 feet higher, there was no permanent sea ice cap in the Arctic, and very little ice on Antarctica and Greenland.
Tripati was part of a research team at England’s University of Cambridge that developed a new technique to assess carbon dioxide levels in the much more distant past — by studying the ratio of the chemical element boron to calcium in the shells of ancient single-celled marine algae. Tripati has now used this method to determine the amount of carbon dioxide in Earth’s atmosphere as far back as 20 million years ago: "We are able, for the first time, to accurately reproduce the ice-core record for the last 800,000 years — the record of atmospheric C02 based on measurements of carbon dioxide in gas bubbles in ice. We then applied this technique to study the history of carbon dioxide from 800,000 years ago to 20 million years ago. We report evidence for a very close coupling between carbon dioxide levels and climate. When there is evidence for the growth of a large ice sheet on Antarctica or on Greenland or the growth of sea ice in the Arctic Ocean, we see evidence for a dramatic change in carbon dioxide levels over the last 20 million years. A slightly shocking finding is that the only time in the last 20 million years that we find evidence for carbon dioxide levels similar to the modern level of 387 parts per million was 15 to 20 million years ago, when the planet was dramatically different.”
It has been known that modern-day levels of carbon dioxide are unprecedented over the last 800,000 years, but the finding that modern levels have not been reached in the last 15 million years is new: “During the Middle Miocene (the time period approximately 14 to 20 million years ago), carbon dioxide levels were sustained at about 400 parts per million, which is about where we are today,” Tripati said. “Globally, temperatures were 5 to 10 degrees Fahrenheit warmer, a huge amount.” Tripati’s new chemical technique has an average uncertainty rate of only 14 parts per million.
Some projections show carbon dioxide levels rising as high as 600 or even 900 parts per million in the next century if no action is taken to reduce carbon dioxide. Such levels may have been reached on Earth 50 million years ago or earlier, said Tripati, who is working to push her data back much farther than 20 million years and to study the last 20 million years in detail. More than 50 million years ago, there were no ice sheets on Earth, and there were expanded deserts in the subtropics, Tripati noted. The planet was radically different.
- Frequently Asked Global Change Questions, Carbon Dioxide Information Analysis Center
- Mauna Loa CO2 annual mean data from NOAA. "Trend" data was used. See also: Trends in Carbon Dioxide from NOAA.
- "Annual Mean Growth Rate for Mauna Loa, Hawaii". Trends in Atmospheric Carbon Dioxide. NOAA Earth System Research Laboratory. Retrieved 28 April 2010.
- "IPCC AR4 SYR Appendix Glossary" (PDF). Retrieved 14 December 2008.
- 2007 IPCC Fourth Assessment Report (AR4) by Working Group 1 (WG1), Chapter 2 "Changes in Atmospheric Constituents and in Radiative Forcing" which contains information on global warming potential (GWP) of greenhouse gases.
- Plant Growth Factors: Photosynthesis, Respiration, and Transpiration
- Carbon dioxide
- "Biochar from pyrolysis key to climate change mitigation: report" Biomass Digest, August 2010.
- David Ibata, "Study: Southern Company plants are 3 biggest greenhouse gas emitters" Atlanta Journal-Constitution, January 11, 2012.
- "EPA Report Reveals Top Ten Greenhouse Gas Emitting Power Plants in U.S." Think Progress, Jan 12, 2012.
- Jonathan Smith, "2010 to have Highest CO2 Emissions Since Tracking Started" The Energy Collective, Nov. 26, 2010.
- Tom Zeller, "rospects For Reaching CO2 Benchmark And Curbing Global Warming Grow Dimmer" HuffPo, June 3, 2011.
- Jessica Dailey, "US Carbon Emissions Rose 4% in 2010, Partly Due to Increased Coal Use" Inhabitat, Aug. 22, 2011>
- Robert Barnes and Juliet Eilperin, "High Court Faults EPA Inaction on Emissions" The Washington Post, April 3, 2007.
- "Endangerment and Cause or Contribute Findings for Greenhouse Gases under the Clean Air Act" United States Environmental Protection Agency, December 18, 2009.
- [http://www.corpwatch.org/article.php?id=5769 "USA: Republican 'Clear Skies' Toxic to Democrats" Environmental News Service February 28th, 2003
- "Waxman-Markey Strips EPA of Clean Air Act Authority to Fight Global Warming," Friends of the Earth, accessed August 2009.
- John M. Broder, "E.P.A. Clears Way for Greenhouse Gas Rules," New York Times, April 17, 2009
- "EPA Finds Greenhouse Gases Pose Threat to Public Health, Welfare / Proposed Finding Comes in Response to 2007 Supreme Court Ruling," EPA news release, April 17, 2009
- "Proposed Endangerment and Cause or Contribute Findings for Greenhouse Gases under the Clean Air Act," EPA
- "EPA’s Carbon Decision Gives Obama Copenhagen Tool," Bloomberg, December 7, 2009.
- "EPA Moves to Regulate CO2 as a Hazard to Health," Time, December 7, 2009.
- "EPA Waits for 2013 on Carbon Emissions of 50,000 Tons a Year" Kim Chipman, Bloomberg March 3, 2010.
- "Rockefeller Introduces Bill to Delay EPA Carbon Rules" Simon Lomax, Bloomberg March 5, 2010.
- "EPA to Set Modest Pace for Greenhouse Gas Standards / Agency stresses flexibility and public input in developing cost-effective and protective GHG standards for largest emitters" EPA, Dec. 23, 2010.
- "EPA Sets Timetable on Carbon-Cutting Regs for Coal and Oil" Stacy Feldman, Reuters, December 23, 2010.
- "Putting EPA’s announcement on CO2 from power plants in context" Grist, Dec. 23, 2010.
- "House Votes To Block EPA From Regulating Greenhouse Gases" AP, Feb. 18, 2011.
- John Broder, "Inhofe and Upton: Just Say No to the E.P.A." NY Times, March 3, 2011.
- David Malakoff, "Imposing a Cap With Holes," Science, March 27, 2012.
- Josh Dzieza, "Obama Administration Issues New Rules Capping Carbon Emissions From New Coal Plants," Daily Beast, Sep 20, 2013.
- Eric de Place, "Coal Exports Are Bigger Threat Than Tar Sands Pipeline: A carbon comparison of Northwest coal plans and Keystone XL project" Sightline, November 16, 2011.
- Stuart Wolpert, "Last time carbon dioxide levels were this high: 15 million years ago, scientists report" UCLA, Oct. 8, 2009.
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