Category Archives: Climate Change

Climate Choices Part I — N.C. and the Regional Greenhouse Gas Initiative

January 4, 2023.  By coincidence rather than design,  two different approaches to reducing greenhouse gas emissions from the electric power sector have been under discussion by North Carolina agencies since 2021. This post will describe draft rules being considered by the N.C. Environmental Management Commission (EMC) in response to a petition for rulemaking submitted by Clean Air Carolina and the N.C. Coastal Federation.  The rulemaking petition asked the EMC to adopt rules requiring units serving electric generators of 25 MW or greater to participate in a market-based program to reduce CO2 emissions.

A later post will cover the North Carolina Utilities Commission (NCUC)  Carbon Reduction Plan.  The two approaches share goals of reducing greenhouse gas emissions 70% by 2030 (from a 2005 baseline) and achieving carbon neutrality by 2050.  The approaches differ in the generating units affected (although there is overlap) and the mechanism relied on to achieve the reductions.

The  Proposed  EMC Rules: The draft rules being considered by the EMC would set the stage for North Carolina to join 11 other states in a  market-based program — the Regional Greenhouse Gas Initiative (RGGI) — to reduce carbon dioxide (CO2)  emissions from electric generators.   RGGI relies on a market concept similar to the “cap and trade” program EPA used to incentivize reductions in sulfur dioxide (SO2) emissions contributing to acid rain.

Background on RGGI.  Seven northeastern states created RGGI in 2005. Over time, RGGI has expanded to include eleven east coast states:  Connecticut, Delaware, Maine, Maryland, Massachusetts, New Hampshire, New Jersey, New York, Rhode Island, Vermont and Virginia.

RGGI uses cost to drive down CO2 emissions from electric generating units (EGUs) by requiring each EGU to buy an “allowance”  for each short ton of carbon dioxide it emits annually. In the RGGI context, an “EGU”  means a unit generating electricity for distribution to customers —  an electric utility. Each participating RGGI state sets an annual emission budget that caps CO2 emissions from those EGUs; the combined state CO2 budgets become a regional budget for the RGGI states.  The CO2 emissions budget gradually declines over time; currently, RGGI has a goal of reducing CO2 emissions by 30% (from a 2020 baseline) by 2030.

RGGI conducts quarterly auctions of available allowances (the number based on the CO2 emissions budget and other factors).  EGUs can also purchase allowances directly from other emission sources.   The net proceeds of the RGGI allowance auction (minus an administrative fee)  go back to the participating state governments in proportion to the  state’s share of the total RGGI  emissions budget. RGGI characterizes itself as a “cap and invest” program  because many of the participating states direct their auction revenue to support renewable energy; energy efficiency; measures to mitigate climate impacts; and assistance to low-income households.

Note:  This is a very simple overview  of the way RGGI operates. The RGGI program includes complex provisions on the conduct of auctions; calculation of emissions; emissions record-keeping and reporting; and measures to prevent allowance prices from going either too high or too low. More detailed information can be found through the RGGI website homepage.

The RGGI rulemaking petition. N.C. General Statute 150B-20 allows anyone to petition a state agency to adopt or amend a rule. In January 2021, Clean Air Carolina and the N.C. Coastal Federation filed a  rulemaking petition requesting the EMC to adopt draft rules (included in the petition)  creating the regulatory framework necessary for North Carolina participation in RGGI.

In July 2021, the EMC voted to approve the rulemaking petition. Approval of the  rulemaking petition just means that the EMC has agreed to begin the rulemaking process based on draft rules submitted by the petitioners; it does not commit the EMC to adopt the rules.  The EMC is still in the first stage of the  rule-making process, which requires preparation of a regulatory impact analysis describing the rule’s effects,  including the potential fiscal impact on state government, local government, and others affected by the rule. Once the fiscal analysis has been completed and approved by the Office of State Budget and Management, the  draft rule and the regulatory impact analysis will be released to the public for review and comment.

At this stage of the rulemaking process, the EMC cannot change the draft rule as proposed by the petitioners.  Once the public comment period has closed, the EMC can take one of three actions: 1. adopt the petitioners’ rule draft; 2. adopt the rule with changes to address questions or concerns raised in public comment or EMC discussion; or 3. decline to adopt the rule in any form.

Comparison of the Proposed N.C. Rules to Existing RGGI States. The draft rules submitted to the EMC by Clean Air Carolina and N.C. Coastal Federation use the basic structure of the RGGI program — a state CO2 emissions budget that declines over time and a requirement that each regulated generating unit must purchase an allowance for each short ton of CO2 that it emits. The draft rules differ from those adopted by other RGGI states in some key ways:

♦ The rules apply to a broader set of CO2 emission sources. In the other RGGI states, only electric generating units (EGUs)  associated with electric utilities are required to hold allowances for CO2 emissions.  The proposed N.C. rules would also apply to generating units  of 25 MW or greater that are operated by industries or institutions to generate electricity for their own use. As a result, the N.C. rules refer to “CO2 budget units” rather than EGUs. Under the draft N.C. rules, EGUs are a subset of “CO2 budget units”.

♦ The rules apply to emissions from additional types of fuel. The proposed N.C. rules would apply to CO2 emissions associated with biomass or biofuels as well as fossil fuels.

♦  No North Carolina state agency would directly participate in the RGGI auction process.  Unlike other RGGI states, North Carolina would not allocate the state’s CO2  allowances to the RGGI auction directly. Instead,  the state would develop a state CO2 budget;  create “conditional” allowances based on the budget; and assign those allowances — at no cost — to the regulated generating units in N.C.  The draft rule requires those units to consign their allowances to  RGGI and purchase the allowances back through the RGGI auction before they can be used to comply with the rule.

♦ Net proceeds of the RGGI auction would go back to the CO2 budget units  instead of becoming state revenue.  In other participating RGGI states,  a designated state agency receives the net auction revenues and directs the use of those funds consistent with state law. The draft N.C. rules have the net auction revenues return to the regulated generating units. As a result,  no N.C. state agency would have any direct involvement in the RGGI auction process at either the beginning (consignment of allowances to the auction) or end (receipt of revenues from the auction).

The draft N.C. rules include a provision allowing  CO2 budget units to  use auction proceeds “for public benefit, strategic energy, or other purposes approved by the [N.C. Utilities] Commission”.  Note that a number of the CO2 budget units covered by the draft N.C. rule are not EGUs regulated by the N.C. Utilities Commission;  municipal and co-op systems fall outside the NCUC’s jurisdiction. The Division of Air Quality has determined that the draft N.C. rule would also cover a small number of generating units  operated by an institution or industry to generate power solely for its own use.  In any case, the draft rule language  seems to be sufficiently broad to allow most generating units to use auction revenue just as they use revenue from rates or other sources.  Units that fall under the NCUC jurisdiction would continue to be subject to that commission’s usual oversight with respect to rates and plans to meet electricity demand. 

Since the fiscal analysis of the N.C. rule hasn’t been completed, there is not yet an estimate of the amount of revenue likely to return to the electric generating units covered by the N.C. rule. But the revenues returning to existing RGGI states (reported on the RGGI website ) have been substantial. For example, the state of New York’s revenue  has ranged from  $300,000,000  to $500,000,000 for each 3-year RGGI auction cycle.

♦ The draft rules propose a steeper reduction in CO2 emissions than that required by current RGGI states. The draft N.C. rules require a 70% reduction by 2030 (from a 2005 baseline) and carbon neutrality by 2050. The existing RGGI program has  a goal of 30% reduction in CO2 emissions by 2030, although the participating RGGI states have decided to review the goal given progress to date. The difference would mean a  steeper reduction curve  for N.C. sources compared to those in states currently participating in RGGI.

Next Steps. Before the EMC makes any decision about adoption of the proposed rules, the draft rules will be published for public review and comment along with the regulatory impact/fiscal analysis. The Division of Air Quality originally anticipated that the fiscal analysis would be complete in November 2022, allowing the EMC to receive public comments in early 2023 and make a rulemaking decision in May 2023.   Final approval of the fiscal analysis has been delayed, however,  to allow more time for review by the Office of State Budget and Management. The delay means the EMC may not be able to take any action on the proposed rules until later in the summer of 2023.

Late 2018 — Bits and Pieces

January 30, 2019.  A fall trip to South Africa, followed closely by the holidays,  made October-December something of a blur.

Leopard: Thornybush Game Preserve (photo G.Whaley)

Leopards, lions, and zebra – oh my!  Also elephants, giraffes, rhinos (of the non-political variety), Cape buffalo,  baboons, uninvited monkeys at lunch, hippos, wildebeests, hyenas, warthogs and an unexpected (to me) penguin colony.

African Penguin: The Cape

 

 

 

Also, a different set of environmental challenges: drought and drinking water supply; rhinoceros poaching; managing heavily vegetated bush and grassland habitat; and protecting the Cape’s extraordinary biodiversity.

 

 

 

Back to  North Carolina developments in late 2018:

Executive Order on Climate Change and Clean Energy: On October 29, 2018, N.C. Governor Roy Cooper issued an executive order on climate change and clean energy. Executive Order 80 supports the 2015 Paris Agreement and sets several goals for the state to meet by 2025:

  1. Reduce state greenhouse gas emissions by 40% from 2005 levels.
  2. Increase the number of zero-emission vehicles in the state to 80,000.
  3. Reduce energy use per square foot in state-owned buildings by 40% from 2002-2003 levels.

The state has already made significant progress toward the first goal as a result of the 2002 Clean Smokestacks Act and 2007 adoption of a renewable energy portfolio standard (REPS) for major energy producers. (For background on the REPS law, see an earlier  post on the first of several unsuccessful attempts to repeal the REPS standard.) Those two pieces of legislation had already begun to reduce the state’s greenhouse gas emissions by transitioning more base power generation from coal to natural gas  (which produces lower levels of greenhouse gas emissions, although not emission-free)  and greatly increased development of solar and wind generation facilities.

The most direct effect of the executive order will be on state government operations. The order provides new guidance to cabinet agencies on vehicle use; energy efficiency in state facilities; and priority for  greenhouse gas reduction/clean energy  in planning and allocation of economic incentives. Some state agencies received very specific direction —  the Department of Transportation to encourage use of zero-emission vehicles and the Department of Commerce  to  use state incentives to recruit and develop clean energy businesses.

Executive Order 80 also  directs all  cabinet agencies to evaluate the impact of their activities on climate change and to

integrate climate adaptation and resiliency planning into their policies, programs and operations (i) to support communities and sectors of the economy that are vulnerable to the effects of climate change and (ii) to enhance the agencies’ ability to protect human life and health, property, natural and built infrastructure, cultural resources and other public and private assets…

Executive Order 80  now gives agencies ranging from  NCDOT  to  DEQ and commissions like the Environmental Management Commission and Coastal Resources Commission clear direction to consider the impacts of climate change in exercising their planning and regulatory authority.

It is too early to know how  agencies will respond to the mandates in Executive Order 80.  The order creates a new N.C. Climate Change Inter-Agency Council chaired by the Secretary of Environmental Quality to coordinate efforts to reduce greenhouse gas emissions, increase clean energy development and improve state government’s energy efficiency. It also requires preparation of a N.C. Climate Risk Assessment and Resiliency Plan by March 1, 2020; that process will be led by DEQ  and involve stakeholder input.

It isn’t difficult to imagine ways state agency decision-making might consider climate change adaption and resiliency. Rising sea levels and more frequent flood events could factor into planning the location of future roads and other public infrastructure as well as design standards for private development.  An executive order cannot conflict with existing statutes or give a state agency authority it does not already have under N.C. law, but it can guide the use of existing authority.

December 2018 Legislative Session (Third Extra Session):   Senate Bill 469  made two changes to state stormwater policies.  Section 26 (a) of the bill amended language in G.S. 143-214.7(b2)  that already allowed development in a  buffer required under stormwater rules as long as stormwater from the entire developed area was collected, treated and discharged in the buffer.  The provision has been amended to:

1. Apply to development in any buffer required under state stormwater rules. Previously, the exception applied only to development in buffers adjacent to shellfish waters, high quality waters, and outstanding resource waters, which are among the most highly protected waters in the state.

2. Require discharge of the collected and treated stormwater through a “segment” of the buffer. The law had originally simply required discharge of the treated stormwater through the buffer.

The more significant change may be in Section 26(b) which amends G.S. 143-214.7(b3). The law already prevented application of state stormwater rules to previously developed properties and limited application of the rules to property being partially or entirely redeveloped:

(b3) Stormwater runoff rules and programs shall not require private property owners to install new or increased stormwater controls for (i) preexisting development or (ii) redevelopment activities that do not remove or decrease existing stormwater controls. When a preexisting development is redeveloped, either in whole or in part, increased stormwater controls shall only be required for the amount of impervious surface being created that exceeds the amount of impervious surface that existed before the redevelopment.

Senate Bill 469 added a new sentence to extend those limitations to local government stormwater ordinances whether those ordinances implement state stormwater standards or have been adopted under other authority. Those “other” sources of authority could include federal Clean Water Act permits issued to local governments for municipal stormwater discharges and local government power under state law to regulate land use.  In the first instance, the new limitation on stormwater controls for redevelopment projects may conflict with the local government’s federal permit. In the second instance, the amended law could frustrate local government efforts to reduce flooding by requiring better stormwater management  as properties are redeveloped.

An example of the second problem: A developer bulldozes an old shopping center built before stormwater rules applied with the intent of redeveloping the property as condominiums.  The amended law prevents the local government from requiring any stormwater controls for the condominium project unless the new development creates more impervious surface (paved or built-on areas) than the shopping center had.  Then, the local government could only require control of stormwater from the additional impervious surface — likely to be a very small percentage of the total new development project.

The limits in G.S. 143-214.7(b3) on applying state stormwater rules to redevelopment projects had effectively shut the door on reducing stormwater pollution from areas developed before the rules existed. Extension of those limitations to local government ordinances under any source of local government authority will also  make it more difficult for cities and towns to reduce future flooding after rain events. That is a public safety as well as a water pollution problem.

One other note on Senate Bill 469.  The bill, titled “An Act to Make Various Technical, Clarifying, and Conforming Changes to the General Statutes and Session Laws”,  included substantive changes like the stormwater amendments in Sec. 26 that could not by any normal definition fall into any of those categories. In the past, the legislature has been careful not to include substantive amendments in a bill designated by title for “technical, clarifying and conforming changes”.  The moral of the story: do not judge a bill by its title.

Today: The  2019 Regular Session of the North Carolina General Assembly convenes.

Court Refuses to Stay EPA Rule Reducing Power Plant CO2 Emissions

January 24, 2016.     An earlier post described the basic requirements  of a new federal rule  (the Clean Power Plan) requiring existing  power plants to reduce carbon dioxide (CO2) emissions.   Note: That post described the draft rule out for public comment in  2014; the final  rule approved by the U.S. Environmental Protection Agency in August  2015 differed from the draft rule  in some details — including the specific  state  CO2  reduction targets — but the basic requirements did not change.

North Carolina’s Department of Environmental Quality (formerly DENR)  opposed the rule early on and in October of 2015 joined 23 other states in a lawsuit challenging the final rule.  (More on the McCrory administration’s objections to the EPA rule here.)   Both the states and several business/industry groups  attacking the rule in separate lawsuits  asked the federal court to issue a preliminary injunction  (or “stay”) to prevent EPA from implementing  the Clean Power Plan rule until the lawsuits are resolved.

On January 21, the federal Court of Appeals for the District of Columbia denied all requests to stay implementation of the Clean Power Plan rule. The court’s  order did not discuss the basis for denial in detail; the court simply said the requests failed to meet the high standards for issuance of a preliminary injunction, citing the U.S. Supreme Court decision in  Winter v. Natural Resources Defense Council (2008).  First,  the court must be persuaded that the plaintiff is ultimately likely  to win the case. A court will not give a  plaintiff the immediate advantage of a stay restricting the defendant’s actions if the plaintiff’s arguments are unlikely to win out in the end.  Even if the court finds the plaintiff has a likelihood of winning the case, the court will not issue a stay unless the plaintiff also shows that:

— The plaintiff is likely to suffer irreparable harm if the court doesn’t issue a preliminary injunction. In this case, the plaintiffs  had to convince the court that allowing EPA to move ahead with implementation of the Clean Power Plan rule  would cause immediate harm to the plaintiffs and that  harm could not be remedied by a later ruling in the plaintiffs’ favor.

— The balance of equities tips in the plaintiff’s favor.  In very simplified terms,  the plaintiffs had to show that a stay would do more good than harm.

— An injunction is in the public interest.  The public interest standard can work in favor of either the plaintiff or the defendant depending on the case. In the Winter v. Natural Resources Defense Council case, the U.S. Supreme Court decided that a preliminary injunction was not in the public interest because it would have restricted a particular type of military training exercise.

Since the Court of Appeals for the D.C. Circuit did not provide specific reasons for refusing to stay the Clean Power Plan rule,  it is impossible to know exactly which of those standards the plaintiffs failed to meet.  The decision doesn’t necessarily mean the court thinks the state and business/industry plaintiffs have a weak case against the rule; failure to meet the other criteria could also lead to denial of a stay.  It is probably safe to say, however,  that the court did not believe the states or the business/industry plaintiffs  will  be harmed by allowing the Clean Power Plan rule to go into effect.

In asking for a stay, the states  identified two kinds of harm —  waste of state resources to comply with a federal rule that may be struck down by the courts and a much more nebulous harm to state sovereignty.  On the question of potentially wasted state resources, EPA pointed out: 1. the federal rule gives states until 2018  to develop a state plan to meet the CO2 reduction targets;  and  2. a state can also simply opt out and let EPA develop a CO2 reduction plan for its electric utilities.  The first actual CO2 reduction target comes several years after approval of  the state plans. The court seemed persuaded that the long planning and implementation timeline means states will not have to sink major, unrecoverable costs into Clean Power Plan compliance before the lawsuits are resolved.

It is hard to know what the court made of the somewhat novel argument that immediate implementation of the Clean Power Plan rule  would irreparably harm state sovereignty.  EPA pointed out that the Clean Power Plan rule gives states a lot of flexibility in developing plans to meet the  CO2 emissions reduction targets.  It is also difficult to argue the Clean Power Plan rule attacks state sovereignty without going to the next — much more radical step — of arguing that the federal government has no authority to regulate to protect air quality in the first place.   In any case, if the federal court strikes down the Clean Power Plan rule as either unconstitutional or beyond EPA’s statutory authority that would seem to adequately  remedy any hypothetical harm to  state sovereignty.

The Court of Appeals agreed to expedite the Clean Power Plan lawsuits and set the case for hearing on June 2, 2016.

Practical effects — States will continue to face a 2018 deadline for submission of  CO2 reduction plans. In one way, the impact on  N.C.  will be minimal  because the state  is  already on a fast track to submit a  plan to EPA in  2016.  The catch, however, is that the plan proposed by N.C.’s Department of Environmental Quality relies entirely on tighter emissions limits for a small set of existing coal-fired power plants and will only result in a fraction of the CO2 reductions the federal rule requires.  See another post  for background on the McCrory administration’s intent to submit a plan that does not take  credit for CO2 reductions associated with  increased renewable energy generation and energy efficiency improvements already required under  state law.  The shortfall in CO2 reductions in the plan being prepared by DEQ will almost certainly result in EPA disapproval.  Given the federal court’s denial of a stay, N.C.’s decision to deliberately fast track an unapprovable plan may mean  the state will have to revisit the plan sooner rather than later.

The North Carolina Response to EPA’s Clean Power Plan Rule

July 26, 2015.  In one way, the proposed  U.S. Environmental Protection Agency (EPA) rule to limit carbon dioxide (CO2) emissions from power plants  — expected to be final in August — looks like a typical air quality rule. The Clean Power Plan rule sets state by state reduction goals for a pollutant (CO2) from a particular set of of sources (electric generating facilities).  But the rule takes an unusual and  innovative approach to meeting those goals. The rule identifies  four components  (or “building blocks” in EPA rule-speak ) of a plan to reduce CO2 emissions associated with power generation : 1. reducing power plant CO2 emissions (the traditional Clean Air Act approach); 2. energy efficiency measures; 3. increased  electric generation from renewable energy sources;  and 4. transition of electric generation facilities from coal to natural gas.   In effect, the rule aims to lower CO2 emissions per kilowatt hour used and allows the  states to take credit for CO2 emissions avoided through increased energy efficiency and by shifting electric generation to energy sources with low or no CO2 emissions.

The proposed EPA rule requires each state to submit a plan for meeting its CO2 reduction target by June 30, 2016. The state plan can rely on any or all of the four “building blocks” in the EPA rule; it can also include measures that fall outside those categories as long as the plan achieves the CO2 reduction target for regulated electric generation facilities. If a state fails to develop a plan, EPA can create a federal plan for the state.  An earlier post  provides more detail on the  proposed federal rule.

The McCrory administration has opposed the Clean Power Plan rule in  written comments and in testimony before Congressional committees. In part,  the administration has argued that the Clean Air Act does not authorize EPA to issue  a rule that relies on measures — such as energy efficiency and increased reliance on renewable energy — that go beyond limiting  pollutant emissions from regulated power plants.  Last week,  the practical implications of  that   position became more clear when DENR  Secretary Donald van der Vaart  told a Senate committee that  the McCrory administration intends to resist the flexibility offered under the federal rule and submit a CO2 reduction plan  based entirely on requiring additional CO2 emission reductions at  power plants.

The Secretary’s comments came  as a state Senate committee debated House Bill 571, which requires DENR to develop  a state CO2 reduction plan with the participation of the public and the electric utilities. DENR did not support House Bill 571, but the bill passed the House with a bipartisan majority and the support of  the state’s major electric utilities and environmental organizations. Last Wednesday, the  Senate Agriculture and Environment Committee took up a substitute draft of  H 571 that would prohibit DENR from taking any action or expending any state resources on development of a CO2 reduction plan until all legal challenges to the federal rule had been resolved or until July 1, 2016 (whichever came later).  Asked to comment on the proposed substitute bill,   Secretary van der Vaart  indicated that DENR  would prefer to submit a CO2 reduction plan by June 30, 2016 as required under the federal rule — but a plan based entirely on reducing  power plant emissions.

Based on the Secretary’s statement, the McCrory administration response to the Clean Power Plan rule puts the state in a strange place:

♦  DENR has argued for an interpretation of  the Clean Air Act that would force the federal rule to be more rigid and offer the state less flexibility to meet CO2 reduction targets.   (A number of environmental law experts disagree with this narrow interpretation of EPA authority; the issue will likely have to be settled in court.)

♦  Based on this narrow interpretation of EPA authority, DENR intends to develop a state CO2 reduction plan that relies entirely on further reducing  CO2 emissions from power plants even though existing  state policies have North Carolina on a path to achieve much (if not all)  of the necessary reductions through increased renewable energy generation, greater energy efficiency, and  transition of power plants from coal to natural gas.  Although DENR has not provided an analysis of the state’s ability to meet the state’s CO2 reduction target based on those existing policies, others have. You can find one (an analysis by the Natural Resources Defense Council)  here.

♦  Relying  entirely on lowering power plant emissions could  make meeting the CO2 reduction target more difficult and more costly for electric utilities and consumers. Again, DENR has not provided a comparative analysis of the cost of relying entirely on power plant pollution controls versus  a comprehensive CO2 plan that takes credit for energy efficiency measures, renewable energy generation and transitioning power plants from coal to natural gas.

Most states have started planning to meet the  CO2 reduction targets. Even in coal-producing states where political opposition to the EPA rule tends to be highest,  state air quality agencies have begun sketching out CO2 reduction scenarios in case the rule survives the expected legal challenges. Only one state — Oklahoma — has prohibited its environmental agency from developing a plan. A recent Washington Post story  reported that even coal-dominated states like Kentucky seem confident of meeting the  CO2 reduction target thanks in part to recent investments in renewable energy generation. It isn’t clear that any state other than North Carolina has decided to develop a plan based solely on CO2 reductions at coal-fired power plants.

Which leaves something of a public policy mystery. A state with significant advantages in renewable energy, energy efficiency and already on the road to transitioning power plants from coal to natural gas seems to have settled on a policy that throws those advantages away. Instead of working with electric utilities, consumers and environmental organizations to develop the most cost-effective  CO2 reduction plan for the state, DENR intends  to unilaterally develop a plan based entirely on reducing power plant emissions.  It isn’t clear why or what that policy choice could cost the state.

Note: The Senate committee approved the substitute draft of House Bill 571 on Wednesday, but offered to continue talking to DENR about the content of the bill. The bill was pulled off the Senate calendar last Thursday; when the bill  reappears on the Senate calendar, there may be amendments as a result of the ongoing discussions.

Update: The original post has been revised to make it clear that state CO2 reduction plans can also rely on measures other than those covered by the  four “building blocks” identified in the EPA rule.

A Citizen’s Guide to Climate Change, Part II: The “Greenhouse” Effect

February 16, 2015.  At its most basic, the theory that human activity can affect the climate has  two parts: 1. Changes in  Earth’s atmosphere can affect surface temperature;  and 2. Human activity can alter the makeup of Earth’s atmosphere. This post provides an overview of the science behind both principles, relying on scientific reports and a number of  sources that collect and report data on the link between atmospheric gasses and climate.  This post  focuses on carbon dioxide (CO2) as one of the most significant contributors to warming; other “greenhouse” gasses include methane, nitrous oxide and fluorinated gasses.

How the atmosphere affects temperature; the history of the  “greenhouse effect”.  The scientific  theory  that Earth’s atmosphere affects  the planet’s surface temperature — the “greenhouse effect” — goes back nearly 200 years. As early as the 1820s,   French scientist Jean Baptiste Fourier  theorized that gasses surrounding the Earth retained heat,  allowing the planet to warm more than the sun’s influence alone could explain. British physicist  John Tyndall did some of the earliest experimental work to prove the relationship,  demonstrating that water vapor and carbon dioxide  hold more heat than oxygen and nitrogen.  In 1861, Tyndall published the results  in a  paper titled On the Absorption and Radiation of Heat by Gases and Vapours, and on the Physical Connexion of Radiation, Absorption, and Conduction.  In 1896, Swedish  scientist  Svante Arrhenius published  a  paper  that for the first time quantified the  relationship between CO2  in the atmosphere and  Earth’s surface temperature.

Tabletop experiments:  A number of educational and scientific websites provide instructions on how to do your own table-top experiment demonstrating how changes in the atmosphere affect temperature. For a demonstration, see this BBC video.

Sources:  Discovery of Global Warming  website (maintained by Spencer Weart  and hosted by the American Institute of Physics); the National Aeronautic and Space Administration (NASA); the National Oceanic and Atmospheric Administration (NOAA);  the University of York’s Tyndall correspondence website;  and the Tyndall Centre  for Climate  Change Research. For an overview of the history of climate science carried forward through the 20th century, see a post by John Mason on the Skeptical Science website.

Trends in Atmospheric CO2. Scientists have been taking monthly measurements of  CO2 at the Mauna Loa Observatory  (Hawaii) since 1958. The chart below shows the trend line.

co2_data_mlo

 

The red line plots the CO2  measurements; the black line represents the seasonally adjusted CO2 level. In 2014, CO2 levels measured at Mauna Loa reached 400 parts per million for the first time since modern record-keeping began.   Research indicates that current CO2  levels are the highest in  hundreds of thousands of years. Or as science writer Andrew Freedman put it more colorfully in an article for Climate Central:

The last time there was this much carbon dioxide (CO2) in the Earth’s atmosphere, modern humans didn’t exist. Megatoothed sharks prowled the oceans, the world’s seas were up to 100 feet higher than they are today, and the global average surface temperature was up to 11°F warmer than it is now.

Englishman seated on jaw of megatooth shark.

Englishman seated on jaw of megatooth shark

Most of the increase in atmospheric CO2 has occurred since the beginning of the Industrial Revolution (in the late 1700s) when atmospheric levels were around 280 parts per million and the rate of change has increased in the last 50 years. The upward curve in CO2 looks very similar to the upward curve in mean global temperature since 1960 shown in the previous post:

Mean Surface Temps

 

Questions about human activity and  increased CO2 levels

Haven’t CO2 levels on Earth been higher in the past? Yes, but the highest levels occurred around 500 million years ago when Earth was a very different place.  The last time CO2 levels were similar to those being measured now was about 7,000 years ago. CO2 levels fell over  several intervening  centuries; then the curve  reversed  and the rate of increase accelerated  within the last 50 years.

How do we know human activity has caused the recent increase in CO2? Scientists have looked at the relationship in several different ways. Two indications of human influence:

1. Mathematical accounting for the conversion of carbon to CO2.   CO2 comes from both natural processes and human activity.  People convert carbon to CO2 by burning fossil fuels and by clearing and burning forested areas.    Scientists can  calculate both the amount of CO2 produced by human activity (which has greatly increased in the last 150 years) and the capacity of oceans and forests to absorb CO2.  Excess CO2  — the difference between the amount produced and the amount taken up by  the oceans or by plant life — goes into the atmosphere. Atmospheric CO2  significantly increased  as CO2 emissions from industry and energy generation spiked,  indicating a large human  contribution. Human  activity  also  overwhelms   CO2  increases associated with  natural sources like volcanic eruptions.

2. Studying the atomic “fingerprints” of atmospheric CO2. Not all carbon atoms are created the same. Elements like carbon can occur in different forms (called “isotopes”) based on the number of neutrons in each atom. Carbon occurs as three isotopes — 14C (radioactive and least common), 13C (about 1% of carbon isotopes) and 12C (the most common).  Fossil fuels like oil and coal contain  no 14C because the radioactivity has long since  decayed.  Both plants and fossil fuels  tend to have a low ratio of 13C to 12C. Scientists have found that the mix of atmospheric CO2 has become “lighter” in the last 150 years. An increase in carbon associated with plant-based fossil fuels seems to  have changed the ratio of “light” carbon to “heavy” carbon in the atmosphere. The change has tracked the significant increases in CO2 emissions from combustion of  fossil fuels for industrial purposes and electricity generation.

What kinds of human activities contribute to atmospheric CO2? Based on reporting of greenhouse gas emissions, the U.S. Environmental Protection Agency has created a chart showing the most significant sources.

gases-co2

Sources:  “How do we know that recent CO2 increases are due to human activities?”, www.realclimate.org, (December 22, 2004); Andrew Freedmen: “The Last Time CO2 was this High,  Humans Didn’t Exist”,  www.climatecentral.org, (May 2, 2013); World Meteorological Organization: 2013 Global Greenhouse Gas Report; NOAA Earth Science Research Laboratory, Global Monitoring Division website; Scripps CO2 Program website; “Sources of Greenhouse Gas Emissions”, U.S Environmental Protection Agency website; NASA:Vital Signs of the Planet: Carbon Dioxide; Caitlyn Kennedy: “Earth’s Hottest Topic is Just Hearing Up”, www.climate.gov (2009).

A Citizen’s Guide to Climate Change, Part I: Temperature

January 30,  2015. Controversy over EPA’s proposed carbon reduction rule (see an earlier post)  has again focused attention on the  climate change debate.  This post will look at global  temperature trends as reported by the National Oceanic and Atmospheric Administration (NOAA) and the National Aeronautic and Space Administration (NASA).

The most recent temperature data. In  2014, the average combined land and sea surface temperature on Earth reached the highest level since modern record-keeping began in the 1880s.   The latest temperature data can be found in the National Oceanic and Atmospheric Administration (NOAA)   2014  Global Climate Report here. Similar results reported by  NASA can be found here. Although NOAA and NASA use somewhat different baselines and methods, the two agencies reached very similar results. NASA calculated an increase of 1.4 ° (F) over the historical baseline; NOAA found an increase of 1.24° (F). Both found that higher ocean temperatures made a slightly greater contribution to the total increase than land surface temperatures.

The  chart below has been adapted from a NOAA Chart showing the ten warmest years on record based on the global average temperature. All of those years, with the exception of one, have occurred since 2000.  The third  column shows the increase in temperature by reference to the historical average (1880-2014).

Rank (1=Warmest) Year Increase (Fº)
1  2014  +1.24
2 (Tie) 2010/2005  + 1.17
4 1998  +1.13
5 (Tie) 2013/2003  +1.12
7 2002  +1.10
8 2006  +1.08
9 (Tie) 2009/2007  +1.06

Some temperature fluctuation from year to year can be accounted for by El Nino (warming) and La Nina (cooling) trends in the Pacific Ocean, but the 2014 high occurred under neutral El Nino conditions.  Find the original NOAA chart and other information about NOAA’s  2014 temperature analysis here.

NOAA also provides a bar chart showing the trend in global temperature over the entire period

Comparison to past temperature variation on Earth. Scientists have estimated average global temperature during past warming and cooling  periods based on a variety of natural records — glacial ice, tree rings, geological formations, and fossils. There have been periods in the past when Earth’s average temperature was much higher than it is now.  But once Earth cooled down from a hot rock to  a planet capable of supporting life,  the warming event that followed the last ice age occurred  very slowly.  See NOAA’s  introduction to  climate history here.   The overviews of historical climate studies provided by NOAA and by NASA’s  Climate Observatory  put  context around recent temperature increases:

♦  Earth’s average temperature varies from year to year in response to many influences,  but in recent  decades, the cooler years have represented “noise” in an overall upward trend.

♦ Earth’s climate has been relatively stable for much of the history of human civilization (the past 10,000 years).

♦ The last significant warming period (which  began around 11,000  years ago) led to an increase in the Earth’s average surface temperature of between 7° – 12° F.  That warming occurred very gradually  over a period of about 5,000 years and then another cooling trend began.

♦  The current warming trend began in the 20th century and temperature increases are happening  10  times  times faster than the last  ice age  warming period. (NASA).

For more detail on climate history, both the NASA and NOAA  sites provide links to the scientific studies used as references.

Do these increases in global temperature matter?  An increase of 1.4° F over the average global surface temperature seems — and is —  small, but  even small increases can affect patterns of plant and animal life.  In 2012,  the  U.S. Department of Agriculture released an updated U.S.  plant  hardiness zone map.  The map divides the U.S. into  zones based on the average annual low temperature;  going from north to south, each zone on the map represents  a 10° increase in the average low temperature. By comparison to the 1990 map, the new map shows a half-zone shift (or  5° F) toward the warmer zones. USDA has been careful to say the data sets for the 1990 and 2012 maps differed in a number of ways — the new map reflects data from more  locations and use of more sophisticated technology as well as additional years of data.  But the shifts are consistent with the general trend in global temperature data since the 1980s and suggest that farmers and gardeners  may already be seeing changes affecting plant life.

While a  1.2°- 1.4° increase in the average temperature over 30 years may already be affecting   the environment, concern about rising global temperature really focuses on the future. Two of the greatest concerns:

1. The rapid pace of warming and the unknown stopping point. Earth’s last major ice age warming event took place over a period of 5,000 years and at a time before modern human civilization and reliance on large-scale agricultural production.   Earth’s current  warming  is occurring  at a much faster rate (as much as 10 times faster), increasing the risk that plant and animal life may not be able to adapt quickly enough to changing temperature regimes. While Unites States agriculture has not been harmed by  the  1.2 – 1.4 ° (F) increase in recent decades,  it could be much more difficult to maintain agricultural productivity in the face of continuing, rapid temperature increases.  Other, warmer,  parts of the globe will be much more vulnerable to agricultural disruption because of temperature increases. Temperature increases can also   affect other human food sources like fisheries.

2. The chain-reaction effect of rapid warming on other parts of the human environment. The chain reaction talked about most often:

Higher global temperature ⇒ melting of land ice ⇒more rapidly rising sea levels ⇒ flooding of coastal areas.

The potential for accelerated sea level rise gets attention because of the direct risk to human populations. In 2010, 39%  of the population of the U.S. lived in a shoreline county;  more than half of the population lived within  50  miles of an ocean shoreline. (Source: U.S. census data as reported in NOAA’s State of the Coast Report.)  As a result, accelerated sea level rise could affect some  of the most highly populated areas in the United States.

Note: NASA’s Vital Signs of the Planet website provides visualizations of  changes in the extent of sea ice and land ice.

How reliable is the data?   Temperature records date back to the 1880s and the amount and quality of the data has only gotten better.  NASA describes the records used in the Goddard Institute of Space Sciences temperature calculations this way:

The GISS analysis incorporates surface temperature measurements from 6,300 weather stations, ship- and buoy-based observations of sea surface temperatures, and temperature measurements from Antarctic research stations. This raw data is analyzed using an algorithm that takes into account the varied spacing of temperature stations around the globe and urban heating effects that could skew the calculation. The result is an estimate of the global average temperature difference from a baseline period of 1951 to 1980.

Next: The role of carbon dioxide and other “greenhouse” gasses in raising global temperature.