A Quarterly Publication of Zephyr Environmental Corporation | JANUARY 2015 O Whatever Happened to the Ozone Hole? zone in the air we breathe is a hot topic for environmental regulators today. Just last month, EPA proposed another round of tightening of the National Ambient Air Quality Standards for ozone. However, three decades earlier, the world’s attention was drawn to the blanket of ozone trapped in the portion of the atmosphere between 30,000 and 50,000 feet above the earth’s surface known as the stratosphere. This layer of ozone protects the earth from the sun’s ultraviolet (UV) radiation — a type of radiation that, in excess, increases the incidence of skin cancer and cataracts, reduces crop yields, and disrupts the marine food chain by destroying plankton in the ocean. And scientists had found a hole in the ozone layer. Ozone is destroyed by certain chlorine- and brominecontaining chemicals, which are used as refrigerants, pesticides, solvents, and fire extinguishers. While most of these substances, referred to as ozone depleting substances (ODSs), are extremely stable in the lower atmosphere, after they reach the stratosphere, the sun’s UV radiation causes them to release chlorine and bromine atoms which react, in turn, to destroy the ozone. One chlorine atom can destroy 100,000 ozone molecules, and bromine atoms are even more destructive than chlorine atoms. In 1976, the United States Academy of Sciences linked the release of ODSs to ozone depletion, and subsequent studies confirmed this relationship. In response, representatives from 24 countries signed the 1987 Montreal Protocol on Substances that Deplete the Ozone Layer, agreeing to start phasing out the manufacturing of ODSs in 1989. The treaty has been amended several times, and today more than 190 countries have ratified it. In a 2014 article celebrating the 25th anniversary of implementing the Montreal Protocol, the Associated Press acclaimed the treaty “one of the great success stories of international collective action in addressing a c o n s u l t i n g u global environmental change phenomenon.” But before trumpeting the Montreal Protocol as a ‘great success story,’ it’s important to look at the facts. Has the treaty actually accomplished what it set out to do? The National Aeronautics and Space Administration (NASA) and the National Oceanic and Atmospheric Administration (NOAA) have monitored the ozone layer and stratospheric concentrations of ODSs since the 1970s. However, concerns were not raised until the 1980s, when measurements first showed a significant reduction in the ozone layer during September and October, giving the appearance of a hole over Antarctica — a phenomenon that was later observed over the Arctic. Even with reductions in ODSs under the Montreal Protocol, the situation didn’t immediately improve. From a size over 3.3 million square kilometers in 1980, NASA and NOAA measurements showed that the ozone hole grew by 900 percent to a peak area of 29.9 million square kilometers by 2000. In the last 15 years, the size of t r a i n i n g ozone hole >>> continued on page 8 u d a t a s y s t e m s FROM THE TRENCHES We’re Going on a Toad Hunt S ometimes you get more than you bargain for. That was the case when Zephyr was awarded a project to obtain the environmental permits for a new crude oil pipeline in Texas. The project began with conducting the usual environmental constraints analysis, followed by an extensive field survey of the entire 450 miles of the proposed right-of-way (ROW). We soon discovered the ROW would pass right through the potential habitat of a federally endangered species, the Houston toad. We met several times with the client to discuss whether the pipeline could be re-routed around the habitat, or if we could go under it, or if we could go over it, or if we must go through it. It reminded me of a game I played as a child with my grandmother called “We are going on a bear hunt.” Her answer always seemed to be “we must go through it.” As it turns out this project was no different; we had to go through it. Zephyr has considerable experience in assessing threatened or endangered species habitat, but this project was unlike anything that had been attempted within Houston toad habitat. Years ago, a Houston toad had actually been heard at a nearby pond, but there were no visual sightings to confirm that the toad occupied the woods and ponds of Robertson County adjacent to the proposed ROW. Therefore, we had to choose one of two options: A) assume that the project area was occupied by the Houston toad and prepare to mitigate the project’s impacts on the species habitat, or B) conduct up to three years of surveys to verify whether the toad actually occupied the area. This was a pivotal choice; if we selected option B) our client would not be able to meet the aggressive project schedule. As we considered our options, we consulted with the Houston toad species expert (yes, the Houston toad has a species expert). As expected, he first asked “Can’t you go around it?” But after our explanation, he suggested that we assume that the habitat is occupied by the toad. Then we knew “we must go through it!” Following the expert’s guidance, we began to identify conservation measures to minimize or avoid impacts to the Houston toad and its potential habitat. The mitigation plan based on these measures was submitted to the U.S. Fish and Wildlife (USFWS) and, with some modification, it was approved. Then the real fun began! Our first task was to begin surveys to determine whether the toad still called the area woodlands home. These surveys, conducted at night when conditions were favorable for breeding, consisted of two trained biologists driving to pre-selected spots along roads adjacent to ponds or water features. You may be thinking that it would be hard to see a toad at night from a road — and you’re right. But it’s much easier to hear a toad than see one! When 2 Photo credit: John T. Williams atmospheric conditions are just right the male Houston toad does what most all other toads do, he searches for a mate. He finds the nearest pond and does his best to let every female within earshot know he’s there. The “chorusing” of a Houston toad distinguishes it from all other toads and frogs — its call is described as a high, clear trill that lasts an average of 14 seconds. So imagine yourself, standing along the road at night near a pond, straining to pick out the call of the rare and endangered Houston toad from the cacophony of frogs and toads and crickets. It’s actually quite enjoyable. Most nights we heard many toads and frogs common to the southeastern U.S. Then, on one especially warm and muggy night, from the edge of a road in Robertson County, the call of a lone Houston toad rang out! On that particular night, two project biologists and two representatives of the USFWS were present. The sound was coming not from some distant pond, but from under our very feet! We froze and waited. Waited a long time. Then we heard it again, and there, hidden in the tall grass, was a beautiful specimen of a male Houston toad! So it was confirmed that night that the Houston toad did indeed call Robertson County home. This story has more than one happy ending. Our client was pleased that we had made it possible to complete the pipeline project on time and within our budget. The USFWS was happy because it was possible to construct the pipeline without the “take” of one Houston toad and pleased that a new population of Houston toads had been documented outside Bastrop County. Regarding the Houston toad, he probably would have preferred that we had gone on a “real bear hunt.” Z Steve McVey, PG Principal AN ATTORNEY’S PERSPECTIVE The Daubert Standard and “Abuse of Discretion” I n 1993, the U.S. Supreme Court instructed federal district judges to act as “gatekeepers” to ensure that expert witness testimony is both relevant and reliable before it is presented to a jury. The goal of the Supreme Court in the landmark Daubert decision was to keep so-called “junk science” out of the courtroom. In the aftermath of the decision, most states, including Texas, adopted the standard and even some states that did not formally do so have, nevertheless, encouraged trial judges to act as gatekeepers, albeit under the slightly different Frye standard. Prior to Daubert, the focus was almost exclusively on an expert’s qualifications, not the expert’s methodology. Essentially, if the trial court found the expert qualified, the expert was free to testify about practically anything, no matter how unreliable, so long as it was within the expert’s field. For example, in the litigation from which Daubert arose, medical causation experts (doctors and epidemiologists) testified that Bendectin, a widely prescribed drug for morning sickness, caused birth defects. There was only one problem: over 30 studies comparing the rates of birth defects in women who took Bendectin to the rates in women who didn’t found that the rates were similar in both groups. Indeed, not a single controlled study showed a statistically significant increased risk, but this did not deter the experts hired by Bendectin plaintiffs from attributing birth defects to Bendectin. In Daubert, the Supreme Court outlined four non-exclusive factors relating to the expert witness’s methodology to be considered by district courts in exercising their gatekeeping duties: (1) whether the expert’s theory or technique can be and has been tested, (2) whether it has been subjected to publication in the peer-reviewed literature, (3) the known or potential rate of error associated with the theory or technique, and (4) the degree to which it is generally accepted as reliable by the relevant scientific community. This last factor relating to general acceptance is the Frye standard that Daubert replaced. Daubert essentially ended the Bendectin litigation because courts found that it is not reliable to opine as to medical causation in the face of an overwhelming body of controlled studies refuting the causation hypothesis. Similarly, application of the Daubert standard ultimately ended litigation relating to the theory that silicone breast implants cause autoimmune diseases. In 1992, the FDA announced a moratorium on silicone breast implants in response to safety concerns, and tens of thousands of women sued. As was true in the Bendectin context, more than 25 controlled studies demonstrated that the rate of autoimmune disease was similar in both implanted and non-implanted women. Eventually, courts in both Daubert and non-Daubert jurisdictions began excluding the expert witnesses for the breast implant plaintiffs and the FDA ultimately concluded that silicone breast implants are safe and effective. Has all of this gatekeeping by trial judges resulted in a decrease in junk science in the courtroom? Although there is little empirical research on the topic, the likelihood that an expert opinion will be excluded as scientifically unreliable has increased significantly in the years since Daubert (in both Daubert and non-Daubert jurisdictions). And junk science in the courtroom is still alive and well — the likelihood that an expert will get excluded remains small. All kinds of claims with little scientific basis continue to be litigated in both Daubert and non-Daubert jurisdictions. For example, cases involving various types of air, ground, and/or water emissions have been allowed to go forward even where there is no dispute that the emissions did not violate any regulatory health based standard. How can this be? Three words: abuse of discretion. This is the standard appellate courts use when reviewing a trial court’s decision relating to the admission or exclusion of expert testimony. Trial judges have a great deal of discretion in determining whether an expert’s methodology passes muster under Daubert. The vast majority of appeals involving both the admission and exclusion of expert evidence under Daubert affirm the decision of the trial court. For example, one federal court of appeals affirmed one trial judge who admitted the breast implant causation evidence even though the very same court of appeals had previously affirmed a different trial judge’s exclusion of essentially the very same evidence. Accordingly, perhaps the most important question a litigant can ask with respect to whether a Daubert challenge will be granted or denied is the following: who is the judge? Z David P. Herrick, Esq. Herrick and Associates PC 3 News Briefs national news EPA Proposes More Stringent Ozone Standard On December 17, the U.S. Environmental Protection Agency (EPA) proposed to lower the national ambient air quality standards (NAAQS) level for ozone (O3) to 65-70 ppb. However, EPA isn’t ruling out retaining the current 75-ppb level and is accepting comments by March 17, 2015 on an even lower 60-ppb standard. The proposal also addresses implementation timing and procedures, extending the O3 monitoring season, and changes to monitoring requirements. Under a separate rulemaking, EPA is considering revising how it determines whether a source causes or contributes to a violation of the NAAQS. EPA is under a court order to make a final O3 NAAQS determination by October 1, 2015. For more information, contact Lucy Fraiser at 512.879.6652 or [email protected] CO2 Emissions from Electric Power Generation Trend Downward According to an October Energy Information Administration report, U.S. energy-related carbon dioxide (CO2) emissions have decreased in five of the past eight years. Notably, 2013 power plant CO2 emissions were about 15 percent lower than 2005 levels, mainly due to lower than expected electricity demand, replacement of coal- and oil-fired generation with natural gas-fired units, and increased use of renewable energy sources such as wind and solar power. Despite the overall 8-year trend, market conditions in 2013 and 2014 have made coal generation more economically attractive, leading to a small rise in power sector CO2 emissions. For more information, contact Lou Corio at 410.312.7912 or [email protected] OSHA Seeks Input on Managing Chemical Exposures in the Workplace On October 10, the Occupational Safety and Health Administration (OSHA) requested stakeholder input on best approaches and strategies for regulating chemicals in the workplace. In its evaluation of procedures for reducing and controlling exposures to workplace chemicals, OSHA is considering updating permissible exposure limits. Public input must be received by April 8, 2015. For more information, contact Molly McKenna at 512.579.3837 or [email protected] EPA Makes Preliminary Determination to Regulate Strontium in Drinking Water On October 20, EPA made a preliminary determination to regulate strontium in drinking water due to the potential adverse health effects of this chemical — at elevated levels, strontium can weaken bones in persons who are calcium deficient. EPA intends to decide in 2015 whether to move forward with rulemaking. For more information, contact Miranda Briones at 512.879.3957 or [email protected] Final EPA Climate Change Adaptation Plan Released On October 31, the White House released the final version of EPA’s Climate Change Adaptation Plan — a document identifying how EPA’s mission is vulnerable to climate change and describing planning EPA needs to conduct to ensure it will be able to continue to fulfill its mission in the face of climate change. Vulnerabilities identified include, among other things, impacts of changing precipitation patterns on long-term water infrastructure, impacts of more intense weather events on disaster response, and climate change impacts on ozone air quality. The plan was prepared in response to a 2013 presidential executive order that federal agencies develop plans to adapt their programs to the effects of climate change. For more information, contact Lou Corio at 410.312.7912 or [email protected] 4 Court Lifts Stay on Cross-State Air Pollution Rule On October 23, the D.C. Circuit Court of Appeals ordered that its 2011 stay of EPA’s Cross-State Air Pollution Rule (CSAPR) be lifted — an action consistent with the Supreme Court’s April 2014 decision upholding CSAPR (see July 2014 issue of Currents). In response to the latest ruling, EPA, on November 21, amended the dates by which CSAPR emissions budgets must be implemented, pushing forward the first phase of emissions reductions to 2015 and 2016 and the second phase to 2017 and beyond. Other amended deadlines include those for 1) monitoring system certification, 2) emissions reporting and allocation, 3) emissions allowances recording, 4) revision of state implementation plans (SIPs), and 5) sunsetting of the Clean Air Interstate Rule (CAIR). In a parallel December 3 action, EPA provided notice of revised emissions allowances allocations to existing generating units. For more information, contact Roger Brower at 410.312.7907 or [email protected] state news EPA Approves GHG Permitting Program in Texas In two actions on November 10, EPA formally handed over authority of the Texas greenhouse gas (GHG) Prevention of Significant Deterioration (PSD) permitting program to the Texas Commission on Environmental Quality (TCEQ). In the first action, EPA approved the revisions to the state’s GHG PSD permitting rules, and, in the second, EPA withdrew the federal implementation plan (FIP) that had previously established EPA as the Texas GHG permitting authority. The TCEQ has updated its new source review air quality permit application Form PI-1 to accommodate GHG permitting. For more information, contact Eric Quiat at 512.579.3823 or [email protected] TCEQ Kicks-Off Expedited Air Quality Permitting On November 13, the TCEQ issued rules providing for expediting air quality permit reviews (see July 2014 issue of Currents). Under the new rules, the TCEQ may, subject to the availability of agency resources, expedite the review of applications for permits by rule, new source review and standard permits, and Title V permits if applicants can demonstrate the projects will “benefit the economy of this state or an area of this state.” To expedite an application, the applicant must submit the new Expedited Permitting Request Form APD-EXP and pay a surcharge sufficient to cover the expenses incurred by the TCEQ in expediting the review. For more information, contact Kristin Parsons at 512.579.3842 or [email protected] EPA Proposes Reductions in Haze-Forming Emissions from Texas Power Plants On December 16, EPA proposed to partially approve and partially disapprove the Texas plan for protecting visibility in national parks and wilderness areas from the effects of haze-forming pollutants emitted in Texas. To remedy shortcomings identified in the plan, EPA proposed a FIP that sets emission limits for 15 of the state’s coal-fired electric generating units. The FIP would rely on sulfur dioxide scrubber retrofits or upgrades on the affected units but would not mandate particular technologies. Sources requiring scrubber retrofits would have five years to meet the new emission limits, and sources that require only scrubber upgrades would have three years. For more information, contact Bob Breeze at 512.879.3671 or [email protected] TCEQ Continues to Seek Input in Developing TPDES Temperature Screening Procedures The TCEQ will continue to host meetings through March 2015 seeking stakeholder input on Texas Pollutant Discharge Elimination System (TPDES) permitting screening for potential compliance of industrial wastewater thermal discharges with receiving water temperature limits. Until EPA approves the TCEQ’s thermal discharge evaluation procedures, it will accept the use of interim TPDES permit conditions, which require that an applicant develop a plan to characterize the thermal plume resulting from industrial wastewater discharges that have temperature as a contaminant. For more information, contact Dave Sorrells at 512.879.6626 or [email protected] Maryland Study Concludes Fracking Can Be Safely Managed In a November report, the Maryland Department of the Environment (MDE) and the Maryland Department of Natural Resources (DNR) concluded that natural gas production from the Marcellus Shale via hydraulic fracturing (fracking) can be managed without unacceptable risks to public health, safety, the environment, and natural resources, provided that all recommended best practices are followed and that the state is able to rigorously monitor and enforce compliance. Best practices include applicant development and state approval of a mandatory comprehensive gas development plan and applicant submittal of an environmental assessment as a condition of receiving a drilling permit. The Maryland portion of the Marcellus Shale formation underlies only Garrett and Allegany Counties. For more information, contact Lou Corio at 410.312.7912 or [email protected] TCEQ Proposes to Lift Penalty Fees for Failure to Comply with Old Ozone Standard On November 19, the TCEQ proposed to revise its existing ozone NAAQS compliance agreement with EPA to remove obligatory penalty fees assessed on sources in the Houston-GalvestonBrazoria (HGB) area for failure of the area to meet a November 2007 deadline to comply with the 1979 one-hour ozone NAAQS — a standard that was revoked in 2005. The TCEQ proposed revision anticipates EPA’s mid-2015 passage of rules that would provide a mechanism for a state to lift such obligations. To qualify for the lifting of penalty fees under the mechanism proposed by EPA, the TCEQ would be required to demonstrate that the area is now and will remain in attainment with the revoked standard for the next 10 years. For more information, contact Curtis Harder at 512.879.6643 or [email protected] Pennsylvania Revises Ozone Precursor Emissions Limits for Existing Major Sources In November, the Pennsylvania Department of Environmental Protection (PADEP) revised its Reasonably Available Control Technology (RACT2) rules for controlling emissions of ozone precursors (nitrogen oxides and volatile organic compounds) from news briefs >>> continued on page 6 5 news briefs >>> continued from page 5 existing major sources. The affected source categories include electric generating units, combustion units, and cement kilns. Under the rule changes, presumptive emission limits for combined-cycle and larger simple-cycle combustion turbines have been relaxed, facilities that need to install controls to meet either the presumptive or approved alternative limits may petition PADEP for up to a 3-year extension of compliance with the limits, and the facility-wide or system-wide nitrogen oxide (NOx) emission averaging scheme for meeting RACT limits has been modified — a change that will benefit sources that need to average. PADEP estimates that with the implementation of the final RACT 2 rules, NOx emissions will be reduced by 42 percent compared to current RACT allowable emissions. The final rule is expected to go into effect by mid-2015. For more information, contact Lou Corio at 410.312.7912 or [email protected] TCEQ Removes Benzene and Hydrogen Sulfide from the Texas City Watch List On November 13, the TCEQ finalized the removal of benzene and hydrogen sulfide from the Texas City Air Pollution Watch List (APWL) area (see October 2013 issue of Currents). Texas City, however, remains on the APWL for propionaldehyde. TCEQ will post a revised APWL map and additional information regarding the delisting on its website. For more information, contact Jill Parkes at 512.579.3836 or [email protected] Maryland Proposes Historical Hazardous Substance Release Reporting Rule On October 31, the MDE proposed to change to its hazardous substance response plan rules to require reporting of previously unreported information regarding past hazardous substance releases. A person who possesses a sample result or other environmental assessment that indicates the presence of a released hazardous substance at or above an MDE clean-up standard would be required to report the information to the MDE. Information of this kind is commonly generated during property acquisitions, site investigations, and routine operations, and is not always shared with the MDE. For more information, contact David Mahler at 410.312.7909 or [email protected] Foundation Announces $13.2 Million for Gulf Restoration Projects in Texas On November 17, the National Fish and Wildlife Foundation announced roughly $13.2 million in grants of criminal settlement funds from the Deepwater Horizon oil spill litigation to finance 6 expansion of wildlife refuges, restoration of threatened habitat, and protection of habitat from erosion along the Texas Gulf Coast. These projects are designed to remedy harm or reduce the risk of future impacts to natural resources impacted by the 2010 spill. The $13.2 million grant is only a small portion of the $203 million to be allocated over a 5-year period for the state of Texas. For more information, contact Bob Fisher at 281.668.7349 or [email protected] TCEQ Considers Changes to Evaporation Pond General Permit In March 2014, the TCEQ issued a new general permit to authorize the disposal of wastewater by evaporation from surface impoundments adjacent to waters of the state. With this issuance, all wastewater evaporation ponds must be authorized either under the general permit or another permitting mechanism. The TCEQ is considering changes to the general permit to allow certain existing evaporation ponds that previously had obtained a Texas Land Application Permit or had provided notice to the TCEQ in accordance with 30 TAC §335.2(d) and §335.6 that was acknowledged in writing, prior to the effective date of this general permit amendment. Following a December 11 stakeholders meeting, the TCEQ is considering whether conditionally exempt small quantity generators that use evaporation ponds were required to notify the TCEQ under §335.6 and receive written acknowledgement of the ponds. The TCEQ is requesting stakeholder input on the proposed general permit changes. For more information, contact Betty Moore at 512.879.6622 or [email protected] Fifth Circuit Denies Request to Reopen Whooping Crane Case On December 15, the Fifth Circuit of Appeals denied a petition by plaintiffs to reopen the issue of whether the TCEQ failed to manage the waters of the Guadalupe River, resulting in the death of endangered whooping cranes in 2008 (see April 2013 issue of Currents). The Court’s December decision upholds a June 30 decision of a panel of this court reversing the 2013 decision of the Corpus Christi District Court to enjoin the TCEQ from issuing permits to withdraw water that flows to the estuary where the whooping cranes spend the winter The plaintiffs in the case have 90 days to file an appeal with the U.S. Supreme Court. For more information, contact Clay V. Fischer at 512.879.6629 or [email protected] Z FROM THE PRESIDENT Is it Time for a New Green Revolution? T he “green revolution” was a seminal development in the history of humanity. It commonly refers to a series of research, development, and technology transfer initiatives that occurred between the 1940s and the late 1960s, in which global agricultural production increased dramatically. The initiative is credited with saving over a billion people in the developing world from starvation and has led to food security for most of the world. One net result is that our planet is sustaining over seven billion human lives, with all the creative energy and demand for resources that implies. But agricultural researchers are very concerned as to whether our current agricultural practices are sustainable. As noted in the December 2014 issue of Scientific American, it takes 1,000 years to generate three centimeters of topsoil. According to a senior UN official, at current rates of degradation the world’s topsoil could be gone within 60 years (nearly a third of the world’s topsoil has already been degraded). The causes of soil degradation include chemical-heavy farming techniques, deforestation which causes erosion, and global warming. An official with the Food Agricultural Organization said that unless new approaches are adopted, the global amount of arable and productive land per person in 2050 will be only a quarter of the 1960 area. This is hugely problematic considering ninetyfive percent of our food comes from the soil. No comprehensive solutions are apparent, although organic farming proponents suggest that organic farming could be a big part of the solution. Z I would like to add a quick note to announce Zephyr’s new office in York, Pennsylvania. Our team of qualified consultants in York will appreciably add to our ability to deliver our Mid-Atlantic clients all of the services Zephyr provides. More information can be found on our website at www.zephyrenv.com. Joe Zupan President Zephyr is a full-service environmental, health, and safety firm offering consulting, training, and data systems services to clients worldwide. We specialize in air and water quality, waste management and cleanup issues, incident management, natural resources, and workplace and community safety. Currents is published quarterly by Zephyr Environmental Corporation, is edited by David Cabe of Cabe Environmental Solutions, and designed by Allen Griffith of Eye 4 Design. Current and past issues of this newsletter are available at our website. For more information about Currents, or to add your name to our subscription list, please email: [email protected] or visit www.zephyrenv.com. 7 PRSRT STD U.S. POSTAGE PAID AUSTIN,TEXAS PERMIT NO. 1718 Corporate Headquarters 2600 Via Fortuna Suite 450 Austin, Texas 78746 Visit Zephyr’s web sites: www.zephyrenv.com and www.HazMatAcademy.com ozone hole >>> continued from page 1 the ozone hole has not shown any real trends, varying from 29.6 million square kilometers in 2006 to 21.1 million square kilometers in 2012, with little change in the past two years. These trends are generally corroborated by the World Meteorological Organization (WMO) and the United Nations (UN), who reported in their Twenty Questions and Answers about the Ozone Layer: 2010 Update that stratospheric ozone declined over most of the planet during the 1980s and early 1990s, and has remained relatively unchanged since 2000. The trends in levels of stratospheric ozone since 1989 beg the question: why is the ozone hole today bigger than it was before Montreal Protocol ODS emissions reductions began? According to the WMO/UN report, total annual emissions of ODSs, on a basis weighted by their potential to destroy ozone, steadily increased until 1990 and then began decreasing. However, the ozone hole continued to grow for another 10 years, maxing out in 2000 at 29.9 million square miles. The WMO/ UN report states that by 2010, emissions of ODSs had dropped to one-third of their 1990 levels and that measured stratospheric concentrations of chlorine- and bromine-containing substances originating from ODSs had finally started to decline, but by only about 10 to 15 percent from their peak values 10 to 15 years earlier. The WMO and the UN concluded that “actions taken under the Montreal Protocol . . . are enabling the return of the ozone layer toward 1980 levels.” A December 11, 2013 press release by NASA’s Goddard Space Flight Center is more cautious about the effec- tiveness of ODS bans on the restoration of stratospheric ozone. According to NASA, “We are still in the period where small changes in chlorine do not affect the area of the ozone hole, which is why it’s too soon to say that the ozone hole is recovering.” In one study, NASA evaluated the ozone holes of 2006 and 2011, two of the largest in the past decade, and was surprised to find that they contained different amounts of ozone-depleting chlorine. Using a model designed to simulate the influence of chemical and meteorological factors, scientists simulated the effects on stratospheric ozone levels of “turning off” ozone-destroying chemical reactions. From this modeling, NASA concluded that until chlorine levels in the lower stratosphere decline below the early 1990s level (expected by 2030), wind patterns and temperature, not the levels of ozonedepleting chlorine, will dictate the variable area of the hole in any given year, and that stratospheric ozone concentrations will not reach 1980 benchmark levels until the middle to last half of this century. At first blush, the strategy to address stratospheric ozone depletion seems relatively simple: reduce emissions of ODSs and shrink the ozone hole. However, the data and the models suggest that the chemical and meteorological relationships between ODSs and stratospheric ozone levels are anything but simple and that restoration of stratospheric ozone is not occurring along the timelines originally predicted. Z Jennifer Sharp Seinfeld Principal © 2015, All Rights Reserved, Zephyr Environmental Corporation. No part of this publication may be copied or used without the permission of Zephyr Environmental Corporation.
© Copyright 2018