As so clearly articulated by Blumm, Michael C. and Wood, Mary C., in their analysis of Juliana v. United States, while governments continue to waffle on implementing measures to mitigate or adapt to climate change, "there is little or no scientific question that the world has entered an era of climate instability, if not imminent catastrophe." 2016 marked the year that atmospheric carbon dioxide officially passed the symbolic 400 parts per million mark, "never to return below it in our lifetimes." Nine of the ten hottest years on record have occurred since 2005. Thermal expansion of warmer waters and melting ice from Antarctica and Greenland, is incrementally accelerating the rate of global sea level rise over time rather than, as previously thought, increasing at a steady rate. By 2100, chronic flooding will impact coastal cities. A recent study found that 670 coastal communities in the United States, including Cambridge, Massachusetts; Oakland, California; Miami and St. Petersburg, Florida; and four of the five boroughs of New York City will be affected. Canadian cities such as Charlottetown, Halifax, and Vancouver are also vulnerable.

Over the last few years, there has been an irrepressible push towards utilizing courts to accomplish what elected governments will not. According to a recent UN Environment Programme analysis on the status of global environmental litigation, as of March 2017, over 900 climate change cases have been filed in 25 countries (including the European Union), with 654 cases filed in the U.S. and over 230 cases filed in all other countries combined. Judges are becoming increasingly open to hearing arguments that would place responsibility for climate change with governments and businesses. The sheer number of cases brought forth, and specifically the NYC v. Oil and Gas Corps. case, has also arguably led an Ontario legislator to introduce a Bill making it easier to force fossil fuel companies to pay for infrastructure improvements needed to protect communities from climate impacts. The bill, Liability for Climate-Related Harms Act of 2018, would impose strict liability—liability without proof of fault—on fossil fuel companies for climate impacts and is similar to legislation used to hold tobacco companies liable. This is perhaps not so surprising considering research [for eg. the articles by Ekwurzel, B. et al., Frumhoff, P.C., et al., and Heede, R.] that quantifies the contributions of historical emissions to global warming has found a surprisingly limited number of organisations responsible for global warming.

Notable Climate Litigation Cases

Some notable ongoing climate litigation cases include, the youth led case of Juliana v. United States, the Peruvian farmer's case against the largest German energy company, RWE, the suit against Norway for approving new oil and gas leases in the Arctic Ocean, the California communities (plus San Francisco and Oakland), trying to make fossil fuel companies pay for the climate impacts their products have already caused and will cause in the future, and most recently, the city of New York against five of the largest oil and gas corporations in the world. These cases have employed a wide range of legal strategies in an attempt to hold accountable those most responsible for climate change.

Juliana v. United States involves 21 individual plaintiffs, all aged 19 or younger at the time of the original claim in 2015, who contend that the federal government is failing to protect their constitutional rights to life, liberty and property through energy policies that promote wholesale fossil fuel development. The plaintiffs requested the federal district court to compel the defendants to take action to reduce carbon dioxide emissions so that atmospheric carbon dioxide concentrations will be no greater than 350 parts per million by 2100. On March 7, 2018, the Ninth Circuit Court of Appeals ruled that the United States had not met the "high bar" for the appellate court to order a district court to dismiss the climate change lawsuit and that the matter should proceed to trial.

In a case similar to that of Juliana v. United States, Nature & Youth together with Greenpeace Nordic have sued the Norwegian government for approving new oil and gas leases in the Arctic Ocean. The case was heard on November 14, 2017, in the Oslo District Court where the environmental groups argued that the Norway government is failing to uphold a section of its constitution that guarantees the right to a healthy environment. The plaintiffs contend that the government failed to protect its citizens' rights when it granted the permits that in effect created new sources of greenhouse gas emissions. The plaintiffs seek the invalidation of 10 licenses granted by the government to 13 companies that opened up a new section of the Arctic to oil exploration.

In 2015, Saul Luciano Lluiya argued before a German court, that RWE, Germany's largest power company and one of the world largest emitters of carbon dioxide, must cover its share of the expenses for climate change adaptation measures to protect Huaraz. Huaraz, Mr Lluiya's hometown, is at risk from a glacier lake overflowing from melting snow and ice. Mr. Lluiya is seeking a judgment of $20,000 and he Higher Regional Court Hamm issued a decision on November 30, 2017, overruling a lower court to declare the case should proceed.

In 2017, five California municipalities (on July 17 San Mateo County, Marin County, and the City of Imperial Beach as a first group, and on September 20, San Francisco and Oakland as a second) filed statements of claim against many of the world's largest oil and gas companies. The long list of companies include Chevron, ExxonMobil, British Petroleum ("BP"), Shell, Citgo, ConocoPhillips, Phillips 66, Peabody Energy, Total, Eni, Arch Coal, Rio Tinto, Statoil, Anadarko, Occidental, Repsol, Marathon, Hess, Devon, Encana, Apache, and unspecified "Company Does." The plaintiffs allege these companies are responsible for about 20% of global greenhouse gas ("GHG") emissions from 1965 to 2015, an amount which is a "substantial portion" of the climate change problem.

The two other California cities, San Francisco and Oakland, filed their complaints against five oil and gas companies, ExxonMobil, British Petroleum ("BP"), Chevron, ConocoPhillips, and Shell to hold them accountable for billions of dollars of current and future damage from their role in global warming-driven sea level rise. The lawsuits allege the companies are "substantial contributors" to the public nuisance of global warming which they have knowingly exacerbated, with their products, for decades. The complaints also allege that the companies, rather than taking steps to mitigate the harm, utilized the methods of tobacco companies to undermine climate science and mislead the public by claiming fossil fuel production is environmentally responsible. Both cities are asking the California Superior Court to compel the five oil and gas companies to fund a sea level rise abatement program that will be used to protect about $49 billion in San Franciscan public and private property and between $22 and $38 billion for threatened Oakland property. The cities cited research that says sea level may rise up to 10 feet by 2100, causing "catastrophic" damage.

NYC v. Oil and Gas Corps.

The latest US jurisdiction filing a claim as part of the growing list of climate litigants includes New York City ("NYC"). On January 9, 2018, NYC filed a lawsuit against five of the largest oil and gas corporations doing business in New York State - BP, Chevron, ExxonMobil, ConocoPhillips, and Shell (collectively, "defendants"). As described by Giulio Corsi in an excellent overview of the case, NYC has made virtually the same argument as San Francisco and Oakland in bringing its complaint against the same five fossil fuel corporations. In its complaint, NYC alleges that these five corporations knowingly discharged a significant amount of all the GHG emissions from industrial sources that account for over 11% of all the carbon and methane pollution has accumulated in the atmosphere since the Industrial Revolution. That while knowing for decades that their products were altering the atmosphere and causing global warming, the defendants acted to protect their own assets while orchestrating a campaign of deception and denial regarding the risks of climate change and promoting fossil fuel use. A campaign that continues today. Under the 'polluter pays' principle, the defendants actions in producing, marketing, and selling fossil fuels for decades and at ever more dangerous levels while knowing of the harm that was substantially certain to occur leaves them responsible for the costs of remediation.

NYC relies on three main causes of action to argue that the continued activities of the five corporations resulted in the torts of public nuisance, private nuisance, and trespass against the City; the fundamental legal principles underpinning environmental law in common law jurisdictions including the U.S. and Canada.

Public Nuisance

Public nuisance in the United States is defined as "an unreasonable interference with a right common to the general public." For the interference to be actionable, the defendant must exert a certain degree of control over its source. Traditionally, the scope of nuisance claims has been limited to interference connected with real property or infringement of public rights. Public nuisance is a well established cause of action that has been successfully employed on a number of occasions in US legal history, including in such high-profile public interest suits brought over tobacco, asbestos, lead paint, guns, cigarettes, the gas additive MTBE, global warming, opioids, polychlorinated biphenyls, and contaminated drinking water.

NYC's claim of public nuisance is based on the undue threat or harm to its public areas and residents from the effects of climate change, the proximate cause of which is the defendants' promotion and commercialization of fossil fuels. The defendants' conduct, as alleged by NYC, has been a "substantial factor" in causing and continuing to cause sea level rise and extreme weather events such as floods, storms, and high temperatures, forcing NYC to take proactive steps to protect itself and its residents. In support of its argument, NYC describes the damages that New York suffered from the aftermath of Hurricane Sandy. In 2012, Sandy left NYC with 43 dead, and $19 billion in damages. It provided a stark illustration of the city's vulnerability to the impact of climate change. As noted by Giulio Corsi and worth repeating here: "If these arguments are proven, it would follow that under the 'polluter pays' principle, the defendants should cover all of the costs for remediation and reparation deriving from the stated climate change-related incidents."

The allegation of a "substantial portion", "substantial contributors", and "substantial factor" made by the California cities and NYC is legally significant. To establish liability, plaintiffs must demonstrate the causal link between the defendants and the alleged harms. Establishing this link is challenging when the harms alleged are attributed to climate change. Global climate change, of course, cannot be linked to any single actor, and similarly, sea level rise and its repercussion are attributable to multiple factors, including climate change. The allegation can be refuted by the defendants by arguing that they are not the only parties who can or should bear responsibility or blame. However, as noted by Michael Burger, causation can be demonstrated by proving that the defendants are a "substantial factor," or that they contributed significantly to the harm. Relying on a cumulative carbon analysis, plaintiffs may make a strong case that that standard is met.

Private Nuisance

In the U.S., a private nuisance is defined as an interference with the use or enjoyment of land that causes an injury in relation to an ownership right in the land. Actionable conduct for a private nuisance is similar to that of a public nuisance except the interest in property involved is private. NYC claims the conduct of the defendants that led to the undue threat or harm to its public areas and residents also threatens property that uniquely belongs to NYC. In fact, the impacts resulting from the defendants' actions are indivisible injuries, and include harms to City property.

Trespass

Trespass in the New York is the intentional invasion of another's property. A trespasser is liable for property damages caused by his or her action. A trespass may include the unintentional (but inevitable) consequences of an intentional act. In its claim, NYC alleges that the defendants' conduct was a substantial factor in causing global warming impacts, including accelerated sea level rise and concomitant flooding, that resulted in the invasion of the City's property, and should, therefore, be held responsible for trespass.

The implication of the California and New York Cases

Aside from the legal causes of action brought by San Francisco, Oakland, and now NYC, the most compelling facet of these cases is each city's allegation that, for the past forty years, the five oil and gas companies engaged in campaigns of disinformation designed to obfuscate climate science and delay regulation in an effort to protect their business interests. This allegation is formed on the basis of a large number of peer-reviewed articles that demonstrate: 1. the oil and gas companies, and ExxonMobil in particular, were well aware of the risks associated with climate change and the contribution made by their commercial activities, and 2. the companies' systematic efforts to vilify climate science and scientists through advertisements, newspaper articles, and funding disingenuous research.

In its case, NYC provides evidence that the American Petroleum Institute ("API"), a national trade association that represents the interests of the oil and natural gas industry, began warning its members that fossil fuels pose a climate threat as early as the 1950s. By 1968 API was "almost certain" that carbon dioxide emissions, most likely attributable to fossil fuel, would produce "significant" temperature increases by 2000. Some of the fossil fuel companies also produced their own internal analyses of climate change. For example, Exxon knew in the late 1970s and early 1980s that its products posed a considerable threat to the global climate, and that fossil fuel use would have to be significantly reduced to mitigate the harm. Based on their own climate models, by the mid-1980s, many of the world's major oil companies including Exxon, Mobil and Shell, took measures to protect their own infrastructure, including raising the decks of offshore platforms and protecting pipelines from increasing coastal erosion.

NYC's complaint provides further evidence that, despite their foreknowledge, the five oil and gas companies engaged in a public relations campaign to promote their products by downplaying the risks posed by fossil fuels and climate change. These campaigns relied on lobbyists and think tanks to channel large sums of money into creating uncertainties about basic climate change science, and used denialist groups to attack well-respected scientists. Scientists and academics such as aerospace engineer Dr Wei Hock Soon, who received over $1.2 million between 2001 and 2012 from various fossil fuel interests, including Exxon and the API to publish several papers denying the existence of climate change, including one in 2009 attributing climate change to solar activity. In the early 2000s, Exxon again attacked Dr Michael Mann, the scientist who published a peer-reviewed article that included what has come to be known as the "hockey stick" graph, relied on by the IPCC in its 2001 report finding that humans were causing global warming. Exxon sponsored the Fraser Institute, a Canadian organization that specializes in climate denialism with $120,000 over the course of two years (2003–2004) to refute Dr Mann's "hockey stick" graph. In 2003, Senior Fraser Institute Fellow Dr Ross McKitrick, an economist, and Stephen McIntyre a mining company executive co-authored a paper without peer review and without offering Dr Mann and his co-authors an opportunity to respond before publication. The McIntyre and McKitrick paper was subsequently debunked by a number of authors (including Rutherford, S., et al.) but continues to be cited by climate deniers.

The cases brought by San Francisco, Oakland, and New York have particular relevance to a country like the United States, where climate change skepticism is endemic. Now that complaints about oil and gas companies misleading the public about the existence and severity of climate change are being brought to light in the courts, the evidence supporting these claims, if accepted, could result in rulings that finally put to rest numerous climate change myths. Debunking climate change myths may, hopefully, encourage progress in climate policy, if for no other reason than a better-informed electorate. These cases also signal a shift in the approach being taken by large cities to mitigate and adapt to climate change. Suing the largest of the global fossil fuel corporations sends a clear message to the U.S. federal government that, regardless of any regulatory vacillation or rollback, cities will continue to combat climate change.

Ultimately, however, the position of the plaintiff's in all of these cases, that the defendants' actions are demonstrably contributing to anthropogenic climate change, would be untenable if it were not for the significant body of evidence that repeatedly establishes the link between GHG emissions, climate change, and its effects, such as sea level rise and extreme weather. Should any one of the San Francisco, Oakland, or New York lawsuits succeed, a cascade of climate change litigation may result in not only in the U.S. but also in Canada and the rest of the world.

Indeed, the filing of the New York's complaint may itself have initiated an Ontario Member of Provincial Parliament ("MPP"), Peter Tabuns, to table a Bill that would impose strict liability on a fossil fuel producer for climate-related harms that occur in Ontario, if the producer is responsible for GHG emissions at a globally detectable level. Peter Tabuns, the former executive director of Greenpeace, mirrored the sentiment likely underlying the San Francisco, Oakland, and New York complaints when he stated "The world's largest fossil fuel corporations have to start paying their fair share of the damages that are going to be inflicted by climate change and they also have to pay for the steps necessary to protect people from those climate damages."

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