The carbon bubble is a hypothesized bubble in the valuation of companies dependent on fossil-fuel-based energy production, because the true costs of carbon dioxide in intensifying global warming are not yet taken into account in a company's stock market valuation. Currently the price of fossil fuels companies' shares is calculated under the assumption that all fossil fuel reserves will be consumed. An estimate made by Kepler Chevreux puts the loss in value of the fossil fuel companies due to the impact of the growing renewables industry at US$28 trillion over the next two decades-long. A more recent analysis made by Citi puts that figure at $100 trillion. Analysts in both the petroleum and financial industries are concluding that the "age of oil" has already reached a new stage where the excess supply that appeared in late 2014 may continue to prevail in the future. A consensus appears to be emerging that an international agreement will be reached to introduce measures to constrain the combustion of hydrocarbons in an effort to limit global temperature rise to the nominal 2 °C that is consensually predicted to limit environmental harm to tolerable levels. According to the UK's Committee on Climate Change, overvaluing companies that produce fossil fuels and greenhouse gases poses a serious threat to the economy. The committee warned the British government and Bank of England of the risks of the carbon bubble in 2014. The following year, Mark Carney, the Governor of the Bank of England, in his lecture to Lloyd's of London, warned that limiting global warming to 2 °C appears to require that the "vast majority" of fossil fuel reserves be "stranded assets", or "literally unburnable without expensive carbon-capture technology", resulting in "potentially huge" exposure to investors in that sector. He concluded that "the window of opportunity is finite and shrinking" for responding to the threat that climate change poses to financial resilience and longer-term prosperity, which he called the "tragedy of the horizon". That same month, the Prudential Regulation Authority of the Bank of England issued a report discussing the risks and opportunities that climate change presents to the insurance industry. In his speech announcing his denial of the proposal to build the Keystone XL oil pipeline, United States President Barack Obama gave as one reason for the decision "... ultimately, if we're going to prevent large parts of this Earth from becoming not only inhospitable but uninhabitable in our lifetimes, we're going to have to keep some fossil fuels in the ground...".
Etymology
The term "carbon bubble" arose in the early 21st century from the increasing awareness of the impact of fossil fuel combustion on global temperatures. The term was coined by the Carbon Tracker Initiative which published key reports in July 2011 and April 2013. and it was further popularised in the New Scientist magazine in October 2011. A widely shared article by Bill McKibben was published in Rolling Stone magazine in July 2012, bringing the idea to the attention of a popular audience. These were followed later in 2013 by a report from the Demosthink tank.
Value
Author Bill McKibben has estimated that to sustain human life in the world, up to $20 trillion worth of fossil fuel reserves will need to remain in the ground. The Stern report in 2006 stated that the benefits of strong, early action to decrease the use of oil, coal and gas considerably outweigh the costs. Fossil fuel contributors, the building industry, and land use practices ignore the responsibility of the external costs and ignore the polluter pays principle according to which climate change costs will be paid by historical climate polluters.
Prospects for orderly bubble deflation
A planned and orderly transition away from dependence on fossil fuels could prevent a disruptive "bursting of the carbon bubble". A number of developments are supporting such a transition.
