Carbon bubbleThe carbon bubble is a hypothesized bubble in the valuation of companies dependent on fossil-fuel-based energy production, resulting from future decreases in value of fossil fuel reserves as they become unusable in order to meet carbon budgets and recognition of negative externalities of carbon fuels which are not yet taken into account in a company's stock market valuation. While most campaigns to reduce the investment, production, and use of fossil fuels has been based on ethical reasons, financial analysts, economists, and financial institutions have increasingly argued in favor of doing so for financial reasons.
Negative temperatureCertain systems can achieve negative thermodynamic temperature; that is, their temperature can be expressed as a negative quantity on the Kelvin or Rankine scales. This should be distinguished from temperatures expressed as negative numbers on non-thermodynamic Celsius or Fahrenheit scales, which are nevertheless higher than absolute zero. The absolute temperature (Kelvin) scale can be understood loosely as a measure of average kinetic energy. Usually, system temperatures are positive.
Fuel taxA fuel tax (also known as a petrol, gasoline or gas tax, or as a fuel duty) is an excise tax imposed on the sale of fuel. In most countries the fuel tax is imposed on fuels which are intended for transportation. Fuel tax receipts are often dedicated or hypothecated to transportation projects, in which case the fuel tax can be considered a user fee. In other countries, the fuel tax is a source of general revenue. Sometimes, a fuel tax is used as an ecotax, to promote ecological sustainability.
