An environmental disaster or ecological disaster is defined as a catastrophic event regarding the natural environment that is due to human activity. This point distinguishes environmental disasters from other disturbances such as natural disasters and intentional acts of war such as nuclear bombings.

Environmental disasters show how the impact of humans' alteration of the land has led to widespread and/or long-lasting consequences. These disasters have included deaths of wildlife, humans and plants, or severe disruption of human life or health, possibly requiring migration.

Generally speaking, diesel fuel , also called diesel oil, is any liquid fuel specifically designed for use in a diesel engine, a type of internal combustion engine in which fuel ignition takes place without a spark as a result of compression of the inlet air and then injection of fuel. Therefore, diesel fuel needs good compression ignition characteristics.

The most common type of diesel fuel is a specific fractional distillate of petroleum fuel oil, but alternatives that are not derived from petroleum, such as biodiesel, biomass to liquid (BTL) or gas to liquid (GTL) diesel are increasingly being developed and adopted. To distinguish these types, petroleum-derived diesel is increasingly called petrodiesel in some academic circles.In many countries, diesel fuel is standardised. For example, in the European Union, the standard for diesel fuel is EN 590. Diesel fuel has many colloquial names; most commonly, it is simply referred to as diesel. In the UK, diesel fuel for on-road use is commonly abbreviated DERV, standing for diesel-engined road vehicle, which carries a tax premium over equivalent fuel for non-road use. In Australia, diesel fuel is also known as distillate, and in Indonesia, it is known as Solar, a trademarked name by the local oil company Pertamina.

Ultra-low-sulfur diesel (ULSD) is a diesel fuel with substantially lowered sulfur contents. As of 2016, almost all of the petroleum-based diesel fuel available in the UK, mainland Europe, and North America is of a ULSD type.

Before diesel fuel had been standardised, the majority of diesel engines typically ran on cheap fuel oils. These fuel oils are still used in watercraft diesel engines. Despite being specifically designed for diesel engines, diesel fuel can also be used as fuel for several non-diesel engines, for example the Akroyd engine, the Stirling engine, or boilers for steam engines.