Provenance covers an object's complete documented history. An artifact may thus have both a provenience and a provenance. The provenance of works of fine art, antiques and antiquities is of great importance, especially to their owner. There are a number of reasons why painting provenance is important, which mostly also apply to other types of fine art. A good provenance increases the value of a painting, and establishing provenance may help confirm the date, artist and, especially for portraits, the subject of a painting. It may confirm whether a painting is genuinely of the period it seems to date from. The
Issues relating to biofuels ecosystems including rainforest in South America. In forest ecosystems, these effects themselves will undermine the climate benefits of alternative fuels, in addition to representing a major threat to global biodiversity. Although biofuels are generally considered to improve net carbon output, biodiesel and other fuels do produce local air pollution, including nitrogen oxides, the principal cause of smog. Issues relating to biofuels There are various social, economic, environmental and technical issues with biofuel production and use, which have been discussed in the popular media and scientific journals. These include: the effect of moderating oil prices, the "food vs fuel" debate, poverty