Provenance provenance of paintings can help resolve ownership disputes. For example, provenance between 1933 and 1945 can determine whether a painting was looted by the Nazis. Many galleries are putting a great deal of effort into researching the provenance of paintings in their collections for which there is no firm provenance during that period. Documented evidence of provenance for an object can help to establish that it has not been altered and is not a forgery, a reproduction, stolen or looted art. Provenance helps assign the work to a known artist, and a documented history can be of use in helping
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