views which may be traced to the different philosophical underpinnings. Another context in which externalities apply is when globalization permits one player in a market who is unconcerned with biodiversity to undercut prices of another who is - creating a race to the bottom in regulations and conservation. This, in turn, may cause loss of natural capital with consequent erosion, water purity problems, diseases, desertification, and other outcomes that are not efficient in an economic sense. This concern is related to the subfield of sustainable development and its political relation, the anti-globalization movement. Environmental economics was once distinct from resource economics. Natural resource economics as a subfield began when the main concern of researchers was the optimal commercial exploitation of natural resource stocks. But resource managers and policy-makers eventually began to pay attention to the broader importance of natural resources (e.g. values of fish and trees beyond just their commercial exploitation). It is now difficult to distinguish "environmental" and "natural resource" economics as separate fields as the two became associated with sustainability. Many of the more radical green economists split off to work on an alternate political economy. Environmental economics was a major influence on the theories of natural capitalism and environmental finance, which could be said to be two sub-branches of environmental economics concerned with resource conservation in production, and the value of biodiversity to humans, respectively. The theory of natural capitalism (Hawken, Lovins, Lovins) goes further than traditional environmental economics by envisioning a world where natural services are considered on par with physical capital. The more radical green economists reject neoclassical economics in favour of a new political economy beyond capitalism or communism that gives a greater emphasis to the interaction of the human economy and the natural environment, acknowledging that "economy is three-fifths of ecology" - Mike Nickerson. This political group is a proponent of a transition to renewable energy. These more radical approaches would imply changes to money supply and likely also a bioregional democracy so that political, economic, and ecological "environmental limits" were all aligned, and not subject to the arbitrage normally possible under capitalism. An emerging sub-field of environmental economics studies its intersection with development economics. Dubbed "envirodevonomics" by Michael Greenstone and B. Kelsey Jack in their paper "Envirodevonomics: A Research Agenda for a Young Field", the sub-field is primarily interested in studying "why environmental quality [is] so poor in developing countries." A strategy