The field of environmental economics is concerned with the management of the negative consequences of human actions leading to environmental problems including air pollution, deterioration in land and water quality, toxic substances, solid waste, and climate change. Valuation of the environment to enable evaluation of projects  when there are environmental impacts is an important component of environmental economics. Natural Resource economics is a broader field encompassing the economically efficient and sustainable allocation of renewable resources and the economically efficient extraction of non-renewable natural resources over time. These include water, marine and forestry resources, agricultural and recreational land, energy resources and mineral stocks.