Protection of world's croplands Soil erosion Deforestation Water resources depletion Melting glaciers Decreasing groundwaters Energy depletion Peak oil Energy conservation and sustainability Renewable energy Garbage reduction and recycling. Environmentalist and author Issuing warnings After a talk at Catawba College in 2008, the college newspaper referred to him as an "environmental Paul Revere," [as] he warned his audience that "unless civilization changes its ways, its end is truly near... we're in a race between natural tipping points and political tipping points, - 'what we need most of all is for the market to tell the environmental truth.' " He added, "We don't need to go beyond our ice melts to know that we're in trouble. How much are we willing to spend to avoid a 23 foot rise in sea level?" He explained that "indirect costs are shaping our future," and by ignoring these, "we're doing exactly the same thing as Enron- leaving costs off the books. Consuming today with no concern for tomorrow is not a winning philosophy." He spoke of rapid population growth, deforestation, and "two new stresses – rising food and oil prices." "As oil prices go up, grain prices will follow," he said. Offering solutions In 2001 Brown suggested a "tax shifting" structure which would reduce income taxes and offset them with taxes on environmentally destructive activities such as carbon emissions. It would lead to an "honest market", he said, by adding a tax on carbon to pay for the hidden costs of climate change. It would also account for the environmental costs of things such toxic waste, the overuse of raw materials, mercury emissions, the generation of garbage, the use of pesticides, and the use of throwaway products such as plastic bottles, all activities that would be discouraged by taxing. He says that by keeping such environmental costs "off the books," and thereby hidden, society risks the same fate as a large company such as Enron, which failed immediately after auditors learned they had kept major costs off their books. Brown subsequently added that such a tax shift would amount to an "honest market," explaining, "The key to restructuring the economy is the creation of an honest market, one that tells the ecological truth." In 2011 he estimated the cost of such a tax shift, including the effects of better technology, the use of renewables and "updating the concept of national security." In December 2008, Brown