sufficient amounts of water, Lomborg says that wars will probably not erupt over water because fighting such wars is not cost-effective (he argues that one week of war with the Palestinians, for instance, would cost Israel more than five desalination plants, according to an Israeli officer). Lomborg emphasizes the need for better water management, as water is distributed unequally around the world. 3. Pollution as a threat to human prosperity Lomborg considers pollution from different angles. He notes that air pollution in wealthy nations has steadily decreased in recent decades. He finds that air pollution levels are highly linked to economic development, with moderately developed countries polluting most. Again, Lomborg argues that faster growth in emerging countries would help them reduce their air pollution levels. Lomborg suggests that devoting resources to reduce the levels of specific air pollutants would provide the greatest health benefits and save the largest number of lives (per amount of money spent), continuing an already decades-long improvement in air quality in most developed countries. Concerning water pollution, Lomborg notes again that it is connected with economic progress. He also notes that water pollution in major Western rivers decreased rapidly after the use of sewage systems became widespread. Concerning waste, Lomborg argues that fears are overblown, as the entire waste produced by the United States in the 21st century could fit into a square 100 feet thick and 28 km along each side, or 0.009% of the total surface of the United States. 4. Future threats to human prosperity In this last section, Lomborg puts forward his main assertion: based on a cost-benefit analysis, the environmental threats to human prosperity are overstated and much of policy response is misguided. As an example, Lomborg cites worries about pesticides and their link to cancer. He argues that such concerns are vastly exaggerated in the public perception, as alcohol and coffee are the foods that create by far the greatest risk of cancer, as opposed to vegetables that have been sprayed with pesticides. Furthermore, if pesticides were not used on fruit and vegetables, their cost would rise, and consequently their consumption would go down, which would cause cancer rates to increase. He goes on to criticize the fear of a vertiginous decline in biodiversity, proposing that 0.7% of species have gone extinct in the last 50 years (as compared to a maximum of 50%, as claimed by some biologists). While