In the last 50 years a rising human population has polluted or overexploited. 2/3 of the ecosystems on which life depends, including clean air and fresh water. Ocean stress: 90% of fisheries overexploited or collapsing. Fresh water demand > exhaustion of sources (rivers and aquifers ) Paul ehrlich: human population has grown beyond the carrying capacity of the planet k selected v sigmoid growth. Julian simon: humans are the ultimate resource no limits to growth. >90% of growth in pop. in developing countries. Poverty: absolute = income < per year. Master equation: i= p x c x t. Barry commoners calculation and the role of technology. Thomas homer-dixon, robert kaplan: environmental scarcity combined with population growth > increased conflict esp. in 3rd world. Desertification and land degradation scarcity> resource capture> conflict. In the year prior to 2011 wheat prices rose by 80%. Climate change: more than 90% of historical emissions in 1st world, impacts overwhelmingly in 3rd world.