Addressing global warming could help lessen the harm to ecosystems that now provide us with multiple benefits. For example, rising seas threaten coastal barrier reefs, which protect communities from storm surges, and wetlands, which filter impurities from water. Drought and pests threaten forests, which provide lumber. Warming temperatures and growing acidification threaten oceans, lakes, and rivers, which sustain our fisheries. Because nature does not charge market prices for these services, we tend to greatly undervalue them.
Moreover, many animal and plant species that provide us with important medicines and other products—in addition to having intrinsic value—could face extinction. According to the Nobel prize–winning Intergovernmental Panel on Climate Change (IPCC), if global temperatures rise more than 3˚–5˚F, up to 30 percent of plant and animal species could become extinct. Many projections suggest that the low end of that temperature range could be breached by mid-century. While we cannot avoid some of these harms, lowering our emissions quickly would give us a chance to diminish them.