Even setting aside the question of the supply of fossil fuels, their use has led to serious environmental problems. Burning oil and coal releases massive amounts of carbon dioxide (CO₂) into the atmosphere, the leading cause of climate change, or global warming. While the future effects of climate change are difficult to predict, the vast majority of climatologists agree that global warming is proceeding far more quickly than previously predicted and that some climatic disruption is now unavoidable. Rising average temperatures already play havoc with familiar weather patterns, melting glaciers and polar ice packs, and drying up freshwater resources. Moreover, in the next fifty years rising sea levels may well flood low-lying coastal areas around the world.

Since the 1990s the EU has spearheaded efforts to control energy consumption and contain climate change. EU leaders have imposed tight restrictions on CO₂ emissions, and Germany, the Netherlands, and Denmark have become world leaders in harnessing alternative energy sources such as solar and wind power. Some countries, hoping to combat the future effects of global warming, have also taken pre-emptive measures. The Dutch government, for example, has spent billions of dollars constructing new dikes, levees, and floodgates. These efforts provided models for U.S. urban planners after floodwaters churned up by Hurricane Sandy swamped low-lying swaths of New York City in October 2012.

Environmental degradation encompasses a number of problems beyond climate change. Overfishing and toxic waste threaten the world’s oceans and freshwater lakes, which once seemed to be inexhaustible sources of food and drinking water. The disaster that resulted when an offshore oil rig exploded in the Gulf of Mexico in April 2010, spewing millions of gallons of oil into the gulf waters, underscored the close connections between energy consumption and water pollution. Deforestation, land degradation, soil erosion, and overfertilization; species extinction related to habitat loss; the accumulation of toxins in the air, land, and water; the disposal of poisonous nuclear waste — all will continue to pose serious problems in the twenty-first century.

Though North American and European governments, NGOs, and citizens have taken a number of steps to limit environmental degradation and regulate energy use, the overall effort to control energy consumption has been an especially difficult endeavor, underscoring the interconnectedness of the contemporary world. Rapidly industrializing countries such as India and China — the latter surpassed the United States in 2008 as the largest emitter of CO₂ — have had a difficult time balancing environmental concerns and the energy use necessary for economic growth. Because of growing demand for electricity, for example, China currently accounts for about 47 percent of the world’s coal consumption, causing hazardous air pollution in Chinese cities and contributing to climate change.20

Can international agreements and good intentions make a difference? In December 2015 representatives of almost two hundred nations met at the annual United Nations Climate Change Conference in Paris, France. They extended the Kyoto Protocol on climate change, set ambitious goals for the reduction of CO₂ emissions by 2020, and promised to help developing countries manage the effects of climate change. Such changes would require substantial modifications in the planet’s consumption of energy derived from fossil fuels, however, and the ultimate success of ambitious plans to limit the human impact on the environment remains uncertain.