Global climate is changing, and the main cause is our rapid burning of coal, oil, and natural gas. Many different kinds of evidence confirm that global climate is changing, from melting of mountain glaciers and polar ice to higher ocean temperatures to rising sea level to the changing chemistry of the atmosphere. Analysis of the atmosphere confirms that our rapid burning of fossil fuels is the main cause. The oceans, which are already under stress from overfishing, pollution and coastal development, are sensitive to these added pressures. People and natural ecosystems must adapt to the changes that cannot be avoided, but there is still time to limit their impact. Now is the time to reduce our consumption of fossil fuels for the sake of our communities, future generations, and Earth’s biodiversity.