Global Warming
The planet has warmed around 2 degrees Fahrenheit since the late 1800s (and is tied for the hottest year on record), when the spread of industrialization led to rising emissions of greenhouse gasses. Since 1980, warming has averaged about 0.32 degrees Fahrenheit per decade. According to climate scientists, the world is seeing an increase in heat waves, storms and other extreme weather as the planet warms, and in disasters like droughts, floods and wildfires that result. Last year offered no respite, with record fires in Australia and California, and severe drought in central South America and the American Southwest. Some forecasters had thought that the arrival of cooler sea-surface temperatures in the Pacific Ocean — part of the recurring global climate phenomenon called La Niña — would lower temperatures this year. Clearly La Nina was overshadowed by the rise in temperatures throughout the year. La Niña only emerged in September, and is expected to continue at least through winte...