Another year of extreme weather brought the Philippines a super typhoon and the United States the widest tornado ever observed, deadly wildfires, severe drought and killer floods. President Barack Obama released his plan to battle climate change and its impact on people and wildlife, but the warming planet passed another troubling milestone as heat-trapping greenhouse gases continued to accumulate. Here is a look back at some of 2013’s most significant events to affect the environment.
Carbon dioxide: Recorded carbon dioxide levels in the atmosphere reached the unsettling milestone of 400 parts per million on May 10, a level of the heat-trapping gas unseen for 3 million to 5 million years. The burning of fossil fuels is primarily responsible for the increase.
Tornadoes: A rare EF-5 tornado in Moore, Okla., on May 20 killed 25 people, injured hundreds and obliterated more than 1,000 homes along a 17-mile path of destruction. The storm reached speeds of more than 200 miles per hour, killing seven third-graders in an elementary school when a wall collapsed on them. A few weeks later, the deadly El Reno, Okla., tornado was measured as the widest ever.
Oil pipeline: Mr. Obama unveiled his long-awaited climate action plan on June 25, ordering the Environmental Protection Agency to propose limits on carbon dioxide emissions from existing coal- and gas-fired power plants. He also said he would approve the Keystone XL pipeline, which would carry crude from Canadian oil sands fields to refineries in the Gulf of Mexico, only if it did not “significantly exacerbate” climate change.
Flooding: Severe, widespread flooding in Colorado killed five people and prompted the biggest civilian airlift since Hurricane Katrina in 2005.
Global warming: It’s “extremely likely” that humans are the main cause of global warming, the Intergovernmental Panel on Climate Change said on Sept. 27. The past three decades have been the hottest since 1850, and carbon concentrations in the atmosphere are up 40 percent from that year.
Wildfires: The Yosemite Rim Fire was scary not only because it burned for two months ending Oct. 25 and ranked as the third-largest wildfire in the history of California, a state that has seen its share of monster burns. It followed a giant Arizona wildfire that killed 19 elite firefighters, the Granite Mountain Hotshots, in June. On top of that, it followed what meteorologists say was the driest year ever in California, where Death Valley tied the record for the highest temperature ever in June, 129 degrees.
Typhoon: Haiyan, dubbed a “super” typhoon, struck the Philippines Nov. 7 with sustained maximum winds of 195 mph and gusts of 235 mph, one of the most intense storms in modern times. Nearly 4 million people were forced from their homes, and the death toll has reached 6,000.
Moose, frogs, butterflies: Moose were eaten alive by ticks, two subspecies of butterflies in Florida disappeared, frog and amphibian populations plummeted, and a new study showed that crabs will super-size in the coming years by ingesting increased carbon in oceans. Warmer winters in New Hampshire aren’t killing ticks, so up to 150,000 hitch a ride and get dinner from a single moose.
Elephants and rhinos: Wildlife poachers kill millions of animals each year, but this year was especially deadly for African elephants and rhinoceroses, whose tusks and horns are valued for carvings and traditional medicine. In Zimbabwe this year, poachers laced watering holes and salt licks with cyanide, killing at least 300 elephants. Wildlife officials’ 18 seizures of tusks yielded 41 tons but they estimate that only one-tenth of smugglers are caught. The toll of slaughtered rhinoceros reached 890 this year in South Africa alone, easily topping the 2012 total. Over the past decade, rhino poaching has increased by 3,000 percent.