Keeping you current

CO2 Levels Reached an 800,000-year High in 2017

That’s just one of many sobering facts about our changing world in the “State of the Climate in 2017” report released late last week

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smithsonian.com

Using ice cores drilled in Greenland and Antarctica, scientists have a pretty good record of how the composition of Earth’s atmosphere has fluctuated over the last 800,000 years. That’s why scientists know carbon dioxide levels are higher than they’ve ever been in that amount of time.

Last year, the concentration of carbon dioxide reached a whopping 405 parts per million, according to the State of the Climate in 2017, an annual report put together by the American Meteorological Society. That's higher than any year contained in the ice cores and higher than any of the direct measurements taken in the past 38 years.

And that’s just one of the alarms the study sounds about our rapidly changing climate.

Elizabeth Gamillo at Science reports that the latest edition of the report was put together by 524 scientists working in 65 countries. Depending on what records are used, 2017 was either the second or third hottest year since modern temperature measures began in the mid-1800s. But it was the hottest year ever without the help of an El Niño event, a cyclical warming of the Pacific Ocean that often temporarily warms the climate. In fact, 2017 was a La Niña year, which usually has a slight cooling effect on the global climate, making 2017’s record-level heat even more concerning.

Other facts about 2017 show that many of the predictions about climate change from previous decades are coming to pass. Concentrations of other greenhouse gases, in particular methane and nitrous oxide, have reached their highest recorded levels as well.

Sea level also set a record and is now three inches higher than it was in 1993. The top 2,300 feet of the ocean reached record high temperatures. Average sea surface temperatures were the second highest recorded, only surpassed by the El Nino year of 2016.

The sea-ice in Antarctica was also the lowest recorded in 38 years, covering just 811,000 square miles in March of 2017, and glaciers around the world also shed mass for the 38th consecutive year. According to the report, since 1980 “the loss is equivalent to slicing 22 meters (72 feet) off the top of the average glacier.”

That’s a lot to take in, but it’s likely all these records will continue to be broken in coming years. “[Even if humanity] stopped the greenhouse gasses at their current concentrations today, the atmosphere would still continue to warm for the next couple decades to maybe a century,” Greg Johnson, oceanographer at NOAA’s Pacific Marine Environmental Laboratory said during a press call, reports Gamillo.

And humanity is nowhere near close to eliminating greenhouse gas emissions.

While for decades researchers were hesitant to blame certain weather phenomenon on climate change, last year they began attributing some events to a warming world. For instance, scientists estimate that Hurricane Harvey, which dumped up to 50 inches of rain on parts of Texas, produced 38 percent more precipitation due to climate change. Other major rain events in 2017 included massive monsoons in India that killed 800 people and massive floods in Venezuela and Nigeria.

Oliver Milman at The Guardian also reports that a three-year-long global coral bleaching event, which has killed half the coral in the Great Barrier Reef, was also made much worse by climate change. “I find it quite stunning, really, how these record temperatures have affected ocean ecosystems,” Johson tells Milman.

The warming trend has become more pronounced in the past decade. According to a press release, the 10 warmest years on record have occurred since 1998, and the four warmest years have all occurred since 2014.

So far, 2018 is shaping up to be the fourth warmest year on record with the late 2017 La Niña pattern cooling off the first few months of the year. But there are signs that climate change is still showing off this year. Europe has experienced one of its worst summer heat waves with record temperatures stretching all the way past the Arctic Circle. In North America, Death Valley just set the record for the highest monthly temperature on Earth, averaging 108.1 degrees Fahrenheit throughout July.

About Jason Daley

Jason Daley is a Madison, Wisconsin-based writer specializing in natural history, science, travel, and the environment. His work has appeared in Discover, Popular Science, Outside, Men’s Journal, and other magazines.

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