State of the Earth in Four Climate Trends

What better day to step back and take stock of the planet than Earth Day? Started in 1970 to raise awareness in the U.S. about the environmental state of the planet,  is now celebrated in more than 190 countries and has led to the creation of legislation in the U.S. aimed at protecting the environment. But one global trend has continued to alter the world—the  and other greenhouse gas emissions, which have led to an .

It’s easy to get caught up in individual records or wondering what influence . But to really understand climate change, the trends are what matter. Here are four that make it clear how our planet is changing.

 

The Number: 400 ppmThe Trend: Current level of CO2, up from pre-industrial levels of 280 ppmheat-trapping ability helps prevent Earth from being cold and barren, like Mars. But there can be too much of a good thing: Since the beginning of the Industrial Revolution in the 19th century, the amount of carbon dioxide in the air has been steadily rising due to human activities like , with the excess CO2 trapping ever more heat and raising global temperatures. It is the trend that drives all of the others associated with global warming.

The concentration of CO2 in the atmosphere has risen from about 280 parts per million (ppm) in pre-industrial times to , already appreciably raising Earth’s temperature. While that still makes CO2 a relatively small part of the atmosphere, it is extremely long-lived, so its heating power will hang around for thousands of years.

The inexorable rise of CO2 is clearly chronicled by the now-famous —the daily measurements made atop Hawaii’s Mauna Loa volcano since 1958, first begun by the scientist Charles Keeling and now continued by his son, Ralph. CO2 levels go up by about 2 ppm each year, and  on May 2013. It was the  that CO2 levels were that high. The 400 ppm mark has been hit earlier each year since, and experts expect that CO2 levels will be above 400 ppm year-round within a year or two. The rise of the Keeling Curve and the heating it drives doesn’t look to end anytime soon.

 

The Number: 1.6°FThe Trend: Rise in global temperatures since 1880

Warming has accelerated since the first Earth Day in 1970. The global average temperature has risen by about 0.3°F per decade since then. In comparison, the rise up until that point was about 0.1°F per decade. The speed up in warming since 1970 has been tied to a number of factors, particularly a reduction in human aerosol emissions throughout the 1970s, which cool the planet.

Scientists have warned that warming should be limited to 3.6°F above pre-industrial levels—more commonly represented by its even —to avoid severe consequences of climate change.

 

The Number: 361The Trend: Consecutive months of above-normal tempsstory   when it comes to the global average temperature: it’s above normal. Occasionally—and more frequently in recent years—it’s .

While any one month might reinforce the reality that the world is warming, it’s the trend that really stands out. As of March, the globe has had 361 consecutive months of above-normal temperatures according to the National Climatic Data Center (NCDC).

You’d have to go back to February 1985 to find the last cooler-than-average month. Which means if you’re younger than 30, you’ve never experienced a cooler-than-average month.

“It tells us pretty darn definitively we live in a changed world. We don’t live in a world that may change, we’re in a changed world and it will continue to change,” Deke Arndt, a scientist who runs , said.

 

The Number: 10The Trend: The 10 hottest years on record have occurred since 19982015 is on track to take the crown). The odds of that happening by chance alone? About 1-in-27 million.

Despite the spate of record-hot years—and the fact that the  occurred in 1911—some have referred to the past 15 years as a global warming hiatus because surface temperatures haven’t risen as fast as they did in the previous decades. It’s more of a slowdown than the disappearance of global warming.

“We’re in a really warm neighborhood. We slowed down in a neighborhood we’ve never slowed down in before,” Arndt said.

A number of studies have pointed out that  have contributed to the slowdown, but that it could possibly  as those patterns flip. And regardless of surface warming trends, oceans have continued to take up a whopping  that greenhouse gases emissions are trapping here on Earth. So calling it a slowdown is a bit of a misnomer; it’s more like a global warming shell game.

Climate Central. The article was