Feb 24, 2017

The U.S. Geological Survey hails an early spring — and ties it to climate change

Washington, DC
Chelsea Harvey
Washington Post
People on the Mall during warm weather Feb. 23, 2017, in Washington. Photo: Brendan Smialowski, Agence France-Presse via Getty Images
People on the Mall during warm weather Feb. 23, 2017, in Washington. Photo: Brendan Smialowski, Agence France-Presse via Getty Images

As the nation basks in some of the warmest February weather it has seen in decades, the U.S. Geological Survey has been quick to point out that the early spring conditions are another symptom of climate change.

On Thursday, the USGS shared a new analysis just released by the USA-National Phenology Network, which the agency helps to fund, showing that an early spring has already swept through the Southeast and is continuing to work its way across the country. As the agency points out, the new analysis reaffirms a fact scientists have known for at least a decade now — that “climate change is variably advancing the onset of spring across the United States.”

The analysis relies on a special “spring index,” which defines the start of spring as the point when temperatures allow for certain early-season events in plants, such as the emergence of leaves and blooms. The index was created using data that has been collected for a citizen science project over the past few decades, according to Jake Weltzin, executive director of the USA-National Phenology Network and an ecologist with the U.S. Geological Survey, which helped fund the project.

Since the 1950s, volunteers have been collecting information about the leafing and blooming of certain plants, such as lilacs and honeysuckle, Weltzin said. More recently, climatologist Mark Schwartz of the University of Wisconsin at Milwaukee used this information to develop an algorithm that can be used with national temperature data to determine where and when “spring” has arrived across the country. 

By comparing this year’s temperatures with data from previous years, the scientists are able to determine which locations are seeing an unusually early spring, compared with the average. Washington D.C., for instance, saw its spring arrive a whopping 22 days early, according to the analysis.

In general, the new season has already made its appearance throughout most of the Southeast and as far north as southern Illinois and Indiana. It’s now starting to show up scattered locations across the Western states, including in parts of Colorado, New Mexico and Arizona, and has begun to creep into California. 

The same index was also used in a recent study that demonstrated that spring is arriving earlier and earlier in many national parks throughout the United States. Looking at data spanning the past 112 years, the study found that spring has been advancing in 76 percent of the nation’s national parks. And more than half of all parks are experiencing extreme early springs, compared with 95 percent of the historical record.  

These findings, along with the newly released maps of this year’s springs, are just another way of pointing to the progression of climate change, Weltzin noted.