They're called "ghost forests"—dead trees along vast swaths of coastline invaded by rising seas. The process has occurred naturally for thousands of years, but it has accelerated in recent decades as polar ice melts and raises sea levels, scientists say, pushing salt water farther inland and killing trees in what used to be thriving freshwater plains. Efforts are underway worldwide to determine exactly how quickly the creation of ghost forests is increasing, per the AP. It's happening around the world, but researchers say new ghost forests are particularly apparent in North America, with hundreds of thousands of acres of salt-killed trees stretching from Canada down the East Coast, around Florida and over to Texas.
"There is a lot of change going on," says Greg Noe, a research ecologist with the US Geological Survey. "It's dramatic and it's changing faster than it has before in human history." The intruding salt water changes coastal ecosystems, creating marshes where forests used to be. This has numerous effects on the environment, though many scientists caution against viewing them in terms of "good" or "bad." What benefits one species or ecosystem might harm another one, they say. "I think ghost forests are the most obvious indicator of climate change anywhere on the Eastern coast of the US," said Matthew Kirwan, a professor at the Virginia Institute of Marine Science who's studying ghost forests in his state and Maryland. "It was dry, usable land 50 years ago; now it's marshes with dead stumps and dead trees." (Read more environment stories.)