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The Arctic has warmed more than 5 degrees Fahrenheit since 2000 because of human-driven climate change, scientists announced last month. This has caused , and threatened the overall health and viability of the world's northernmost ecosystem.

"The impacts of a persistent warming trend over the last 30 years is clearly evident ," Kit Kovacs, a biologist at the Norwegian Polar Institute, said at a press conference. "And we can expect to see continued, widespread, and systematic change to the Arctic" in the coming decades as the world continues to warm.

Kovacs is a co-author of the 10th annual , a peer-reviewed scientific analysis of the region by 72 researchers from 11 countries—organized by the U.S. National Oceanic and Atmospheric Administration—which was published last month.

It contained some sobering news about the state of the region: Walruses, for instance, have declined 50 percent in the North Pacific in the past decade. The Arctic tundra has browned as plants have died from the warmth. Lower-latitude fish like cod have moved north in search of cooler climes, displacing native Arctic fish populations. Early ice and snow melt in Alaska helped to fuel the state's second-worst wildfire season on record. Maximum sea ice extent peaked 15 days earlier than average in February and was the lowest since 1979, when records began. More than 50 percent of the Greenland Ice Sheet experienced some melting and Arctic snow cover hit a near-record low in June.

Last month in Paris, 195 nations agreed to limit global warming to less than 2 degrees Celsius from pre-industrial temperatures. But even that amount of warming will have major consequences, scientists argue, and what is happening in the Arctic today is a warning of what's ahead in many parts of the world.

"Warming is happening twice as fast in the Arctic as anywhere else in the world," said Rick Spinrad, the chief scientist at NOAA. "But what happens in the Arctic doesn't stay in the Arctic...The trailing indicators for the region are in fact the leading indicators for the rest of the world."

Warmer air and sea temperatures in the Arctic mean faster ice melt and expanding seas that can raise sea levels elsewhere in the world, threatening low-lying coastal communities like New York City, South Florida, and the Chesapeake Bay.

What sea ice is forming in the Arctic is younger and thinner than what used to be there, the report says. The percentage of stronger, thicker "old" ice in the region has fallen from 85 percent to 30 percent in three decades. Newer ice is more vulnerable to collapse or early melting. Animals like walruses and seals are shifting toward land as their habitat and hunting grounds disappear.

Scientists also said they are closely monitoring whether this year's record El Niño in the Pacific Ocean could make a bad situation worse in the Arctic in the coming months. Spinrad said NOAA has redirected research vessels and resources to examine the relationship.

"There is a possibility, but not a certainty" that this year's El Niño could impact the Arctic, said Jim Overland, an oceanographer and Arctic scientist for NOAA. "We'll be studying it closely."

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