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[00:00.41] A recently released study says the average yearly temperature on Greenland has increased by 1.5 degree Celsius above the average for the 20th century for a 15-year period ending in 2011.

[00:19.01] Scientists used examples of Greenland’s ice to get information about temperatures from hundreds of years in the past.

[00:29.90] Until recently, Greenland’s ice cores had not shown a clear sign of warming on the remotest north-central part of the island.

[00:41.58] Those findings were based on cores from 1995.

[00:46.90] Researchers involved in the recent study examined cores that were drilled in 2011.

[00:53.80] They said their work showed a rise in temperature in the previous 15 years.

[01:00.71] The German researchers published their study in Nature.

[01:07.09] Maria Hoerhold, the study's lead writer, said this a clear signal of climate change.

[01:15.58] “We keep on (seeing) rising temperatures between 1990s and 2011,” she said.

[01:24.09] Hoerhold is a glaciologist at the Alfred Wegener Institute in Germany. “We have now a clear signature of global warming.”

[01:33.65] Scientists take years to study ice core data.

[01:38.96] Hoerhold has new cores from 2019. But she has not finished studying them.

[01:49.85] She expects the temperature rise to continue.

[01:51.18] The study said Greenland's ice sheet and glaciers have been melting.

[01:56.23] Information from ice cores has been used to estimate temperatures in Greenland from the year 1000 to 2011.

[02:12.69] Scientific models suggest average temperatures fell a little for the first 800 years of that period.

[02:13.76] Temperatures then increase a little and then go down until a sudden increase from the 1990s until 2011.

[02:25.18] The increase in temperatures after 1995 was much larger than pre-industrial times before the mid-19th century.

[02:37.66] There is an “almost zero” chance that it is anything but human-caused climate change, Hoerhold said.

[02:45.90] Hoerhold said Greenland’s natural weather changes in the past had hidden human-caused climate change.

[02:53.34] But, as of about 25 years ago, the warming became too big to be hidden, she said.

[02:59.71] Scientists say past data shows that Greenland is not warming as fast as the rest of the Arctic, the extreme northern part of the world.

[03:12.19] Some scientists suggest the temperature of the Arctic is now increasing at a rate four times faster than the average world temperature is.

[03:24.15] Hoerhold and scientists not involved in the research said the new warming data is bad because Greenland’s ice is melting.

[03:37.43] The study ends with data from 2011.

[03:40.88] Hoerhold said that, in the following year, a lot of ice melted across Greenland, and the island’s ice loss has been high since then.

[03:51.77] Jason Box is a scientist with the Danish Meteorological Institute.

[03:58.41] He said, “We should be very concerned about North Greenland warming because that region has a dozen sleeping giants in the form of wide tidewater glaciers and an ice stream.”

[04:12.76] As temperatures continue to get warmer, more ice will melt in Greenland, he said.

[04:20.73] Twila Moon is a scientist with the U.S. National Snow and Ice Data Center.

[04:28.16] Melting glaciers in Greenland means “rising seas that threaten homes, businesses, economies and communities," she said.