Nightly News   |  November 29, 2012

Polar ice melting faster than expected

A new study published in Science found the ice in Greenland is melting five times faster than in the early 1990s, contributing to rising seas. NBC’s Anne Thompson reports.

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>>> good evening, at a time when so many people are still suffering, right now tonight more than one month after a monster storm hit a giant population center , today we learned some facts about how this earth is changing and how fast. for starters, polar ice sheets in greenland are melting at five times the pace, than just a few years ago. new research shows that antarctica is melting. while it takes a lot of ice to melt the ocean levels they say that is in fact what is happening. and they believe just an incremental rise in the ocean levels made the damage worse when hurricane sandy hit the east coast and took so much away from us. the big question is the future, of course, and a new kind of normal for all of those living along the water. it is where we begin tonight, our chief environmental affairs correspondent, anne thompson has more on what we learned.

>> reporter: well, the information comes from a group of international scientists, brian and shows we're living climate changes in real time . this july was the warmest month on record. and tonight, there is new information that reveals just how fast the world's ice sheets are melting. the numbers are staggering. 344 billion metric tons of ice melting in antarctica and greenland a year. the weight of more than a million empire state buildings, the information was published in the journal, from researchers who looked at the data gathered over the last 20 years. creating what they say is the most accurate picture of melting. in antarctica , the east region is gaining ice, but it is not enough to make up for the loss on the rest of the continent. in greenland , it is shown here in red and is losing ice five times faster than in the early '90s.

>> the faster speeds we're seeing in greenland are not going to slow down. that is not the way ice sheets behave.

>> reporter: the melting accounts for 20% of sea level rises in the past two decades, adding 11 mm , it doesn't sound like much, until you consider it is like pouring in 26 lake tahoes.

>> greenland has the most vast levels of ice. all told they hold hundreds of feet of sea level rises that is the worry, many of the

>> reporter: that is the worry, many of the world's cities are in the cross hair .

>> most of the people live in the coastal areas, where the ports are. they are at sea level . so even small level rises can displace many in those areas.

>> reporter: look at what happened on the east coast , this could be the impact of five feet of sea level rises, and could impact others in just a few centuries. today, new jersey and new york are still recovering from the punishing effect of sandy, a storm fuelled by higher seas. in greenland , this photographer used time lapse cameras to record the melting five years ago.

>> i want to show people the reality of what is happening.

>> reporter: what he found here is the subject of the documentary, "chasing ice".

>> and that effect, more ice is going into the ocean as it is speeding up.

>> reporter: confirmed by the results of today's study. now another report this week says sea level rises are happening 60% faster than the united nations predicted in 2007 . this is all critical information because more than half of all americans live within 50 miles of the coastline.

>> bracing bunch of numbers today, anne thompson leading us off tonight, thank you.

>>> tonight here at the u.n.,