deborah patta is tracking it as the it floats away. thread for months.giant chung of ice, the size of delaware has snapped off. at more than 2200 square miles, the massive fracture certainly looks dramatic, but scientists are not pressing the panic button just yet. if the fracturing of this iceberg cause for alarm? >> at the moment. i would say no. >> david born says it is all part of regular house keeping in the antarctica. but may provide scientific exclusives long term. >> an ice shelf is a permanent floating sheet of ice attached to land. an iceberg will snap off every few decade. but the ice shelf usually grows again as it gains new ice from land. the warmer temperatures have seen some ice shelves retreat to such a pin the that they ear unable to ge determine if this is one such case. of more immediate concern, however, is that without an ice shelf to hold it back, the glacial ice behind it will flow into the sea and contribute to driving sea levels up more quickly than predicted for this century. deborah patta, cbs news, london. >>> there its anoth

here is deborah patta. >> reporter: it has been hanging on by a thread for months.ut finally, a giant chunk of ice, the size of delaware, has snapped off. at more than 2200 square miles, the massive fracture certainly looks dramatic, but scientists are not pressing the panic button just yet. if the fracturing of this iceberg cause for alarm? >> at the moment i would categorically say no. >> david borne says it is all part of regular house keeping in the antarctica, but may provide scientific clues long term. >> the question is whether this is the beginning of a retreat of this ice shelf that may eventually be linked to climate change. >> an ice shelf is a permanent floating sheet of ice attached off to land. an iceberg will snap off every few decade. but of the ice shelf usually grows again as it gains new ice from land. the warmer temperatures have seen some ice shelves retreat to such a pin toint that they're ue to regenerate. scientists will be able to determine if this is one such case. >> we will take sediment samp s samples. which will tell us how often this e

deborah patta has the story from our london bureau. >> reporter: although information is not exactly being forth coming from iran, this is what we do know about the foreign national found guilty of spying. iranian state media has named him as 37 year old chinese-american xi xiyow wang, a principleson university academic who was conducting historical research in iran. but officials accuse him of gathering information under the direct guidance of the u.s. and for this he has been sentenced to ten years in an iranian jail. releasing scant information about prisoners is nothing new in iran. "washington post" journalist jason rezaian was one of the most high profile u.s. citizens found guilty of espionage. after his release he described how he was for his jailers. >> for much of the 18 months i was in prison my iranian intergators told me that "the washington post" did not exist. that no one knew of my plight, and that the united states government would not lift a finger for my release. >> reporter: in fact, there was a global effort to free rezain culminating in his release in january 20

deborah patta has the story from our london bureau. >> reporter: although information has not exactly been forth coming from iran, this is what we do know about the foreign national found guilty of spying. iranian state media has named him as 37-year-old chinese american xiyue wang. he is a princeton university academic who was conducting historical research in iran but officials accuse him of gathering information under the direct guidance of the u.s. and for this he has been sentenced to ten years in an iranian jail. releasie ining scant informatio about prisoners is nothing new in iran. "washington post" journalist jason rezaian was one of the most high-profile u.s. citizens found guilty of espionage. after his release he described how he was deliberately lied to by his jailers. >> for much of the 18 months i was in prison my iranian interrogators told me that the "washington post" did not exist, that no one knew of my fligplig and that the united states government would not lift a finger for my release. >> reporter: in fact, there was a global effort to free rezaian, culminating i