The Greenpeace press release in question is identified as having been dated the 15th of July. I've located what I think is the source of the claim that "we are looking at ice-free summers in the Arctic as early as 2030" claim referred to by Sackur.
It is perfectly obvious Greenpeace were referring to sea ice, not the Greenland ice cap. So Sackur was badgering his interviewee, trying to get him to defend a claim that Greenpeace never made:
Bad news is coming from other sources as well. A recent NASA study has shown that the ice cap is not only getting smaller, it’s getting thinner and younger. Sea ice has dramatically thinned between 2004 and 2008. Old ice (over 2 years old) takes longer to melt, and is also much harder to replace. As permanent ice decreases, we are looking at ice-free summers in the Arctic as early as 2030.
They say you can't be too thin or too young, but this unfortunately doesn't apply to the Arctic sea ice. Polar bears are the first to suffer from it, but many other species could be affected as well. (2)
Pretty poor interviewing, as it merely created a false impression, rather thangetting to the truth. If he'd shown the press release, or even bothered to read it himself, it would have been perfectly obvious what was being described.
This is one of the problems with Hardtalk - the interviewers are so intent on maintaining control and authority, and appearing to be fierce and untrelenting, that is often produces some pretty bollocks journalism.
1 - "Greenpeace Leader Admits Arctic Ice Exaggeration," extract from a BBC Hardtalk interview with Gerd Leipold, interview conducted by Steven Sackur. Date of broadcast unclear, probably 10th of August, 2009, going by the BBC world headlines scrolling across the screen. Clip posted on EclippTV, by persons unknown, 20th of August, 2009. (http://eclipptv.com/viewVideo.php?video_id=6933)
2 - "Urgent action needed as Arctic ice melts," unattributed Greenpeace News item (NOT a press release], posted on the Greenpeace website, 15th of July, 2009. (http://www.greenpeace.org/international/news/urgent-action-needed-as-arctic)