. >> andy mahoney is a geophysicist, he has been studying polar sea ice for the last 15 years. >> this part of the arctic, the alaska arctic if you like has seen the most extensive retreat of sea ice. >> in mostly open water we can see one reason scientists think the arctic is warming faster. that's while because the land reflects sea ice, the ocean absorbs it. >> melts more ice and propagates the cycle. >> phil torres reporting from the arctic. >>> los angeles police officers are now wearing body cams. planning to deploy more than 7,000 cameras in the next month. the traffic officers will not be wearing cameras. the cameras are necessary in today's climate. >> i think it's important with today's society that we're in with social media and videos of police officers it's important to give the point of view from the officer. so it's very proactive, it's very moving-forward with the society we're in today. so it's definitely the right move. for 1.5% of officers that are actually bad apples and are actually doing illegal actions or unethical actions i think it will put them on the forefron

. >> reporter: andy mahoney is a geophysicist at the university of alaska fairbanks. he's been studying polar sea ice for 15 years. >> in this part of the alaska arctic, it has seen some of the fastest and most extensive retreats of sea ice anywhere are in the arctic. >> reporter: watching ice floes drift in mostly open water, we can see one reason scientists think the arctic is warming faster. that's because while sea ice reflects sunlight, the ocean absorbs it. >> it's a vicious circumstance am. you remove the ice and expose water. that water is more able to absorb sunlight and heat. so it causes more warming, which melts more ice and propagates the cycle. >> that's phil torres reporting from the arctic. >>> republican governor scott walker lays out his version of an immigration reform plan and says building a border may be a good idea, but it's not where you think. >>> an academic article by an assistant professor at west point stirs controversy calling critics of the war on terrorism traitors. >>> welcome back to al jazeera america. it's 7:46 eastern time. taking