Bear scare

Here's another inconvenient truth for you: Scientists say polar bears may be endangered because their habitat is melting. You can hear more about it tonight at the Brattle when photographer Steven Kazlowski speaks about his book "The Last Polar Bear." Kazlowski, who also has a book called "Alaska's Bears of the North," will project his nature photos (pictured) on the big screen while he talks about his travels through Alaska and the Yukon. The event will be followed by a reception at the Globe Corner Bookstore down the street. Reservations recommended. 6 p.m. Free. 617-497-6277. Brattle Theatre, 40 Brattle St., Cambridge. www.globe cornerbookstore.com/blogs/events