小林大介君 dear life

ここのdearの用法を説明して下さい。（教え子より）
AN emotional Prime Minister Julia Gillard has toured the Japanese community of Minami Sanriku, a once tranquil fishing town that was obliterated by the recent tsunami.
Ms Gillard joined the town's mayor, Jin Sato, to survey the devastated frame of a building that was formerly the town's disaster management centre.

Mr Sato was inside the building when the torrent of water hit. He fled to the roof and hung on for dear life as the wave engulfed the building, sweeping his friends and colleagues to their deaths.
Ms Gillard was close to tears and gave Mr Sato a comforting embrace as he told her his story.
http://www.news.com.au/world/obliterated-town-of-minami-sanriku-leaves-julia-gillard-speechless-and-close-to-tears/story-e6frfl00-1226043728796#ixzz1KKuTYDht