Scientists discussing global warming are considering whether it will happen much faster than we thought.
A recent study suggests that all oceans may run out of oxygen by 2030 as a result of global warming [http://www.i4u.com/2016/05/109639/oceans-are-running-out-oxygen].
Additionally, James Hansen is the former NASA scientist who called attention to global warming in 1988. His new paper suggests our models may underestimate the speed of the change. Here is the link to the paper: http://www.atmos-chem-phys-discuss.net/15/20059/2015/acpd-15-20059-2015.html
For a detailed and non-technical presentation which includes other scientists' views, read Chris Mooney in the Washington Post here ; http://www.washingtonpost.com/news/energy-environment/wp/2015/07/20/the-worlds-most-famous-climate-scientist-just-outlined-an-alarming-scenario-for-our-planets-future/
Additional projections of sea warming effects on the marine food chain are available here : http://www.eurekalert.org/pub_releases/2015-10/uoa-gma100915.php
The possibility that warming and glacial melting may happen very quickly moves the Doomsday Clock forward.