Thanks to El Niño and climate change, last year broke temperature records – and reduces any importance attached to the global warming 'hiatus.'
There's no agreed definition, no agreed starting point – and no data to back it up.
Study of natural variability explains slowdowns in the rate of warming in recent decades – and is key to improving climate models.
NASA's former climate chief, James Hansen, is lead author on a paper that predicts rapidly rising seas this century, but not all climate scientists believe the study's models are convincing.
NOAA review reveals that difficult-to-explain slowdown in higher temperatures from global warming was based on faulty data.