El Niños in the past have raised temperatures for a period, then cooling follows shortly there after. Look at this ENSO history and you can see that warming is often followed by rapid cooling.
The problem will be that the warmers will use this temporary warming as a sign global warming has returned and we need to double down on CO2 reductions. But, the problem is rapid cooling soon follows the warming.
If the El Niño is from 2015-2016, unless we have a two years El Niño, then it would be 2015-2017 with a possible deep La Niña in 2017-2018 or 2018-2019, and by then the sunspots are projected to vanish and the planet will be on the cusp of a little ice age according to US and Russian scientist. More HERE in the update and discussion in the comment section at The Next Grand Minimum.