Per my comment above, we actually just experienced the largest 2-year drop in temp in the last 100 years. The danger with a hugely complex system like "global warming" (i.e. world climate) is that it can be attributed to be the cause of anything.
https://climate.nasa.gov/vital-signs/global-temperature/
It seems some years are cooler than others, but the general trend is upwards.
I don't see where the last two years indicate much of a temperature drop. Do you have a source of information for your statement?
While 2017 was slightly cooler than the year preceding, it was the second hottest year since global temperature records began in 1880.
From the same page you linked. https://www.giss.nasa.gov/research/news/20180118/
We'll see how 2018 compares. Look at the chart and you can see that it's not a straight line, it has ups and downs. I see no reason at all to assume that it's trending downward for the next few decades to erase the increase seen over the last century.