The "hiatus" doesn't exist.
That is the conclusion of a new study published in Science yesterday. Tom Karl and his co-authors used a newly available database of weather station data that combined the Global Historical Climatology Network (GHCN) used by NOAA and NASA with over 40 other historical data sources, effectively doubling the size of the available land temperature data set. They applied the same corrections for changes in location, urban heat island effect, etc as with the GHCN-only data set and used the same algorithms to calculate the global average over land. To get a global average, they used the Extended Reconstructed Sea Surface Temperature dataset version 4 (ERSST4), which better integrates ship-based temperature data and buoy-based temperature data, and merged it with their new land data. Karl et al. then created a third global temperature average that also fills in the gaps between weather stations in the polar regions. Their new data set shows much higher trends than the GHCN-only data, e