Temperatures have been rising for 100 years

 Global temperatures have been rising for over a hundred years, though the faster rise only began from the 1970s onwards.  This coincided with a steady expansion in CO2 and other greenhouse gas emissions, which accelerated after WW2 and again with the rise of China.   Note 1) the occasional random spikes up, and down; 2) cycles around the rising trend caused by such natural cycles as ENSO  (El Niño Southern Oscillation); 3) occasional 2-3 year blips caused by volcanic eruptions (for example after the Mt Pinatubo eruption in 1991).  

Temperatures have drifted lower since the last El Niño, in 2016, just as they did in the one before in 1998.  The post 1998 decline led many to conclude that global temperatures had stopped rising, though that notion was dispelled when the next ENSO cycle came along.  Over the next couple of years, the volcanic eruption in Tonga will likely cool the Earth by at least 0.5 degrees, because of the emission of sulphur dioxide aerosols.

(Chart from  Our World in Data)