The important thing is the mean AVERAGE temperature.
Naturally temperature appear to oscillate with a roughly constant mean for the past 600,000 years,[1]
Natural oscillations tend to lead to relatively quick changes in temperature, for example the El Nino Southern Oscillation can change Pacific temperatures by up to 5C. But the average temperature change this causes over decades or centuries is minimal.
The same is true for the Summer/Winter cycle (the northern hemisphere has a lower heat capacity so dominates this cycle), the 11 year solar cycle etc.
Humans appear to be introducing a constant increasing trend thanks to greenhouse gases (as well as other changes, like reflectivity etc). This is the important aspect.
Temperatures now are lower than 1998, but this doesn't mean that global warming is over. 1998 was a very strong El Nino[2]. Stronger than any year since, partly explaining its warmth.
2008 was still warmer than any year before 1997. So you could say we've continued warming since 1996, or any year before. Current climate models expect ocean currents and the likes to hold back warming for years, but human caused global warming is still the accepted theory[3].