Lands warm up more than oceans. We're already past 1.5°C of temperature rise and we probably won't do anything to prevent 2°C. Most probably, we'll hit +3-+4°C in 2100. However even +2°C is a global average; oceans are cooler, and 75% of the surface. It can easily be +1°C on the oceans, and +5°C on land, averaging to +2°C.
The situation of complex systems such as climate, the world economy and global ecosystems doesn't simply gently degrade over time. There are quick, catastrophic changes that occur rapidly when reaching certain thresholds. So all could be mostly fine for 1 year, or 5, or 10, then collapse suddenly any time because we've gone through one particular threshold we don't know (ocean acidity, surface temperature, oxygen concentration, forests dying from the heat and becoming carbon sources, etc).
Prepare for a tough, violent future. Be scared to death.