I don't understand that graph. Why is it so spiky? for any particular year. It almost looks like the temperature varies by ~0.5 degrees week to week. Can someone explain it to me?
The anomaly is the variation from the average, and the anomaly is measured daily. What happens on any given day is _weather_, and it is expected to vary greatly based on things like cloud cover and wind speed and direction. The 2C anomaly on November 18th was just the anomaly on that day and doesn't represent climate change having reached 2 degrees.