This line chart shows the evolution of mean annual temperature anomalies from 1880 to 2014. The data is a subset of the NOAA’s GISS Surface Temperature Analysis (GISTEMP).
On the X axis, we display the year and on the Y axis we represent the global, northern hemisphere and southern hemisphere anomalies. The range selector under the chart allows to zoom into a particular period. Hovering the mouse over the graph shows the anomaly values in the legend. Use the small box in the lower-left corner to smooth the line by setting any rolling period.
As we can see, there is a global warming trend only interrupted in the middle of the 20th century. The shaded areas help us to discern which hemisphere anomaly is above or bellow the global anomaly. Notice that northern and southern hemispheres alternate being above or bellow the global anomaly. Also, when they shift their position, the new arrangement persists for several decades. This pattern is better perceived setting a rolling period of 4 or 5 years.