Climate science is the study of how various factors, such as sunlight, tilt of the earth, ocean currents, etc., combine to produce various weather events. It has advanced to the point that forecasters can recognize forming hurricanes, but not to the point where tornadoes can be predicted. There is a real need for better understanding of climate.
The wild chase after “global warming”, unfortunately, takes time, money, and resources away from studying the questions that still need to be answered.
There are at least a couple of issues with the chart you posted. One is that it covers such a short time span—it certainly does not cover sufficient time to establish any temperature patterns—humans have not been measuring temperature for a long enough time to have any but a rough idea of temperature patterns. Another is that it is highly doubtful that the average temperature of the earth can be measured, especially not to within 1/10 of a degree (about the height of one of those vertical bars on the data points). With extremely reliable and sensitive thermometers, we can’t even achieve that kind of precision when measuring the temperature of a single human being, which is a far more constant temperature system than the earth. So the idea that the earth’s average temperature can be measured to within 1/10 of a degree, and that the average can then be shown to have varied over a range of 0.6 degrees over the last 25 years is ludicrous. I would say that the 0.6 degree range shown on that chart falls well within background noise—meaning that it means nothing at all.
Where did you find that chart?
That's the definition of weather science. Climate Science is supposed to address the longer term ~ 30 yr +. To date, though there are many scientists working in the area, there is no Climate Science as they can't yet predict squat. The figure is apparently part of the IPCC 5th report, now leaking out. The predictions/projections from their models have been overcome by events.