Because ever recorded is a code word for only recently - sea surface average is about around the medieval climate optimum and under the roman age warming period.
Not to say climate is not warming up, but news reels always go for the most sensationalistic take they have available because that sell, while more nuanced takes tend to be buried under pressure from the ministry of truth to control the message, as they believe us to be simpletons.
It's relative to 1981-2010 baseline. Negative is lower, positive is higher. In 1995, presumably, it was also the average temperature for the 1981-2010 time.
The two colors are negative and positive, a potentially unimportant dramatization.
Clarifying based on what I understood: Data from 1940-today show that the period from 1985-today had 8x more heat added than the period from 1958-1985, and that each decade since 1958 has increased in temperature.
Not to say climate is not warming up, but news reels always go for the most sensationalistic take they have available because that sell, while more nuanced takes tend to be buried under pressure from the ministry of truth to control the message, as they believe us to be simpletons.