Group years by decade in seaborn barplot

Question

If I have a DataFrame with a column 'Year' and another column 'Average temperature' and I want to represent them in a barplot to see if the global average temperature has risen over the last decades, how do you convert years to decades?

For example, between 1980 and 1989 I need it to be represented in x axis as 1980. For 1990 and 1999 as 1990, and so on.

Note that:

x axis = Year

y axis = Average temperature

Many thanks