From the CO2Science Archive: In honor of our US neighbour’s July 4th Independence Day celebrations we bring you the CO2Science summary of the effects of extra CO2 on the US National Tree, the mighty oak. There are, apparently, more than 60 oak species but we will look at Red Oak, which is particularly popular for woodworking and building. There were 16 experiments from 1986 to 2012 estimating the photosynthesis response to adding 300 ppm CO2 to the air, yielding an average increase of 63%. There was one experiment looking also at the response to adding 600 ppm and it resulted in an 82% increase. Long live the mighty oak and the nation for which it stands, and long may both enjoy the extra CO2 enriching its air.