Actually yes, planting trees (especially the wrong trees) is not always a good thing. Darker leaves will attract more heat (imagine if it was possible to turn the polar regions into trees - this would have a very negative effect).

Also mono cultures and replacing natural vegetation with man-made forestation can actually be more limited to the amount of carbon they can capture long term.

Source: https://spiral.imperial.ac.uk:8443/bitstream/10044/1/80271/6...