From IVAR AANDERAA
In the story ‘Global warming rings true’, it is suggested that the thicker
tree rings observed during recent years may indicate global warming (New
Scientist, Science, 21 September). This may be so. But it appears to me
that it could also be because of the fertilising effect of acid rain and
the increase in atmospheric carbon dioxide during recent years. Plants grow
faster these days owing to acid rain and the higher content of CO2
in the atmosphere.
Ivar Aanderaa Bergen Norway
