By sheer coincidence I was just browsing for dead trees having seen
a huge number of Poplars dead or dying in northern Europe

It seems that large numbers of many species of trees worldwide are
suffering from what is tentatively considered UV overexposure.

It may be also increased global temperatures which are stressing the
trees or allowing more southerly pests to migrate north.

If there is more ozone at lower levels from road traffic perhaps it's
time to pump it back up where it actually does some good?

If all the trees are lost our views of the sky may be improved but at
what cost?