Which specific species of trees Rick? Ivy does grow over trees, and anything else in its way, but doesn't usually kill a full size tree unless it already has other problems.

As Moongrower says, exactly, although sometimes, after some years, a mass of ivy up in the top of a healthy tree can eventually kill it, just by preventing photosynthesis of the tree's leaves as it smothers it and keeps out sunlight. But Ivy, once growing, will grow over anything and everything in its path, including upwards, without intervention by humans.

This isn't a new thing - is normal.

yes perfectly normal and as already said rarely compromises the tree if it is healthy.

BTW Rick ivy is just that, there isn't a special 'tree ivy'.

I have noticed the same over the years but an old countryman explained that years ago a farmer used to employ a man full time to go round his land hedging and ditching by hand and keeping the ivy from climbing right up the trees. Nowadays they hire in a man with a hedgecutter machine once a year and neglect the ditches until they are blocked and cause the land to flood and ignore the ivy altogether! (His words, not mine!)
I have sometimes pulled ivy off the bases of trees when out with the dog, but I don't suppose it retards it much!

I know exactly what you mean. In my area of Hertfordshire the ivy seems to have accelerated its growth spurt over the past few years and in my garden, I have lived here for over 60 years, I have noticed the sudden increase of ivy growth.

Beware , I cut it back hard at ground level and climbed in amongst the ivy growth up th tree to let some light in to find that I had become extremely allergic to the oil that ivy produces and ended up in hospital with severe burns to my hands arms and legs and face. From now on not only do I use strong gloves but I cut back any ivy as soon as I see it emerge on its journey up the trunks and leave it well alone.

Yup just keep cutting back... Think the ivy has grown faster over the past few years due to the mild winters and, I could be completely wrong!