[titzer]

There's a lot of global changes that could be underlying contributing factors. Global air and water pollution, pesticides, microplastics. Things that were regional that are becoming global as Earth's massive interconnected recycling systems chug on our waste. The entire planet has traces of radioactive isotopes that were essentially non-existent before nuclear testing. Light pollution. Global insect apocalypse. You can create a list and rank them by the potential contributions. I didn't read the whole article because paywall, but there are lots of things that are all globally different than a century ago.