Early Spring

Warming in last decades has pushed spring forward — cherry blossom and lilac festivals across the country now celebrated days earlier than ever before. It also means birds are laying eggs earlier than before, or — sometimes — not at all.

It's this kind of subtle mistiming that could spell disaster for our environment, jeopardizing the bees, birds, frogs and trees, and pushing them into extinction.

Now, more scientists than ever are involved at tracking the changes, and involving citizens — or amateur scientists — to gather data across the country.

This hour, On Point: on Earth Day, we're talking about global warning's effect on spring's timing.Guests:

Heidi Cullen, climate expert at the Weather Channel and host of "The Climate Code with Dr. Heidi Cullen."

Andre Dhondt, ornithologist at Cornell University.

Jake F. Weltzin, Executive Director, USA National Phenology Network.