JOHN YANG: And finally, tonight, an annual celebrated event took place in Washington this past week, and it didn't have anything to do with politics.

JOHN YANG (voice-over): It's known as peak bloom the day 70 percent of the blossoms are open on Washington's iconic cherry trees around the Tidal Basin.

This year's was two weeks earlier than average after the warmest Washington January on record.

Cherry blossom season in the nation's capitol draws a million and a half people from across the country and abroad.

Lorna Phillip and her sister came from Trinidad and Tobago.

LORNA PHILLIP: On of our main reasons for coming she wanted to see the cherry blossoms and bloom, and I mean just nature at its best.

JOHN YANG (voice-over): But for 158 of the trees, this will be their last bloom.

The National Park Service's cutting them down later this spring as part of a project to rebuild the Tidal Basin sea walls, which have sunk over the years in some places as much as five feet as a result in floods twice a day at high tide driven by rising waters due to climate change.

MIKE LITTERST, National Park Services: In inundates the roots of cherry trees resulting in the deaths of many trees and threatens infrastructure like sidewalks.

It's even forced us to close the Jefferson Memorial from time to time, as the water overflows the walkways leading to the site.

JOHN YANG (voice-over): That twice a day diet of brackish water has hollowed out the trunk of a beloved tree known as stomping, it stubbornly continues to bloom despite being in what botanists call a mortality spiral.

It's getting even more attention this year since it's one of those on the show chopping block.

MIKE LITTERST: Our partners at the National Arboretum will take clippings of stumpy and create genetic matches essentially clones with the same genetic material is that tree and we'll plant those around the title base and when the work is finished.

EMMY VICKERS: Well I'm glad they waited.

They're going to wait until after that cherry blossom season.

Yeah, it will be interesting.

I will be here every year like I always do.

JOHN YANG (voice-over): And as this year's display of beauty fades, a reminder of the cycles of life, both human and botanical.