“Fat man” atomic bomb: 22 kt = .000022 gigatons (GT)
Chelyabinsk meteorite (2013): 300 kT = .0003 GT
Castle Bravo: 15 MT = 0.015 GT
Tsar Bomba: 50 MT = 0.05 GT
Tunguska event: 100 MT= 0.1 GT
This event here: 2,700 MT = 2.7 GT
KT-impactor (the “asteroid that killed the dinosaurs): 100 teratons = 100,000 GT
If this asteroid hits the earth, it’s going to leave a mark although it won’t cause mass extinctions.
It all depends on where the impact happens, of course. Most of the Earth's landmasses are above the Equator. Even if there's not a mass extinction of whole taxa, as with the impacts that caused the paleontological boundaries, an impactor of 340 meters is, uh, serious, could destroy our technical civilization, and run our surviving asses off into a much earlier period of development.