I would say a natural disaster like a forest fire that could kill trees that are their homes. A forest fire could kill the trees and also the cones they eat for food and thus destroy their habitat and also a source of food and the branches they use to travel from one tree to another in the upper stories of the forest.
Pollution from factory discharges and waste dumping. Also biodiversity from deforestation and other natural habitat losses
Answer:
The carbon cycle would die instantly
Explanation:
Since eukaryotes are everything in the carbon cycle. Eubacteria and archaebacteria don't actually do anything to help the carbon cycle flow.