Earlier species thanks to evolution. hope this helped!
Answer:
1. Carbon dioxide, increase of green house gas
2. Stop deforestation, cut down amount of cars on the road (encourage public to take public transport), reduce the amount of time u on the air-conditioning
A.atomic mass(a)=16
atomic mass(b)=18
b.a and b are isotopes
c.(a)=2,6
(b)=2,6
