The functions of the atmosphere today are

sustaining life with oxygen
filtering harmful rays from the sun
to protect earth from meteor collisions
removes nutrients from the soil
keeps the earth's climate unstable

The best answer I would preferthat it is sustaining life with oxygen

Wetlands form where water and land meet. a lake with a wetland fringe can fill in with decayed plant and animal material to become a wet meadow. a pond can fill in to become a bog or fen. sediment can fill in a river marsh to become a swamp.flooding of coastal lowlands from rising sea levels has created broad coastal marshes that are protected from wave action by barrier islands or reefs. coastal wetlands also form when rivers deposit sediment as they reach the ocean. plants then take root and hold the soil firm against the forces of tides and waves.