Answer:
They have a choice whether to live in water or on land
Explanation:
since they can live on water and land they can choose where they live
Clouds can cover up the sun, which is the natural source for heat everywhere. When the sun is not in sight, or thickly covered by clouds, this limits the suns radiation and heat waves therefore causing less light and heat.
The main sources are humans which is why it is stated that the global warming is man made. The levels have increased beyond all measure, increasing since the 1950s by a 100 CO2 parts per million, and it keeps increasing by 2ppm on a yearly basis. The statistics from the industrial revolution era are not much different and show how much we've increased the CO2 in modern times.
Fertile soil and mild climate!