The thing that would most likely to happen if the phytoplankton in the ocean were reduced is that the amount of carbon dioxide will increase since these plants are the one who is consuming most CO2 in the water.
I believe that substance would be water.
Answer: A warm front forms when a warm air mass pushes into a cooler air mass, also shown in the image. Warm fronts often bring stormy weather as the warm air mass at the surface rises above the cool air mass, making clouds and storms.
I am sure that it is Typhoons which is a tropical storm in the region of the Indian or western Pacific oceans.