Give me half a tanker of iron," he joked, "and i'll give you the next ice age." explain this quote from john martin's original article.

The idea was that fertilizing the ocean and seas would lead to the in increase growth of phytoplankton population.

The oceanic plants do not release carbon dioxide into the air when they die because the sinks into the sea carrying with them the carbon dioxide for several centuries. This would then decrease the levels of carbon dioxide from the air as plants absorb carbon dioxide from the air during the process of photosynthesis.

for  example, forests have higher evapotranspiration than other ecosystems,  such  as grasslands, because of their deeper roots and greater leaf area. thus forests have a net moistening effect on the atmosphere and become a moisture source for downwind ecosystems.