The world's oceans cover an area of roughly 360 million square kilometres. What is the annual net primary production of all the world's oceans? The world's tropical rainforests cover roughly 30 million square kilometres. What is the annual net primary production of all the world's rainforests? (Use a conversion factor of 1 km2 = 1,000,000 m2 as needed.) Does the answer surprise you? What are the main sources of production in each biome