oh so climate change is seasonal is it?
now you blame a invisible colorless odorless, inert gas and want to sacrifice the poor of the world by constricting the energy supply as a virtue signaling solution
Seaweed and other plants are indeed a "seasonal thing". Leaves fall off trees seasonally. And trees grow faster and produce more leaves when there is more CO2. Ask any marijuana grower!
Same thing with sargassum seaweed. And overproduction of sargassum is a visible early indicator of increased levels of CO2 and increased ocean temps because it grows on the surface of the ocean. Algae consumes way more CO2 than trees as do other marine plants, like kelp. In fact, there is a lot of research going on around carbon sequestration through ocean biomass. Ironically, all that sargassum is doing a job of capturing all the CO2. Sucks for humans living near those beaches though. Maybe even a good thing if you think about it because it means less airliners flying to those beaches.
But it is a good CO2 'canary in the coal mine'.
Oh, and C02's role in climate change has nothing to do with being "inert". It has to do with the CO2 molecules size interfering with infrared wavelength energy's radiation back into space. This is why they call it a "greenhouse gas".
Think of it as a gaseous glass bubble around the earth. And think of the glass in an actual greenhouse. It looks "invisible". But glass is
clearly 
not invisible to the "invisible" ultraviolet and
infrared spectrums of solar energy we refer to as light.