TL;DR
Microplastics degrade photosynthesis by 7-12% on average, 6-18% in terrestrial crops such as corn and wheat, 2-12% in marine plants, 4-14% in algae. The entire web of life is impacted.
These reductions translate into a range of 4-13.5% yield loss for farmers per year over the next 25 years (forecasted). It also impacts climate change as reduced photosynthesis reduces the carbon sink in climate models making target changes needed that much harder to meet.
No international agreement on reducing plastic pollution/production has been ratified with the last serious discussion happening in 2017 by the UN.
