Core Insights - A recent study published in the journal Nature Microbiology indicates that global warming poses a significant threat to Prochlorococcus, a crucial oxygen-producing marine microorganism, with potential population reductions of up to 51% by 2100 under moderate to high warming scenarios [1][5]. Group 1: Impact of Climate Change - Prochlorococcus, a vital cyanobacterium found in 75% of the sunlit surface oceans, contributes approximately 20% of the world's oxygen through photosynthesis [3]. - Predictions suggest that sea surface temperatures in many tropical and subtropical regions may frequently exceed 30°C by 2100, endangering marine ecosystems [3][5]. - Previous assumptions indicated that Prochlorococcus would expand its distribution with rising ocean temperatures, but these estimates were primarily based on laboratory data [3]. Group 2: Research Findings - The study analyzed a decade of data collected from ships traversing the tropical and subtropical Pacific Ocean from 2010 to 2023, revealing that the growth and division rates of Prochlorococcus are temperature-dependent [5]. - Contrary to earlier predictions, the study found that the division rate of Prochlorococcus sharply declines when sea surface temperatures exceed 28°C [5]. - Simulations indicate that under representative concentration pathways 4.5 and 8.5, Prochlorococcus productivity could decrease by 17% to 51% compared to current levels in future moderate and high warming scenarios [5][7]. Group 3: Research Limitations - The authors acknowledge that their field sampling may have missed rare heat-tolerant Prochlorococcus strains, and the ship-based data may not adequately represent some hotter tropical regions [7].