Misconceptions of the marine biological carbon pump in a changing climate: Thinking outside the "export" box.

The marine biological carbon pump (BCP) stores carbon in the ocean interior, isolating it from exchange with the atmosphere and thereby coregulating atmospheric carbon dioxide (CO ). As the BCP commonly is equated with the flux of organic material to the ocean interior, termed "export flux," a change in export flux is perceived to directly impact atmospheric CO , and thus climate. Here, we recap how this perception contrasts with current understanding of the BCP, emphasizing the lack of a direct relationship between global export flux and atmospheric CO .

Implications of plastic pollution on global marine carbon cycling and climate.

Plastic pollution can both chemically and physically impede marine biota. But it can also provide novel substrates for colonization, and its leachate might stimulate phytoplankton growth. Plastic contains carbon, which is released into the environment upon breakdown.

Enhanced silica export in a future ocean triggers global diatom decline.

Diatoms account for up to 40% of marine primary production and require silicic acid to grow and build their opal shell. On the physiological and ecological level, diatoms are thought to be resistant to, or even benefit from, ocean acidification. Yet, global-scale responses and implications for biogeochemical cycles in the future ocean remain largely unknown.

What are small-size microplastic distributions telling us?

Writing in this issue of Global Change Biology, Shiye Zhao and co-authors report a microplastic soup extending thousands of meters below the South Atlantic Subtropical Gyre. This discovery contributes two pieces to the missing plastic puzzle- (1) nets have been under-sampling the smallest microplastic size fraction, which is actually not missing when using high-volume filtration, and (2) small microplastics in particular find their way below the surface. But their results also contribute several new questions, because some of what they found is quite surprising.