Last week in class, we were talking about elemental composition of the oceans and atmosphere, and the ways that biological feedbacks affect that composition and shape the environment for life. It seems that scientists keep learning about new ways in which biology feeds back on processes typically classified as earth science, with implications for the large scale patterns in evolution. Sure enough, there’s a new one in the news.
It turns out that undersea volcanoes are more active when the weight of the sea above them is lowered. This was discovered by looking at activity through the cycle of tides. But it has profound implications for variation in volcanism through glacial cycles. During glaciations, sea-level is reduced and volcanism should increase, and it’s even possible that the resulting volcanoes spewing CO2 help to end those glacial periods. Although the article doesn’t make the connection explicitly, it follows that anthropogenic warming should slow down seafloor spreading by increasing the weight of the oceans. It’s a sensitive world we live in, and this study just gives us one more feedback mechanism that defines our “pale blue dot”.