I have received some interesting email of late that states that seafloor volcanoes are altering the Globe’s climate. So, I have been combing through the internet to see what I could find on this topic.
One theory is that seafloor volcanoes are more active in the time of glaciations than at time of the warming period in between. The thinking is that the increased weight of the ocean’s water, as it rises due to glaciers melting, reduces the activity of the many seafloor volcanoes. The converse is true about the land-based volcanoes that would become more active as the weight of the glacial ice disappears. The ash emitted from land-based volcanoes can cause cooling of the atmosphere but seafloor ash does not get into the atmosphere.
Additional theory is that the Sun and the Moon’s gravity have an effect on seafloor volcanoes was made in a posting by the Lamont-Doherty Earth Observatory titled “Seafloor Volcano Pulses May Alter Climate. One of the sources used by this posting was a study published in the journal of Geophysical Research Letters, by Maya Tolstoy, a marine geophysicist at the Lamont-Doherty Earth Observatory.
“Volcanically active mid-ocean ridges crisscross earth’s seafloors like stitching on a baseball, stretching some 37,000 miles. They are the growing edges of giant tectonic plates; as lavas push out, they form new areas of seafloor, which comprise some 80 percent of the planet’s crust. Conventional wisdom holds that they erupt at a fairly constant rate–but Tolstoy finds that the ridges are actually now in a languid phase. Even at that, they produce maybe eight times more lava annually than land volcanoes. Due to the chemistry of their magmas, the carbon dioxide they are thought to emit is currently about the same as, or perhaps a little less than, from land volcanoes—about 88 million metric tons a year. But were the undersea chains to stir even a little bit more, their CO2 output would shoot up, says Tolstoy.”
One of the inherent problems with seafloor volcanoes is that by their very nature, they are hard to observe. From the posting:
” However, Tolstoy and other researchers recently have been able to closely monitor 10 submarine eruption sites using sensitive new seismic instruments. They have also produced new high-resolution maps showing outlines of past lava flows. Tolstoy analyzed some 25 years of seismic data from ridges in the Pacific, Atlantic and Arctic oceans, plus maps showing past activity in the south Pacific.
“Seismic signals interpreted as eruptions followed fortnightly low tides at eight out of nine study sites. Furthermore, Tolstoy found that all known modern eruptions occur from January through June. January is the month when Earth is closest to the sun, July when it is farthest—a period similar to the squeezing/unsqueezing effect Tolstoy sees in longer-term cycles. “If you look at the present-day eruptions, volcanoes respond even to much smaller forces than the ones that might drive climate,” she said.
Below is a TED presentation by Tolstoy. It precedes her publication that we have been discussing , but she does mention learning more about volcanoes. Further she elaborates on the gravitational mechanisms that affect the volcanoes.
Many seafloor volcanoes have been studied but no one really knows the whole picture. The work that Tolstoy and her group are doing will certainly be helpful in filling in the picture. Better information about the numbers of seafloor volcanoes, their size and their location will better define the effect they have on climate.
The next posting will cover some postings about what one calls posting calls “plate climatology theory”.