[Rockhounds] silicate weathering

[Kreigh Tomaszewski]

The Earth’s climate has undergone some big changes, from global volcanism
to planet-cooling ice ages and dramatic shifts in solar radiation. And yet
life, for the last 3.7 billion years, has kept on beating.

Now, a study by MIT researchers in *Science Advances *confirms that the
planet harbors a “stabilizing feedback” mechanism that acts over hundreds
of thousands of years to pull the climate back from the brink, keeping
global temperatures within a steady, habitable range.

Just how does it accomplish this? A likely mechanism is “silicate
weathering” — a geological process by which the slow and steady weathering
of silicate rocks involves chemical reactions that ultimately draw carbon
dioxide out of the atmosphere and into ocean sediments, trapping the gas in
rocks.

Scientists have long suspected that silicate weathering plays a major role
in regulating the Earth’s carbon cycle. The mechanism of silicate
weathering could provide a geologically constant force in keeping carbon
dioxide — and global temperatures — in check. But there’s never been direct
evidence for the continual operation of such a feedback, until now.

The new findings are based on a study of paleoclimate data that record
changes in average global temperatures over the last 66 million years. The
MIT team applied a mathematical analysis to see whether the data revealed
any patterns characteristic of stabilizing phenomena that reined in global
temperatures on a  geologic timescale.

They found that indeed there appears to be a consistent pattern in which
the Earth’s temperature swings are dampened over timescales of hundreds of
thousands of years. The duration of this effect is similar to the
timescales over which silicate weathering is predicted to act.

https://www.eurekalert.org/news-releases/971289