He tells Newsweek the findings play into a bigger picture, where
we see large volcanic eruptions having an impact on the global climate that causes a chain effect resulting in social unrest.
Not exact matches
It's also now well understood that
large volcanic eruptions have a short - term cooling effect,
see GW FAQ: effect of
volcanic activity (short - term being the key phrase, after Church et al Nature 2005, and also http://www.llnl.gov/str/JulAug02/Santer.html)
You can also experience the desolation and beauty of the Valley of 10,000 smokes while at Katmai to
see a wondrous area left by the
largest volcanic eruption of the last century.
Barring any
large volcanic eruption, I don't
see any reason for the decadal trends to depart much from the anticipated ~ 0.2 ºC / decade.
If
volcanic emissions were significant in a climate context, we'd
see notable spikes in CO2 following some of the
largest historical
eruptions.
After a
large volcanic eruption, the layer of sulfate aerosols in the stratosphere gets thicker, and we
see, in the historic record, that the Earth cools down in response.
If you look at the average global response to
large volcanic eruptions, from Krakatoa to Pinatubo, you would
see that the global temperature decreased by only about 0.1 °C while the hypersensitive climate models give 0.3 to 0.5 °C, not
seen in reality.
If you look at the the lower stratospheric temperature, you do
see a
large positive temperature perturbation immediately after the
volcanic eruption (this is expected of course), but rather than returning to the same relatively constant temperature, it shifts to a new, lower temperature operating point.
You can
see in Figure 3 that some of these chemistry - climate models do capture this overshoot behaviour following the effects of
large volcanic eruptions.
Given the fact that internally the earth itself has
large temperature changes which melts the upper mantle and deep crust producing
volcanic eruptions at the surface, it is not difficult to
see that the thermal energy involved and the mass of the earth itself, that the earth's own internal temperature fluctuations might have bigger effect on the atmosphere's temperature than the sun.
Then throw in massive
volcanic eruptions and huge continent wide brush fires caused by volcanoes or meteor showers (both theories I have
seen in the literature) and you have many events that could cause climate disruption on a
large scale.
Similarly, if global temperatures drop for some reason (for example, a
large volcanic eruption dumping massive amounts of aerosols into the air), we should expect to
see water vapor concentrations decrease.
We'd expect to
see the imprint of this
large error in comparisons with observed surface temperature changes over the 20th century (37 - 42), and in comparisons with the observed cooling after
large volcanic eruptions (30, 43, 44).