What evidence is there for the assumption that climate sensitivity based
on paleo record is applicable to present day?
Do the high - frequency signals from these eruptions show up in
other paleo records, specifically other T proxies?
And that's consistent with generally higher CS value deduced
from paleo record rather than from direct observations.
«I think that's a really interesting field of research that requires us to go back and look
at paleo records.»
There are good reasons for doing so in the cited articles, specifically the much better historical and
paleo records for the NH.
But if all
different paleo records react just in a way that the climatic effects of the major erruptions are hidden and unobservable then — as you said it — we have a problem.
So for
global paleo record we should switch to Loehle 2007, and for longer time span the Greenland drill record is not bad as well.
Of the 73
proxy paleo records used in the original Marcott thesis research, Marcott et al. moved forward in time 10 of the individual paleo - datasets and 9 backward in time - the other 54 dataset ending dates did not change
In looking at the disparity
between paleo records and instrumental observed records It would be useful to see historical climatologists and modellers work more closely with each other in order that the past climate states and their variability can be more accurately depicted.
* The CET comparison to the global instrumental record (shown from 1900 in figure 4) is pretty good as is its comparison to the 50
year paleo records.
A sensitivity of 6 degC (with positive water feedback) is rediculous since in
the paleo record there are many instances of high CO2 levels and cool temperatures as well as rising CO2 levels and cooling temperatures.
In
the paleo record, the biosphere responded to atmospheric, solar and GHG changes in the way that provided selective advantage.
I agree that the consequences of GW aren't quite settled yet but there is enormous evidence from Earth's
paleo record on how the planet responds to sudden warming, like the aftermath of the Paleocene - Eocene thermal maximum.
Why should the late 20th century be any different from any other time, and where are these decadal weather forcings in
the paleo record?
We look to the real world and
the paleo record to constrain those aspects of the climate system that have non-negligible uncertainties (most often climate sensitivities in a general sense).
You implied that there was nothing in
the paleo record showing a rapid release of methane but there was a paper in October suggesting a very rapid release which caused warming of 5C in 13 years (and rendered the ocean surface acidic).
Yet
the paleo record clearly demonstrates there is.
It does seem from
the paleo record that the 20th century was overall wetter than normal and, in particular, the decade and a bit leading up to the 1922 Colorado River pact and then the last two decades of the 20th century when population growth really took off.
The current drought fits into our sense of what climate variability can bring to the region once you use
the paleo record to fully assess the possibilities.
I'm unaware of
a paleo record confirming an ECS of 3 degrees.
This timescale of melt was also confirmed by the ANDRILL record (Naish headed at least one of these expeditions) and
another paleo record showing that the sea level rose rapidly around a corresponding time.
However it's clear that now, modern [changes] forced by higher CO2 are accelerating at rates faster than historical and
paleo records would suggest.
I certainly don't think we'll melt all of Antarctica or even Greenland, but we know from
the paleo record very significant melting and sea level rise are possible once the warming epoch gets under way.
This is an example of energy transport affecting the energy balance and a valid argument by itself that
the paleo records aren't a reliable way to estimate current climate sensitivity, isn't it?