About 8,000 years ago,
when CO2 levels were near
260 ppm (415 ppm today),
ice core records suggest
surface temperatures
in Iceland were about
3°C warmer than today.
Iceland’s extensive lakes
and glaciers topography
provides a record of the
region’s historical climate.
Scientists can infer summer
temperatures 3°C warmer
than today in Iceland,
to account for the millennia
when glaciers “disappeared”
from the landscape
(Geirsdóttir et al., 2019):
A new study
(Harning et al., 2020),
using the history of the
Drangajökull glacier,
also affirms the surface
temperatures were
about 3°C warmer
than the late
20th century.
even though
CO2 levels were
about 150 ppm
LOWER than today
This is not consistent
with claims that CO2
variations are a driver
of temperatures or
glacier melt.
The early- to mid-Holocene
climate was as warm,
or warmer, than today !
Glacier extent was smaller,
as a function of altitude
and latitude, than it is today.
The tree line
was higher up
the mountains
than today.
A massive warming
of land based glaciers,
starting 20,000 years ago,
caused a 120 meters
( 400 foot )
sea level rise
over the next
10,000 years.
The estimates of
the historical
atmospheric CO2
levels come from ice cores,
which are not disputed
over the past several
hundred thousand years
( especially during our
current warm interglacial,
the Holocene, over the
past 10,000 years ).
CO2 never
controlled
earth’s surface
temperatures
in the past.
A change of temperature
always preceded the
corresponding change
in CO2 levels, in the ice core
records, by hundreds
of years.