From the
"climate science
is not settled
department":
Several recent studies
claim that cloud cover
changes:
“control the Earth’s
hydrological cycle”,
“regulate the
Earth’s climate”,
and “dominate
the melt signal”
for the Greenland
ice sheet,
via modulation
of absorbed
shortwave
radiation.
CO2 is not mentioned
as a contributing factor.
Climate modeling of factors
influencing Greenland warming,
and surface melt have been
100% wrong.
A few years ago
scientists
acknowledged:
“a major disparity in trends
between models from the
Coupled Model
Intercomparison Project 5
(CMIP5)
and observations
( actual temperature
measurements )
for the last
20-30 years”
All 36 climate models
simulating blocking
over Greenland
were wrong.
Poor performance of
the modeling relative
to observations
has been ongoing
for the last
20 to 30 years.
In all other
scientific fields,
a one hundred percent
failure rate for decades
would have discredited
the models.
(Hanna et al., 2018).
Within a matter of hours,
the radiative forcing effects
from clouds can vary
by ±40 W/m² in the Arctic.
From one year
to the next,
cloud radiative effects
can vary by 70 W/m²,
and overall cloud
radiative effects
can reach 360 W/m² !
(Ebell et al., 2020).
In contrast, the total
accumulated change
in net impact
from CO2 forcing
is only 1.82 W/m²
since 1750.
(Feldman et al., 2015).
Cloud forcing
dominates
in the Arctic.
Clouds regulate
Greenland’s
climate,
and models
grossly fail
to simulate this.
According to
a new study,
clouds:
"control the Earth’s
hydrological cycle”,
“regulate the Earth’s
climate”, and drive
polar ice melt.
Further,
"the surface melt
climate is strongly
dependent on
the representation
of clouds and related
radiation fluxes“.
Models of
cloud effects
over Greenland
are biased
– or wrong –
by 25-50 W/m².
(Lenaerts et al., 2020)
Another new study
finds reduced
cloud cover
from 1994-2017
led to enhanced
shortwave radiation
( +7.3 W/m² ) ,
and drove
the warming
from the 1990s
to mid-2000s.
This shortwave
cloud forcing trend
is what “dominates”
the melt signal
for Greenland.
Greenland’s warming
trend is shown to
taper off into a pause,
or a slight cooling,
trend since ~2005.
The ice melt trend
spiked in 2012,
but has been flat
(or declining) overall
since about 2005 too.
There is no clear
indication that
atmospheric CO2
concentration changes
can even remotely
compete with cloud
radiative effects
as drivers of
climate trends
over Greenland.
( Hahn et al., 2020 )