> Among them, cloud feedbacks,
http://www.grida.no/climate/ipcc_tar/wg1/271.htm
The potential complexity of the response of clouds to climate change
was identified in the SAR as a major source of uncertainty for climate
models. Although there has been clear progress in the physical content
of the models, ****clouds remain a dominant source of uncertainty*****,
because of the large variety of interactive processes which contribute
to cloud formation or cloud-radiation interaction: dynamical forcing
- large-scale or sub-grid scale, microphysical processes controlling
the growth and phase of the various hydrometeors, complex geometry with
possible overlapping of cloud layers. Most of these processes are
sub-grid scale, and need to be parametrized in climate models.
> surface level albedo changes,
http://www.grida.no/climate/ipcc_tar/wg1/291.htm
At present, only limited global data sets for LSPs are available and
these need to be further improved. A comprehensive land-use/land cover
data set, providing a global time-series of vegetation and soil
parameters over the last two centuries at GCM resolution, would be a
very useful tool to separate land-use change impacts on regional
climate from global scale warming effects. Additionally, for both
historical analyses and future projections, there is a need for
interactive vegetation models that can simulate changes in vegetation
parameters and carbon cycle variables in response to climate change.
These proposed fourth generation models are just beginning to be
designed and implemented within climate models.
> spectrum responses,
we've been through this one, the "grey atmosphere assumption"
> solar variations,
http://www.grida.no/climate/ipcc_tar/wg1/244.htm
The difference between these two assessments depends critically on
the corrections necessary to compensate for problems of unexplained
drift and uncalibrated degradation in both the Nimbus 7/ERB and ERBS
time series. Thus, longer-term and more accurate measurements are
required before trends in TSI can be monitored to sufficient accuracy
for application to studies of the radiative forcing of climate.
> long term cycles of all stripes,
http://www.grida.no/climate/ipcc_tar/wg1/025.htm#e3
As can be seen, there is a wide range of global scale internal
variability in these models.
> plant species responses (some plant species grow FAR better than the current
> mix under high co2 conditions, expect to see those plants becoming more
> prevalent),
neglected, never mentioned, but a fact over any real timescale
nevertheless.
> methane release due to melting permafrost,
4.5.3 Feedbacks through Natural Emissions
Natural emissions of N2O and CH4 are currently the dominant
contributors to their respective atmospheric burdens, with terrestrial
emissions greatest in the tropics. Emissions of both of these gases are
clearly driven by changes in physical climate as seen in the ice-core
record (Figure 4.1e). Soil N2O emissions are sensitive to temperature
and soil moisture and changes in rates of carbon and nitrogen cycling
(Prinn et al., 1999). Similarly, methane emissions from wetlands are
sensitive to the extent of inundation, temperature rise, and changes in
rates of carbon and nitrogen cycling. Natural emissions of the
pollutants NOx, CO, and VOC play an important role in production of
tropospheric O3 and the abundance of OH; and these emissions are
subject to similar forcings by both the physical and chemical climates.
Terrestrial and aquatic ecosystems in turn respond to near-surface
pollution (O3, NO2, acidic gases and aerosols) and to inadvertent
fertilisation through deposition of reactive nitrogen (often emitted
from the biosphere as NO or NH3). This response can take the form of
die back, reduced growth, or changed species composition competition
that may alter trace gas surface exchange and ecosystem health and
function. The coupling of this feedback system - between build-up of
greenhouse gases, human-induced climate change, ecosystem responses,
trace gas exchange at the surface, and back to atmospheric composition
-*****has not been evaluated in this assessment*****. The variety and
complexity of these feedbacks relating to ecosystems, beyond simple
increases with rising temperatures and changing precipitation, argues
strongly for the full interactive coupling of biogeochemical models of
trace gas emissions with chemistry and climate models.
> and the
> absolutely stupid ghg value that is used for long term methane (it has
> an atmospheric half life of 1-2 years, after which it decomposes into
> CO2 and water, the stupidity is that in most climate modeling, they
> pretend that the water stays in the atmosphere, as though it were
> separate water not subject to rain)
I am sure that methane has a 500 year gwp of 6 if you keep all the
reaction products in the same test tube, however, in the atmosphere, it
has a 500 year (and in fact a 50 year) gwp of 1.
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