Second, they took a second
set of climate model simulations which were identical to the first set, except that CO2 concentrations were kept constant at 19th century levels.
Between 801 and 1800 ce, the surface cooling trend is qualitatively consistent with an independent synthesis of terrestrial temperature reconstructions, and with a sea surface temperature composite derived from an
ensemble of climate model simulations using best estimates of past external radiative forcings.
An evaluation
of climate model simulations used in the latest IPCC -LSB--RSB- reports finds that the atmospheric changes that account for most of the 113 year warming trend are not predicted to result from historical radiative changes, including both natural and anthropogenic forcings.
Daily snowfall in a
range of climate model simulations has recently been made available through the Coupled Model Intercomparison Project — a growing archive of climate modeling output, including snowfall, that modeling centers and researchers around the world contribute to and analyze.
The disagreement arises from different assessments of the value and importance of particular classes of evidence as well as disagreement about the appropriate logical framework for linking and assessing the evidence — my reasoning is weighted heavily in favor of observational evidence and understanding of natural internal variability of the climate system, whereas the IPCC's reasoning is weighted heavily in
favor of climate model simulations and external forcing of climate change.
Analysis by
Collins of climate model simulations indicated that increased CO2 may result in ENSO events becoming larger in amplitude and more frequent than under present conditions.
Figure 1 shows the impact on the global average temperature trend for all trend lengths between 10 and 35 years (incorporating our educated guess as to what the 2013 temperature anomaly will be), and compares that to the
distribution of climate model simulations of the same period.
Also, perhaps I'm misunderstanding the methodology you've described, but I find the idea of delivering short term predictions from AR4 models a little strange, based on previous discussions made here about the Cox and Stephenson's «sweet spot»
of climate model simulations of ~ 20 - 50 years.
That understanding will be advanced by new and more extensive data collection efforts, improvements to methods used to synthesise that data, and more extensive and collaborative use
of climate model simulations over this period — both to understand the forcing / response of the climate, but also to serve as testbed for the various reconstruction methodologies.
With the help of precise satellite data and an extensive
suite of climate model simulations the current research was able to observe that the upper - ocean warming was underestimated by up to 58 percent.
An ensemble
of climate model simulations reveals that limiting anthropogenic warming to 1.5 °C instead of 2 °C can markedly reduce the area undergoing, and thus the population exposed to, aridification.
Temperature trends ranging in length from 10 to 35 years (ending in a preliminary 2013) calculated using the data from the U.K. Hadley Center (blue dots), the adjustments to the U.K. Hadley Center data made by Cowtan and Way (red dots) extrapolated through 2013, and the
average of climate model simulations (black dots).
A large ensemble
of climate model simulations suggests that the frequency of extreme wet - to - dry precipitation events will increase by 25 % to 100 % across California due to anthropogenic forcing.
These temperature estimates will be interesting for the current debate about the representation of volcanically - induced cooling in temperature reconstructions, and for
testing of climate model simulations.
These papers provide the information required to produce a standard
set of climate model simulations that can be scientifically exploited to address the three broad scientific questions of CMIP6: (i) How does the Earth system respond to forcing?
-LSB-...] my reasoning is weighted heavily in favor of observational evidence and understanding of natural internal variability of the climate system, whereas the IPCC's reasoning is weighted heavily in favor
of climate model simulations and external forcing of climate change.
As can be seen in Figure 2, the observational data (in black) falls within the range
of climate model simulations that are run using all forcings (shaded red), but lies outside the range of model simulations run using only natural forcings (dashed blue lines).