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.
We prefer this result since it was based on a comprehensive analysis using extensive proxy data from both land and ocean in combination with
an ensemble of climate model simulations, in a paper focused entirely on LGM cooling.
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.
it says «Large
ensembles of climate model simulations have shown that the ability of models to simulate present climate has value in constraining climate sensitivity.».
Not exact matches
The first is the development
of a comprehensive, closely coordinated
ensemble of simulations from 18
modeling groups around the world for the historical and future evolution
of the earth's
climate.
To understand the role
of human - induced
climate change in these new records they compare
simulations of the Earth's
climate from nine different state -
of - the - art
climate models and the very large
ensemble of climate simulations provided by CPDN volunteers for the weather@home ANZ experiments for the world with and without human - induced
climate change.
Murphy, J.M., et al., 2004: Quantification
of modelling uncertainties in a large
ensemble of climate change
simulations.
A large
ensemble of Earth system
model simulations, constrained by geological and historical observations
of past
climate change, demonstrates our self ‐ adjusting mitigation approach for a range
of climate stabilization targets ranging from 1.5 to 4.5 °C, and generates AMP scenarios up to year 2300 for surface warming, carbon emissions, atmospheric CO2, global mean sea level, and surface ocean acidification.
M2009 use a simplified carbon cycle and
climate model to make a large
ensemble of simulations in which principal uncertainties in the carbon cycle, radiative forcings, and
climate response are allowed to vary, thus yielding a probability distribution for global warming as a function
of time throughout the 21st century.
Recently I have been looking at the
climate models collected in the CMIP3 archive which have been analysed and assessed in IPCC and it is very interesting to see how the forced changes — i.e. the changes driven the external factors such as greenhouse gases, tropospheric aerosols, solar forcing and stratospheric volcanic aerosols drive the forced response in the
models (which you can see by averaging out several
simulations of the same
model with the same forcing)-- differ from the internal variability, such as associated with variations
of the North Atlantic and the ENSO etc, which you can see by looking at individual realisations
of a particular
model and how it differs from the
ensemble mean.
Ensemble simulations conducted with EMICs (Renssen et al., 2002; Bauer et al., 2004) and coupled ocean - atmosphere GCMs (Alley and Agustsdottir, 2005; LeGrande et al., 2006) with different boundary conditions and freshwater forcings show that
climate models are capable
of simulating the broad features
of the observed 8.2 ka event (including shifts in the ITCZ).
Natural variability from the
ensemble of 587 21 - year - long segments
of control
simulations (with constant external forcings) from 24 Coupled
Model Intercomparison Project phase 3 (CMIP3)
climate models is shown in black and gray.
To ensure their
models are accurate, Ault said researchers distinguished and separated normal climatic variability from long - term atmospheric alterations, by using a new
ensemble of climate change
simulations.
IPCC relied on
climate models (CMIP5), the hypotheses under test if you will, to exclude natural variability: «Observed Global Mean Surface Temperature anomalies... lie well outside the range
of Global Mean Surface Temperature anomalies in CMIP5
simulations with natural forcing only, but are consistent with the
ensemble of CMIP5
simulations including both anthropogenic and natural forcing...» (Ref.: Working Group I contribution to fifth assessment report by IPCC.
Ensemble - A group
of parallel
model simulations used for
climate projections.
Van Haren et al (2012) also nicely illustrate the dependence
of regional skill on lateral boundary conditions:
simulations of (historic) precipitation trends for Europe failed to match the observed trends when lateral boundary conditions were provided from an
ensemble of CMIP3 global
climate model simulations, while a much better correspondence with observations was obtained when reanalyses were used as boundary condition.
Ensembles made with the same model but different initial conditions only characterize the uncertainty associated with internal climate variability, whereas multi-model ensembles including simulations by several models also include the impact of model dif
Ensembles made with the same
model but different initial conditions only characterize the uncertainty associated with internal
climate variability, whereas multi-
model ensembles including simulations by several models also include the impact of model dif
ensembles including
simulations by several
models also include the impact
of model differences.
In this way, we can obtain the expected range
of projected
climate trends using the interannual statistics
of the observed NAO record in combination with the
model's radiatively - forced response (given by the
ensemble - mean
of the 40
simulations).
We make use
of a 40 - member
ensemble of climate change
simulations under historical and RCP8.5 radiative forcing scenarios for the period 1920 — 2100 conducted with the Community Earth System
Model Version 1 (CESM1; Hurrell et al. 2013).
They ran an
ensemble of simulations with a
climate model of intermediate complexity to evaluate the causes
of past
climate changes.
The fact that the CMIP
simulations ensemble mean can reproduce the 1970 — 2010 US SW temperature increase without inclusion
of the AMO (the AMO is treated as an intrinsic natural
climate vari - ability that is averaged out by taking an
ensemble mean
of individual
simulations) suggests that the CMIP5
models» predicted US SW temperature sensitivity to the GHG has been significantly (by about a factor
of two) overestimated.
«The fact that the CMIP
simulations ensemble mean can reproduce the 1970 — 2010 US SW temperature increase without inclusion
of the AMO (the AMO is treated as an intrinsic natural
climate variability that is averaged out by taking an
ensemble mean
of individual
simulations) suggests that the CMIP5
models» predicted US SW temperature sensitivity to the GHG has been significantly (by about a factor
of two) overestimated.»
Where precision is an issue (e.g., in a
climate forecast), only
simulation ensembles made across systematically designed
model families allow an estimate
of the level
of relevant irreducible imprecision... In each
of these
model —
ensemble comparison studies, there are important but difficult questions: How well selected are the
models for their plausibility?
Stainforth et al. (2007) argue that
model inadequacy and an inadequate number
of simulations in the
ensemble preclude producing meaningful probability PDFs from the frequency
of model outcomes
of future
climate.
M2009 use a simplified carbon cycle and
climate model to make a large
ensemble of simulations in which principal uncertainties in the carbon cycle, radiative forcings, and
climate response are allowed to vary, thus yielding a probability distribution for global warming as a function
of time throughout the 21st century.
Alternatively, an automated procedure based on a cluster initialization algorithm is proposed and applied to changes in 27
climate extremes indices between 1986 — 2005 and 2081 — 2100 from a large
ensemble of phase 5
of the Coupled
Model Intercomparison Project (CMIP5)
simulations.
Simulations by regional climate models show good agreement with observations in the seasonal and spatial variability of the joint distribution, especially when an ensemble of simulation
Simulations by regional
climate models show good agreement with observations in the seasonal and spatial variability
of the joint distribution, especially when an
ensemble of simulationssimulations was used.
In CMIP5 there is no correlation between aerosol forcing and sensitivity across the
ensemble, so the implication that aerosol forcing affects the
climate sensitivity in such «forward» calculations is false... The spread
of model climate sensitivities is completely independent
of historical
simulations.»
Continuous daily streamflow
simulations from 1976 to 2100 (Alfieri et al. 2015a), forcing a distributed hydrological
model (Lisflood, van der Knijff et al. 2010) with an
ensemble of seven EURO - CORDEX (Jacob et al. 2014) RCP 8.5 downscaled regional
climate scenarios over Europe.
It is true that the
model replications
of past conditions are not perfect, which is to be expected given the chaotic variations
of the
climate about its now - changing baseline; however, the
ensemble of model simulations has been tested against previously observed perturbations to
climate (such as the response to volcanic eruptions) and overall they correspond well with what is observed to occur.
The influence
of reduced solar forcing (grand solar minimum or geoengineering scenarios like solar radiation management) on the Atlantic Meridional Overturning Circulation (AMOC) is assessed in an
ensemble of atmosphere — ocean — chemistry —
climate model simulations.
These fingerprints will be based on a large, multi-
model ensemble of state -
of - the - art
climate model simulations.
«A strong warming and severe drought predicted on the basis
of the
ensemble mean
of the CMIP
climate models simulations is supported by our regression analysis only in a very unlikely case
of the continually increasing AMO at a rate similar to its 1970 — 2010 increase» 7
One approach is to use an MME, which consists
of simulations contributed by different
models of climate research institutes from around the world, often referred to as an «
ensemble of opportunity».
In the present study,
simulations of the present - day
climate by two kinds
of climate model ensembles, multi-
model ensembles (MMEs)
of CMIP3 and single
model ensembles (SMEs)
of structurally different
climate models, HadSM3 / CM3, MIROC3.2, and NCAR CAM3.1, are investigated through the rank histogram approach.
In this study, we primarily investigate the reliability
of the climatology (long - term mean
of model simulation)
of large - scale features
of climate model ensembles, but we also consider the trend for surface air temperature where transient
simulations are available (that is, for the coupled ocean — atmosphere
models).
Nature provides only one single realization
of many possible realizations
of temperature variability over time from a whole distribution
of possible realizations
of a chaotic system for the given
climate conditions, whereas the
ensemble mean
of models is an average over many
of the possible realizations (117
model simulations in this case).
To answer this question, large
ensemble simulations of regional
climate models will be carried out for an East Asian domain for two worlds: (1) Real world condition for which the observed sea surface temperatures will be prescribed and (2) Counter-factual world condition for which we will use adjusted sea surface temperatures obtained by removing human - induced ocean warming patterns.
In a new study published in the Journal
of Climate, the Community Earth System
Model Large
Ensemble (CESM - LENS)
of simulations is used to explore how various characteristics
of the mid-latitude atmospheric circulation (zonal flow, synoptic blockings, jet stream meanders) evolve along the course
of the 21st century under the RCP8.5 scenario
of anthropogenic emissions.