First, doesn't
the model uncertainty include both model noise (i.e., weather fluctuations) and systematic differences among the models?
Not exact matches
Any detailed, careful reading of the climate
models includes a great deal of
uncertainty.
Also, the
model - based approach
includes measures of
uncertainty about our population estimates, which are not usually provided by more common approaches and are crucial for understanding the level of confidence we have about our estimates.»
She also explores the value of scientific thinking in our everyday lives,
including the importance of scale, scientific
modeling,
uncertainty, and risk assessment.
Bansal said that, in the future, the
model could be implemented to help improve guidance from experts in other industries,
including the biofuel industry and semiconductor industry, that typically operate under heavy supply
uncertainty.
For example,
models don't currently
include permafrost methane emissions — as there's too much
uncertainty about them.
Limitations of the present studies
include their performance in mice only and
uncertainty of the relevance of rodent
models to SARS - CoV vaccines in humans.
What is more surprising is the small
uncertainty interval given by this paper, and this is probably simply due to the fact that not all relevant
uncertainties in the forcing, the proxy temperatures and the
model have been
included here.
There are limitations in using a Monte Carlo simulation,
including the analysis is only as good as the assumptions, and despite
modeling for a range of
uncertainties in the future, it does not eliminate
uncertainty.
A comprehensive risk assessment would determine flood hazard for individual structures by
modeling watershed and floodplain characteristics at fine spatial scales; it would describe the varying levels of protection offered by all elements of a flood protection system and mitigation measures; and it would account explicitly for
uncertainties,
including those related to current and future flood hazard, structure value and vulnerability, and the current and future performance of flood protection measures.
It seems clear that the new data (
including HadSST3) will be closer to the
models than previously, if not quite perfectly in line (but given the
uncertainties in the magnitude of the Krakatoa forcing, a perfect match is unlikely).
I am probably as aware of any reader here of
modeling challenges in general, and can appreciate the work your groups have performed, but I can also appreciate the implications of the mismatch that prompted your post: there is fundamental
uncertainty in the interaction of the complex mechanisms that drive climate change,
including the human effect.
Re # 128, CGMs do not currently
include the carbon cycle, so your concern is not with the
models as they now exist but with the
uncertainties of the forcings which are applied to them.
For those forcings that have been
included in attribution analyses,
uncertainties associated with the temporal and spatial pattern of the forcing and the
modelled response can affect the results.
Nevertheless, climate
models use the available data to account for their influence, and their projections
include the associated
uncertainties.
Windchasers, «Which means that in about 10,000 years, his
model of the
uncertainty is supposed to
include temperatures below absolute zero.»
The meeting
included focus sessions on computational methods for
modeling and handling large amounts of data, characterizing
uncertainty, research on dust and aerosols, soils, urban systems and individual topics that are too numerous to list, from science communication and stellar astrophysics to biogeochemistry.
However, some forcings are still omitted by many
models and
uncertainties remain in the treatment of those forcings that are
included by the majority of
models.
Sensitivity of the climate to carbon dioxide, and the level of
uncertainty in its value, is a key input into the economic
models that drive cost - benefit analyses,
including estimates of the social cost of carbon.
His research goals
include improving accuracy of resource assessment, obtaining reliable
uncertainty estimation and
modelling wake effects and applying satellite derived winds in resource assessment systems.
They show the «limits» of their
model outputs which show the general direction, and
includes projected directional
uncertainties.
According to Beven, some of the key difficulties with
modelling include computational limitations, limited measurement techniques, and «
uncertainty about
uncertainty estimation».
Even when the representation of all
included processes is decided the
models include many parameters that are only weakly constrained by other data, meaning there is parametric
uncertainty (2)(McWilliams, 2007; Betz, 2009a; Parker, 2010; Katzav, 2013).
Koutsoyiannis (2011) showed that an ensemble of climate
model projections is fully contained WITHIN the
uncertainty envelope of traditional stochastic methods using historical data,
including the Hurst phenomena... the Hurst phenomena (1951) describes the large and long excursions of natural events above and below their mean, as opposed to random processes which do not exhibit such behavior.
Given the large
uncertainties in forcings and
model inadequacies (
including a factor of 2 difference in CO2 sensitivity), how is it that each
model does a credible job of tracking the 20th century global surface temperature anomalies (AR4 Figure 9.5)?
This
includes model verification using observations, quantification of
model probabilities and
uncertainties, identification of key vulnerabilities as well as adaptation potentials, and, finally, developing response strategies.
When Roger says «the output of these
models are routinely being provided to the impact communities and policymakers as robust scientific results»... I don't think he means the large
model ensembles with their
included uncertainty.
The question for the climate change adaptation community is whether the
uncertainty (
including model errors) in the projected climate change is small enough to be useful in a decision making framework.
The structural
uncertainties above are not expressed in trivial intermodel variability, but lie at the core of IPCC climate
modeling,
including its reliance on the radiative forcing paradigm.
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 differences.
Lack of
including ocean oscillations in global climate
models further amplifies the
uncertainties.
IPCC has stated (AR4 WG1 Ch.9) that the «global mean warming observed since 1970 can only be reproduced when
models are forced with combinations of external forcings that
include anthropogenic forcings... Therefore
modeling studies suggest that late 20th - century warming is much more likely to be anthropogenic than natural in origin...» whereas for the statistically indistinguishable early 20thC warming period «detection and attribution as well as
modeling studies indicate more
uncertainty regarding the causes of early 20th - century warming.»
''... a much wider exploration of aerosol
uncertainty than previously carried out in
models that now
include a much more sophisticated treatment of aerosol physics.
The sources of
uncertainty are many,
including the trajectory of greenhouse gas emissions in the future, their conversion into atmospheric concentrations, the range of responses of various climate
models to a given radiative forcing and the method of constructing high resolution information from global climate
model outputs (Pittock, 1995; see Figure 13.2).
1) William Nordhaus update just released Dec., 2016 on the Dice
model to
include uncertainties in the long term forecast and new treatment of
uncertainties.
At least weather
models include reasonable
uncertainty.
However, if a 5 dBA to 8 dBA increase in sound due to the proximity of the ocean were assumed and an additional + / − 3dBA were
included to account for
model uncertainties, noise levels may exceed 45 dBA.
The rub, I suspect, is that they are not adequately
modeling the
uncertainty ADDED to the analysis by
including thousands of infill data points.
This new experiment will be the first combining atmospheric
uncertainties with all aspects of land surface
uncertainties,
including model parameter perturbations and the spatial distribution of land use.
Second, the IPCC clearly states «
models [of sea level rise] used to date do not
include uncertainties in climate - carbon cycle feedbacks nor do they
include the full effect of changes in ice sheet flow.»
«We are also developing our system to
include uncertainties arising from
model errors in addition to those coming from imperfect initial conditions.»
More complete exploration of climate
model uncertainty,
including unknowns and
model structural
uncertainty
The main new aspect i introduce here is NUSAP, which is a way to categorize and assess
uncertainty (
including pedigree) in complicated multi premise problems and
models, which has been widely applied in water resources and other environmental problems.
In Sect. 2, we describe the
model ensembles and the application of the rank histogram approach,
including a description of the statistical method used to define the reliability of
model ensembles from the rank histogram, and a method for handling
uncertainties in the observations.
Conference topics of emphasis will
include dynamics, high performance computing, numerical analysis, cloud systems behavior, data assimilation, dimension reduction,
uncertainty quantification,
model hierarchy, and statistical approaches.
The differences are that in the present study we
include the
uncertainty in the observations as described in Sect. 2.4 and there are also small differences due to the different number of
model runs used.
Thus, using various kinds of climate
model ensembles
including both MMEs and SMEs, we may expect to reduce
uncertainties in climate prediction in the future.
Should the semi-empirical
models have been
included in the
uncertainty range of the IPCC projections?
This
uncertainty derives from the complexities involved in
modelling the whole Earth system (
including the strength of feedbacks from clouds, etc.) and also from predicting the future path of human activities.
Such solecisms throughout the IPCC's assessment reports (
including the insertion, after the scientists had completed their final draft, of a table in which four decimal points had been right - shifted so as to multiply tenfold the observed contribution of ice - sheets and glaciers to sea - level rise), combined with a heavy reliance upon computer
models unskilled even in short - term projection, with initial values of key variables unmeasurable and unknown, with advancement of multiple, untestable, non-Popper-falsifiable theories, with a quantitative assignment of unduly high statistical confidence levels to non-quantitative statements that are ineluctably subject to very large
uncertainties, and, above all, with the now - prolonged failure of TS to rise as predicted (Figures 1, 2), raise questions about the reliability and hence policy - relevance of the IPCC's central projections.