Modelling climate change: the role of unresolved processes

2005 ◽  
Vol 363 (1837) ◽  
pp. 2931-2946 ◽  
Author(s):  
Paul D Williams
Keyword(s):  
Climate Change ◽  
Climate Models ◽  
Random Noise ◽  
Climate System ◽  
Personal Perspective ◽  
Physical Processes ◽  
Current State ◽  
Explicit Consideration ◽  
Key Aspects

Our understanding of the climate system has been revolutionized recently, by the development of sophisticated computer models. The predictions of such models are used to formulate international protocols, intended to mitigate the severity of global warming and its impacts. Yet, these models are not perfect representations of reality, because they remove from explicit consideration many physical processes which are known to be key aspects of the climate system, but which are too small or fast to be modelled. The purpose of this paper is to give a personal perspective of the current state of knowledge regarding the problem of unresolved scales in climate models. A recent novel solution to the problem is discussed, in which it is proposed, somewhat counter-intuitively, that the performance of models may be improved by adding random noise to represent the unresolved processes.

Predicting regional climate change: living with uncertainty

1999 ◽  
Vol 23 (1) ◽  
pp. 57-78 ◽  
Author(s):  
Timothy D. Mitchell ◽  
Mike Hulme
Keyword(s):  
Climate Change ◽  
Climate Models ◽  
Thermohaline Circulation ◽  
Regional Climate ◽  
Regional Climate Change ◽  
Climate Prediction ◽  
Climate System ◽  
Global System ◽  
Regional Climate Prediction

Regional climate prediction is not an insoluble problem, but it is a problem characterized by inherent uncertainty. There are two sources of this uncertainty: the unpredictability of the climatic and global systems. The climate system is rendered unpredictable by deterministic chaos; the global system renders climate prediction uncertain through the unpredictability of the external forcings imposed on the climate system. It is commonly inferred from the differences between climate models on regional scales that the models are deficient, but climate system unpredictability is such that this inference is premature; the differences are due to an unresolved combination of climate system unpredictability and model deficiencies. Since model deficiencies are discussed frequently and the two sources of inherent uncertainty are discussed only rarely, this review considers the implications of climatic and global system unpredictability for regional climate prediction. Consequently we regard regional climate prediction as a cascade of uncertainty, rather than as a single result process sullied by model deficiencies. We suggest three complementary methodological approaches: (1) the use of multiple forcing scenarios to cope with global system unpredictability; (2) the use of ensembles to cope with climate system unpredictability; and (3) the consideration of the entire response of the climate system to cope with the nature of climate change. We understand regional climate change in terms of changes in the general circulations of the atmosphere and oceans; so we illustrate the role of uncertainty in the task of regional climate prediction with the behaviour of the North Atlantic thermohaline circulation. In conclusion we discuss the implications of the uncertainties in regional climate prediction for research into the impacts of climate change, and we recognize the role of feedbacks in complicating the relatively simple cascade of uncertainties presented here.

Response of the NCAR Climate System Model to Increased CO2and the Role of Physical Processes

2000 ◽  
Vol 13 (11) ◽  
pp. 1879-1898 ◽  
Author(s):  
Gerald A. Meehl ◽  
William D. Collins ◽  
Byron A. Boville ◽  
Jeffrey T. Kiehl ◽  
T. M. L. Wigley ◽  
...  
Keyword(s):  
Climate System ◽  
System Model ◽  
Physical Processes ◽  
Climate System Model

Effects of Hydrologic Model Choice and Calibration on the Portrayal of Climate Change Impacts

2015 ◽  
Vol 16 (2) ◽  
pp. 762-780 ◽  
Author(s):  
Pablo A. Mendoza ◽  
Martyn P. Clark ◽  
Naoki Mizukami ◽  
Andrew J. Newman ◽  
Michael Barlage ◽  
...  
Keyword(s):  
Climate Change ◽  
Water Resources ◽  
Climate Models ◽  
Climate Change Impacts ◽  
Hydrologic Model ◽  
Global Climate Models ◽  
Change Scenario ◽  
Hydrologic Models ◽  
Climate System Model

Abstract The assessment of climate change impacts on water resources involves several methodological decisions, including choices of global climate models (GCMs), emission scenarios, downscaling techniques, and hydrologic modeling approaches. Among these, hydrologic model structure selection and parameter calibration are particularly relevant and usually have a strong subjective component. The goal of this research is to improve understanding of the role of these decisions on the assessment of the effects of climate change on hydrologic processes. The study is conducted in three basins located in the Colorado headwaters region, using four different hydrologic model structures [PRMS, VIC, Noah LSM, and Noah LSM with multiparameterization options (Noah-MP)]. To better understand the role of parameter estimation, model performance and projected hydrologic changes (i.e., changes in the hydrology obtained from hydrologic models due to climate change) are compared before and after calibration with the University of Arizona shuffled complex evolution (SCE-UA) algorithm. Hydrologic changes are examined via a climate change scenario where the Community Climate System Model (CCSM) change signal is used to perturb the boundary conditions of the Weather Research and Forecasting (WRF) Model configured at 4-km resolution. Substantial intermodel differences (i.e., discrepancies between hydrologic models) in the portrayal of climate change impacts on water resources are demonstrated. Specifically, intermodel differences are larger than the mean signal from the CCSM–WRF climate scenario examined, even after the calibration process. Importantly, traditional single-objective calibration techniques aimed to reduce errors in runoff simulations do not necessarily improve intermodel agreement (i.e., same outputs from different hydrologic models) in projected changes of some hydrological processes such as evapotranspiration or snowpack.

Large contribution from anthropogenic warming to an emerging North American megadrought

Science ◽  
2020 ◽  
Vol 368 (6488) ◽  
pp. 314-318 ◽  
Author(s):  
A. Park Williams ◽  
Edward R. Cook ◽  
Jason E. Smerdon ◽  
Benjamin I. Cook ◽  
John T. Abatzoglou ◽  
...  
Keyword(s):  
Climate Change ◽  
Soil Moisture ◽  
North America ◽  
Relative Humidity ◽  
Climate Models ◽  
Hydrological Modeling ◽  
Drought Severity ◽  
Large Contribution ◽  
Moderate Drought

Severe and persistent 21st-century drought in southwestern North America (SWNA) motivates comparisons to medieval megadroughts and questions about the role of anthropogenic climate change. We use hydrological modeling and new 1200-year tree-ring reconstructions of summer soil moisture to demonstrate that the 2000–2018 SWNA drought was the second driest 19-year period since 800 CE, exceeded only by a late-1500s megadrought. The megadrought-like trajectory of 2000–2018 soil moisture was driven by natural variability superimposed on drying due to anthropogenic warming. Anthropogenic trends in temperature, relative humidity, and precipitation estimated from 31 climate models account for 46% (model interquartiles of 34 to 103%) of the 2000–2018 drought severity, pushing an otherwise moderate drought onto a trajectory comparable to the worst SWNA megadroughts since 800 CE.

scholarly journals DIGITAL TRANSFORMATION (DIGITALIZATION) OF LIBRARIES IN UKRAINE: CURRENT STATE AND PERSPECTIVES

2021 ◽  
pp. 50-56
Author(s):  
Olga Ivashkevych
Keyword(s):  
Digital Transformation ◽  
Public Access ◽  
Scientific Methods ◽  
Current State ◽  
Long Run ◽  
Generation Theory ◽  
Technological Developments ◽  
Key Aspects ◽  
Library User

The purpose of the article is to define and highlighting the role of digital transformation (digitalization) for libraries in the long run: efficiency and problems. Methodology. In the process of research scientific methods of analysis, synthesis, generalization of digitalization of the library industry are applied and the influence of digitalization on the formation of innovations of models of relations library-user taking into account today's civilizational challenges is determined. The scientific novelty The research consists in the analysis of online perspectives in the work of the library industry with an emphasis on key aspects of the dynamics of digital transformation (digitalization): new mobile (electronic) applications, services, application of sharing models. Further key vectors are substantiated and specific most problematic issues of digital transformation of libraries are identified. Conclusions. As a result of the research, today's steps on digitization in libraries, features of the use of platforms, virtual environment services, and sharing products were considered. The tendencies concerning the further steps in the increase of rates of digitalization are investigated. Proved: the practice of digitalization of libraries is especially relevant during the COVID pandemic period, which contributes to public access to information, self-education, as well as access to advanced technological developments, the transformation of libraries taking into account requests, according to generation theory, formation of new digitalization focus of library practices and modifications of library activities.

Science and Climate Change Law—The Role of the IPCC in International Decision-Making

2016 ◽  
Author(s):  
Navraj Singh Ghaleigh
Keyword(s):  
Climate Change ◽  
United Nations Environment Programme ◽  
Intergovernmental Panel ◽  
Current State ◽  
Scientific Papers ◽  
Working Groups ◽  
Scientific Technical ◽  
Change Impact ◽  
Change Climate

This chapter describes the contributions of the scientific community in the development of international climate change law, highlighting in particular the Intergovernmental Panel on Climate Change’s (IPCC’s) assessment and research of the scientific, technical, and socio-economic information relevant for the understanding of the risk of climate change. Since the Panel’s establishment under the United Nations Environment Programme (UNEP) and the World Meteorological Organization (WMO) in 1988, it has released several scientific papers that provide a clear scientific view on the current state of knowledge in climate change. The chapter examines the core of the IPCC’s assessment reports, which are divided into three working groups that deal respectively with the ‘Physical Science Basis of Climate Change’, ‘Climate Change Impact, Adaptation and Vulnerability’, and ‘Mitigation of Climate Change’. The IPCC also addresses specific areas, such as renewable energy, disaster management, and climate engineering.

scholarly journals Rethinking Air Quality and Climate Change after COVID-19

2020 ◽  
Vol 17 (14) ◽  
pp. 5167 ◽  
Author(s):  
Joseph Ching ◽  
Mizuo Kajino
Keyword(s):  
Climate Change ◽  
Air Quality ◽  
Disaster Preparedness ◽  
Climate System ◽  
Economic Activities ◽  
Short Article ◽  
System Improvement ◽  
Negative Impacts ◽  
The Relationship

The world is currently shadowed by the pandemic of COVID-19. Confirmed cases and the death toll has reached more than 12 million and more than 550,000 respectively as of 10 July 2020. In the unsettling pandemic of COVID-19, the whole Earth has been on an unprecedented lockdown. Social distancing among people, interrupted international and domestic air traffic and suspended industrial productions and economic activities have various far-reaching and undetermined implications on air quality and the climate system. Improvement in air quality has been reported in many cities during lockdown, while the death rate of COVID-19 has been found to be higher in more polluted cities. The relationship between the spread of the SARS-CoV-2 virus and air quality is under investigation. In addition, the battle against COVID-19 could bring short-lived and long-lasting and positive and negative impacts to the warming climate. The impacts on the climate system and the role of the climate in modulating the COVID-19 pandemic are the foci of scientific inquiry. The intertwined relationship among environment, climate change and public health is exemplified in the pandemic of COVID-19. Further investigation of the relationship is imperative in the Anthropocene, in particular, in enhancing disaster preparedness. This short article intends to give an up-to-date glimpse of the pandemic from air quality and climate perspectives and calls for a follow-up discussion.

scholarly journals Climate projections of a multi-variate heat stress index: the role of downscaling and bias correction

2019 ◽  
Author(s):  
Ana Casanueva ◽  
Sven Kotlarski ◽  
Sixto Herrera ◽  
Andreas M. Fischer ◽  
Tord Kjellstrom ◽  
...  
Keyword(s):  
Climate Change ◽  
Heat Stress ◽  
Bias Correction ◽  
Climate Models ◽  
Dew Point ◽  
Added Value ◽  
Stress Index ◽  
Corrected Data ◽  
Heat Stress Index

Abstract. Along with the higher demand of bias-corrected data for climate impact studies, the number of available data sets has largely increased in the recent years. For instance, the Inter-Sectoral Impact Model Intercomparison Project (ISIMIP) constitutes a framework for consistently projecting the impacts of climate change across affected sectors and spatial scales. These data are very attractive for any impact application since they offer worldwide bias-corrected data based on Global Climate Models (GCMs). Complementary, the CORDEX initiative has incorporated experiments based on regionally-downscaled bias-corrected data by means of debiasing and quantile mapping (QM) methods. In light of this situation, it is challenging to distil the most accurate and useful information for climate services, but at the same time it creates a perfect framework for intercomparison and sensitivity analyses. In the present study, the trend-preserving ISIMIP method and empirical QM are applied to climate model simulations that were carried out at different spatial resolutions (CMIP5 GCM and EURO-CORDEX Regional Climate Models (RCMs), at approximately 150 km, 50 km and 12 km horizontal resolution, respectively) in order to assess the role of downscaling and bias correction in a multi-variate framework. The analysis is carried out for the wet bulb globe temperature (WBGT), a heat stress index that is commonly used in the context of working people and labour productivity. WBGT for shaded conditions depends on air temperature and dew point temperature, which in this work are individually bias-corrected prior to the index calculation. Our results show that the added value of RCMs with respect to the driving GCM is limited after bias correction. The two bias correction methods are able to adjust the central part of the WBGT distribution, but some added value of QM is found in WBGT percentiles and in the intervariable relationships. The evaluation in present climate of such multivariate indices should be performed with caution since biases in the individual variables might compensate, thus leading to better performance for the wrong reason. Climate change projections of WBGT reveal a larger increase of summer mean heat stress for the GCM than for the RCMs, related to the well-known reduced summer warming of the EURO-CORDEX RCMs. These differences are lowered after QM, since this bias correction method modifies the change signals and brings the results for GCM and RCMs closer to each other. We also highlight the need of large ensembles of simulations to assess the feasibility of the derived projections.

How many modes does it take to describe climate change?: The lessons from an experiment

2021 ◽  
Author(s):  
Berengere Dubrulle
Keyword(s):  
Climate Change ◽  
Co2 Emissions ◽  
Degrees Of Freedom ◽  
Climate Models ◽  
Present Climate ◽  
Finite Resolution ◽  
Small Scales ◽  
Impossible Task ◽  
Laboratory Analog

<p>According to everyone's experience, predicting the weather reliably for more than 8 days seems an impossible task for our best weather agencies. At the same time, politicians and citizens are asking scientists for decades of climate predictions to help them make decisions, especially on CO2 emissions. To what extent is this request scientifically admissible?</p><p> </p><p>In this lecture I will investigate this question, focusing on the topic of predictions of bifurcations of the atmospheric or oceanic circulations. In such case, the issue is whether present climate models, that have necessarily a finite resolution and a smaller number of degrees of freedom than the actual terrestrial systems, are able to reproduce spontaneous or forced bifurcations. For this, I will use recent results obtained by my group in a laboratory analog of such systems, so called von Karman flow, in which spontaneous bifurcations of the circulation take place. I will detail the analogy, and investigate the nature of bifurcations, the number of degrees of freedom that characterizes it and discuss what is the effect of reducing the number of degrees of freedom in such system.</p><p>I will also discuss the role of fluctuations and their origin, and stress the importance of describing very small scales to capture fluctuations of correct intensity and scale.</p>

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