The Greenhouse Theory of Climate Change: A Test by an Inadvertent Global Experiment

Science ◽  
1988 ◽  
Vol 240 (4850) ◽  
pp. 293-299 ◽  
Author(s):  
V. RAMANATHAN
Keyword(s):  
Climate Change ◽  
Climate System ◽  
Radiative Heating ◽  
Climate Feedback ◽  
Interglacial Period ◽  
Climate Variations ◽  
Surface Warming ◽  
Historical Times ◽  
Natural Climate ◽  
Atmospheric Concentrations

Since the dawn of the industrial era, the atmospheric concentrations of several radiatively active gases have been increasing as a result of human activities. The radiative heating from this inadvertent experiment has driven the climate system out of equilibrium with the incoming solar energy. According to the greenhouse theory of climate change, the climate system will be restored to equilibrium by a warming of the surfacetroposphere system and a cooling of the stratosphere. The predicted changes, during the next few decades, could far exceed natural climate variations in historical times. Hence, the greenhouse theory of climate change has reached the crucial stage of verification. Surface warming as large as that predicted by models would be unprecedented during an interglacial period such as the present. The theory, its scope for verification, and the emerging complexities of the climate feedback mechanisms are discussed.

Climate Measurement and Modeling

1997 ◽  
Author(s):  
Douglas V. Hoyt ◽  
Kenneth H. Shatten
Keyword(s):  
Climate Change ◽  
Carbon Dioxide ◽  
Climate Variability ◽  
Atmospheric Carbon Dioxide ◽  
Climate Models ◽  
Climate Variations ◽  
Noise Sources ◽  
Earth’S Climate ◽  
Definition Of ◽  
Natural Climate

Having considered the sun and its variations, we now turn to Earth’s climate and climatic variations. We examine the definition of climate and the difficulties in measuring it. Awareness of these complexities is critical for an appreciation of how difficult it is to demonstrate changing climate. Separating trends from random variations is the first step in defining climate change. After reviewing the statistical properties of climate, we deal with theoretical climate models. This background is important for understanding how solar variations might affect climate. The following four chapters review specific sun/climate relationships, and the statistical and physical guidelines developed now will be used to select pertinent studies. As the heat source that drives Earth’s climate, the variable sun is important when studying climate change. With many, if not most, modern popular accounts focusing on how humanity is altering climate, it is important to realize that solar variations may play a significant role in the background natural variability. To understand anthropogenic (human-made) influences on climate change, we must be able to make distinctions among the contributions that arise from naturally occurring climate variability. Natural climate variations include a possible solar-irradiance component. Man-made climatic changes are not well known, and natural climate variations are uncertain too. For example, we do not know whether a man-made doubling of atmospheric carbon dioxide provides a 1.5 or a 4.5 °C increase in mean global temperature. This uncertainty arises, in part, because natural climate variability acts as “noise” to confuse our measures of man-made influences. To obtain accurate results, we must understand and remove these background noise sources. Although these temperature changes seem small, they can have tremendous global impact on the survivability of species and on many different aspects of life. In addition, the uncertainty factor of 3 is highly important because it tells us that the risk in emitting a quantity of carbon dioxide is uncertain by this same factor.

scholarly journals The Cloud Feedback Model Intercomparison Project (CFMIP) contribution to CMIP6

2017 ◽  
Vol 10 (1) ◽  
pp. 359-384 ◽  
Author(s):  
Mark J. Webb ◽  
Timothy Andrews ◽  
Alejandro Bodas-Salcedo ◽  
Sandrine Bony ◽  
Christopher S. Bretherton ◽  
...  
Keyword(s):  
Climate Change ◽  
Climate Models ◽  
Regional Climate ◽  
Climate System ◽  
Climate Feedback ◽  
Grand Challenge ◽  
Compact Set ◽  
Coupled Models ◽  
Cloud Feedbacks ◽  
Non Linear

Abstract. The primary objective of CFMIP is to inform future assessments of cloud feedbacks through improved understanding of cloud–climate feedback mechanisms and better evaluation of cloud processes and cloud feedbacks in climate models. However, the CFMIP approach is also increasingly being used to understand other aspects of climate change, and so a second objective has now been introduced, to improve understanding of circulation, regional-scale precipitation, and non-linear changes. CFMIP is supporting ongoing model inter-comparison activities by coordinating a hierarchy of targeted experiments for CMIP6, along with a set of cloud-related output diagnostics. CFMIP contributes primarily to addressing the CMIP6 questions How does the Earth system respond to forcing? and What are the origins and consequences of systematic model biases? and supports the activities of the WCRP Grand Challenge on Clouds, Circulation and Climate Sensitivity.A compact set of Tier 1 experiments is proposed for CMIP6 to address this question: (1) what are the physical mechanisms underlying the range of cloud feedbacks and cloud adjustments predicted by climate models, and which models have the most credible cloud feedbacks? Additional Tier 2 experiments are proposed to address the following questions. (2) Are cloud feedbacks consistent for climate cooling and warming, and if not, why? (3) How do cloud-radiative effects impact the structure, the strength and the variability of the general atmospheric circulation in present and future climates? (4) How do responses in the climate system due to changes in solar forcing differ from changes due to CO2, and is the response sensitive to the sign of the forcing? (5) To what extent is regional climate change per CO2 doubling state-dependent (non-linear), and why? (6) Are climate feedbacks during the 20th century different to those acting on long-term climate change and climate sensitivity? (7) How do regional climate responses (e.g. in precipitation) and their uncertainties in coupled models arise from the combination of different aspects of CO2 forcing and sea surface warming?CFMIP also proposes a number of additional model outputs in the CMIP DECK, CMIP6 Historical and CMIP6 CFMIP experiments, including COSP simulator outputs and process diagnostics to address the following questions. How well do clouds and other relevant variables simulated by models agree with observations?What physical processes and mechanisms are important for a credible simulation of clouds, cloud feedbacks and cloud adjustments in climate models?Which models have the most credible representations of processes relevant to the simulation of clouds?How do clouds and their changes interact with other elements of the climate system?

scholarly journals Estimations of climate sensitivity based on top-of-atmosphere radiation imbalance

2009 ◽  
Vol 9 (6) ◽  
pp. 24731-24753
Author(s):  
B. Lin ◽  
L. Chambers ◽  
P. Stackhouse Jr. ◽  
B. Wielicki ◽  
Y. Hu ◽  
...  
Keyword(s):  
Climate Sensitivity ◽  
Deep Ocean ◽  
Climate System ◽  
Radiative Heating ◽  
Climate Feedback ◽  
Ocean Heat Transport ◽  
Middle Range ◽  
Condition Problem ◽  
System Memory ◽  
Feedback Coefficient

Abstract. Large climate feedback uncertainties limit the accuracy in predicting the response of the Earth's climate to the increase of CO2 concentration within the atmosphere. This study explores a potential to reduce uncertainties in climate sensitivity estimations using energy balance analysis, especially top-of-atmosphere (TOA) radiation imbalance. The time-scales studied generally cover from decade to century, that is, middle-range climate sensitivity is considered, which is directly related to the climate issue caused by atmospheric CO2 change. The significant difference between current analysis and previous energy balance models is that the current study targets at the boundary condition problem instead of solving the initial condition problem. Additionally, climate system memory and deep ocean heat transport are considered. The climate feedbacks are obtained based on the constraints of the TOA radiation imbalance and surface temperature measurements of the present climate. Currently, there is a lack of high accuracy measurements of TOA radiation imbalance. Available estimations indicate that TOA net radiative heating to the climate system is about 0.85 W/m2. Based on this value, a positive climate feedback with a feedback coefficient ranging from −1.3 to −1.0 W/m2/K is found. The range of feedback coefficient is determined by climate system memory. The longer the memory, the stronger the positive feedback. The estimated time constant of the climate is large (70~120 years) mainly owing to the deep ocean heat transport, implying that the system may be not in an equilibrium state under the external forcing during the industrial era. For the doubled-CO2 climate (or 3.7 W/m2 forcing), the estimated global warming would be 3.1 K if the current estimate of 0.85 W/m2 TOA net radiative heating could be confirmed. With accurate long-term measurements of TOA radiation, the analysis method suggested by this study provides a great potential in the estimations of middle-range climate sensitivity.

Internal stresses in the cross-grain direction in glulam induced by climate variations

Holzforschung ◽  
2004 ◽  
Vol 58 (2) ◽  
pp. 154-159 ◽  
Author(s):  
J. Jönsson
Keyword(s):  
Climate Change ◽  
Experimental Investigation ◽  
Cross Section ◽  
Moisture Gradient ◽  
Internal Stresses ◽  
Stress Distributions ◽  
Climate Variations ◽  
Before And After ◽  
Stress States ◽  
Natural Climate

Abstract Results are presented from an experimental investigation to determine internal stress states perpendicular to grain in glulam induced by moisture variations. The stresses are determined by measuring the released strains before and after cutting. Stress distributions are determined for specimens seasoned in constant humidity, specimens exposed to an artificial single climate change, specimens exposed to cyclic climate change and for specimens exposed to natural climate outdoors under shelter. Results for seasoned specimens show that internal stresses exist in glulam without the presence of moisture gradients. Stresses in specimens with an induced moisture gradient become larger when moistening from a specific climate A to another climate B than when drying from B to A. Tests in an outdoor sheltered climate show large variations in strains and stresses. The tensile stress level in the inner part of the glulam cross section exceeds the characteristic strength of 0.5 MPa during a period of approximately 80 days.

From “Inconvenient Truth” to Effective Governance

2018 ◽  
Author(s):  
Richard Passarelli ◽  
David Michel ◽  
William Durch
Keyword(s):  
Climate Change ◽  
Global Climate ◽  
Climate System ◽  
Global Public Good ◽  
Environmental Groups ◽  
Quarter Century ◽  
Effective Governance ◽  
Political Response ◽  
Earth’S Climate ◽  
National Governments

The Earth’s climate system is a global public good. Maintaining it is a collective action problem. This chapter looks at a quarter-century of efforts to understand and respond to the challenges posed by global climate change and why the collective political response, until very recently, has seemed to lag so far behind our scientific knowledge of the problem. The chapter tracks the efforts of the main global, intergovernmental process for negotiating both useful and politically acceptable responses to climate change, the UN Framework Convention on Climate Change, but also highlights efforts by scientific and environmental groups and, more recently, networks of sub-national governments—especially cities—and of businesses to redefine interests so as to meet the dangers of climate system disruption.

Large ensemble assessment of how the global surface warming response to cumulative carbon differs for negative and positive carbon emissions  

2021 ◽  
Author(s):  
Negar Vakilifard ◽  
Katherine Turner ◽  
Ric Williams ◽  
Philip Holden ◽  
Neil Edwards ◽  
...  
Keyword(s):  
Carbon Emissions ◽  
Radiative Forcing ◽  
Climate Model ◽  
Climate Feedback ◽  
Climate Response ◽  
Ocean Heat Uptake ◽  
Transient Climate Response ◽  
Surface Warming ◽  
Radiative Processes ◽  
Negative Emission

<p>The controls of the effective transient climate response (TCRE), defined in terms of the dependence of surface warming since the pre-industrial to the cumulative carbon emission, is explained in terms of climate model experiments for a scenario including positive emissions and then negative emission over a period of 400 years. We employ a pre-calibrated ensemble of GENIE, grid-enabled integrated Earth system model, consisting of 86 members to determine the process of controlling TCRE in both CO<sub>2</sub> emissions and drawdown phases. Our results are based on the GENIE simulations with historical forcing from AD 850 including land use change, and the future forcing defined by CO<sub>2</sub> emissions and a non-CO<sub>2</sub> radiative forcing timeseries. We present the results for the point-source carbon capture and storage (CCS) scenario as a negative emission scenario, following the medium representative concentration pathway (RCP4.5), assuming that the rate of emission drawdown is 2 PgC/yr CO<sub>2</sub> for the duration of 100 years. The climate response differs between the periods of positive and negative carbon emissions with a greater ensemble spread during the negative carbon emissions. The controls of the spread in ensemble responses are explained in terms of a combination of thermal processes (involving ocean heat uptake and physical climate feedback), radiative processes (saturation in radiative forcing from CO<sub>2</sub> and non-CO<sub>2</sub> contributions) and carbon dependences (involving terrestrial and ocean carbon uptake).  </p>

scholarly journals Pan-spectral observing system simulation experiments of shortwave reflectance and long-wave radiance for climate model evaluation

2015 ◽  
Vol 8 (7) ◽  
pp. 1943-1954 ◽  
Author(s):  
D. R. Feldman ◽  
W. D. Collins ◽  
J. L. Paige
Keyword(s):  
Climate Change ◽  
Climate Model ◽  
Coupled Model ◽  
Climate System ◽  
Spectral Measurements ◽  
Intergovernmental Panel ◽  
Climate System Model ◽  
Detection And Attribution ◽  
Long Wave ◽  
Hadley Centre

Abstract. Top-of-atmosphere (TOA) spectrally resolved shortwave reflectances and long-wave radiances describe the response of the Earth's surface and atmosphere to feedback processes and human-induced forcings. In order to evaluate proposed long-duration spectral measurements, we have projected 21st Century changes from the Community Climate System Model (CCSM3.0) conducted for the Intergovernmental Panel on Climate Change (IPCC) A2 Emissions Scenario onto shortwave reflectance spectra from 300 to 2500 nm and long-wave radiance spectra from 2000 to 200 cm−1 at 8 nm and 1 cm−1 resolution, respectively. The radiative transfer calculations have been rigorously validated against published standards and produce complementary signals describing the climate system forcings and feedbacks. Additional demonstration experiments were performed with the Model for Interdisciplinary Research on Climate (MIROC5) and Hadley Centre Global Environment Model version 2 Earth System (HadGEM2-ES) models for the Representative Concentration Pathway 8.5 (RCP8.5) scenario. The calculations contain readily distinguishable signatures of low clouds, snow/ice, aerosols, temperature gradients, and water vapour distributions. The goal of this effort is to understand both how climate change alters reflected solar and emitted infrared spectra of the Earth and determine whether spectral measurements enhance our detection and attribution of climate change. This effort also presents a path forward to understand the characteristics of hyperspectral observational records needed to confront models and inline instrument simulation. Such simulation will enable a diverse set of comparisons between model results from coupled model intercomparisons and existing and proposed satellite instrument measurement systems.

scholarly journals Thermodynamic Control on the Poleward Shift of the Extratropical Jet in Climate Change Simulations: The Role of Rising High Clouds and Their Radiative Effects

2019 ◽  
Vol 32 (3) ◽  
pp. 917-934 ◽  
Author(s):  
Ying Li ◽  
David W. J. Thompson ◽  
Sandrine Bony ◽  
Timothy M. Merlis
Keyword(s):  
Climate Change ◽  
Radiative Effects ◽  
Considerable Uncertainty ◽  
Surface Warming ◽  
Thermodynamic Constraint ◽  
Poleward Shift ◽  
Cloud Radiative Effects ◽  
Underlying Mechanisms ◽  
High Clouds

Extratropical eddy-driven jets are predicted to shift poleward in a warmer climate. Recent studies have suggested that cloud radiative effects (CRE) may enhance the amplitude of such shifts. But there is still considerable uncertainty about the underlying mechanisms, whereby CRE govern the jet response to climate change. This study provides new insights into the role of CRE in the jet response to climate change by exploiting the output from six global warming simulations run with and without atmospheric CRE (ACRE). Consistent with previous studies, it is found that the magnitude of the jet shift under climate change is substantially increased in simulations run with ACRE. It is hypothesized that ACRE enhance the jet response to climate change by increasing the upper-tropospheric baroclinicity due to the radiative effects of rising high clouds. The lifting of the tropopause and high clouds in response to surface warming arises from the thermodynamic constraints placed on water vapor concentrations. Hence, the influence of ACRE on the jet shift in climate change simulations may be viewed as an additional “robust” thermodynamic constraint placed on climate change by the Clausius–Clapeyron relation. The hypothesis is tested in simulations run with an idealized dry GCM, in which the model is perturbed with a thermal forcing that resembles the ACRE response to surface warming. It is demonstrated that 1) the enhanced jet shifts found in climate change simulations run with ACRE are consistent with the atmospheric response to the radiative warming associated with rising high clouds, and 2) the amplitude of the jet shift scales linearly with the amplitude of the ACRE forcing.

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