Syukuro Manabe

• Senior Researcher at Princeton University

Climate models have become the most powerful tool not only for predicting climate change but also for understanding it. Here, I discuss the role of greenhouse gases such as carbon dioxide and water vapour in global warming, using a hierarchy of climate models with increasing complexity.

Today I would like to address the topics of global warming and water resources. I talked about this topic ten years ago, when Nagoya University opened its Graduate School of Environmental Studies. The issue has become more serious over the last ten years, and it is an appropriate theme for the conference. This is the main reason why I decided to ta...

In the climate system, two types of radiative feedback are in operation. The feedback of the first kind involves the radiative damping of the vertically uniform temperature perturbation of the troposphere and Earth's surface that approximately follows the Stefan-Boltzmann law of blackbody radiation. The second kind involves the change in the vertic...

Using the historical surface temperature dataset compiled by Climatic Research Unit of the University of East Anglia and the Hadley Centre of the United Kingdom, this study examines the seasonal and latitudinal profile of the surface temperature change observed during the last several decades. It reveals that the recent change in zonal-mean surface...

IPCC (Intergovernmental Panel on Climate Change) AR4 (Fourth Assessment Report) GCMs (General Circulation Models) predict a tropical tropospheric warming that increases with height, reaches its maximum at ∼200 hPa, and decreases to zero near the tropical tropopause. This study examines the GCM-predicted maximum warming in the tropical upper troposp...

Syukuro Manabe was awarded the 2010 William Bowie Medal at the AGU Fall Meeting Honors Ceremony, held on 15 December 2010 in San Francisco, Calif. The medal is for ``outstanding contributions to fundamental geophysics and for unselfish cooperation in research.''

Based upon the results obtained from coupled ocean-atmosphere models of various complexities, this review explores the role of ocean in global warming. It shows that ocean can play a major role in delaying global warming and shaping its geographical distribution. It is very encouraging that many features of simulated change of the climate system ha...

The sensitivity of the global climate is essentially determined by the radiative damping of the global mean surface temperature anomaly through the outgoing radiation from the top of the atmosphere (TOA). Using the TOA fluxes of terrestrial and reflected solar radiation obtained from the Earth radiation budget experiment (ERBE), this study estimate...

By use of a coupled ocean–atmosphere–land model, this study explores the changes of water availability, as measured by river discharge and soil moisture, that could occur by the middle of the 21st century in response to combined increases of greenhouse gases and sulphate aerosols based upon the "IS92a" scenario. In addition, it presents the simulat...

By use of a coupled ocean–atmosphere–land model, this study explores the changes of water availability, as measured by river discharge and soil moisture, that could occur by the middle of the 21st century in response to combined increases of greenhouse gases and sulphate aerosols based upon the ȁIS92aȁ scenario. In addition, it presents the simulat...

It has been suggested that, unless a major effort is made, the atmospheric concentration of carbon dioxide may rise above four times the pre-industrial level in a few centuries. Here we use a coupled atmosphere-ocean-land model to explore the response of the global water cycle to such a large increase in carbon dioxide, focusing on river discharge...

This study evaluates the equilibrium response of a coupled ocean–atmosphere model to the doubling, quadrupling, and halving of CO2 concentration in the atmosphere. Special emphasis in the study is placed upon the response of the thermohaline circulation in the Atlantic Ocean to the changes in CO2 concentration of the atmosphere. The simulated inten...

1] Using the results obtained from a coupled ocean-atmosphere-land model with medium computational resolution, we investigated how the hydrology of the continents changes in response to the combined increases of greenhouse gases and sulfate aerosols in the atmosphere, which are determined based upon the IS92a scenario. In order to extract the force...

The goal of this study is to estimate the cloud radiative feedback effect on the annual variation of the global mean surface temperature using radiative flux data from the Earth Radiation Budget Experiment. We found that the influence of the cloud feedback upon the change of the global mean surface temperature is quite small, though the increase of...

This lecture discusses the low-frequency variability of surface temperature using a coupled ocean-atmosphere-land-surface model developed at the Geophysical Fluid Dynamics Laboratory/NOAA. Despite the highly idealized parametrization of various physical processes, the coupled model simulates reasonably well the variability of local and global mean...

 We examine 800-year time series of internally generated variability in both a coupled ocean-atmosphere model where water vapor anomalies are not allowed to interact with longwave radiation and one where they are. The ENSO-like phenomenon in the experiment without water vapor feedback is drastically suppressed both in amplitude and geographic exten...

Using two versions of the GFDL coupled ocean-atmosphere model, one where water vapor anomalies are allowed to affect the longwave radiation calculation and one where they are not, we examine the role of water vapor feedback in internal precipitation variability and greenhouse-gas-forced intensification of the hydrologic cycle. Without external forc...

This study examines the responses of the simulated modern climate of a coupled ocean–atmosphere model to the discharge of freshwater into the North Atlantic Ocean. Two numerical experiments were conducted. In the first numerical experiment in which freshwater is discharged into high North Atlantic latitudes over the period of 500 years, the thermoh...

The influence of differing rates of increase of the atmospheric CO2 concentration on the climatic response is investigated using a coupled ocean-atmosphere model. Five transient integrations are performed each using a different constant exponential rate of CO2 increase ranging from 4% yr1 to 0.25% yr1. By the time of CO2 doubling, the surface air t...

To understand water vapor feedback's role in unperturbed surface temperature variability, a version of the GFDL coupled ocean-atmosphere model is integrated for 1000 years in two configurations, one with water vapor feedback, and one without. The model with water vapor feedback has more surface temperature variability on all spatial and time scales...

The standard version of the coupled ocean–atmosphere model developed at the Geophysical Fluid Dynamics Laboratory (GFDL) of NOAA has at least two stable equilibria. One has a realistic and active thermohaline circulation (THC) with sinking regions in the northern North Atlantic Ocean. The other has a reverse THC with extremely weak upwelling in the...

The standard version of the coupled ocean–atmosphere model developed at the GeophysicalFluid Dynamics Laboratory (GFDL) of NOAA has at least two stable equilibria. One has arealistic and active thermohaline circulation (THC) with sinking regions in the northern NorthAtlantic Ocean. The other has a reverse THC with extremely weak upwelling in the No...

This article discusses the rô le of the THC in climate, based upon the results of several numerical experiments which use a coupled ocean-atmosphere model developed at the Geophysical Fluid Dynamics Laboratory of NOAA, USA. The first part of the article explores the mechanism which is responsible for the abrupt climate change such as the Younger Dr...

This study investigates the temporal and spatial variation of soil moisture associated with global warming as simulated by long-term integrations of a coupled ocean-atmosphere model conducted earlier. Starting from year 1765, integrations of the coupled model for 300 years were performed for three scenarios: increasing greenhouse gases only, increa...

This article discusses the role of the THC in climate, based upon the results of several numerical experiments which use a coupled ocean-atmosphere model developed at the Geophysical Fluid Dynamics Laboratory of NOAA, USA. The first part of the article explores the mechanism which is responsible for the abrupt climate change such as the Younger Dry...

In this report, global coupled ocean–atmosphere models are used to explore possible mechanisms for observed decadal variability and trends in Pacific Ocean SSTs over the past century. The leading mode of internally generated decadal (�7 yr) variability in the model resembles the observed decadal variability in terms of pattern and amplitude. In the...

A 1995 report of the Intergovernmental Panel on Climate Change provides a set of illustrative anthropogenic CO2 emission models leading to stabilization of atmospheric CO2 concentrations ranging from 350 to 1,000p.p.m. (refs 1-4). Ocean carbon-cycle models used in calculating these scenarios assume that oceanic circulation and biology remain unchan...

This paper is based on the commemorative lecture which was delivered at the award ceremony of the Volvo Environmental Prize. The author describes his early attempt to study the greenhouse effect using a one-dimensional model of radiative, convective equilibrium of the atmosphere. This is followed by the description of a recent study of global warmi...

This study investigates changes in surface air temperature (SAT), hydrology and the thermohaline circulation due to the the radiative forcing of anthropogenic greenhouse gases and the direct radiative forcing (DRF) of sulfate aerosols in the GFDL coupled ocean-atmosphere model. Three 300-year model integrations are performed with increasing greenho...

This study explores the responses of a coupled ocean-atmosphere model to the discharge of freshwater into the North Atlantic Ocean. In the first numerical experiment in which freshwater is discharged into high North Atlantic latitudes over a period of 500 years, the thermohaline circulation (THC) in the Atlantic Ocean weakens, reducing surface air...

 Sea surface temperature (SST) and salinity (SSS) time series from four ocean weather stations and data from an integration of the GFDL coupled ocean-atmosphere model are analyzed to test the applicability of local linear stochastic theory to the mixed-layer ocean. According to this theory, mixed-layer variability away from coasts and fronts can be...

Pronounced oscillations of ocean temperature and salinity occur in the Greenland Sea in a 2000 year integration of a coupled ocean-atmosphere model. The oscillations, involving both the surface and subsurface ocean layers, have a timescale of approximately 40-80 years, and are associated with fluctuations in the intensity of the East Greenland Curr...

An analysis is presented of simulated ENSO phenomena occurring in three 1000-yr experiments with a low-resolution (R15) global coupled ocean-atmosphere GCM. Although the model ENSO is much weaker than the observed one, the model ENSO's life cycle is qualitatively similar to the `delayed oscillator' ENSO life cycle simulated using much higher resolu...

The geological record provides evidence that suggests a link between mountain uplift and changes in climate over substantial regions of the world.1 One approach to understanding the effect of mountain uplift on the evolution of climate is to investigate the role of present-day orography in determining the modern distribution of climates. A better u...

This lecture evaluates the low-frequency variability of surface air temperature that was obtained from a 1000-yr integration of a coupled ocean-atmosphere-land surface model. The model simulates reasonably well the variability of local and global mean surface air temperature (SAT) at decadal timescales. The physical mechanisms responsible for this...

Observations of the vertical structure of atmospheric temperature changes over the past three decades show that while the global-average lower atmosphere has warmed, the upper troposphere and lower stratosphere have cooled. While these changes may be due to observed anthropogenic increases of greenhouse gases, decreases of lower stratospheric ozone...

The study analyzes the variability of surface air temperature (SAT) and sea surface temperature (SST) obtained from a 1000-yr integration of a coupled atmosphere-ocean-land surface model, which consists of general circulation models of the atmosphere and oceans and a heat and water budget model of land surface.It also explores the role of oceans in...

Following the pioneering contributions of Arrhenius, Callendar and others, climate models emerged as a very promising tool for the study of greenhouse warming. In the early 1960s, a one-dimensional, radiative-convective equilibrium model was developed as the first step towards the development of a three-dimensional model of climate. Incorporating n...

To improve understanding of the mechanisms responsible for COâ-induced, midcontinental summer dryness, several integrations were performed using a GCM with idealized geography. The simulated reduction of soil moisture in middle latitudes begins in late spring, caused by excess of evaporation over precipitation. Increase of carbon dioxide and the as...

TEMPERATURE records from Greenland ice cores1,2 suggest that large and abrupt changes of North Atlantic climate occurred frequently during both glacial and postglacial periods; one example is the Younger Dryas cold event. Broecker3 speculated that these changes result from rapid changes in the thermohaline circulation of the Atlantic Ocean, which w...

The time-mean response over the tropical Pacific region to a quadrupling of COâ is investigated using a global coupled ocean-atmosphere general circulation model. Tropical Pacific sea surface temperatures (SSTs) rise by about 4°-5°C. The zonal SST gradient along the equator decreases by about 20%, although it takes about one century (with COâ inc...

The impact of a COâ-induced global warming on ENSO-like fluctuations in a global coupled ocean-atmosphere GCM is analyzed using two multi-century experiments. In the 4xCOâ experiment, COâ increases by a factor of four in the first 140 years and then remains constant at 4xCOâ for another 360 years; in the control experiment, COâ ramains constant at...

SINCE the late nineteenth century, the global mean surface air temperature has been increasing at the rate of about 0.5 °C per century1–3, but our poor understanding of low-frequency natural climate variability has made it very difficult to determine whether the observed warming trend is attributable to the enhanced green-house effect associated wi...

To speculate on the future change of climate over several centuries, three 500-year integrations of a coupled ocean-atmosphere model were performed. In addition to the standard integration in which the atmospheric concentration of carbon dioxide remains unchanged, two integrations are conducted. In one integration, the CO2 concentration increases b...

A fully coupled ocean-atmosphere model is shown to have irregular oscillations of the thermohaline circulation in the North Atlantic Ocean with a time scale of approximately 50 years. The irregular oscillation appears to be driven by density anomalies in the sinking region of the thermohaline circulation (approximately 52°N to 72°N) combined with m...

A coupled ocean-atmosphere climate model is presently used to project the evolution of the world's climate over the course of several centuries characterized by (1) a doubling and (2) a quadrupling of atmospheric CO2. Global mean surface air temperature increases of 3.5 and 7 percent, respectively, are seen over a period of 500 years; these project...

Manabe and Stouffer reply to comments about their paper presenting a coupled ocean-atmospheric system. They state that the results from the main experiments do not confirm the speculation that the extensive spreading of fresh water could be attributed to the excessively large horizontal mixing in the oceanic component of the model. However, after d...

Syukuro Manabe was presented with the Roger Revelle Medal at the AGU Spring Meeting in Baltimore last May. The Revelle Medal recognizes outstanding accomplishments or contributions toward an understanding of the Earth's atmospheric processes, including its dynamics, chemistry, and radiation, or the roles of atmosphere or atmosphere-ocean coupling i...

A number of climate modeling studies have been conducted at the Geophysical Fluid Dynamics Laboratory to study the interaction of continental ice sheets with the climate system. This paper reviews some of the primary results from these studies. Substantial changes in atmospheric circulation, location and intensity of storm tracks, precipitation dis...

This study investigates the response of a climate model to a gradual increase of atmospheric carbon dioxide. The model is a general circulation model of the coupled ocean–atmosphere–land surface system with a global computational domain, smoothed geography, and seasonal variation of insolation. It is found that the simulated increase of sea surface...

The role of mountains in maintaining extensive midlatitude arid regions in the Northern Hemisphere was investigated using simulations from the GFDL Global Climate Model with and without orography. In the integration with mountains, dry climates were simulated over central Asia and the interior of North America, in good agreement with the observed c...

This study investigates the seasonal variation of the transient response of a coupled ocean-atmosphere model to a gradual increase (or decrease) of atmospheric carbon dioxide. The model is a general circulation model of the coupled atmosphere-ocean-land surface system with a global computational domain, smoothed geography, and seasonal variation of...

This paper describes the response of a coupled ocean-atmosphere-land surface model developed at GFDL to gradual changes of atmospheric carbon dioxide. It summarizes the results in three recently published papers (Stouffer et al., 1989 Manabe et al., 1991, 1992). They represent the current state of the art in predicting further climate change induce...

The transient response of a coupled ocean-atmosphere model to an increase of carbon dioxide has been the subject of several studies (Bryan et al., 1982; Spelman and Manabe, 1984; Bryan and Spelman, 1985; Schlesinger and Jiang, 1988; Schlesinger et al., 1985; Bryan et al., 1988; Manabe et al., 1990; Washington and Meehl, 1989). The models used in th...

This study investigates the response of a climate model to a gradual increase or decrease of atmospheric carbon dioxide. The model is a general circulation model of the coupled atmosphere-ocean-land surface system with global geography and seasonal variation of insulation. To offset the bias of the coupled model toward settling into an unrealistic...

The importance of clouds in the upper troposphere (cirrus) for the sensitivity of the Earth's climate e.g., requires that these clouds be modeled accurately in general circulation model (GCM) studies of the atmosphere. Bearing in mind the lack of unambiguous quantitative information on the geographical distribution and properties of high clouds, th...

The utility of current generation climate models for studying the influence of greenhouse warming on the tropical storm climatology is examined. A method developed to identify tropical cyclones is applied to a series of model integrations. The global distribution of tropical storms is simulated by these models in a generally realistic manner. While...

The transient response of climate to an instantaneous increase in the atmospheric concentration of carbon dioxide has been investigated by a general circulation model of the coupled ocean-atmosphere-land system with global geography and annual mean insulation. An equilibrium climate of the coupled model is perturbed by an abrupt doubling of the atm...

The temporal variability of soil wetness and its interactions with the atmosphere were studied using a general circulation model of the atmosphere. It was found that time series of soil wetness computed by the model contain substantial amounts of variance at low frequencies. Long time-scale anomalies of soil moisture resemble the red noise response...

Simulations from a global climate model with and without orography have been used to investigate the role of mountains in maintaining extensive arid climates in middle latitudes of the Northern Hemisphere. Dry climates similar to those observed were simulated over central Asia and western interior North America in the experiment with mountains, whe...

The main equilibrium changes in climate, due to doubling CO 2, deduced from models are given below: Near the Earth's surface the global average warming lies between 1.5°C and 4.5°C, with a "best guess' of 2.5°C. There is much greater effect in high latitudes, than in the tropics. At the same time, the stratosphere cools. Global average precipitatio...

THE transient response of a coupled ocean-atmosphere model to an increase of atmospheric carbon dioxide has been the subject of several studies1-8. The models used in these studies explicitly incorporate the effect of heat transport by ocean currents and are different from the model used by Hansen et al. 9. Here we evaluate the climatic influence o...

The influence of land surface processes on near-surface atmospheric variability on seasonal and interannual time scales is studied using output from two integrations of a general circulation model. In the first experiment of 50 years duration, soil moisture is predicted, thereby taking into consideration interactions between the surface moisture bu...

Two stable equilibria have been obtained from a global model of the coupled ocean-atmosphere system developed at the Geophysical Fluid Dynamics Laboratory of NOAA. The model used for this study consists of general circulation models of the atmosphere and the world oceans and a simple model of land surface. Starting from two different initial condit...

Numerical experiments are carried out using a general circulation model of a coupled ocean-atmosphere system with idealized geography, exploring the transient response of climate to a rapid increase of atmospheric carbon dioxide. The computational domain of the model is bounded by meridians 120 degrees apart, and includes two hemispheres. The ratio...

An atmospheric general circulation model with prescribed sea surface temperature and cloudiness was integrated for 50 years in order to study atmosphere-land surface interactions. The temporal variability of model soil moisture and precipitation have been studied in an effort to understand the interactions of these variables with other components o...

The model used is a general circulation model of the atmosphere coupled with a mixed layer model of the oceans. The sensitivity of each version of the model is inferred from the equilibrium response of the model to a doubling of the atmospheric concentration of carbon dioxide. In response to the increase of atmospheric carbon dioxide, cloudiness in...

The response of a coupled atmosphere-ocean model is determined over a wide range of atmospheric CO2 levels. The solutions indicate the type of ocean circulations expected over a very wide range of climatic conditions. In climates warmer than the present one, the north-south gradient of temperature is significantly reduced, but, owing to the elevati...

The change in soil wetness in response to an increase of atmospheric concentration of carbon dioxide is investigated by two versions of a climate model which consists of a general circulation model of the atmosphere and a static mixed layer ocean. In the first version of the model, the distribution of cloud cover is specified whereas it is computed...

The contributions of expanded continental ice, reduced atmospheric CO2, and changes in land albedo to the maintenance of the climate of the last glacial maximum (LGM) are examined. A series of experiments is performed using an atmosphere-mixed layer ocean model in which these changes in boundary conditions are incorporated either singly or in combi...

A climate model, consisting of an atmospheric general circulation model coupled with a simple model of the oceanic mixed layer, is used to investigate the effects of the continental ice distribution of the last glacial maximum (LGM) on North American climate. This model has previously been used to simulate the LGM climate, producing temperature cha...

A CO2-induced reduction of soil moisture over extensive continental regions in the Northern Hemisphere during the summer season is obtained from numerical integrations of a mathematical model of climate. An analysis of these results indicates that, although the soil moisture is reduced in the version of the model with prescribed clouds, this summer...

The geographical distribution of the change in soil wetness in response to an increase in atmospheric carbon dioxide was investigated by using a mathematical model of climate. Responding to the increase in carbon dioxide, soil moisture in the model would be reduced in summer over extensive regions of the middle and high latitudes, such as the North...

The role of cloud cover in determining the sensitivity of climate has been a source of great uncertainty. This article reviews the distributions of cloud cover change from several climate sensitivity experiments conducted at the Geophysical Fluid Dynamics Laboratory of NOAA (GFDL) and other institutions. Two of the sensitivity experiments conducted...

The actual timing of the outset of climate change is controlled by heat exchange with the ocean, which has a heat capacity order of magnitude larger than the atmosphere. The chapter discusses the physical processes involved in this transient response. Transient tracers produced by the bomb tests of the late fifties and early sixties provide one sou...

This chapter examines CO2-induced change in hydrology, using of general circulation models of climate with various complexities. Two long-term integrations of a climate model are performed with normal and above-normal concentration of carbon dioxide. To facilitate the identification of the CO2-induced change superposed on natural hydrologic fluctua...

An attempt has been made to use paleoclimatic data from the last glacial maximum to evaluate the sensitivity of two versions of an atmosphere/mixed-layer ocean model. Each of these models has been used to study the C02-induced changes in climate. The models differ in their treatment of cloudiness, with one using a fixed cloud distribution and the o...

The effect of large changes of atmospheric CO2 was studied, using the coupled ocean-atmosphere model of Bryan et al. (1982), for derivation of six climatic equilibria (cases with 1/2 to 8 times the present CO2 concentration). An increase of atmospheric CO2 to the level of 8 times the normal concentration is accompanied by a decrease in the meridion...

The climate influence of the land ice that existed 18,000 years before present (18K B.P.) is investigated by use of a general circulation model of the atmosphere coupled with a static mixed layer ocean. Simulated climates are obtained from two versions of the model; one with the land ice distribution of the present and the other with that of 18K B....

Papers are presented on large-scale eddies and the general circulation of the troposphere; the role of barotropic energy conversions in the general circulation; balance conditions in the earth's climate system, climate sensitivity; CO2 and hydrology; modeling of paleoclimates; and the southern oscillation and El Nino. Topics treated include the str...

Describes a series of numerical experiments simulating the effect of large-scale irrigation on short-term changes of hydrology and climate. This is done through the use of a simple general circulation model with a limited computational domain and idealized geography.-from Authors

While the spectral analysis of data from deep sea cores supports the suggestion that the temporal variation of the earth’s orbital parameters is responsible for triggering the growth and decay of continental ice during the Quaternary (1), the physical factors responsible for maintaining a global ice age climate are less well understood. One of the...

The influence of oceanic heat transport on the sensitivity of climate to an increase of the atmospheric CO2 concentration is studied by comparing the CO2-induced changes of two mathematical models. The first model is a general circulation model of the coupled ocean-atmospheric system which includes ocean currents. In the second model the oceanic co...

The climatic influence of the land ice which existed 18 ka BP is investigated using a climate model developed at the Geophysical Fluid Dynamics Laboratory of the National Oceanic and Atmospheric Administration. The model consists of an atmospheric general circulation model coupled with a static mixed layer ocean model. Simulated climates are obtain...

The climatic influence of the land ice which existed 18 ka BP is investigated using a climate model developed at the Geophysical Fluid Dynamics Laboratory of the National Oceanic and Atmospheric Administration. The model consists of an atmospheric general circulation model coupled with a static mixed layer ocean model. Simulated climates are obtain...