Earth's Energy Balance Research Articles

Technical Note: Evaluating a simple parameterization of radiative shortwave forcing from surface albedo change

Abstract. Land-use activities affect Earth's energy balance not only via biogeochemical emissions, but also through perturbations in surface albedo, the latter of which is often excluded in impact assessment studies. In this short technical note, we present and compare a simple model for estimating shortwave radiative forcings at the top of Earth's atmosphere to a more sophisticated 8-stream radiative transfer model based on a discrete ordinate method. Outcomes from monthly albedo change simulations for ten globally distributed regions and a single year revealed that the simple model – based on a single exogenously supplied meteorological variable – performed quite well, having a sample correlation coefficient of 0.93 and a normalized root mean square error of 7.2%. Simple models like the one presented here can offer an attractive and efficient means for non-experts to begin including albedo change considerations in climate impact assessment studies enveloping land use activities.

Earthshine observations at high spectral resolution: exploring and detecting metal lines in the Earth's upper atmosphere

Observations of the Earth as a planet using the earthshine technique (i.e. looking at the light reflected from the darkside of the Moon), have been used for climate and astrobiology studies. They provide information about the planetary albedo, a fundamental parameter of the Earth's energy balance. Here we present for the first time, observations of the earthshine taken at high spectral resolution. The high spectral resolution was chosen in order to investigate the possibility of detecting metallic layers in the Earth's atmosphere of geological or meteoritic origin. The SARG echelle spectrograph at the Telescopio Nazionale Galileo in La Palma was used to acquire the earthshine data. Observations were carried out on several nights in February 2011, with the spectral resolution set at 29,000, covering a spectral range from the near-ultraviolet (360 nm) to near-infrared (1011.9 nm). While we find evidence for the detection of a Na layer in the earthshine, other atomic species are not detected, perhaps due to the low signal-to-noise ratio of the observations and the difficult telluric corrections. The Na layer is found to vary between observation dates, which we speculate is due to physical variations in mesospheric Na concentrations.

A simple model of global aerosol indirect effects

Most estimates of the global mean indirect effect of anthropogenic aerosol on the Earth's energy balance are from simulations by global models of the aerosol lifecycle coupled with global models of clouds and the hydrologic cycle. Extremely simple models have been developed for integrated assessment models, but lack the flexibility to distinguish between primary and secondary sources of aerosol. Here a simple but more physically based model expresses the aerosol indirect effect (AIE) using analytic representations of cloud and aerosol distributions and processes. Although the simple model is able to produce estimates of AIEs that are comparable to those from some global aerosol models using the same global mean aerosol properties, the estimates by the simple model are sensitive to preindustrial cloud condensation nuclei concentration, preindustrial accumulation mode radius, width of the accumulation mode, size of primary particles, cloud thickness, primary and secondary anthropogenic emissions, the fraction of the secondary anthropogenic emissions that accumulates on the coarse mode, the fraction of the secondary mass that forms new particles, and the sensitivity of liquid water path to droplet number concentration. Estimates of present‐day AIEs as low as −5 W m−2 and as high as −0.3 W m−2 are obtained for plausible sets of parameter values. Estimates are surprisingly linear in emissions. The estimates depend on parameter values in ways that are consistent with results from detailed global aerosol‐climate simulation models, which adds to understanding of the dependence on AIE uncertainty on uncertainty in parameter values.

천리안 위성을 사용한 방출장파복사량 검증 : 청미천, 설마천

방출장파복사량은 수치예보모형, 수문모형, 증발산 등에 사용되는 인자로 지구의 에너지 균형을 이해하는데 필수적이다. 현재 국내외에서는 이를 정확하게 관측하기가 어려우며, 또한 공간적인 제약이 따른다. 따라서, 본 연구에서는 원격탐사 기술을 적용함으로써 지상관측의 단점을 보완하기 위해 정지궤도 위성인 Communication, Ocean and Meteorological Satellite (COMS)를 사용하여 방출장파복사량(Outgoing Longwave Radiation, <TEX>$R_{lu}$</TEX> )를 계산하였다. 이 자료의 검증을 위해 유량조사사업단에서운영 관리하는 청미천/설마천 Flux Tower의 자료를 사용하여 계산된 <TEX>$R_{lu}$</TEX> 와 MODIS 위성자료를 사용하여 계산된 <TEX>$R_{lu}$</TEX> 를 비교 및 검증하였다. 전반적으로 COMS의 자료가 높은 상관계수를 나타내어 COMS의 사용가능성을 보여주었다. 이러한 결과를 바탕으로 향후 COMS를 이용한 증발산 산정 연구를 할 계획이다. The outgoing longwave radiation (Rlu) for estimation of evapotranspiration is essential to understand energy balance of earth. However, the ground measurement based Rlu has a limitation that the observation can just stand for the exact site, not for an area. In this study, remote sensing technique is adopted to compensate the limitation of ground observation using the geostationary satellite. We calculated Rlu using Communication, Ocean and Meteorological Satellite (COMS). We validated Rlu from COMS with Cheongmicheon (CFK) and Sulmacheon (SMK) flux tower observations controlled by Hydrological Survey Center. The results showed that Rlu from COMS represented reasonable correlation with ground based measurement. Based on the results in this study, COMS will be able to be used for estimation of evapotranspiration.

Validation of a Meteosat Second Generation solar radiation dataset over the northeastern Iberian Peninsula

Abstract. Solar radiation plays a key role in the Earth's energy balance and is used as an essential input data in radiation-based evapotranspiration (ET) models. Accurate gridded solar radiation data at high spatial and temporal resolution are needed to retrieve ET over large domains. In this work we present an evaluation at hourly, daily and monthly time steps and regional scale (Catalonia, NE Iberian Peninsula) of a satellite-based solar radiation product developed by the Land Surface Analysis Satellite Application Facility (LSA SAF) using data from the Meteosat Second Generation (MSG) Spinning Enhanced Visible and Infrared Imager (SEVIRI). Product performance and accuracy were evaluated for datasets segmented into two terrain classes (flat and hilly areas) and two atmospheric conditions (clear and cloudy sky), as well as for the full dataset as a whole. Evaluation against measurements made with ground-based pyranometers yielded good results in flat areas with an averaged model RMSE of 65 W m−2 (19%), 34 W m−2 (9.7%) and 21 W m−2 (5.6%), for hourly, daily and monthly-averaged solar radiation and including clear and cloudy sky conditions and snow or ice cover. Hilly areas yielded intermediate results with an averaged model RMSE (root mean square error) of 89 W m−2 (27%), 48 W m−2 (14.5%) and 32 W m−2 (9.3%), for hourly, daily and monthly time steps, suggesting the need of further improvements (e.g., terrain corrections) required for retrieving localized variability in solar radiation in these areas. According to the literature, the LSA SAF solar radiation product appears to have sufficient accuracy to serve as a useful and operative input to evaporative flux retrieval models.

Ice nuclei in marine air: biogenic particles or dust?

Abstract. Ice nuclei impact clouds, but their sources and distribution in the atmosphere are still not well known. Particularly little attention has been paid to IN sources in marine environments, although evidence from field studies suggests that IN populations in remote marine regions may be dominated by primary biogenic particles associated with sea spray. In this exploratory model study, we aim to bring attention to this long-neglected topic and identify promising target regions for future field campaigns. We assess the likely global distribution of marine biogenic ice nuclei using a combination of historical observations, satellite data and model output. By comparing simulated marine biogenic immersion IN distributions and dust immersion IN distributions, we predict strong regional differences in the importance of marine biogenic IN relative to dust IN. Our analysis suggests that marine biogenic IN are most likely to play a dominant role in determining IN concentrations in near-surface-air over the Southern Ocean, so future field campaigns aimed at investigating marine biogenic IN should target that region. Climate-related changes in the abundance and emission of biogenic marine IN could affect marine cloud properties, thereby introducing previously unconsidered feedbacks that influence the hydrological cycle and the Earth's energy balance. Furthermore, marine biogenic IN may be an important aspect to consider in proposals for marine cloud brightening by artificial sea spray production.

Rocky Mountain hydroclimate: Holocene variability and the role of insolation, ENSO, and the North American Monsoon

Over the period of instrumental records, precipitation maximum in the headwaters of the Colorado Rocky Mountains has been dominated by winter snow, with a substantial degree of interannual variability linked to Pacific ocean–atmosphere dynamics. High-elevation snowpack is an important water storage that is carefully observed in order to meet increasing water demands in the greater semi-arid region. The purpose here is to consider Rocky Mountain water trends during the Holocene when known changes in earth's energy balance were caused by precession-driven insolation variability. Changes in solar insolation are thought to have influenced the variability and intensity of the El Niño Southern Oscillation (ENSO), Pacific Decadal Oscillation (PDO), and North American Monsoon and the seasonal precipitation balance between rain and snow at upper elevations. Holocene records are presented from two high elevation lakes located in northwest Colorado that document decade-to-century scale precipitation seasonality for the past ~7000years. Comparisons with sub-tropical records of ENSO indicate that the snowfall-dominated precipitation maxima developed ~3000 and 4000years ago, coincident with evidence for enhanced ENSO/PDO dynamics. During the early-to-mid Holocene the records suggest a more monsoon affected precipitation regime with reduced snowpack, more rainfall, and net moisture deficits that were more severe than recent droughts. The Holocene perspective of precipitation indicates a far broader range of variability than that of the past century and highlights the non-linear character of hydroclimate in the U.S. west.

Environmental Pragmatism, Global Warming, and Climate Change

This paper begins with a presentation of some important aspects of the science behind global warming. Following that, I argue that attempts to address global warming and climate change as problems facing humanity ought not to center around economic understandings of the problem or it solutions. Moreover, I argue that (environmental) pragmatism is especially vulnerable to this sort of misappropriation in seeking solutions to climate change, and that environmental pragmatists ought to make a conscious effort to avoid potential mischaracterizations of pragmatism by providing a clearer sense of the boundaries that delimit its approach to climate change, or any other environmental crisis.Public discourse concerning the rising average surface temperature of our planet is not far to seek at present. There is almost daily mention of the phenomena in print, radio and television news media; and no shortage of special reports by various stations and channels, Discovery and PBS: Frontline1 are two that come to mind), special issues of periodicals, or documentaries (think former VicePresident Gore) all addressing some aspect of the myriad concerns over the continued burning of fossil fuels and its effect on the climate. In what follows, I first provide a lay account of the science of global warming; one that I hope will interest readers not already preoccupied with the subject, as well as further inform those who are. Following that I argue that attempts to address global warming and climate change as problems facing humanity ought not to center around economic understandings of the problem or it solutions, and that pragmatism especially ought to resist such an approach.1. The Balance of EnergyEarth receives energy from the Sun in the form of light (much of which is not within the visible range of human beings). Various frequencies of light carry energy across the 150 million kilometer wide vacuum that separates the Sun from the Earth.3 The heat provided by the sun is crucial to making our planet inhabitable. Theoretically, the Earth should overtime radiate or reflect back into space the same amount of energy that it receives from the Sun - barring temporary or regional imbalances.4 I will refer to this throughout this essay as the Earth's energy balance or energy budget.What this means is that if we consider the total amount of solar energy that reaches the Earth that same amount of energy must be returned to space by the Earth. All solar energy comes at the Earth from one direction, but energy is radiated from the Earth in all directions. Light that is reflected by the Earth's atmosphere back into space never reaches the planet's surface. The total energy release from the earth can be divided into two broad categories: heat radiated and light reflected. The first category - the heat radiated from the Earth - accounts for approximately seventy percent - roughly fifty eight percent by clouds and the atmosphere and twelve percent by near surface emissions - of the solar energy that the Earth receives from the Sun. The other category - light reflected - accounts for the solar energy that is reflected back into space - approximately twenty three percent by clouds and atmosphere and seven percent by the surface of the Earth.5 The total amount of visible light reflected - as opposed to radiated - by a body is called its albedo^ and in climatology is sometimes expressed as a percentage of the total incoming light. Earth's albedo is roughly .30; that is, thirty percent of the visible light from the Sun is reflected back into space before it enters the planet's atmosphere.2. The (Anthropogenic) Greenhouse EffectGases present in the Earth's atmosphere are classified as greenhouse or nongreenhouse gases based on whether their molecules are reactive to infrared (IR) light. If a molecule has three or more atoms, it is infrared active. Gases are not good blackbodies - objects that absorb and radiate all frequencies of light - because they are very selective about the frequencies of IR light they will interact with. …

Intercomparison of MODIS albedo retrievals and in situ measurements across the global FLUXNET network

Surface albedo is a key parameter in the Earth's energy balance since it affects the amount of solar radiation directly absorbed at the planet surface. Its variability in time and space can be globally retrieved through the use of remote sensing products. To evaluate and improve the quality of satellite retrievals, careful intercomparisons with in situ measurements of surface albedo are crucial. For this purpose we compared MODIS albedo retrievals with surface measurements taken at 53 FLUXNET sites that met strict conditions of land cover homogeneity. A good agreement between mean yearly values of satellite retrievals and in situ measurements was found (r2=0.82). The mismatch is correlated with the spatial heterogeneity of surface albedo, stressing the relevance of land cover homogeneity when comparing point to pixel data. When the seasonal patterns of MODIS albedo are considered for different plant functional types, the match with surface observations is extremely good at all forest sites. On the contrary, satellite retrievals at non-forested sites (grasslands, savannas, croplands) underestimate in situ measurements across the seasonal cycle. The mismatch observed at grassland and cropland sites is likely due to the extreme fragmentation of these landscapes, as confirmed by geostatistical attributes derived from high resolution scenes.

Climate and Earth’s Energy Flows

Under equilibrium conditions, climate can be viewed in simple terms as the average energy pathways that incoming solar radiation takes before exiting the system in order to maintain overall energy balance. Similarly, future climate change will ultimately be determined by how the Earth's energy balance and average energy pathways change in response to external radiative forcings, such as anthropogenic greenhouse gases, and internal redistributions. Here, we give an overview of climate research in the context of Earth's energy flows and make the case for improved observations of total energy as a more physically robust metric of climate change than the commonly used surface tem- perature record.

Insights on global warming

AbstractThe global temperature increase over the last century and a half (∼ 0.8°C), and the last three decades in particular, is well outside of that which can be attributed to natural climate fluctuations. The increase of atmospheric CO2 over this period has been conclusively demonstrated to be a result largely of fossil fuel burning. The global mean temperature change that results in response to a sustained perturbation of the Earth's energy balance after a time sufficiently long for both the atmosphere and oceans to come to thermal equilibrium is termed the Earth's climate sensitivity. The purely radiative (blackbody) warming from a doubling of CO2 from its preindustrial level of 280 parts‐per‐million (ppm) to 560 ppm is ∼ 1.2°C; the actual warming that would result is considerably larger owing to amplification by climate feedbacks, including that owing to water vapor. Increases in greenhouse gas (GHG) levels are estimated to have contributed about +3.0 W m−2 perturbation (radiative forcing) to the Earth's energy balance. Particles (aerosols), on the whole, exert a cooling effect on climate, with a total forcing estimated by the Intergovernmental Panel on Climate Change (2007)1 as −1.2 W m−2, a value that is subject to considerable uncertainty. If the actual magnitude of aerosol forcing is close to the low end of its estimated uncertainty range, then it offsets a considerably smaller fraction of the GHG forcing and the total net forcing is at the high end of its range, ∼ 2.4 W m−2; at the other extreme, if the actual aerosol cooling is at the high end of its range, then aerosol forcing is currently offsetting a major fraction of GHG forcing, and the total net forcing is only ∼ 0.6 W m−2. To explain the actual global increase in temperature of ∼ 0.8°C, these two extremes have major implications in terms of the Earth's climate sensitivity. Climate sensitivity is determined by the strength of feedbacks, of which cloud feedback is the most uncertain. That the Earth has warmed and that GHGs are responsible is unequivocal; the Earth's climate sensitivity and the effect of aerosols complicate answers to the question: how much warming and how soon? © 2011 American Institute of Chemical Engineers AIChE J, 2011

Aerosol indirect effects in a multi-scale aerosol-climate model PNNL-MMF

Abstract. Much of the large uncertainty in estimates of anthropogenic aerosol effects on climate arises from the multi-scale nature of the interactions between aerosols, clouds and dynamics, which are difficult to represent in conventional general circulation models (GCMs). In this study, we use a multi-scale aerosol-climate model that treats aerosols and clouds across multiple scales to study aerosol indirect effects. This multi-scale aerosol-climate model is an extension of a multi-scale modeling framework (MMF) model that embeds a cloud-resolving model (CRM) within each vertical column of a GCM grid. The extension allows a more physically-based treatment of aerosol-cloud interactions in both stratiform and convective clouds on the global scale in a computationally feasible way. Simulated model fields, including liquid water path (LWP), ice water path, cloud fraction, shortwave and longwave cloud forcing, precipitation, water vapor, and cloud droplet number concentration are in reasonable agreement with observations. The new model performs quantitatively similar to the previous version of the MMF model in terms of simulated cloud fraction and precipitation. The simulated change in shortwave cloud forcing from anthropogenic aerosols is −0.77 W m−2, which is less than half of that (−1.79 W m−2) calculated by the host GCM (NCAR CAM5) with traditional cloud parameterizations and is also at the low end of the estimates of other conventional global aerosol-climate models. The smaller forcing in the MMF model is attributed to a smaller (3.9 %) increase in LWP from preindustrial conditions (PI) to present day (PD) compared with 15.6 % increase in LWP in stratiform clouds in CAM5. The difference is caused by a much smaller response in LWP to a given perturbation in cloud condensation nuclei (CCN) concentrations from PI to PD in the MMF (about one-third of that in CAM5), and, to a lesser extent, by a smaller relative increase in CCN concentrations from PI to PD in the MMF (about 26 % smaller than that in CAM5). The smaller relative increase in CCN concentrations in the MMF is caused in part by a smaller increase in aerosol lifetime from PI to PD in the MMF, a positive feedback in aerosol indirect effects induced by cloud lifetime effects from aerosols. The smaller response in LWP to anthropogenic aerosols in the MMF model is consistent with observations and with high resolution model studies, which may indicate that aerosol indirect effects simulated in conventional global climate models are overestimated and point to the need to use global high resolution models, such as MMF models or global CRMs, to study aerosol indirect effects. The simulated total anthropogenic aerosol effect in the MMF is −1.05 W m−2, which is close to the Murphy et al. (2009) inverse estimate of −1.1±0.4 W m−2 (1σ) based on the examination of the Earth's energy balance. Further improvements in the representation of ice nucleation and low clouds in MMF are needed to refine the aerosol indirect effect estimate.

Photoacoustic Measurements of Amplification of the Absorption Cross Section for Coated Soot Aerosols

A quantitative understanding of the absorption and scattering properties of mixed soot and aerosol particles is necessary for evaluating the Earth's energy balance. Uncertainty in the net radiative forcing of atmospheric aerosols is relatively large and may be limited by oversimplified models that fail to predict these properties for bare and externally mixed soot particles. In this laboratory study of flame-generated soot, we combine photoacoustic spectroscopy, particle counting techniques, and differential mobility analysis to obtain high-precision measurements of the size-dependent absorption cross section of uncoated and coated soot particles. We investigate how the coating of soot by nonabsorbing films of dibutyl phthalate (chosen as a surrogate for sulfuric acid) affects the particles’ morphology and optical properties. Absorption measurements were made with photoacoustic spectroscopy using a laser at λ = 405 nm. We report measurements and model calculations of the absolute cross section, mass absor...

A new, lower value of total solar irradiance: Evidence and climate significance

[1] The most accurate value of total solar irradiance during the 2008 solar minimum period is 1360.8 ± 0.5 W m−2 according to measurements from the Total Irradiance Monitor (TIM) on NASA's Solar Radiation and Climate Experiment (SORCE) and a series of new radiometric laboratory tests. This value is significantly lower than the canonical value of 1365.4 ± 1.3 W m−2 established in the 1990s, which energy balance calculations and climate models currently use. Scattered light is a primary cause of the higher irradiance values measured by the earlier generation of solar radiometers in which the precision aperture defining the measured solar beam is located behind a larger, view-limiting aperture. In the TIM, the opposite order of these apertures precludes this spurious signal by limiting the light entering the instrument. We assess the accuracy and stability of irradiance measurements made since 1978 and the implications of instrument uncertainties and instabilities for climate research in comparison with the new TIM data. TIM's lower solar irradiance value is not a change in the Sun's output, whose variations it detects with stability comparable or superior to prior measurements; instead, its significance is in advancing the capability of monitoring solar irradiance variations on climate-relevant time scales and in improving estimates of Earth energy balance, which the Sun initiates.

On the role of the planetary boundary layer depth in the climate system

Abstract. The planetary boundary layer (PBL) is a part of the Earth's atmosphere where turbulent fluxes dominate vertical mixing and constitute an important part of the energy balance. The PBL depth, h, is recognized as an important parameter, which controls some features of the Earth's climate and the atmospheric chemical composition. It is also known that h varies by two orders of magnitude on diurnal and seasonal time scales. This brief note highlights effects of this variability on the atmospheric near-surface climate and chemical composition. We interpret heat capacity parameter of a Budyko-type energy balance model in terms of quasi-equilibrium h. The analysis shows that it is the shallowest, stably-stratified PBL with the smallest h that should be of particular concern for climate modelling. The reciprocal dependence between the PBL depth and temperature (concentrations) is discussed. In particular, the analysis suggests that the climate characteristics during stably stratified PBL episodes should be significantly more sensitive to perturbations of the Earth's energy balance as well as emission rates. On this platform, h from ERA-40 reanalysis data, the CHAMP satellite product and the DATABASE64 data were compared. DATABASE64 was used to assess the Troen-Mahrt method to determine h through available meteorological profile observations. As it has been found before, the shallow PBL requires better parameterization and better retrieval algorithms. The study demonstrated that ERA-40 and CHAMP data are biased toward deeper h in the shallow polar PBL. This, coupled with the scarcity of in-situ observations might mislead the attribution of the origins of the Arctic climate change mechanisms.

Climate Change

We've all had the experience of finding activities online or in books that, upon close examination, fell down in one or more key areas. Maybe there wasn't enough background, or it wasn't sophisticated enough, for the teachers. Maybe the activities were wrong for the intended age group, or left too many gaps in the students' instructions (or, conversely, provided instructions that left no room for creativity or thought for the students). Maybe the work was unrealistic or required equipment that's unavailable in many schools.Climate Change from Pole to Pole succeeds in all these areas. For high school and college teachers who are already using or experimenting with inquiry methods, this book provides six investigations that are mostly group-oriented and help students connect climate change with real ecological and human health impacts. If you are not already familiar with inquiry methods and facilitating group work, a couple of these investigations are well suited to get you started; the others may require more experience to implement successfully.The book's first four chapters summarize the science of climate change. Beginning with the basics of climate, these chapters cover the greenhouse effect, the methods scientists use to study climate, and the evidence pointing to both a changing climate and the influences of human and natural forcings. One chapter covers the biological effects of climate change. These chapters provide good background and useful references. Some of the latter may be difficult for high school teachers to retrieve without a convenient college library, but several online resources are cited (and the URLs worked!).One complaint: some of the figures used in these chapters are confusing, or fail to work well with their captions. For example, it's hard to distinguish stippled and nonstippled arrows on the black-and-white diagram of Earth's energy balance, and the accompanying text is unclear.Six chapters referred to as ““case studies”” compose the heart of the book. Each chapter is split in two, with comprehensive teacher pages first, followed by reproducible student pages. The teacher pages are uniformly useful, addressing necessary prior knowledge, procedures and materials, rubrics and assessment suggestions, and modifications.The activities cover a good mix of subjects: four are mainly ecological, using penguins, polar bears, wolves, and flycatchers to investigate subjects such as the timing of phenological events and the role of predators in ecosystems. The chapter on wolves and their impact on carrion supply in Yellowstone National Park introduces mathematical modeling and is quite sophisticated —— probably Advanced Placement level or above. Another chapter provides data to help students learn to distinguish correlation and cause. All the chapters involve some data analysis.The last two chapters focus on how climate change may affect human health. Students are guided to look at data involving pollen allergies and heat-related mortality. The suggested student products for these investigations are realistic and challenging: a poster, website, video or other public communication, and a research report. Students are interested and concerned about climate change. This book is a boon for teachers who want to incorporate more active, group-oriented activities into their classrooms.

Recent Energy Balance of Earth

A recently published estimate of Earth’s global warming trend is 0.63 ± 0.28 W/m2, as calculated from ocean heat content anomaly data spanning 1993-2008. This value is not representative of the recent (2003-2008) warming/cooling rate because of a “flattening” that occurred around 2001-2002. Using only 2003-2008 data from Argo floats, we find by four different algorithms that the recent trend ranges from –0.010 to –0.161 W/m2 with a typical error bar of ±0.2 W/m2. These results fail to support the existence of a frequently-cited large positive computed radiative imbalance.

A new one-dimensional simple energy balance and carbon cycle coupled model for global warming simulation

Global warming and accompanying climate change may be caused by an increase in atmospheric greenhouse gasses generated by anthropogenic activities. In order to supply such a mechanism of global warming with a quantitative underpinning, we need to understand the multifaceted roles of the Earth's energy balance and material cycles. In this study, we propose a new one-dimensional simple Earth system model. The model consists of carbon and energy balance submodels with a north–south zonal structure. The two submodels are coupled by interactive feedback processes such as CO2 fertilization of net primary production (NPP) and temperature dependencies of NPP, soil respiration, and ocean surface chemistry. The most important characteristics of the model are not only that the model requires a relatively short calculation time for carbon and energy simulation compared with a General Circulation Model (GCM) and an Earth system Model of Intermediate Complexity (EMIC), but also that the model can simulate average latitudinal variations. In order to analyze the response of the Earth system due to increasing greenhouse gasses, several simulations were conducted in one dimension from the years 1750 to 2000. Evaluating terrestrial and oceanic carbon uptake output of the model in the meridional direction through comparison with observations and satellite data, we analyzed the time variation patterns of air temperature in low- and middle-latitude belts. The model successfully reproduced the temporal variation in each latitude belt and the latitudinal distribution pattern of carbon uptake. Therefore, this model could more accurately demonstrate a difference in the latitudinal response of air temperature than existing models. As a result of the model evaluations, we concluded that this new one-dimensional simple Earth system model is a good tool for conducting global warming simulations. From future projections using various emission scenarios, we showed that the spatial distribution of terrestrial carbon uptake may vary greatly, not only among models used for climate change simulations, but also amongst emission scenarios.

Earth's energy balance since 1950

Earth's energy balance since 1950

An observationally based energy balance for the Earth since 1950

We examine the Earth's energy balance since 1950, identifying results that can be obtained without using global climate models. Important terms that can be constrained using only measurements and radiative transfer models are ocean heat content, radiative forcing by long‐lived trace gases, and radiative forcing from volcanic eruptions. We explicitly consider the emission of energy by a warming Earth by using correlations between surface temperature and satellite radiant flux data and show that this term is already quite significant. About 20% of the integrated positive forcing by greenhouse gases and solar radiation since 1950 has been radiated to space. Only about 10% of the positive forcing (about 1/3 of the net forcing) has gone into heating the Earth, almost all into the oceans. About 20% of the positive forcing has been balanced by volcanic aerosols, and the remaining 50% is mainly attributable to tropospheric aerosols. After accounting for the measured terms, the residual forcing between 1970 and 2000 due to direct and indirect forcing by aerosols as well as semidirect forcing from greenhouse gases and any unknown mechanism can be estimated as −1.1 ± 0.4 W m−2 (1σ). This is consistent with the Intergovernmental Panel on Climate Change's best estimates but rules out very large negative forcings from aerosol indirect effects. Further, the data imply an increase from the 1950s to the 1980s followed by constant or slightly declining aerosol forcing into the 1990s, consistent with estimates of trends in global sulfate emissions. An apparent increase in residual forcing in the late 1990s is discussed.