Response and feedback of land surface research priorities in the field of geoscience. The process to climate change is one of the current study paid more attention to the impacts of global change on land surface proce...Response and feedback of land surface research priorities in the field of geoscience. The process to climate change is one of the current study paid more attention to the impacts of global change on land surface process, but the feedback of land surface process to climate change has been poorly understood. It is becoming more and more meaningful under the framework of Earth system science to understand systematically the relationships between agricultural phenology dynamic and biophysical process, as well as the feedback on climate. In this paper, we summarized the research progress in this field, including the fact of agricultural phenology change, parameterization of phenology dynamic in land surface progress model, the influence of agricultural phenology dynamic on biophysical process, as well as its feedback on climate. The results showed that the agriculture phenophase, represented by the key phenological phases such as sowing, flowering and maturity, had shifted significantly due to the impacts of climate change and agronomic management. The digital expressions of land surface dynamic process, as well as the biophysical process and atmospheric process, were improved by coupling phenology dynamic in land surface model. The agricultural phenology dynamic had influenced net radiation, latent heat, sensible heat, albedo, temperature, precipitation, circulation, playing an important role in the surface energy partitioning and climate feedback. Considering the importance of agricultural phenology dynamic in land surface biophysical process and climate feedback, the following research priorities should be stressed： （1） the interactions between climate change and land surface phenology dynamic; （2） the relations between agricultural phenology dynamic and land surface reflectivity at different spectrums; （3） the contributions of crop physiology characteristic changes to land surface biophysical process; （4） the regional differences of climate feedbacks from phenology dynamic in different climate zones. This review is helpful to accelerate understanding of the role of agricultural phenology dynamic in land surface process and climate feedback.展开更多
Atmospheric carbon dioxide concentration [CO2],incoming solar radiation and sea ice coverage are among the most important factors that control the global climate.By applying the simple cell-to-cell mapping technique t...Atmospheric carbon dioxide concentration [CO2],incoming solar radiation and sea ice coverage are among the most important factors that control the global climate.By applying the simple cell-to-cell mapping technique to a simplified atmosphere-ocean-sea ice feedback climate model,effects of these factors on the stability of the climatic system are studied.The current climatic system is found to be stable but highly nonlinear.The resiliency of stability increases with [CO2] to a summit when [CO2] reaches 290 μL/L which is comparable to the pre-industrial level,suggesting carbon dioxide is essential to the stability of the global climate.With [CO2] rising further,the global climate stability decreases,the mean ocean temperature goes up and the sea ice coverage shrinks in the polar region.When the incoming solar radiation is intensified,the ice coverage gradually diminishes,but the mean ocean temperature remains relatively constant.Overall,our analysis suggests that at the current levels of three external factors the stability of global climate is highly resilient.However,there exists a possibility of extreme states of climate,such as a snow-ball earth and an ice-free earth.展开更多
Forest loss impacts local climate through biophysical processes.However,our understanding of this impact remains limited due to the neglect of its temporal dynamics.Using a space-and-time scheme that incorporates a ch...Forest loss impacts local climate through biophysical processes.However,our understanding of this impact remains limited due to the neglect of its temporal dynamics.Using a space-and-time scheme that incorporates a change-detection method,we assess the dynamics of land surface temperature(LST)responses to various forest-loss types.Globally,LST increased by 0.12 K one year after forest loss,followed by a decreasing trend of0.14 K per decade.Deforestation driven by commodity production and urbanization results in persistent warming,while forest disturbances such as shifting agriculture,forestry,and fire trigger diverse response dynamics with significant spatial variation due to differences in subsequent vegetation recovery.These disturbances cause attenuated warming in low and mid-latitudes,while,in the boreal zone,contrasting dynamics are observed:shifting agriculture causes attenuated cooling,whereas forestry and fire result in enhanced cooling.In addition to amplifying the amplitude of the LST seasonal cycle,forest loss also shifts the seasonal phase,which has not been previously reported.These findings demonstrate that climate feedback from forest loss is climate specific,loss-type dependent,and time varying,providing new insights for the development of local climate policies.展开更多
Climate sensitivity is an important index that measures the relationship between the increase in greenhouse gases and the magnitude of global warming.Uncertainties in climate change projection and climate modeling are...Climate sensitivity is an important index that measures the relationship between the increase in greenhouse gases and the magnitude of global warming.Uncertainties in climate change projection and climate modeling are mostly related to the climate sensitivity.The climate sensitivities of coupled climate models determine the magnitudes of the projected global warming.In this paper,the authors thoroughly review the literature on climate sensitivity,and discuss issues related to climate feedback processes and the methods used in estimating the equilibrium climate sensitivity and transient climate response（TCR）,including the TCR to cumulative CO2 emissions.After presenting a summary of the sources that affect the uncertainty of climate sensitivity,the impact of climate sensitivity on climate change projection is discussed by addressing the uncertainties in 2℃ warming.Challenges that call for further investigation in the research community,in particular the Chinese community,are discussed.展开更多
Monckton of Brenchley et al.(Sci Bull60:122–135, 2015)(hereafter called M15) use a simple energy balance model to estimate climate response. They select parameters for this model based on semantic arguments, leading ...Monckton of Brenchley et al.(Sci Bull60:122–135, 2015)(hereafter called M15) use a simple energy balance model to estimate climate response. They select parameters for this model based on semantic arguments, leading to different results from those obtained in physics-based studies. M15 did not validate their model against observations, but instead created synthetic test data based on subjective assumptions. We show that M15 systematically underestimate warming: since 1990, most years were warmer than their modelled upper limit. During 2000–2010, RMS error and bias are approximately 150 % and 350 % larger than for the CMIP5 median, using either the Berkeley Earth or Cowtan and Way surface temperature data. We show that this poor performance can be explained by a logical flaw in theparameter selection and that selected parameters contradict observational estimates. M15 also conclude that climate has a near-instantaneous response to forcing, implying no net energy imbalance for the Earth. This contributes to their low estimates of future warming and is falsified by Argo float measurements that show continued ocean heating and therefore a sustained energy imbalance. M15's estimates of climate response and future global warming are not consistent with measurements and so cannot be considered credible.展开更多
The atmospheric latent energy and incoming energy fluxes of the atmosphere are analyzed here based on the historical simulations of nine coupled models from the Coupled Model Intercomparison Project Phase 5 （CMIP5） ...The atmospheric latent energy and incoming energy fluxes of the atmosphere are analyzed here based on the historical simulations of nine coupled models from the Coupled Model Intercomparison Project Phase 5 （CMIP5） and two reanalysis datasets. The globally averaged atmospheric latent energy is found to be highly correlated with several types of energy flux, particularly the surface latent heat flux, atmosphere absorbed solar radiation flux, and surface net radiation flux. On the basis of these connections, a hydrological cycle controlled feedback （HCCF） is hypothesized. Through this feedback, the atmosphere absorbed solar radiation is enhanced and causes intensification of the surface latent heat flux when the atmospheric latent energy is abnormally strong. The representativeness of the HCCF during different periods and over different latitudinal zones is also discussed. Although such a feedback cannot be confirmed by reanalysis, it proves to be a common mechanism for all the models studied.展开更多
基金China Postdoctoral Science Foundation, No.2016M601115 National Natural Science Foundation of China, No.41571088, No.41371002
文摘Response and feedback of land surface research priorities in the field of geoscience. The process to climate change is one of the current study paid more attention to the impacts of global change on land surface process, but the feedback of land surface process to climate change has been poorly understood. It is becoming more and more meaningful under the framework of Earth system science to understand systematically the relationships between agricultural phenology dynamic and biophysical process, as well as the feedback on climate. In this paper, we summarized the research progress in this field, including the fact of agricultural phenology change, parameterization of phenology dynamic in land surface progress model, the influence of agricultural phenology dynamic on biophysical process, as well as its feedback on climate. The results showed that the agriculture phenophase, represented by the key phenological phases such as sowing, flowering and maturity, had shifted significantly due to the impacts of climate change and agronomic management. The digital expressions of land surface dynamic process, as well as the biophysical process and atmospheric process, were improved by coupling phenology dynamic in land surface model. The agricultural phenology dynamic had influenced net radiation, latent heat, sensible heat, albedo, temperature, precipitation, circulation, playing an important role in the surface energy partitioning and climate feedback. Considering the importance of agricultural phenology dynamic in land surface biophysical process and climate feedback, the following research priorities should be stressed： （1） the interactions between climate change and land surface phenology dynamic; （2） the relations between agricultural phenology dynamic and land surface reflectivity at different spectrums; （3） the contributions of crop physiology characteristic changes to land surface biophysical process; （4） the regional differences of climate feedbacks from phenology dynamic in different climate zones. This review is helpful to accelerate understanding of the role of agricultural phenology dynamic in land surface process and climate feedback.
基金Funded by the National Natural Science Foundation of China(No.20877105)
文摘Atmospheric carbon dioxide concentration [CO2],incoming solar radiation and sea ice coverage are among the most important factors that control the global climate.By applying the simple cell-to-cell mapping technique to a simplified atmosphere-ocean-sea ice feedback climate model,effects of these factors on the stability of the climatic system are studied.The current climatic system is found to be stable but highly nonlinear.The resiliency of stability increases with [CO2] to a summit when [CO2] reaches 290 μL/L which is comparable to the pre-industrial level,suggesting carbon dioxide is essential to the stability of the global climate.With [CO2] rising further,the global climate stability decreases,the mean ocean temperature goes up and the sea ice coverage shrinks in the polar region.When the incoming solar radiation is intensified,the ice coverage gradually diminishes,but the mean ocean temperature remains relatively constant.Overall,our analysis suggests that at the current levels of three external factors the stability of global climate is highly resilient.However,there exists a possibility of extreme states of climate,such as a snow-ball earth and an ice-free earth.
基金support from the National Natural Science Foundation of China(grant no.41921001)the China Postdoctoral Science Foundation(certificate number 2023M733812)。
文摘Forest loss impacts local climate through biophysical processes.However,our understanding of this impact remains limited due to the neglect of its temporal dynamics.Using a space-and-time scheme that incorporates a change-detection method,we assess the dynamics of land surface temperature(LST)responses to various forest-loss types.Globally,LST increased by 0.12 K one year after forest loss,followed by a decreasing trend of0.14 K per decade.Deforestation driven by commodity production and urbanization results in persistent warming,while forest disturbances such as shifting agriculture,forestry,and fire trigger diverse response dynamics with significant spatial variation due to differences in subsequent vegetation recovery.These disturbances cause attenuated warming in low and mid-latitudes,while,in the boreal zone,contrasting dynamics are observed:shifting agriculture causes attenuated cooling,whereas forestry and fire result in enhanced cooling.In addition to amplifying the amplitude of the LST seasonal cycle,forest loss also shifts the seasonal phase,which has not been previously reported.These findings demonstrate that climate feedback from forest loss is climate specific,loss-type dependent,and time varying,providing new insights for the development of local climate policies.
基金Supported by the Strategic Priority Research Program of the Chinese Academy of Sciences(XDA05110300)National Natural Science Foundation of China(41330423)
文摘Climate sensitivity is an important index that measures the relationship between the increase in greenhouse gases and the magnitude of global warming.Uncertainties in climate change projection and climate modeling are mostly related to the climate sensitivity.The climate sensitivities of coupled climate models determine the magnitudes of the projected global warming.In this paper,the authors thoroughly review the literature on climate sensitivity,and discuss issues related to climate feedback processes and the methods used in estimating the equilibrium climate sensitivity and transient climate response（TCR）,including the TCR to cumulative CO2 emissions.After presenting a summary of the sources that affect the uncertainty of climate sensitivity,the impact of climate sensitivity on climate change projection is discussed by addressing the uncertainties in 2℃ warming.Challenges that call for further investigation in the research community,in particular the Chinese community,are discussed.
文摘Monckton of Brenchley et al.(Sci Bull60:122–135, 2015)(hereafter called M15) use a simple energy balance model to estimate climate response. They select parameters for this model based on semantic arguments, leading to different results from those obtained in physics-based studies. M15 did not validate their model against observations, but instead created synthetic test data based on subjective assumptions. We show that M15 systematically underestimate warming: since 1990, most years were warmer than their modelled upper limit. During 2000–2010, RMS error and bias are approximately 150 % and 350 % larger than for the CMIP5 median, using either the Berkeley Earth or Cowtan and Way surface temperature data. We show that this poor performance can be explained by a logical flaw in theparameter selection and that selected parameters contradict observational estimates. M15 also conclude that climate has a near-instantaneous response to forcing, implying no net energy imbalance for the Earth. This contributes to their low estimates of future warming and is falsified by Argo float measurements that show continued ocean heating and therefore a sustained energy imbalance. M15's estimates of climate response and future global warming are not consistent with measurements and so cannot be considered credible.
基金Supported by the National Basic Research Program of China(2010CB950503)West Light Foundation of the Chinese Academy of Sciences to Han Bo,National Natural Science Foundation of China(41205005 and 41130961)+1 种基金100-Talent Program of the Chinese Academy of Sciences to Gao YanhongExcellent Young Scholars Fund of CAREERI(Y451251001)
文摘The atmospheric latent energy and incoming energy fluxes of the atmosphere are analyzed here based on the historical simulations of nine coupled models from the Coupled Model Intercomparison Project Phase 5 （CMIP5） and two reanalysis datasets. The globally averaged atmospheric latent energy is found to be highly correlated with several types of energy flux, particularly the surface latent heat flux, atmosphere absorbed solar radiation flux, and surface net radiation flux. On the basis of these connections, a hydrological cycle controlled feedback （HCCF） is hypothesized. Through this feedback, the atmosphere absorbed solar radiation is enhanced and causes intensification of the surface latent heat flux when the atmospheric latent energy is abnormally strong. The representativeness of the HCCF during different periods and over different latitudinal zones is also discussed. Although such a feedback cannot be confirmed by reanalysis, it proves to be a common mechanism for all the models studied.
