An empirical evaluation of earth’s surface air temperature response to radiative forcing, including feedback, as applied to the CO2-climate problem

1984 ◽  
Vol 34 (1-2) ◽  
pp. 1-19 ◽  
Author(s):  
S. B. Idso
Keyword(s):  
Air Temperature ◽  
Radiative Forcing ◽  
Empirical Evaluation ◽  
Temperature Response ◽  
Surface Air Temperature ◽  
Climate Problem

Timescale-dependent stability of surface air temperature and the forced temperature response

2021 ◽  
Author(s):  
Beatrice Ellerhoff ◽  
Kira Rehfeld
Keyword(s):  
Air Temperature ◽  
Radiative Forcing ◽  
Temperature Response ◽  
Surface Air Temperature ◽  
Careful Consideration ◽  
Temperature Variability ◽  
Local Temperature ◽  
Joint Power ◽  
Global And Local ◽  
Paleoclimate Data

<p><span>Earth's climate can be understood as a dynamical system that changes due to external forcing and internal couplings. It can be characterized from the evolution of essential climate variables, such as surface air temperature. Yet, the mechanisms, amplitudes, and spatiotemporal patterns of global and local temperature fluctuations around its mean, called temperature variability, are insufficiently understood. Discrepancies exist between temperature variability from model and paleoclimate data at the temporal scale of years to centuries and at the local scale, both of which are important socio-economic scales for long-term planning.</span> <br><span>Here, we clarify whether global and local temperature signals from the last millennia show a stationary variance on these timescales and thus behave in a stable manner or not. Therefore, we contrast power spectral densities and their scaling behaviors using simulated, observed, and reconstructed temperatures on periods between 10 and 200 years. Despite careful consideration of possible spectral biases, we find that local temperatures from paleoclimate data tend to show unstable behavior, while simulated temperatures almost exclusively show stable behavior. Conversely, the global mean temperature tends to be stable. We explain this by introducing the gain as a powerful tool to analyze the forced temperature response, based on a novel estimate of the joint power spectrum of radiative forcing.</span> <br><span>Our analysis identifies main deficiencies in the properties of temperature variability and offers new insights into the linkage between raditative forcing and temperature response, relevant to the understanding of Earth’s dynamics and the assessment of climate risks.</span></p>

scholarly journals Influence of radiative forcing factors on ground–air temperature coupling during the last millennium: implications for borehole climatology

2018 ◽  
Vol 14 (11) ◽  
pp. 1583-1606 ◽  
Author(s):  
Camilo Melo-Aguilar ◽  
J. Fidel González-Rouco ◽  
Elena García-Bustamante ◽  
Jorge Navarro-Montesinos ◽  
Norman Steinert
Keyword(s):  
Air Temperature ◽  
Land Surface ◽  
Radiative Forcing ◽  
Spatial Scales ◽  
Ground Surface ◽  
Surface Air Temperature ◽  
Small Variation ◽  
Last Millennium ◽  
Reconstruction Methods

Abstract. Past climate variations may be uncovered via reconstruction methods that use proxy data as predictors. Among them, borehole reconstruction is a well-established technique to recover the long-term past surface air temperature (SAT) evolution. It is based on the assumption that SAT changes are strongly coupled to ground surface temperature (GST) changes and transferred to the subsurface by thermal conduction. We evaluate the SAT–GST coupling during the last millennium (LM) using simulations from the Community Earth System Model LM Ensemble (CESM-LME). The validity of such a premise is explored by analyzing the structure of the SAT–GST covariance during the LM and also by investigating the evolution of the long-term SAT–GST relationship. The multiple and single-forcing simulations in the CESM-LME are used to analyze the SAT–GST relationship within different regions and spatial scales and to derive the influence of the different forcing factors on producing feedback mechanisms that alter the energy balance at the surface. The results indicate that SAT–GST coupling is strong at global and above multi-decadal timescales in CESM-LME, although a relatively small variation in the long-term SAT–GST relationship is also represented. However, at a global scale such variation does not significantly impact the SAT–GST coupling, at local to regional scales this relationship experiences considerable long-term changes mostly after the end of the 19th century. Land use land cover changes are the main driver for locally and regionally decoupling SAT and GST, as they modify the land surface properties such as albedo, surface roughness and hydrology, which in turn modifies the energy fluxes at the surface. Snow cover feedbacks due to the influence of other external forcing are also important for corrupting the long-term SAT–GST coupling. Our findings suggest that such local and regional SAT–GST decoupling processes may represent a source of bias for SAT reconstructions from borehole measurement, since the thermal signature imprinted in the subsurface over the affected regions is not fully representative of the long-term SAT variations.

scholarly journals Offsetting effects of aerosols on Arctic and global climate in the late 20th century

2014 ◽  
Vol 14 (8) ◽  
pp. 3969-3975 ◽  
Author(s):  
Q. Yang ◽  
C. M. Bitz ◽  
S. J. Doherty
Keyword(s):  
20Th Century ◽  
Air Temperature ◽  
Radiative Forcing ◽  
Global Climate ◽  
Surface Air Temperature ◽  
The Arctic ◽  
Late 20Th Century ◽  
Climate Effect ◽  
Climate System Model ◽  
Arctic Surface

Abstract. We examine the impacts of atmospheric aerosols on Arctic and global climate using a series of 20th century transient simulations from Community Climate System Model version 4 (CCSM4). We focus on the response of surface air temperature to the direct radiative forcing driven by changes in sulfate and black carbon (BC) concentrations from 1975 to 2005 and we also examine the response to changes in sulfate, BC, and organic carbon (OC) aerosols collectively. The direct forcing from sulfate dominates the aerosol climate effect. Globally averaged, simultaneous changes in all three aerosols produce a cooling trend of 0.015 K decade−1 during the period 1975–2005. In the Arctic, surface air temperature has large spatial variations in response to changes in aerosol concentrations. Over the European Arctic, aerosols induce about 0.6 K decade−1 warming, which is about 1.8 K warming over the 30-year period. This warming is triggered mainly by the reduction in sulfate and BC emissions over Europe since the 1970s and is reinforced by sea ice loss and a strengthening in atmospheric northward heat transport. Changes in sulfate concentrations account for about two thirds of the warming and BC for the remaining one third. Over the Siberian and North American Arctic, surface air temperature is likely influenced by changes in aerosol concentrations over Asia. An increase in sulfate optical depth over Asia induces a large cooling while an increase in BC over Asia causes a significant warming.

scholarly journals Offsetting effects of aerosols on Arctic and global climate in the late 20th century

2013 ◽  
Vol 13 (11) ◽  
pp. 30929-30943
Author(s):  
Q. Yang ◽  
C. M. Bitz ◽  
S. J. Doherty
Keyword(s):  
20Th Century ◽  
Air Temperature ◽  
Radiative Forcing ◽  
Global Climate ◽  
Surface Air Temperature ◽  
The Arctic ◽  
Late 20Th Century ◽  
Climate Effect ◽  
Climate System Model ◽  
Arctic Surface

Abstract. We examine the impacts of atmospheric aerosols on Arctic and global climate using a series of 20th century transient simulations from Community Climate System Model version 4 (CCSM4). We focus on the response of surface air temperature to the direct radiative forcing driven by changes in sulfate and black carbon (BC) concentrations from 1975 to 2005 and we also examine the response to sulfate, BC, and organic carbon aerosols varying at once. The direct forcing from sulfate dominates the aerosol climate effect. Globally averaged, all three aerosols produce a cooling trend of 0.015 K decade−1 during the period 1975–2005. In the Arctic, surface air temperature has large spatial variations in response to changes in aerosol concentrations. Over the European Arctic, aerosols induce about 0.6 K decade−1 warming which is about 1.8 K warming over the 30 yr period. This warming is triggered mainly by the reduction in sulfate and BC emissions over Europe since the 1970s and is reinforced by sea ice loss and a strengthening in atmospheric northward heat transport. Over the Siberian and North American Arctic, surface air temperature is likely influenced primarily by changes in aerosol emissions from Asia. An increase in sulfate emissions over Asia induces a large cooling while an increase in BC over Asia causes a significant warming.

scholarly journals Precipitation and temperature response to sea salt injection into low marine clouds over West Africa

2021 ◽  
Vol 3 (3) ◽  
Author(s):  
Mojisola O. Adeniyi ◽  
Blessing E. I. Bassey
Keyword(s):  
West Africa ◽  
Radiative Forcing ◽  
Negative Impact ◽  
Temperature Response ◽  
Surface Air Temperature ◽  
Sea Salt ◽  
Shortwave Radiation ◽  
Temperature Pattern ◽  
Easterly Wind ◽  
Temperature And Precipitation

AbstractSea salt injection into the tropical marine clouds is evaluated for its potentials to reduce the negative impact of the prevailing global warming over West Africa. Radiative forcing is determined as the intercept of the regression of response of radiation parameter to that of surface air temperature. The seasonal responses of temperature and precipitation to geoengineering over West Africa are analysed using temperature and precipitation outputs from IPSL-M5A-LR with three different forcing scenarios. The three scenarios are historical greenhouse gas concentrations, Representative Concentration Pathway 4.5 W/m2 scenario (RCP4.5) and combination of RCP4.5 and geoengineering forcing (sea salt climate engineering, G5). 20-year means in the middle of G5 (2045–2064) are considered for the future period, and the historical climatology from 1986 to 2005 is used. Net downward flux and top of atmosphere outgoing shortwave radiation have negative forcing only at the western Sahel. The G5 reduces the warming in the RCP4.5 scenario over the whole of West Africa. It also shifts ITCZ northward with respect to RCP4.5, thereby increasing wetness over most of the land areas. The areas with wetness response have anomalous westerly with respect to RCP 4.5 and latitudinal location below anomalous easterly wind. Results show that G5 is effective in reducing the RCP4.5 projected warming up to 1.2 K and increasing wetness over most land areas. The G5 has a damaging effect on the temperature pattern at the southern ocean and coastal areas, while it has damaging effect on precipitation patterns at some parts of the Sahel.

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