scholarly journals The relation between natural variations in ocean heat uptake and global mean surface temperature anomalies in CMIP5

2018 ◽  
Vol 8 (1) ◽  
Author(s):  
Sybren Drijfhout
Keyword(s):  
Surface Temperature ◽  
Ocean Heat Uptake ◽  
Temperature Anomalies ◽  
Heat Uptake ◽  
Global Mean Surface Temperature ◽  
Natural Variations ◽  
Global Mean

scholarly journals The magnitudes and timescales of global mean surface temperature feedbacks in climate models

2011 ◽  
Vol 2 (2) ◽  
pp. 213-221 ◽  
Author(s):  
A. Jarvis
Keyword(s):  
Surface Temperature ◽  
Radiative Forcing ◽  
Climate Models ◽  
Systems Approach ◽  
Deep Ocean ◽  
Ocean Heat Uptake ◽  
Positive Feedbacks ◽  
Heat Uptake ◽  
Global Mean Surface Temperature ◽  
Global Mean

Abstract. Because of the fundamental role feedbacks play in determining the response of surface temperature to perturbations in radiative forcing, it is important we understand the dynamic characteristics of these feedbacks. Rather than attribute the aggregate surface temperature feedback to particular physical processes, this paper adopts a linear systems approach to investigate the partitioning with respect to the timescale of the feedbacks regulating global mean surface temperature in climate models. The analysis reveals that there is a dominant net negative feedback realised on an annual timescale and that this is partially attenuated by a spectrum of positive feedbacks with characteristic timescales in the range 10 to 1000 yr. This attenuation was composed of two discrete phases which are attributed to the equilibration of "diffusive – mixed layer" and "circulatory – deep ocean" ocean heat uptake. The diffusive equilibration was associated with time constants on the decadal timescale and accounted for approximately 75 to 80 percent of the overall ocean heat feedback, whilst the circulatory equilibration operated on a centennial timescale and accounted for the remaining 20 to 25 percent of the response. This suggests that the dynamics of the transient ocean heat uptake feedback first discussed by Baker and Roe (2009) tends to be dominated by loss of diffusive heat uptake in climate models, rather than circulatory deep ocean heat equilibration.

scholarly journals Estimating the Effect of Radiative Feedback Uncertainties on Climate Response to Changes in the Concentration of Stratospheric Aerosols

Atmosphere ◽  
2020 ◽  
Vol 11 (6) ◽  
pp. 654
Author(s):  
Sergei Soldatenko
Keyword(s):  
Surface Temperature ◽  
Radiative Forcing ◽  
Deep Ocean ◽  
Climate System ◽  
Ocean Heat Uptake ◽  
Heat Uptake ◽  
Global Mean Surface Temperature ◽  
Radiative Feedbacks ◽  
Global Mean ◽  
System Inertia

Using the two-box energy balance model (EBM), we explore the climate system response to radiative forcing generated by variations in the concentrations of stratospheric aerosols and estimate the effect of uncertainties in radiative feedbacks on changes in global mean surface temperature anomaly used as an indicator of the response of the climate system to external radiative perturbations. Radiative forcing generated by stratospheric sulfate aerosols from the second-largest volcanic eruption in the 20th century, the Mount Pinatubo eruption in June 1991, was chosen for this research. The global mean surface temperature response to a specified change in radiative forcing is estimated as a convolution of the derived impulse response function corresponding to EBM with a function that describes the temporal change in radiative forcing. The influence of radiative feedback uncertainties on changes in the global mean surface temperature is estimated using several “versions” of the EBM. The parameters for different “versions” were identified by applying a specific procedure for calibrating the two-box EBM parameters using the results of climate change simulations conducted with coupled atmosphere–ocean general circulation models from the Coupled Model Intercomparison Project phase 5 (CMIP5). Changes in the global mean surface temperature caused by stratospheric aerosol forcing are found to be highly sensitive not only to radiative feedbacks but also to climate system inertia defined by the effective heat capacity of the atmosphere–land–ocean mixed layer system, as well as to deep-ocean heat uptake. The results obtained have direct implications for a better understanding of how uncertainties in climate feedbacks, climate system inertia and deep-ocean heat uptake affect climate change modelling.

scholarly journals Towards Reliable Probabilistic Time-Series Projections of Global Mean Surface Temperature

2021 ◽  
Author(s):  
Philip G. Sansom ◽  
Donald Cummins ◽  
Stefan Siegert ◽  
David B Stephenson
Keyword(s):  
Time Series ◽  
Global Warming ◽  
Surface Temperature ◽  
Climate Model ◽  
Future Projections ◽  
Perfect Model ◽  
Global Mean Surface Temperature ◽  
Time Series Approach ◽  
Energy Balance Models ◽  
Global Mean

Abstract Quantifying the risk of global warming exceeding critical targets such as 2.0 ◦ C requires reliable projections of uncertainty as well as best estimates of Global Mean Surface Temperature (GMST). However, uncertainty bands on GMST projections are often calculated heuristically and have several potential shortcomings. In particular, the uncertainty bands shown in IPCC plume projections of GMST are based on the distribution of GMST anomalies from climate model runs and so are strongly determined by model characteristics with little influence from observations of the real-world. Physically motivated time-series approaches are proposed based on fitting energy balance models (EBMs) to climate model outputs and observations in order to constrain future projections. It is shown that EBMs fitted to one forcing scenario will not produce reliable projections when different forcing scenarios are applied. The errors in the EBM projections can be interpreted as arising due to a discrepancy in the effective forcing felt by the model. A simple time-series approach to correcting the projections is proposed based on learning the evolution of the forcing discrepancy so that it can be projected into the future. This approach gives reliable projections of GMST when tested in a perfect model setting. When applied to observations this leads to projected warming of 2.2 ◦ C (1.7 ◦ C to 2.9 ◦ C) in 2100 compared to pre-industrial conditions, 0.4 ◦ C lower than a comparable IPCC anomaly estimate. The probability of staying below the critical 2.0 ◦ C warming target in 2100 more than doubles to 0.28 compared to only 0.11 from a comparably IPCC estimate.

scholarly journals Holocene global mean surface temperature, a multi-method reconstruction approach

2020 ◽  
Vol 7 (1) ◽  
Author(s):  
Darrell Kaufman ◽  
Nicholas McKay ◽  
Cody Routson ◽  
Michael Erb ◽  
Christoph Dätwyler ◽  
...  
Keyword(s):  
Surface Temperature ◽  
Global Mean Surface Temperature ◽  
Global Mean

scholarly journals Comparing variability and trends in observed and modelled global-mean surface temperature

2010 ◽  
Vol 37 (16) ◽  
pp. n/a-n/a ◽  
Author(s):  
John C. Fyfe ◽  
Nathan P. Gillett ◽  
David W. J. Thompson
Keyword(s):  
Surface Temperature ◽  
Global Mean Surface Temperature ◽  
Global Mean

scholarly journals Identifying Signatures of Natural Climate Variability in Time Series of Global-Mean Surface Temperature: Methodology and Insights

2009 ◽  
Vol 22 (22) ◽  
pp. 6120-6141 ◽  
Author(s):  
David W. J. Thompson ◽  
John M. Wallace ◽  
Phil D. Jones ◽  
John J. Kennedy
Keyword(s):  
Time Series ◽  
Climate Variability ◽  
Surface Temperature ◽  
High Latitude ◽  
Volcanic Eruptions ◽  
Natural Variability ◽  
Natural Climate Variability ◽  
Global Mean Surface Temperature ◽  
Natural Climate ◽  
Global Mean

Abstract Global-mean surface temperature is affected by both natural variability and anthropogenic forcing. This study is concerned with identifying and removing from global-mean temperatures the signatures of natural climate variability over the period January 1900–March 2009. A series of simple, physically based methodologies are developed and applied to isolate the climate impacts of three known sources of natural variability: the El Niño–Southern Oscillation (ENSO), variations in the advection of marine air masses over the high-latitude continents during winter, and aerosols injected into the stratosphere by explosive volcanic eruptions. After the effects of ENSO and high-latitude temperature advection are removed from the global-mean temperature record, the signatures of volcanic eruptions and changes in instrumentation become more clearly apparent. After the volcanic eruptions are subsequently filtered from the record, the residual time series reveals a nearly monotonic global warming pattern since ∼1950. The results also reveal coupling between the land and ocean areas on the interannual time scale that transcends the effects of ENSO and volcanic eruptions. Globally averaged land and ocean temperatures are most strongly correlated when ocean leads land by ∼2–3 months. These coupled fluctuations exhibit a complicated spatial signature with largest-amplitude sea surface temperature perturbations over the Atlantic Ocean.

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