A Simple Model for Glacial Cycles and Impact of fossil fuel CO2 emissions

2020 ◽  
Author(s):  
Stefanie Talento ◽  
Andrey Ganopolski
Keyword(s):  
Fossil Fuel ◽  
Climate System ◽  
Total Carbon ◽  
Anthropogenic Emissions ◽  
Orbital Forcing ◽  
Glacial Cycles ◽  
Ice Volume ◽  
Global Mean Temperature ◽  
Physically Based ◽  
Linear Differential

<p>We propose a simple physically-based model of the coupled evolution of Northern Hemisphere (NH) landmass ice-volume, atmospheric CO<sub>2</sub> concentration and global mean temperature. The model only external forcings are the orbital forcing (maximum solar insolation at 65°N) and anthropogenic CO<sub>2</sub> emissions. The model consist of a system of 3 coupled non-linear differential equations, representing physical mechanisms relevant for the evolution of the climate system in time-scales longer than thousands of years.</p><p> </p><p>When forced by the orbital forcing only, the model is successful in reproducing the natural glacial-interglacial cycles of the last 800kyr, in agreement with paleorecords and simulations performed with the CLIMBER-2 Earth System Model of intermediate complexity. The model is successful in reproducing both the timing and amplitude of the glacial-interglacial variations, producing a correlation with paleodata of 0.75 in terms of NH ice-volume.</p><p> </p><p>For the next million years, we analyse the model results under different scenarios: the natural scenario (in which only orbital forcing is applied) and scenarios in which various magnitudes of fossil fuel CO<sub>2</sub> emissions are considered (in addition to the orbital forcing).</p><p> </p><p>When anthropogenic emissions are included the model shows that even fairly low CO<sub>2</sub> anthropogenic emissions (100 Pg or larger) are capable of affecting the next glacial inception, expected to occur in 120kyr from now, delaying large NH ice formation by 50kyr. Considering total carbon releases ranging between 1000 and 5000 Pg (a reasonable expectation of fossil fuel CO<sub>2</sub> emissions to occur in the next few hundred years) the temporal evolution of the climate system could be significantly different from the natural progression. Emissions larger than 3000 Pg could have long-lasting effects, being natural conditions not resumed even after 1 Million years have passed. In addition, emissions larger than 4000 Pg prevent glacial cycles in the next half million years.</p>

Evolution of the climate in the next million years: A reduced-complexity model for glacial cycles and impact of fossil fuel CO2

2021 ◽  
Author(s):  
Stefanie Talento ◽  
Andrey Ganopolski
Keyword(s):  
High Probability ◽  
Fossil Fuel ◽  
Natural Occurrence ◽  
Glacial Cycles ◽  
Ice Volume ◽  
Cycle System ◽  
Global Mean Temperature ◽  
Global Ice Volume ◽  
Reduced Complexity ◽  
Linear Differential

<p>We propose a reduced-complexity process-based model for the long-term evolution of the global ice volume, atmospheric CO<sub>2</sub> concentration and global mean temperature. The model only external forcings are the orbital forcing and anthropogenic CO<sub>2</sub> cumulative emissions. The model consists of a system of three coupled non-linear differential equations, representing physical mechanisms relevant for the evolution of the climate – ice sheets – Carbon cycle system in timescales longer than thousands of years. The model is successful in reproducing the glacial-interglacial fluctuations of the last 800 kyr, in good agreement with paleorecords both in terms of timing and amplitude, with a correlation between modelled and paleo global ice volume of up to 0.86.</p><p>Using different model realisations, we generate a probabilistic forecast of the evolution of the Earth system over the next 1 million years under natural and several fossil-fuel CO<sub>2</sub> release scenarios. In the natural scenario, the model assigns high probability of occurrence of long interglacials in the periods between present and 50 kyr after present, and between 400 kyr and 500 kyr after present. The next full glacial conditions are most likely to occur 90 kyr after present. The model shows that even already achieved cumulative CO<sub>2</sub> anthropogenic emissions (500 PgC) are capable of affecting the climate evolution for up to half million years, indicating that the beginning of the next glaciation is highly unlikely in the next 150 kyr. If cumulative fossil-fuel CO<sub>2</sub> emissions reach 3000 PgC, or higher, the model predicts with high probability ice-free Northern Hemisphere landmass conditions will prevail in the next half million years, postponing the natural occurrence of the next glacial inception to 600 kyr after present.</p>

Glaciation cycle models and their pullback attractors

2021 ◽  
Author(s):  
Keno Riechers ◽  
Niklas Boers ◽  
Michael Ghil ◽  
Takahito Mitsui
Keyword(s):  
Explanatory Power ◽  
Power Spectra ◽  
Climate System ◽  
Sustained Oscillation ◽  
Orbital Forcing ◽  
Pullback Attractors ◽  
Glacial Cycles ◽  
Ice Volume ◽  
The Earth ◽  
Dynamic Stochastic

<p><span>The Pleistocene climate was dominated by alternating retreat and regrowth of massive ice sheets accompanied by large variations in the global mean temperature and sea level. Partial agreement between the power spectra of global ice volume proxies and high-latitude summer insolation provides evidence that quasi-periodic changes in the earth’s orbital configuration affect the timing of glaciations and deglaciations. It remains, however, a topic of active debate whether the main cause of glacial cycles is an internal self-sustained oscillation of the climate system that merely phased locked, more or less, to orbital forcing or whether glacial cycles could not exist at all in the absence of orbital forcing. Furthermore, it is unclear whether past ice volume records should be regarded as the result of a purely deterministic process or as a randomly selected trajectory of a stochastic process. To study plausible paths of the earth’s climate system given the orbital forcing, we compute the pullback attractors of several conceptual Pleistocene models. The results are confronted with the power spectra, as well as the time series of proxy records and conclusions will be drawn about the role of internal vs. forced variability and the possible contribution of stochastic processes to the mix of causes. We argue, moreover, that the explanatory power of either a deterministically chaotic or a dynamic-stochastic model cannot be assessed by comparing the model output to observations in the time domain alone.</span></p>

scholarly journals The role of orbital forcing, carbon dioxide and regolith in 100 kyr glacial cycles

2011 ◽  
Vol 7 (4) ◽  
pp. 2391-2411 ◽  
Author(s):  
A. Ganopolski ◽  
R. Calov
Keyword(s):  
Nonlinear Response ◽  
Co2 Concentration ◽  
Orbital Forcing ◽  
Orbital Eccentricity ◽  
Glacial Cycles ◽  
Strongly Nonlinear ◽  
Ice Volume ◽  
The North ◽  
Continental Area

Abstract. The origin of the 100 kyr cyclicity which dominates ice volume variations and other climate records over the past million years remains debatable. Here, using a comprehensive Earth system model of intermediate complexity, we demonstrate that both strong 100 kyr periodicity in the ice volume variations and the timing of glacial terminations during past 800 kyr can be successfully simulated as the direct, strongly nonlinear response of the climate-cryosphere system to the orbital forcing alone, if the atmospheric CO2 concentration stays below its typical interglacial value. The existence of long glacial cycles is primarily attributed to the North American ice sheet and requires presence of a large continental area with exposed rocks. We show that the sharp peak in the power spectrum of ice volume at 100 kyr period results from the long glacial cycles being synchronized with the Earth's orbital eccentricity. Although 100 kyr cyclicity can be simulated with a constant CO2 concentration, temporal variability in the CO2 concentration plays an important role in the amplification of the 100 kyr cycles.

scholarly journals A theory of glacial cycles: resolving Pleistocene puzzles

2021 ◽  
Author(s):  
Hsien-Wang Ou
Keyword(s):  
Freezing Point ◽  
Surface Air Temperature ◽  
Climate System ◽  
Ice Age ◽  
Early Pleistocene ◽  
Polar Ice ◽  
Glacial Cycles ◽  
Convective Flux ◽  
Ice Volume ◽  
Ice Cap

Abstract. Since the summer surface air temperature that regulates the ice margin is anchored on the sea surface temperature, we posit that the climate system constitutes the intermediary of the orbital forcing of the glacial cycles. As such, the relevant forcing is the annual solar flux absorbed by the ocean, which naturally filters out the precession effect in early Pleistocene but mimics the Milankovitch insolation in late Pleistocene. For a coupled climate system that is inherent turbulent, we show that the ocean may be bistable with a cold state defined by the freezing point subpolar water, which would translate to ice bistates between a polar ice cap and an ice sheet extending to mid-latitudes, enabling large ice-volume signal regardless the forcing amplitude so long as the bistable thresholds are crossed. Such thresholds are set by the global convective flux, which would be lowered during the Pleistocene cooling, whose interplay with the ice-albedo feedback leads to transitions of the ice signal from that dominated by obliquity to the emerging precession cycles to the ice-age cycles paced by eccentricity. Through a single dynamical framework, the theory thus may resolve many long-standing puzzles of the glacial cycles.

scholarly journals Late Quaternary vegetation-climate feedbacks

2009 ◽  
Vol 5 (2) ◽  
pp. 203-216 ◽  
Author(s):  
M. Claussen*
Keyword(s):  
Late Quaternary ◽  
Climate System ◽  
Climate Feedbacks ◽  
Glacial Cycles ◽  
Temperature Changes ◽  
Albedo Feedback ◽  
Global Mean Temperature ◽  
Mean Temperature ◽  
Biogeophysical Feedbacks ◽  
Global Mean

Abstract. Feedbacks between vegetation and other components of the climate system are discussed with respect to their influence on climate dynamics during the late Quaternary, i.e., the last glacial-interglacial cycles. When weighting current understanding based on interpretation of palaeobotanic and palaeoclimatic evidence by numerical climate system models, a number of arguments speak in favour of vegetation dynamics being an amplifier of orbital forcing. (a) The vegetation-snow albedo feedback in synergy with the sea-ice albedo feedback tends to amplify Northern Hemisphere and global mean temperature changes. (b) Variations in the extent of the largest desert on Earth, the Sahara, appear to be amplified by biogeophysical feedback. (c) Biogeochemical feedbacks in the climate system in relation to vegetation migration are supposed to be negative on time scales of glacial cycles. However, with respect to changes in global mean temperature, they are presumably weaker than the positive biogeophysical feedbacks.

scholarly journals The role of orbital forcing, carbon dioxide and regolith in 100 kyr glacial cycles

2011 ◽  
Vol 7 (4) ◽  
pp. 1415-1425 ◽  
Author(s):  
A. Ganopolski ◽  
R. Calov
Keyword(s):  
Co2 Concentration ◽  
Orbital Forcing ◽  
Orbital Eccentricity ◽  
Glacial Cycles ◽  
Strongly Nonlinear ◽  
Ice Volume ◽  
The North ◽  
Nonlinear Responses ◽  
Continental Area

Abstract. The origin of the 100 kyr cyclicity, which dominates ice volume variations and other climate records over the past million years, remains debatable. Here, using a comprehensive Earth system model of intermediate complexity, we demonstrate that both strong 100 kyr periodicity in the ice volume variations and the timing of glacial terminations during past 800 kyr can be successfully simulated as direct, strongly nonlinear responses of the climate-cryosphere system to orbital forcing alone, if the atmospheric CO2 concentration stays below its typical interglacial value. The existence of long glacial cycles is primarily attributed to the North American ice sheet and requires the presence of a large continental area with exposed rocks. We show that the sharp, 100 kyr peak in the power spectrum of ice volume results from the long glacial cycles being synchronized with the Earth's orbital eccentricity. Although 100 kyr cyclicity can be simulated with a constant CO2 concentration, temporal variability in the CO2 concentration plays an important role in the amplification of the 100 kyr cycles.

scholarly journals Late Quaternary vegetation – climate feedbacks*

2009 ◽  
Vol 5 (1) ◽  
pp. 635-670 ◽  
Author(s):  
M. Claussen
Keyword(s):  
Late Quaternary ◽  
Climate System ◽  
Climate Feedbacks ◽  
Glacial Cycles ◽  
Temperature Changes ◽  
Albedo Feedback ◽  
Global Mean Temperature ◽  
Mean Temperature ◽  
Biogeophysical Feedbacks ◽  
Global Mean

Abstract. Feedbacks between vegetation and other components of the climate system are discussed with respect to their influence on climate dynamics during the late Quaternary, i.e., the last glacial – interglacial cycles. When weighting current understanding based on interpretation of palaeobotanic and palaeoclimatic evidence by numerical climate system models, a number of arguments speak in favour of vegetation dynamics being an amplifier of orbital forcing. (a) The vegetation – snow albedo feedback in synergy with the sea ice – albedo feedback tends to amplify Northern Hemisphere and global mean temperature changes. (b) Variations in the extent of the largest desert on Earth, the Sahara, appear to be amplified by biogeophysical feedback. (c) Biogeochemical feedbacks in the climate system in relation to vegetation migration are supposed to be negative on time scales of glacial cycles. However, with respect to changes in global mean temperature, they are presumably weaker than the positive biogeophysical feedbacks.

scholarly journals Evolution of the climate in the next million years: A reduced-complexity model for glacial cycles and impact of anthropogenic CO<sub>2</sub> emissions

2021 ◽  
Author(s):  
Stefanie Talento ◽  
Andrey Ganopolski
Keyword(s):  
Fossil Fuels ◽  
Co2 Concentration ◽  
Natural Occurrence ◽  
Ice Volume ◽  
Cycle System ◽  
Global Mean Temperature ◽  
Global Ice Volume ◽  
Anthropogenic Co2 ◽  
Reduced Complexity ◽  
Linear Differential

Abstract. We propose a reduced-complexity process-based model for the long-term evolution of the global ice volume, atmospheric CO2 concentration and global mean temperature. The model only external forcings are the orbital forcing and anthropogenic CO2 cumulative emissions. The model consists of a system of three coupled non-linear differential equations, representing physical mechanisms relevant for the evolution of the Climate – Ice Sheets – Carbon cycle System in timescales longer than thousands of years. The model is successful in reproducing the glacial-interglacial cycles of the last 800 kyr, in good agreement with the timing and amplitude of paleorecord fluctuations, with the best correlation between modelled and paleo global ice volume of 0.86. Using different model realisations, we produce a probabilistic forecast of the evolution of the Earth system over the next 1 million years under natural and several fossil-fuel CO2 release scenarios. In the natural scenario, the model assigns high probability of occurrence of long interglacials in the periods between present and 120 kyr after present, and between 400 kyr and 500 kyr after present. The next glacial inception is most likely to occur ~ 50 kyr after present with full glacial conditions developing ~ 90 kyr after present. The model shows that even already achieved cumulative CO2 anthropogenic emissions (500 PgC) are capable of affecting climate evolution for up to half million years, indicating that the beginning of the next glaciation is highly unlikely in the next 120 kyr. High cumulative anthropogenic CO2 emissions (3000 PgC or higher), which could potentially be achieved in the next two to three centuries if humanity does not curb the usage of fossil-fuels, will most likely provoke Northern Hemisphere landmass ice-free conditions throughout the next half million years, postponing the natural occurrence of the next glacial inception to 600 kyr after present or later.

Emergence of critical climate states during the Pleistocene

2021 ◽  
Author(s):  
Nicholas Golledge
Keyword(s):  
Dynamical Systems ◽  
Late Pleistocene ◽  
Dominant Frequency ◽  
Climate System ◽  
Ice Age ◽  
Early Pleistocene ◽  
Glacial Cycles ◽  
Pleistocene Climate ◽  
System Nodes ◽  
Systems Framework

&lt;p&gt;During the Pleistocene (approximately 2.6 Ma to present) glacial to interglacial climate variability evolved from dominantly 40 kyr cyclicity (Early Pleistocene) to 100 kyr cyclicity (Late Pleistocene to present). Three aspects of this period remain poorly understood: Why did the dominant frequency of climate oscillation change, given that no major changes in orbital forcing occurred? Why are the longer glacial cycles of the Late Pleistocene characterised by a more asymmetric form with abrupt terminations? And how can the Late Pleistocene climate be controlled by 100 kyr cyclicity when astronomical forcings of this frequency are so much weaker than those operating on shorter periods? Here we show that the decreasing frequency and increasing asymmetry that characterise Late Pleistocene ice age cycles both emerge naturally in dynamical systems in response to increasing system complexity, with collapse events (terminations) occuring only once a critical state has been reached. Using insights from network theory we propose that evolution to a state of criticality involves progressive coupling between climate system 'nodes', which ultimately allows any component of the climate system to trigger a globally synchronous termination. We propose that the climate state is synchronised at the 100 kyr frequency, rather than at shorter periods, because eccentricity-driven insolation variability controls mean temperature change globally, whereas shorter-period astronomical forcings only affect the spatial pattern of thermal forcing and thus do not favour global synchronisation. This dynamical systems framework extends and complements existing theories by accomodating the differing mechanistic interpretations of previous studies without conflict.&lt;/p&gt;

scholarly journals Exploring precipitation pattern scaling methodologies and robustness among CMIP5 models

2016 ◽  
Author(s):  
Ben Kravitz ◽  
Cary Lynch ◽  
Corinne Hartin ◽  
Ben Bond-Lamberty
Keyword(s):  
Root Mean Square ◽  
Climate Model ◽  
Cmip5 Models ◽  
Future Climate Change ◽  
Precipitation Pattern ◽  
Mean Square ◽  
Global Mean Temperature ◽  
Physically Based ◽  
Difference Methods ◽  
Time Invariant

Abstract. Pattern scaling is a well established method for approximating modeled spatial distributions of changes in temperature by assuming a time-invariant pattern that scales with changes in global mean temperature. We compare three methods of pattern scaling for precipitation (regression, epoch difference, and a physically-based method) and evaluate which methods are “better” in particular circumstances by quantifying their robustness to interpolation/extrapolation, inter-model variations, and inter-scenario variations. Although the regression and epoch difference methods (the two most commonly used methods of pattern scaling) have better absolute performance in reconstructing the climate model output by two orders of magnitude (measured as an area-weighted root mean square error), the physically-based method shows a greater degree of robustness (less relative root-mean-square variation than the other two methods) and could be a particularly advantageous method if outstanding biases could be reduced. We decompose the precipitation response in the RCP8.5 scenario into a CO2 portion and a non-CO2 portion; these two patterns oppose each other in sign. Due to low signal-to-noise ratios, extrapolating RCP8.5 patterns to re- construct precipitation change in the RCP2.6 scenario results in double the error of reconstructing the RCP8.5 scenario for the regression and epoch difference methods. The methodologies discussed in this paper can help provide precipitation fields for other models (including integrated assessment models or impacts assessment models) for a wide variety of scenarios of future climate change.

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