Using palaeo-climate comparisons to constrain future projections in CMIP5

Schmidt, Gavin A.; Annan, J. D.; Bartlein, Patrick J.; Cook, Benjamin I.; Guilyardi, Éric; Hargreaves, J. C.; Harrison, Sandy P.; Kageyama, Masa; LeGrande, Allegra N.; Konecky, B. L.; Lovejoy, S.; Mann, Michael; Masson‐Delmotte, Valérie; Risi, Camille; Thompson, D. M.; Timmermann, Axel; Tremblay, L. Bruno; Yiou, Pascal

doi:10.5194/cp-10-221-2014

Cited by 223 publications

(241 citation statements)

References 147 publications

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“…Furthermore, in our approach we include changes in land ice sheet (albedo forcing or R [LI] ), while Yin and Berger (2012) There exist some intrinsic uncertainties in our approach based on the underlying data sets, which are not included in the Monte Carlo statistic. For example, the global temperature anomaly in the LGM still disagrees in various approaches (Annan and Hargreaves, 2013;Schmittner et al, 2011;Schmidt et al, 2014), and Pliocene sea level and ice-sheet dynamics are still a matter of debate (Rohling et al, 2014;Dolan et al, 2015;Koenig et al, 2015;Rovere et al, 2014;de Boer et al, 2015). Taking these issues into account might lead to changes in our quantitative estimates but not necessarily to a revision of our main finding of state dependency in S [CO 2 ,LI] .…”

Section: Martínezmentioning

confidence: 61%

“…If we take into consideration that the MARGO (Multiproxy Approach for the Reconstruction of the Glacial Ocean surface) sea surface temperature (SST) data underlying this LGM temperature estimate (Annan and Hargreaves, 2013) are potentially biased towards tropical SSTs that are too warm (Schmidt et al, 2014), the PMIP3 results are a good representation of LGM climate. For both choices of f pa (varying linearly as a function of T NH or as step function over time), the global temperature change at the LGM obtained in our reconstruction is T g = −5.7 ± 0.6 K, so slightly colder than other approaches but overlapping with the PMIP3-based results within the uncertainties.…”

Section: Global Temperature Change ∆T Gmentioning

confidence: 99%

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On the state dependency of the equilibrium climate sensitivity during the last 5 million years

et al. 2015

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Abstract.It is still an open question how equilibrium warming in response to increasing radiative forcing -the specific equilibrium climate sensitivity S -depends on background climate. We here present palaeodata-based evidence on the state dependency of S, by using CO 2 proxy data together with a 3-D ice-sheet-model-based reconstruction of land ice albedo over the last 5 million years (Myr). We find that the land ice albedo forcing depends non-linearly on the background climate, while any non-linearity of CO 2 radiative forcing depends on the CO 2 data set used. This nonlinearity has not, so far, been accounted for in similar approaches due to previously more simplistic approximations, in which land ice albedo radiative forcing was a linear function of sea level change. The latitudinal dependency of icesheet area changes is important for the non-linearity between land ice albedo and sea level. In our set-up, in which the radiative forcing of CO 2 and of the land ice albedo (LI) is combined, we find a state dependence in the calculated specific equilibrium climate sensitivity, S [CO 2 ,LI] , for most of the Pleistocene (last 2.1 Myr). During Pleistocene intermediate glaciated climates and interglacial periods, S [CO 2 ,LI] is on average ∼ 45 % larger than during Pleistocene full glacial conditions. In the Pliocene part of our analysis (2.6-5 Myr BP) the CO 2 data uncertainties prevent a well-supported calculation for S [CO 2 ,LI] , but our analysis suggests that during times without a large land ice area in the Northern Hemisphere (e.g. before 2.82 Myr BP), the specific equilibrium climate sensitivity, S [CO 2 ,LI] , was smaller than during interglacials of the Pleistocene. We thus find support for a previously proposed state change in the climate system with the widespread appearance of northern hemispheric ice sheets. This study points for the first time to a so far overlooked non-linearity in the land ice albedo radiative forcing, which is important for similar palaeodata-based approaches to calculate climate sensitivity. However, the implications of this study for a suggested warming under CO 2 doubling are not yet entirely clear since the details of necessary corrections for other slow feedbacks are not fully known and the uncertainties that exist in the ice-sheet simulations and global temperature reconstructions are large.

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Section: Martínezmentioning

confidence: 61%

Section: Global Temperature Change ∆T Gmentioning

confidence: 99%

On the state dependency of the equilibrium climate sensitivity during the last 5 million years

et al. 2015

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“…Benchmarking using modern observations does not provide an assessment of whether model performance is likely to be realistic under radically different climate conditions. The climate-modelling community use records of the preobservational era to assess how well models simulate climates significantly different from the present (Braconnot et al, 2012;Flato et al, 2014;Harrison et al, 2014Harrison et al, , 2015Schmidt et al, 2014). FireMIP will extend this approach to the evaluation of fire-enabled vegetation models, building on the work of Brücher et al (2014).…”

Section: Carbon Combustibilitymentioning

confidence: 99%

The status and challenge of global fire modelling

et al. 2016

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Abstract. Biomass burning impacts vegetation dynamics, biogeochemical cycling, atmospheric chemistry, and climate, with sometimes deleterious socio-economic impacts. Under future climate projections it is often expected that the risk of wildfires will increase. Our ability to predict the magnitude and geographic pattern of future fire impacts rests on our ability to model fire regimes, using either well-founded empirical relationships or process-based models with good predictive skill. While a large variety of models exist today, it is still unclear which type of model or degree of complexity is required to model fire adequately at regional to global scales. This is the central question underpinning the creation of the Fire Model Intercomparison Project (FireMIP), an international initiative to compare and evaluate existing global fire models against benchmark data sets for present-day and historical conditions. In this paper we review how fires have been represented in fire-enabled dynamic global vegetation models (DGVMs) and give an overview of the current state of the art in fire-regime modelling. We indicate which challenges still remain in global fire modelling and stress the need for a comprehensive model evaluation and outline what lessons may be learned from FireMIP.

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“…One event in particular has been touted as a geological analogue for greenhouse gas-driven global warming: the Paleocene-Eocene Thermal Maximum (PETM, ∼ 56 Ma). This event was a short-lived (∼ 220 kyr) perturbation to the climate and carbon cycle in which global temperatures rose by 4-5 • C within a few thousand years (Sluijs et al, 2007;McInerney and Wing, 2011;Dunkley Jones et al, 2013;Schmidt, 2014), with warming of up to 8 • C in higher latitudes and some coastal settings (Thomas et al, 2002;Sluijs et al, , 2011Zachos et al, 2006;Hollis et al, 2012;Frieling et al, 2014). Multiple lines of evidence suggest that this warming may have been driven by a rapid injection of greenhouse gases, possibly sourced from submarine gas hydrates, as evidenced by coupled negative excursions in oxygen and carbon isotopes (Dickens et al, 1995(Dickens et al, , 1997.…”

Section: Introductionmentioning

confidence: 99%

The Paleocene–Eocene Thermal Maximum at DSDP Site 277, Campbell Plateau, southern Pacific Ocean

et al. 2015

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Abstract. Re-examination of sediment cores from Deep Sea Drilling Project (DSDP) Site 277 on the western margin of the Campbell Plateau (paleolatitude of ∼ 65 • S) has identified an intact Paleocene-Eocene (P-E) boundary overlain by a 34 cm thick record of the Paleocene-Eocene Thermal Maximum (PETM) within nannofossil chalk. The upper part of the PETM is truncated, either due to drilling disturbance or a sedimentary hiatus. An intact record of the onset of the PETM is indicated by a gradual decrease in δ 13 C values over 20 cm, followed by a 14 cm interval in which δ 13 C is 2 ‰ lighter than uppermost Paleocene values. After accounting for effects of diagenetic alteration, we use δ 18 O and Mg / Ca values from foraminiferal tests to determine that intermediate and surface waters warmed by ∼ 5-6 • at the onset of the PETM prior to the full development of the negative δ 13 C excursion. After this initial warming, sea temperatures were relatively stable through the PETM but declined abruptly across the horizon that truncates the event at this site. Mg / Ca analysis of foraminiferal tests indicates peak intermediate and surface water temperatures of ∼ 19 and ∼ 32 • C, respectively. These temperatures may be influenced by residual diagenetic factors and changes in ocean circulation, and surface water values may also be biased towards warm-season temperatures.

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Using palaeo-climate comparisons to constrain future projections in CMIP5

Cited by 223 publications

References 147 publications

On the state dependency of the equilibrium climate sensitivity during the last 5 million years

On the state dependency of the equilibrium climate sensitivity during the last 5 million years

The status and challenge of global fire modelling

The Paleocene–Eocene Thermal Maximum at DSDP Site 277, Campbell Plateau, southern Pacific Ocean

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