Kerry Gallagher’s research while affiliated with University of Rennes 2 and other places

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Publications (1)

Sampling density of the 1012 borehole temperature profiles on the 5° × 5° grid and a comparison of the profile top depth against measurement date across six sub‐regions.
Schematic of the hierarchical model. The key model parameters in each gridcell are the basal heat flux and pre‐reconstruction surface temperature (Tpre), the surface temperature history (T), the prior information width (σp) and the observational noise (σl), all of which are jointly estimated from the data.
Observed and reconstructed temperature variations for (a) the Northern hemisphere (0°–70°N) and (b) the Southern hemisphere (0°–45°S) relative to the late twentieth century mean. The geothermal posterior mean (thick blue) and 95% confidence intervals (thin blue) and a second case where the a priori model includes a global historical era warming of 1°C. Observed land station temperature (I. Harris et al., 2014) filtered with a 20‐year moving window (CRU: black). Multi‐proxy terrestrial temperature reconstructions (Neukom et al., 2019; PAGES2k Consortium, 2017), mean: thin gray lines, green shading: 10%–90% uncertainty limits. Hemispheric‐mean geothermal reconstruction digitized from Huang et al. (2000) (dashed gray). (c and d) The latitudinally averaged warming signal (1955–1980 minus 1500–1550) inferred from the geothermal data. (e) Posterior mean temperature change CE 1950–1980 minus 1500–1550. (f) Posterior 1σ uncertainty on the temperature change CE 1950–1980 minus 1500–1550.
As in Figure 3 but for areas between 30° and 70°N only. The peak temperature anomaly in the posterior mean is 1.9 K.
Global Variability in Multi‐Century Ground Warming Inferred From Geothermal Data
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June 2023

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3 Citations

Peter O. Hopcroft

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Kerry Gallagher

Plain Language Summary Understanding past climate is invaluable for evaluating the natural context of man‐made warming. Long term surface‐air temperature records only exist at a few locations. To reconstruct global trends further back in time proxies must then be used. Measurements from such systems are then calibrated against observed climate variations. Temperatures measured in the ground can provide more direct information on past variations because sustained trends at the surface drive thermal perturbations that penetrate into the subsurface and which can be measured today. These geothermal data have the advantage that they do not require calibration and so are independent of meteorological observations. However, recovering the climate signal is not trivial. For this reason we developed a new statistical approach to infer past temperature variations from a database of 1012 temperature‐depth profiles distributed near‐globally. The results show excellent agreement with observed temperatures and also demonstrate improved agreement with proxy‐based records. One exception is noted over equatorial regions in the northern hemisphere where a potential influence of historical land‐use may be significant.

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Citations (1)

... rj-McMC algorithms find their primary application in seismological studies [Bodin et al., 2012;Poggiali et al., 2019;Zhao et al., 2022], but our results demonstrate that this technique can be successfully used to invert paleoclimate time series. Previous studies used rj-McMC algorithms for paleoclimatic reconstructions (e.g., Hopcroft et al., 2009, andGallagher, 2023), but their analysis encompasses the last millennium, and their forward model does not include a T-CO 2 dependence. Cox and Brenhin Keller (2023) prove an interesting application of Bayesian inversion of a CO 2 time series at Cretaceous-Paleogene Boundary (K-Pg). ...

Reference:

A reversible-jump Markov chain Monte Carlo algorithm to estimate paleo surface CO2 fluxes linking temperature to atmospheric CO2 concentration time series
Global Variability in Multi‐Century Ground Warming Inferred From Geothermal Data
Peter O. Hopcroft

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Kerry Gallagher