Abstract

Abstract. We have compiled, collected, and analyzed 31 temperature–depth profiles from boreholes in the Atacama Desert in central and northern Chile. After screening these profiles, we found that only nine profiles at four different sites were suitable to invert for ground temperature history. For all the sites, no surface temperature variations could be resolved for the period 1500–1800. In the northern coastal region of Chile, there is no perceptible temperature variation at all from 1500 to present. In the northern central Chile region, between 26 and 28∘ S, the data suggest a cooling from ≈ 1850 to ≈ 1980 followed by a 1.9 K warming starting ≈ 20–40 years BP. This result is consistent with the ground surface temperature histories for Peru and the semiarid regions of South America. The duration of the cooling trend is poorly resolved and it may coincide with a marked short cooling interval in the 1960s that is found in meteorological records. The total warming is greater than that inferred from proxy climate reconstructions for central Chile and southern South America, and by the PMIP3-CMIP5 surface temperature simulations for the north-central Chile grid points. The differences among different climate reconstructions, meteorological records, and models are likely due to differences in spatial and temporal resolution among the various data sets and the models.

Highlights

  • To assess and predict the long-term effects of the modern climate warming, it is crucial to simulate and understand Earth’s complex climate and its variability

  • In order to study the climate of northern Chile and South America of the past 500 years, we have compiled and collected borehole temperature–depth profiles, interpreted these data and determined ground surface temperature (GST) variations, and compared our results with climate reconstructions from other proxies and with climate model simulations

  • We collected and analyzed 31 temperature–depth profiles in north-central and northern Chile but only nine independent profiles were retained for inversion of the ground surface temperature history for the past 500 years

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Summary

Introduction

To assess and predict the long-term effects of the modern climate warming, it is crucial to simulate and understand Earth’s complex climate and its variability. In order to study the climate of northern Chile and South America of the past 500 years, we have compiled and collected borehole temperature–depth profiles, interpreted these data and determined ground surface temperature (GST) variations, and compared our results with climate reconstructions from other proxies and with climate model simulations. In an attempt to enlarge the South American borehole temperature data set, we have collected 31 borehole temperature–depth profiles measured in 1994, 2012, and 2015 in northern Chile, a region that was void of data, and reconstructed the GST history for the past 500 years We compare these reconstructions with meteorological data for the region, past climate inferences based on proxy data, and model simulations for central Chile and southern South America to determine climate trends for northern Chile and assess their robustness

Ground surface temperature reconstructions from borehole temperature profiles
Inversion
Simultaneous inversion
Data collection and selection
Inversion results
Comparison with other borehole temperature studies in South America
Comparison with meteorological data
Comparison with other climate proxies
Comparison with models
Conclusions
Vallenar
El Loa
Mansa Mina
Sierra Limon Verde
Copiapó
Totoral
San José de Coquimbana
Full Text
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