DOI: 10.5061/dryad.r4xgxd2kg
title: Data from: More intermittent mid-latitude precipitation accompanied extreme early Paleogene warmth

description: Warming is pushing the Earth system toward unfamiliar climate conditions,
 complicating predictions. Geological archives of past greenhouse climates
 provide essential tests for models under extreme forcing. We investigate
 how precipitation responded to extreme warmth during early Paleogene
 global warming events (66–47.8 million years ago) – a period considered a
 possible analogue for worst-case future scenarios. Here we compile global
 paleoclimate data and develop a multi-proxy approach that integrates
 sedimentary proxies - such as plant fossils, ancient soils and river
 deposits - providing constraints on global precipitation intermittency
 (seasonal and inter-annual variability) and intensity (rainfall rate). The
 data reveal wet or monsoonal polar regions, and aridity punctuated by
 intense rainfall at mid- and low-latitude continental interiors. This
 hydroclimate shift occurred 3 million years before and persisted 7 million
 years after the Paleocene-Eocene Thermal Maximum – the warmest period of
 the Cenozoic Era, suggesting that extreme warmth induces non-linearities
 in the hydrological cycle’s sensitivity to temperature increase. Polar
 humidity and mid-latitude aridity further indicate a departure from the
 expected wet-gets-wetter and dry-gets-drier response. Shifts towards
 aridity were decoupled from mean annual precipitation and driven by
 seasonal and interannual precipitation distribution, such as shorter wet
 season length and longer interannual rainfall recurrence interval. This
 highlights the importance of considering precipitation intermittency and
 intensity, as similar shifts may occur under future warming despite
 differences in boundary conditions.
description: This dataset was collected by compiling published literature on
 terrestrial temperature and precipitation during the Early Paleogene
 (66-47.8 Ma). Mean annual precipitation (MAP), mean annual temperature
 (MAT), and qualitative precipitation intermittency  and intensity values
 were used to assign a climate type with a distinct range of MAP and MAT
 values. Where quantitative information was not available, qualitative
 proxies were assigned a range of potential MAT and MAP values based on
 comparison to modern environments. For a more detailed explanation of the
 methods, please see the published article's supplementary
 information. 
description: # Data from: More intermittent mid-latitude precipitation accompanied
 extreme early Paleogene warmth
 [https://doi.org/10.5061/dryad.r4xgxd2kg](https://doi.org/10.5061/dryad.r4xgxd2kg) This dataset is composed of terrestrial climate proxy records compiled from published literature. The proxy sites are global and span 66-47.8 million years ago with the following variables: 1. Mean annual precipitation (MAP) in millimeters per year 2. Mean annual temperature (MAT) in degrees celsius 3. Qualitative precipitation intermittency, precipitation intensity, and temperature seasonality 4. Precipitation and temperature proxies used 5. Climate type 6. Uncertainty value from 1-5 7. Geochronology method 8. Temperature and precipitation sources 9. DeepMIP model ensemble mean annual precipitation (MAP) in millimeters per year 10. DeepMIP model ensemble mean annual temperature (MAT) in celsius 11. DeepMIP climate type The proxy locations were assigned a climate type with a distinct range of MAP and MAT values based on the data which was originally compiled from published literature. Climate types are given using acronyms described in the manuscript and included in the "Definition Tables" sheet of the SupplementalData1.xls spreadsheet. The original data sources are also included in the "Temperature source" and "Precipitation source" columns. Paleolatitude and paleolongitude were calculated in QGIS after their location was reconstructed based on the Matthews et al., 2016 gplates dataset with the "Modern latitude" and "Modern longitude" values as their starting point at 0 Ma. Modern latitude and longitude were taken from publications where available. Where they were not available, Google Earth was used to extract representative coordinates. The geochronology method was recorded from the associated publication. Uncertainty values were assigned based on quantitative proxy uncertainty where available, and a qualitative assessment based on expert opinion where a quantitative measure was not available. 1 is the most certain and 5 is the least certain, indicating a higher likelihood of the study site having a different climate type than that which was assigned. Precipitation intermittency was estimated qualitatively from low to high based on the proxy data and original authors' interpretations. For the purpose of a model-data comparison, precipitation and temperature data were extracted from the Steinig et al. 2024 web application which provides access to the DeepMIP Eocene climate model ensemble across a range of carbon dioxide concentrations. The data was originally in mm/day and was converted to mm/yr or mm/month depending on the column. Precipitation intermittency was calculated using the monsoon precipitation index (MPI). Similar to the proxy data, the MAP, MAT, and precipitation were used to assign a model climate type, which was compared to the proxy climate type in the associated text. The model data are available in the SuppementalData1.xls spreadsheet sheets 8-13. Sheets 14-20 in the spreadsheet are copies of sheets 2-7 but include additional columns for semi-quantitatively comparing the model and proxy MAP, MAT, and precipitation intermittency. To see an in-depth explanation of the methods for this comparison, please view the text.  This compilation focused on precipitation proxies. As such, MAT cells may read "n/a," indicating that information was not included in the listed sources. There may be published sources containing temperature data for said study site. ## Description of the data and file structure The data are split into 6 different time periods that were of interest to this study: Early Paleocene (66-59 Ma), Late Paleocene (59-55.9 Ma), Paleocene-Eocene Thermal Maximum (PETM) (55.9-55.7 Ma), Post-PETM (55.7-53 ma), Early Eocene Climatic Optimum (EECO) (53-49 Ma), and Post-EECO (49-47.8 Ma). The data were used to create a series of maps illustrating climate through the Early Paleogene (65-47.8 Ma) for comparison to the modern world. ## Sharing/Access information Links to other publicly accessible locations of the data: [https://jslawson298.github.io/EarlyPaleogeneClimate/](https://jslawson298.github.io/EarlyPaleogeneClimate/) ## Code/Software gplates v.2.2.0 QGIS v.3.10 ArcGIS Pro v.3.0