# Global Common Era Multiproxy Temperature Field Reconstructions
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#                World Data Service for Paleoclimatology, Boulder 
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#                     NOAA Paleoclimatology Program 
#             National Centers for Environmental Information (NCEI)
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# NOTE: Please cite Publication, and Online_Resource and date accessed when using these data. 
# If there is no publication information, please cite Investigators, Title, and Online_Resource and date accessed. 
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# Online_Resource: https://www.ncdc.noaa.gov/paleo/study/26850 
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# Online_Resource: https://www1.ncdc.noaa.gov/pub/data/paleo/reconstructions/neukom2019/readme-neukom2019.txt 
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# Original_Source_URL: https://doi.org/10.6084/m9.figshare.c.4498373.v1
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# Description/Documentation lines begin with #
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# Archive: Climate Reconstructions
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# Dataset DOI: 
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# Parameter_Keywords: air temperature 
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# Contribution_Date
#	Date: 2019-07-24
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# File_Last_Modified_Date
#	Date: 2019-07-24
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# Title
#	Study_Name: Global Common Era Multiproxy Temperature Field Reconstructions
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# Investigators
#	Investigators: Neukom, R.; Steiger, N.J.; Gomez-Navarro, J.J.; Wang, J.; Werner J.
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# Description_Notes_and_Keywords
#	Description: Global gridded surface temperature reconstructions for the Common Era at 5 degree resolution. 
#	Reconstruction results in NetCDF format. File names are methods abbreviations as in the paper. 100 reconstruction members in levels.
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#	Zip Archive with input data and code to generate the figures contains:
#	Folder "input_data":
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#	Proxy data used for the reconstructions:
#	proxy_ama_2.0.0_HR-0.67_infilled_DINEOF_1850-2000_PAGES-crit-regional+FDR.txt: 
#	high-resolution (annual and higher) and infilled (calibration period) subset of the PAGES2k v2.0.0 proxy data used for all methods (210 records), 
#	see Methods section and PAGES2k Consortium, 2017, Scientific Data, doi: 10.1038/sdata.2017.88. Data are tab separated, the first row is the "paleoData_TSid" 
#	to identify each record in the metadata file. First column is year CE.
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#	metadata_2.0.0_calib-selection_1881_1916_1995_0.67_infilled_DINEOF_PAGES-crit-regional+FDR.txt: 
#	According metadatam tab separated. Contains a selection of PAGES2k v.2.0.0 database fields in each row: 
#	dataSetName, geo_latitude, geo_longitude, archiveType, resMed (Median resolution in years), paleoData_TSid (the column header in the data files).
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#	Instrumental target:
#	HadCRUT4.3_GraphEM_SP80_18502014_Apr-Mar_corr.nc: April to March aggregated HadCRUT4 instrumental target. Missing values infilled with GraphEM (PAGES2k Consortium, 2017)
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#	ne_110m_coastline: Coastline information for plotting maps. source: http://www.naturalearthdata.com/
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#	Recon_input_and figure_1.R, Create_Fig_2.R, Create_Figs_3-4.R: R scripts to generate the Figures
#	R-Functions_CFR.R: Functions required to run the above scripts
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# Publication 
#	Authors: Raphael Neukom, Nathan Steiger, Juan José Gómez-Navarro, Jianghao Wang and Johannes P. Werner 
#	Published_Date_or_Year: 2019-07-24     
#	Published_Title: No evidence for globally coherent warm and cold periods over the pre-industrial Common Era
#	Journal_Name: Nature
#	Volume: 571
#	Edition: 
#	Issue: 
#	Pages: 550-554
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#	DOI: 10.1038/s41586-019-1401-2
#	Online_Resource: https://www.nature.com/articles/s41586-019-1401-2
#	Full_Citation: 
#	Abstract: Earth's climate history is often understood by breaking it down into constituent climatic epochs. Over the Common Era (the past 2,000 years) these epochs, such as the Little Ice Age, have been characterized as having occurred at the same time across extensive spatial scales. Although the rapid global warming seen in observations over the past 150 years does show nearly global coherence, the spatiotemporal coherence of climate epochs earlier in the Common Era has yet to be robustly tested. Here we use global palaeoclimate reconstructions for the past 2,000 years, and find no evidence for preindustrial globally coherent cold and warm epochs. In particular, we find that the coldest epoch of the last millennium - the putative Little Ice Age - is most likely to have experienced the coldest temperatures during the fifteenth century in the central and eastern Pacific Ocean, during the seventeenth century in northwestern Europe and southeastern North America, and during the mid-nineteenth century over most of the remaining regions. Furthermore, the spatial coherence that does exist over the preindustrial Common Era is consistent with the spatial coherence of stochastic climatic variability. This lack of spatiotemporal coherence indicates that preindustrial forcing was not sufficient to produce globally synchronous extreme temperatures at multidecadal and centennial timescales. By contrast, we find that the warmest period of the past two millennia occurred during the twentieth century for more than 98 per cent of the globe. This provides strong evidence that anthropogenic global warming is not only unparalleled in terms of absolute temperatures, but also unprecedented in spatial consistency within the context of the past 2,000 years.
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# Site_Information 
#	Site_Name: Global 
#	Location: Geographic Region>Global
#	Country:  
#	Northernmost_Latitude: 90
# 	Southernmost_Latitude: -90
# 	Easternmost_Longitude: 180
# 	Westernmost_Longitude: -180
# 	Elevation:  
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# Data_Collection   
#	Collection_Name: Neukom2019temp 
#	Earliest_Year: 1
#	Most_Recent_Year: 2000
#	Time_Unit: CE
#	Core_Length: 
#	Notes: May-April annual average
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# Chronology_Information
#	Chronology: 
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# Variables 
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# Data variables follow are preceded by "##" in columns one and two.
# Data line variables format:  one per line, shortname-tab-variable components (what, material, error, units, seasonality, data type,detail, method, C or N for Character or Numeric data, free text) 
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# Data:
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# Data line format - tab-delimited text, variable short name as header
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