The Climate Change ATLAS is an initiative to develop tools and ready-to-use datasets for reproducible regional analysis of observed and model projected (CMIP5, CMIP6 and CORDEX) climate change information using both time-slices (e.g. 2081-2100) and warming levels (e.g. +1.5º). A new set of sub-continental reference regions is provided as the basis for regional synthesis (building on IPCC AR5 reference regions) and monthly spatially aggregated datasets are produced to facilitate the development of regional climate change information.

The accessibility and reproducibility of results has been a major concern during the development of the Climate Change ATLAS, in order to ensure the transparency of the products (which are all publicly available). The Atlas products are generated using free software community tools, in particular R building on the climate4R framework for data post-processing (data access, regridding, aggregation, bias adjustment, etc.) and evaluation and quality control (when applicable). Provenance/ metadata is generated using the METACLIP RDF-based framework (building on the metaclipR package for the climate4R framework).

A new set of reference regions is produced building on the popular AR5 IPCC reference regions developed for reporting sub-continental CMIP5 (with typical resolution of 2º) projections over a reduced number of regions. The increased reasolution (typically 1º in CMIP6) allows to increase the number of regions for a better climatic representatio (this results in 46 land and 14 ocean reference regions). The coordinates (csv and shapefile) of the regions and related datasets are available at the 'reference-regions' repo.

The IPCC reference regions have been used as the basis to generate popular spatially aggregated datasets, such as the IPCC AR5 seasonal mean temperature and precipitation in IPCC regions for CMIP5. Here we provide a updated version of this dataset using CMIP6 projections (interpolated to a common 1º resolution, see 'referece_masks') for the new regions. Monthly mean values are stored for CMIP5/6 for the historical (1850-2005/1850-2014) and future RCP2.6/SSP1-2.6, RCP4.5/SSP2-4.5 and RCP8.5/SSP5-8.5 scenarios. This will later extended to CORDEX datasets. An inventory of the currently available models and runs is available at the 'ATLAS-inventory'.

Besides the analysis of time-slices (e.g. near-, mid- and long-term, 2021-2040, 2041-2060, 2081-2100, respectively), we also provide information to work with Global Warming Levels (+1.5º, +2º, +3º, +4º); see 'warming-levels'.

Scripts and (jupyter) notebooks are provided in the different sections to ensure reproducibility and reusability of the results.

The Atlas Hub is a cloud facility providing virtual workspace for the Climate Change Atlas code and data (with preinstalled software and accesible data). The Atlas Hub is based on Jupyter to create and run notebooks on a remote machine where all the software is pre-installed. The Atlas Hub builds on the R climate4R package, allowing for transparent climate data access, collocation, post-processing (including bias adjustment) and visualization. Instructions to start working with the Hub are available at the climate4R GitHub repository.

This work is carried out for the purpose of contributing the Sixth Assessment Report of the IPCC. It is in draft status and subject to change. This repository is part of the Second Order Draft of the Working Group I report and is provided for information only