Global 0.25-Degree Grids of Extreme Heat Projection (RCP8.5 2050s) and Baseline Conditions (1980-2005), v1

Even if total cessation of further anthropogenic CO2 emissions by mid-century eventuates as called for by the Paris Agreement, some atmospheric CO2 will diminish within decades, but the remainder will probably take millennia to slowly dissipate. The longevity of atmospheric CO2 commits us to higher global temperatures long after greenhouse gas emission stabilization. As climate change causes average global temperatures to increase over the coming century, higher extreme temperatures during the hottest times of the year will also become more intense. Here extreme heat is determined by calculating the warmest 3-consecutive month period (defined using average monthly maximum temperature) in a given location for the base and future time periods with four global climate models. Representative concentration pathway 8.5 (RCP8.5) was used in all cases; even if the projected RCP8.5 temperatures are not realized by 2050, they may occur decades later, even with zero post-2050 greenhouse gas emissions. 1980-2005 was chosen for the baseline as this time period aligns with publicly available climate data and captures recent climate trends. The 2050s time slice was chosen due to stakeholder interest in projected climate change impacts that could be associated with year 2050.

This data set was developed along with a technical report: The Future We Don’t Want prepared for the C40 Cities Group by the Urban Climate Change Research Network (UCCRN) in 2018. While multi-model means across all grid cells that exceeded 30 degrees Celsius are included in the data set , a temperature threshold of 35°C was applied in the report to identify the urban areas most vulnerable to extreme heat. Cities are particularly at risk because of the urban heat island effect.

The same four global climate models (GCMs) were used in all the multi-model mean calculations (IPSL-CM5A-LR, MIROC-ESM-CHEM, GFDL-ESM2M, NorESM1-M). Grid cells are 0.25 by 0.25 degrees. The data unit is degrees Celsius. Climate data are from the NASA Earth Exchange Global Daily Downscaled Projections (NEX-GDDP) dataset, prepared by the Climate Analytics Group and NASA Ames Research Center using the NASA Earth Exchange, and distributed by the NASA Center for Climate Simulation (NCCS) (NASA, 2017). This analysis was conducted for both the historical model base period (1980-2005) as well as the future 2050s time frame (defined as 2041-2070).

Braneon, C., C. Rosenzweig and D. Bader. 2021. Global 0.25-Degree Grids of Extreme Heat Projection (RCP8.5 2050s) and Baseline Conditions (1980-2005), v1 (Preliminary Release). Palisades, NY: NASA Socioeconomic Data and Applications Center (SEDAC). http://www.ciesin.columbia.edu/data/global-grid-extreme-heat-projection-2050-baseline-1980-2005-v1/. Accessed DAY MONTH YEAR.

This is a preliminary open data release, pending peer review of the data and associated journal articles. Following the peer review process, data curation will be completed by the NASA Socioeconomic Data and Applications Center (SEDAC) and the data will be disseminated through the SEDAC catalog.