Inquiry Regarding Climate Forcing Data Beyond 2100 (up to 2300)

[lucia]

Hello，
I am currently conducting simulations of CO₂ fluxes under different climate scenarios for the period 2006–2300. However, I am uncertain about which CESM-based climate forcing datasets extending to 2300 are currently available.

In the study “Permafrost carbon–climate feedback is sensitive to deep soil carbon decomposability but not deep soil nitrogen dynamics” by Koven et al.2015, I noticed that they used CESM1 ECP8.5 (2101–2300) as the climate forcing. However, I have not been able to locate this dataset in the ESGF archive. At the same time, I found extended anomaly forcing data related to RCP4.5 in the CESM input repository: - Revision 70792: /trunk/inputdata/atm/datm7/anomaly_forcing (e.g., af.tas.ccsm4.rcp45.2006-2300.nc).

I would like to kindly ask the following questions:

1. Are there currently CESM1 or CESM2 climate forcing datasets extending to 2300 for different scenarios (e.g., RCP2.6, RCP4.5, RCP6.0, RCP8.5, or SSP1-2.6, SSP2-4.5, SSP3-7.0, SSP5-8.5)? If so, where can these datasets be downloaded?
2. Are there any publications that provide a detailed description of these extended climate forcing datasets and their construction methods?

I would be very grateful for any response or insights anyone might be able to provide.

Best regards,
lucia

 

[lucia]

One additional note is that I am currently using the CLM5.0 model to simulate terrestrial CO₂ fluxes, requiring six variables from 2006 to 2300: air temperature, precipitation, specific humidity, longwave radiation, shortwave radiation, and wind speed.

 

[slevis]

It seems you find a helpful answer in this post:

Post in thread 'How to do a BSSP126 run with cesm2.1.3 and resolution f09_g17 with the extended SSP126 scenario for years 2100-2300'

Nov 10, 2023

The SSP extensions weren't available at the time that cesm2.1.3 was made. So I recommend that you use:

release-cesm2.1.4

The main change was to add the extensions and get them working. So I'm pretty sure that it will be compatible
with your previous 2.1.3 simulation. However, I do recommend looking over the ChangeLog in the tag to see what
might have changed and if it matters for what you are doing. I just scanned it and only see a couple mentions of things
that sound answer changing (cesm2.1.4-rc.13, and cesm2.1.4-rc.05 has some CAM changes, and SSP emissions updates
in...

• erik

 

[lucia]

Hi Slevis,

Thank you very much for your reply. I have already downloaded the release-cesm2.1.4 version, but I realized that I actually only need to run the land component. I need six variables of climate data for the period 2100–2300 – air temperature, precipitation, specific humidity, longwave radiation, shortwave radiation, and wind speed – to drive CLM5.0.

I downloaded the CLM5.0.34 code corresponding to CESM2.1.4, and I found that it includes the following three case options:

ISSP585ExtClm50BgcCrop : SSP585EXT_DATM%GSWP3v1_CLM50%BGC-CROP_SICE_SOCN_MOSART_CISM2%NOEVOLVE_SWAV
ISSP534ExtClm50BgcCrop : SSP534EXT_DATM%GSWP3v1_CLM50%BGC-CROP_SICE_SOCN_MOSART_CISM2%NOEVOLVE_SWAV
ISSP126ExtClm50BgcCrop : SSP126EXT_DATM%GSWP3v1_CLM50%BGC-CROP_SICE_SOCN_MOSART_CISM2%NOEVOLVE_SWAV

However, I noticed that these cases drive the climate forcing only up to 2014, and all climate fields are repeatedly cycled over 2001–2014. Only CO₂ is fully transient from 2015 to 2500. What I actually need is to also have Solar, Precip, and TPQW changing from 2015 to 2100. I need the climate data for this period. But I could not find the corresponding 2100–2300 climate data at https://svn-ccsm inputdata.cgd.ucar.edu/trunk/inputdata/atm/datm7/anomaly_forcing/.

The streams settings are:

streams = "datm.streams.txt.CLMGSWP3v1.Solar 2001 2001 2014",
"datm.streams.txt.CLMGSWP3v1.Precip 2001 2001 2014",
"datm.streams.txt.CLMGSWP3v1.TPQW 2001 2001 2014",
"datm.streams.txt.presaero.SSP1-2.6 2015 2015 2101",
"datm.streams.txt.topo.observed 1 1 1",
"datm.streams.txt.co2tseries.SSP1-2.6 2015 2015 2500"
taxmode = "cycle", "cycle", "cycle", "cycle", "cycle", "extend"

My question is: do I have to run the CAM6.0 atmosphere model within CESM2.1.4 myself to simulate the six climate variables (air temperature, precipitation, specific humidity, longwave radiation, shortwave radiation, and wind speed) for the extended 2100–2300 period under SSP585 and SSP126? Then, based on the simulation results and following the approach described in Koven et al. 2015 – using their "scale factors" method (i.e., applying monthly climate anomalies/scale factors from a CESM1 simulation for RCP8.5 and ECP8.5 to repeating historical meteorology) – should I scale the repeated historical data to obtain the 2100–2300 climate change trends, and then use that data to drive CLM5.0?

For reference, the Koven et al. 2015:

"We force CLM4.5BGC with time-varying meteorology, CO2 concentration, N deposition, and land use change to estimate the C cycle response to global change. The atmospheric forcing data for 1850–2005 are taken from the combined Climatic Research Unit and National Center for Environment Predication (CRUNCEP) dataset (data available at dods.ipsl.jussieu.fr/igcmg/IGCM/BC/OOL/OL/CRU-NCEP/), which merges high-frequency variability from the National Centers for Environmental Prediction−National Center for Atmospheric Research reanalysis (30) with the monthly mean climatologies from the CRU temperature and precipitation datasets (31). Projection period forcing is calculated by applying monthly climate anomalies/scale factors from a Community Earth System Model, version 1 (CESM1) simulation for the scenarios Representative Concentration Pathway 8.5 (RCP8.5) for the years 2006–2100 and Extended Concentration Pathway 8.5 (ECP8.5) for the years 2100–2300 to repeating 1996–2005 CRUNCEP meteorology. For constant climate (control and biogeochemically forced) runs, atmospheric data are repeated over the period 1901–1920. CO2 concentrations follow transient historical (1850−2005), RCP8.5 (2006−2100), and ECP8.5 (2101−2300) concentrations for biogeochemically and fully forced runs, and remain fixed at 1850 levels (284.7 ppm) for control and climatically forced runs. Atmospheric N deposition is from coupled atmospheric chemistry−climate runs (32), land use follows the historical (1850−2005) and RCP8.5 (2006−2100) scenarios (33), and both are transient in all cases. After 2100, land use is static and wood harvest is zero."

Thank you very much for your help!