Mesoproterozoic Global Climate Model Simulations Fiorella, R.P.; Sheldon, N.D. Fiorella, R.P. Sheldon, N.D. earth science/paleoclimate/paleoclimatic modeling (minimum surface temperature,null,null,kelvin,annual,paleoclimatic modeling,null,null,N,Minimum surface temperature over output period) earth science/paleoclimate/paleoclimatic modeling (latitude,null,null,degree north,null,paleoclimatic modeling,null,null,N,null) earth science/paleoclimate/paleoclimatic modeling (cloud ice mixing ratio,null,null,kilogram per kilogram,annual,paleoclimatic modeling,null,null,N,CLDICE) earth science/paleoclimate/paleoclimatic modeling (cloud cover,null,null,fraction,annual,paleoclimatic modeling,null,null,N,CLDLOW; Vertically-integrated low cloud) earth science/paleoclimate/paleoclimatic modeling (longwave cloud radiative effect,null,null,watt per square meter,annual,paleoclimatic modeling,null,null,N,null) earth science/paleoclimate/paleoclimatic modeling (convective precipitation,null,null,meter per second,annual,paleoclimatic modeling,null,null,N,liquid plus ice) earth science/paleoclimate/paleoclimatic modeling (large-scale precipitation,null,null,meter per second,annual,paleoclimatic modeling,null,null,N,liquid plus ice) earth science/paleoclimate/paleoclimatic modeling (snow depth,null,null,meter,annual,paleoclimatic modeling,null,null,N,snow depth over ice) earth science/paleoclimate/paleoclimatic modeling (cloud condensed water content,null,null,gram per square meter,annual,paleoclimatic modeling,null,null,N,null) earth science/paleoclimate/paleoclimatic modeling (cloud liquid water content,null,null,gram per square meter,annual,paleoclimatic modeling,null,null,N,null) earth science/paleoclimate/paleoclimatic modeling (precipitable water,null,null,kilogram per square meter,annual,paleoclimatic modeling,null,null,N,null) earth science/paleoclimate/paleoclimatic modeling (cloud cover,null,null,fraction,annual,paleoclimatic modeling,null,null,N,CLOUD; total cloud cover) earth science/paleoclimate/paleoclimatic modeling (temperature tendency,null,null,kelvin per second,annual,paleoclimatic modeling,null,null,N,DTCOND; due to moist processes) earth science/paleoclimate/paleoclimatic modeling (surface downwelling longwave radiation,null,null,watt per square meter,annual,paleoclimatic modeling,null,null,N,FLDS) earth science/paleoclimate/paleoclimatic modeling (surface downwelling shortwave radiation,null,null,watt per square meter,annual,paleoclimatic modeling,null,null,N,FSDS) earth science/paleoclimate/paleoclimatic modeling (cloud liquid water mixing ratio,null,null,kilogram per kilogram,annual,paleoclimatic modeling,null,null,N,Prognostic in-cloud water mixing ratio) earth science/paleoclimate/paleoclimatic modeling (surface type,null,null,fraction,annual,paleoclimatic modeling,null,null,N,Fraction of sfc area covered by land) earth science/paleoclimate/paleoclimatic modeling (relative humidity,null,null,percent,annual,paleoclimatic modeling,null,null,N,null) earth science/paleoclimate/paleoclimatic modeling (maximum surface temperature,null,null,kelvin,annual,paleoclimatic modeling,null,null,N,Maximum surface temperature over output period) earth science/paleoclimate/paleoclimatic modeling (eastward wind speed,null,null,meter per second,annual,paleoclimatic modeling,null,null,N,null) earth science/paleoclimate/paleoclimatic modeling (surface net upward clear-sky longwave radiation,null,null,watt per square meter,annual,paleoclimatic modeling,null,null,N,FLNSC) earth science/paleoclimate/paleoclimatic modeling (surface net downward shortwave radiation,null,null,watt per square meter,annual,paleoclimatic modeling,null,null,N,FSNS) earth science/paleoclimate/paleoclimatic modeling (top-of-atmosphere net downward clear-sky shortwave radiation,null,null,watt per square meter,annual,paleoclimatic modeling,null,null,N,FSNTC; top of model) earth science/paleoclimate/paleoclimatic modeling (latent heat flux,null,null,watt per square meter,annual,paleoclimatic modeling,null,null,N,null) earth science/paleoclimate/paleoclimatic modeling (specific humidity,null,null,kilogram per kilogram,annual,paleoclimatic modeling,null,null,N,null) earth science/paleoclimate/paleoclimatic modeling (temperature tendency,null,null,kelvin per second,annual,paleoclimatic modeling,null,null,N,due to shortwave heating) earth science/paleoclimate/paleoclimatic modeling (snow water equivalent,null,null,meter,annual,paleoclimatic modeling,null,null,N,null) earth science/paleoclimate/paleoclimatic modeling (shortwave cloud radiative effect,null,null,watt per square meter,annual,paleoclimatic modeling,null,null,N,null) earth science/paleoclimate/paleoclimatic modeling (surface downward x stress,null,null,pascal,annual,paleoclimatic modeling,null,null,N,eastward wind stress) earth science/paleoclimate/paleoclimatic modeling (cloud ice content,null,null,gram per square meter,annual,paleoclimatic modeling,null,null,N,null) earth science/paleoclimate/paleoclimatic modeling (geopotential height,null,null,meter,annual,paleoclimatic modeling,null,null,N,null) earth science/paleoclimate/paleoclimatic modeling (cloud liquid water mixing ratio,null,null,kilogram per kilogram,annual,paleoclimatic modeling,null,null,N,CLDLIQ) earth science/paleoclimate/paleoclimatic modeling (cloud cover,null,null,fraction,annual,paleoclimatic modeling,null,null,N,CLDTOT; Vertically-integrated total cloud) earth science/paleoclimate/paleoclimatic modeling (cloud cover,null,null,fraction,annual,paleoclimatic modeling,null,null,N,CLDCON; convective cloud cover) earth science/paleoclimate/paleoclimatic modeling (surface downwelling clear-sky longwave radiation,null,null,watt per square meter,annual,paleoclimatic modeling,null,null,N,FLDSC) earth science/paleoclimate/paleoclimatic modeling (surface downwelling clear-sky shortwave radiation,null,null,watt per square meter,annual,paleoclimatic modeling,null,null,N,FSDSC) earth science/paleoclimate/paleoclimatic modeling (insolation,null,null,watt per square meter,annual,paleoclimatic modeling,null,null,N,FSDTOA) earth science/paleoclimate/paleoclimatic modeling (top-of-atmosphere net downward shortwave radiation,null,null,watt per square meter,annual,paleoclimatic modeling,null,null,N,FSNTOA; top of atmosphere) earth science/paleoclimate/paleoclimatic modeling (top-of-atmosphere outgoing shortwave radiation,null,null,watt per square meter,annual,paleoclimatic modeling,null,null,N,FSUTOA) earth science/paleoclimate/paleoclimatic modeling (vertical pressure velocity,null,null,pascal per second,annual,paleoclimatic modeling,null,null,N,null) earth science/paleoclimate/paleoclimatic modeling (insolation,null,null,watt per square meter,annual,paleoclimatic modeling,null,null,N,null) earth science/paleoclimate/paleoclimatic modeling (temperature,null,null,kelvin,annual,paleoclimatic modeling,null,null,N,null) earth science/paleoclimate/paleoclimatic modeling (surface downward y stress,null,null,pascal,annual,paleoclimatic modeling,null,null,N,northward wind stress) earth science/paleoclimate/paleoclimatic modeling (surface air temperature,null,null,kelvin,annual,paleoclimatic modeling,null,null,N,Reference height temperature) earth science/paleoclimate/paleoclimatic modeling (aerosol optical depth,null,null,dimensionless,annual,paleoclimatic modeling,null,null,N,Total Aerosol Optical Depth in visible band) earth science/paleoclimate/paleoclimatic modeling (top-of-atmosphere outgoing longwave radiation,null,null,watt per square meter,annual,paleoclimatic modeling,null,null,N,FLUT) earth science/paleoclimate/paleoclimatic modeling (sea ice cover,null,null,fraction,annual,paleoclimatic modeling,null,null,N,null) earth science/paleoclimate/paleoclimatic modeling (surface type,null,null,fraction,annual,paleoclimatic modeling,null,null,N,Fraction of sfc area covered by ocean) earth science/paleoclimate/paleoclimatic modeling (surface geopotential,null,null,square meter per square second,annual,paleoclimatic modeling,null,null,N,at surface) earth science/paleoclimate/paleoclimatic modeling (convective snowfall,null,null,meter per second,annual,paleoclimatic modeling,null,null,N,water equivalent) earth science/paleoclimate/paleoclimatic modeling (large-scale snowfall,null,null,meter per second,annual,paleoclimatic modeling,null,null,N,water equivalent) earth science/paleoclimate/paleoclimatic modeling (northward wind speed,null,null,meter per second,annual,paleoclimatic modeling,null,null,N,null) earth science/paleoclimate/paleoclimatic modeling (cloud cover,null,null,fraction,annual,paleoclimatic modeling,null,null,N,CLDHGH; Vertically-integrated high cloud) earth science/paleoclimate/paleoclimatic modeling (top-of-atmosphere net downward shortwave radiation,null,null,watt per square meter,annual,paleoclimatic modeling,null,null,N,FSNT; top of model) earth science/paleoclimate/paleoclimatic modeling (surface pressure,null,null,pascal,annual,paleoclimatic modeling,null,null,N,null) earth science/paleoclimate/paleoclimatic modeling (sea level pressure,null,null,pascal,annual,paleoclimatic modeling,null,null,N,null) earth science/paleoclimate/paleoclimatic modeling (sensible heat flux,null,null,watt per square meter,annual,paleoclimatic modeling,null,null,N,null) earth science/paleoclimate/paleoclimatic modeling (wind speed,null,null,meter per second,annual,paleoclimatic modeling,null,null,N,at 10 meters) earth science/paleoclimate/paleoclimatic modeling (cloud cover,null,null,fraction,annual,paleoclimatic modeling,null,null,N,CLDMED; Vertically-integrated mid-level cloud) earth science/paleoclimate/paleoclimatic modeling (cloud ice content,null,null,fraction,annual,paleoclimatic modeling,null,null,N,FICE; Fractional ice content within cloud) earth science/paleoclimate/paleoclimatic modeling (top-of-atmosphere net upward longwave radiation,null,null,watt per square meter,annual,paleoclimatic modeling,null,null,N,FLNT) earth science/paleoclimate/paleoclimatic modeling (cloud ice mixing ratio,null,null,kilogram per kilogram,annual,paleoclimatic modeling,null,null,N,Prognostic in-cloud ice mixing ratio) earth science/paleoclimate/paleoclimatic modeling (evaporation,null,null,kilogram per square meter per second,annual,paleoclimatic modeling,null,null,N,null) earth science/paleoclimate/paleoclimatic modeling (specific humidity,null,null,kilogram per kilogram,annual,paleoclimatic modeling,null,null,N,reference height) earth science/paleoclimate/paleoclimatic modeling (temperature tendency,null,null,kelvin per second,annual,paleoclimatic modeling,null,null,N,due to longwave heating) earth science/paleoclimate/paleoclimatic modeling (surface temperature,null,null,kelvin,annual,paleoclimatic modeling,null,null,N,Surface temperature (radiative)) earth science/paleoclimate/paleoclimatic modeling (northward ocean heat transport,null,null,kelvin meter per second,annual,paleoclimatic modeling,null,null,N,null) earth science/paleoclimate/paleoclimatic modeling (longitude,null,null,degree east,null,paleoclimatic modeling,null,null,N,null) earth science/paleoclimate/paleoclimatic modeling (surface net upward longwave radiation,null,null,watt per square meter,annual,paleoclimatic modeling,null,null,N,FLNS) earth science/paleoclimate/paleoclimatic modeling (top-of-atmosphere net upward clear-sky longwave radiation,null,null,watt per square meter,annual,paleoclimatic modeling,null,null,N,FLNTC) earth science/paleoclimate/paleoclimatic modeling (top-of-atmosphere outgoing clear-sky longwave radiation,null,null,watt per square meter,annual,paleoclimatic modeling,null,null,N,FLUTC) earth science/paleoclimate/paleoclimatic modeling (surface net downward clear-sky shortwave radiation,null,null,watt per square meter,annual,paleoclimatic modeling,null,null,N,FSNSC) earth science/paleoclimate/paleoclimatic modeling (top-of-atmosphere net downward clear-sky shortwave radiation,null,null,watt per square meter,annual,paleoclimatic modeling,null,null,N,FSNTOAC; top of atmosphere) earth science/paleoclimate/paleoclimatic modeling (atmospheric boundary layer thickness,null,null,meter,annual,paleoclimatic modeling,null,null,N,null) earth science/paleoclimate/model (Global>LATITUDE >LONGITUDE ) The Proterozoic Eon (2500-542 Ma) appears to have been a warm period bookended by glaciations, despite a 5%-18% reduction in solar output compared to modern during this interval. Radiative-convective climate models suggest that glaciation could have been avoided if pCO2 were 30-300x preindustrial atmospheric levels (PIAL, 280 ppmv). Constraints from late Mesoproterozoic (ca. 1.2-1.0 Ga) microfossil calcification sheaths and paleosol mass balance, however, suggest that pCO2 may have been no higher than 10x PIAL. In the lower oxygen Mesoproterozoic atmosphere, an increased CH4 flux from methanogenic bacteria may have contributed additional greenhouse warming. We use a fully coupled atmosphere-ocean general circulation model (the U.S. National Center for Atmospheric Research Community Earth System Model, CESM) to test whether these pCO2 constraints are consistent with the absence of widespread glaciation inferred from the geologic record. We vary pCO2 and pCH4 between 1400 and 2800 ppmv and 3.5 and 140 ppmv, respectively, using a reconstructed 1.0 Ga paleogeography and solar output reduced by 9%. Our simulations suggest that ice-free conditions can be maintained at 10x PIAL CO2 when CH4 is 140 ppmv. When CH4 is lowered to 28 ppmv at 10x PIAL CO2, or if pCO2 is lowered to 5x PIAL, permanent land snow cover at high and middle latitudes suggests that glaciation would be more extensive than preindustrial conditions, but with warm tropical regions. Global glaciation occurs if pCO2 is reduced below 5x PIAL. Overall, our simulations suggest that an ice-free climate for the Mesoproterozoic (1.6-1.0 Ga) is consistent with the relatively low pCO2 implied from proxies if CH4 or other greenhouse gas concentrations were sufficiently elevated. STUDY NOTES: Climate model simulations for the Mesoproterozoic (1.6-1.0 billion years ago) using the NCAR CESM1.2 model (modified for Mesoproterozoic conditions). Model runs for atmospheric CO2 at ~1, 5, and 10 times pre-industrial levels, (pCO2 between 1400 and 2800 ppmv) and for pCH4 varying between 3.5 and 140 ppmv. Simulations suggest ice-free conditions could be maintained for 2800ppmv CO2 if CH4 was elevated to 140ppmv. NCDC-Paleoclimatology https://www.ncdc.noaa.gov/data-access/paleoclimatology-data - Bauer Bruce Investigator : Fiorella, R.P. Investigator : Sheldon, N.D. 2017-01-09 ONLINE Files online, ASCII https://www.ncdc.noaa.gov/paleo/study/20990 https://www1.ncdc.noaa.gov/pub/data/paleo/gcmoutput/fiorella2017/ https://www1.ncdc.noaa.gov/pub/data/paleo/gcmoutput/fiorella2017/readme-fiorella2017.txt https://www1.ncdc.noaa.gov/pub/data/paleo/gcmoutput/fiorella2017/ https://www1.ncdc.noaa.gov/pub/data/paleo/gcmoutput/fiorella2017/readme-fiorella2017.txt English https://www.ncdc.noaa.gov/paleo/study/20990 https://www1.ncdc.noaa.gov/pub/data/paleo/gcmoutput/fiorella2017/ https://www1.ncdc.noaa.gov/pub/data/paleo/gcmoutput/fiorella2017/readme-fiorella2017.txt Richard P. Fiorella and Nathan D. Sheldon2017Equable end Mesoproterozoic climate in the absence of high CO2Geology10.1130/G38682.1 START YEAR: 1600000000 cal yr BP * END YEAR: 1000000000 cal yr BP -180 -90 180 90