LOSCAR Model Paleocene-Eocene Thermal Maximum pCO2 Output ----------------------------------------------------------------------- World Data Center for Paleoclimatology, Boulder and NOAA Paleoclimatology Program ----------------------------------------------------------------------- NOTE: Please cite original reference when using these data, plus the data file URL and date accessed. NAME OF DATA SET: LOSCAR Model Paleocene-Eocene Thermal Maximum pCO2 Output LAST UPDATE: 7/2012 (Original receipt by WDC Paleo) CONTRIBUTOR: Zeebe, R.E. IGBP PAGES/WDCA CONTRIBUTION SERIES NUMBER: 2012-111 WDC PALEO CONTRIBUTION SERIES CITATION: Zeebe, R.E. 2012. Paleocene-Eocene Thermal Maximum LOSCAR Model pCO2 Output. IGBP PAGES/World Data Center for Paleoclimatology Data Contribution Series # 2012-111. NOAA/NCDC Paleoclimatology Program, Boulder CO, USA. ORIGINAL REFERENCES: Zeebe, R.E. 2012. LOSCAR: Long-term Ocean-atmosphere-Sediment CArbon cycle Reservoir Model v2.0.4. Geosci. Model Dev., 5, 149-166 www.geosci-model-dev.net/5/149/2012/ doi:10.5194/gmd-5-149-2012 Zeebe, R.E., J.C. Zachos, and G.R. Dickens. 2009. Carbon dioxide forcing alone insufficient to explain Paleocene-Eocene Thermal Maximum warming. Nature Geoscience, 2, 576 - 580, Published online 13 July 2009. doi:10.1038/ngeo578 Komar, N. and R.E. Zeebe. 2011. Oceanic calcium changes from enhanced weathering during the Paleocene-Eocene thermal maximum: No effect on calcium-based proxies. Paleoceanography, 26, PA3211, doi:10.1029/2010PA001979. ABSTRACT (Zeebe 2012): The LOSCAR model is designed to efficiently compute the partitioning of carbon between ocean, atmosphere, and sediments on time scales ranging from centuries to millions of years. While a variety of computationally inexpensive carbon cycle models are already available, many are missing a critical sediment component, which is indispensable for long-term integrations. One of LOSCAR's strengths is the coupling of ocean-atmosphere routines to a computationally efficient sediment module. This allows, for instance, adequate computation of CaCO3 dissolution, calcite compensation, and long-term carbon cycle fluxes, including weathering of carbonate and silicate rocks. The ocean component includes various biogeochemical tracers such as total carbon, alkalinity, phosphate, oxygen, and stable carbon isotopes. LOSCAR's configuration of ocean geometry is flexible and allows for easy switching between modern and paleo-versions. We have previously published applications of the model tackling future projections of ocean chemistry and weathering, pCO2 sensitivity to carbon cycle perturbations throughout the Cenozoic, and carbon/calcium cycling during the Paleocene-Eocene Thermal Maximum. The focus of the present contribution is the detailed description of the model including numerical architecture, processes and parameterizations, tuning, and examples of input and output. Typical CPU integration times of LOSCAR are of order seconds for several thousand model years on current standard desktop machines. The LOSCAR source code in C can be obtained from the author by sending a request to loscar.model@gmail.com. ABSTRACT (Zeebe et al. 2009): The Palaeocene-Eocene Thermal Maximum (about 55 Myr ago) represents a possible analogue for the future and thus may provide insight into climate system sensitivity and feedbacks. The key feature of this event is the release of a large mass of 13C-depleted carbon into the carbon reservoirs at the Earth's surface, although the source remains an open issue. Concurrently, global surface temperatures rose by 5-9°C within a few thousand years. Here we use published palaeorecords of deep-sea carbonate dissolution and stable carbon isotope composition, along with a carbon cycle model to constrain the initial carbon pulse to a magnitude of 3,000 Pg C or less, with an isotopic composition lighter than -50‰. As a result, atmospheric carbon dioxide concentrations increased during the main event by less than about 70% compared with pre-event levels. At accepted values for the climate sensitivity to a doubling of the atmospheric CO2 concentration, this rise in CO2 can explain only between 1 and 3.5°C of the warming inferred from proxy records. We conclude that in addition to direct CO2 forcing, other processes and/or feedbacks that are hitherto unknown must have caused a substantial portion of the warming during the Palaeocene-Eocene Thermal Maximum. Once these processes have been identified, their potential effect on future climate change needs to be taken into account. ABSTRACT (Komar and Zeebe 2011): During the Paleocene-Eocene thermal maximum (PETM -55 Myr ago), prominent climatic and biogeochemical changes took place in the atmosphere, ocean, and on land. For example, deep-sea temperatures rose by 5°C to 6°C, while sea surface temperatures at high latitudes increased by up to 9°C. In the sedimentary record, the onset of the PETM is marked by widespread dissolution of calcium carbonate on the seafloor. In addition, there is evidence for globally higher humidity, precipitation and increased weathering during the PETM. Both calcium carbonate dissolution and enhanced weathering probably affected the seawater calcium concentration. Here we investigate implications that possible changes in the ocean's calcium inventory may have had on boron/calcium (B/Ca) and magnesium/calcium (Mg/Ca) ratios, which are used as proxies for deep water carbonate chemistry and temperature, respectively. We also examine effects on d44Ca of seawater, which is used as an indicator for variations in the marine calcium cycle. We focus on the magnitude of change in the ocean's calcium ion concentration as a result of the carbon perturbation, which resulted in increased weathering fluxes and the dissolution of calcite on the ocean floor during the PETM. Different ranges of carbon input scenarios and their effect on ocean chemistry were examined using the Long-term Ocean-atmosphere-Sediment CArbon cycle Reservoir (LOSCAR) model. We found that under the most plausible scenario, the calcium ion concentration change (D[Ca2+]) was less than 0.7% and around 2% in the most extreme scenario. Our results show that B/Ca and Mg/Ca proxies were not affected within analytical precision by changes in oceanic calcium due to weathering and carbonate dissolution during the PETM. The most extreme scenario (D[Ca2+] = 2%) would result in ∼4 mmol kg-1 uncertainty in reconstruction of D[CO3 2-]. The same scenario affects the temperature reconstruction by -0.2°C. The effect on the ocean’s calcium isotope budget was insignificant as well, resulting in Dd44Casw of less than 0.05‰. GEOGRAPHIC REGION: Global PERIOD OF RECORD: 0 - 200,000 y after Paleocene-Eocene boundary (~56 Ma) DATA FILE URLS: ftp://ftp.ncdc.noaa.gov/pub/data/paleo/climate_forcing/trace_gases/loscar-petm-co2.txt ftp://ftp.ncdc.noaa.gov/pub/data/paleo/climate_forcing/trace_gases/loscar-petm-co2.xls DESCRIPTION: pCO2 output for the Palaeocene-Eocene Thermal Maximum from LOSCAR model (Long-term Ocean-atmosphere-Sediment CArbon cycle Reservoir Model) Model run is for 200,000 y after Paleocene-Eocene boundary (~56 Ma) DATA: Zeebe 2012 LOSCAR PETM pCO2 MODEL OUTPUT Time (y) Atmospheric CO2 (ppmv) 0.00 1000.00 4.46 1000.60 8.91 1001.19 13.37 1001.78 32.11 1004.24 50.84 1006.69 69.58 1009.14 108.92 1014.32 148.25 1019.55 187.59 1024.86 226.93 1030.26 293.20 1039.50 359.48 1048.91 425.75 1058.41 492.02 1067.97 558.29 1077.53 649.00 1090.60 739.70 1103.61 830.41 1116.51 921.11 1129.29 1011.82 1141.95 1162.58 1162.72 1313.35 1183.18 1464.11 1203.37 1614.88 1223.32 1765.65 1243.08 1901.65 1260.79 2037.66 1278.45 2173.67 1296.11 2309.68 1313.80 2445.68 1331.48 2637.94 1356.39 2830.20 1381.15 2967.31 1398.73 3104.43 1416.11 3241.54 1433.42 3378.66 1450.83 3515.78 1468.34 3571.25 1475.46 3626.73 1482.57 3682.21 1489.69 3737.69 1496.80 3793.17 1503.91 3872.12 1514.01 3951.07 1524.11 4030.01 1534.20 4108.96 1544.29 4187.90 1554.36 4430.03 1585.18 4502.66 1594.40 4575.30 1603.61 4647.93 1612.80 4720.57 1621.98 4793.21 1631.15 4915.30 1646.55 5037.40 1661.96 5159.50 1677.40 5281.59 1692.88 5403.69 1708.40 5586.62 1731.70 5769.56 1755.02 5952.49 1778.29 6007.37 1781.56 6062.25 1781.80 6117.13 1780.97 6172.01 1780.07 6226.90 1779.21 6340.13 1776.91 6453.37 1774.04 6566.60 1770.77 6679.84 1767.23 6866.99 1761.17 7054.15 1755.04 7241.31 1749.05 7428.47 1743.30 7718.78 1734.95 7935.05 1729.18 8151.32 1723.79 8300.87 1720.27 8417.50 1717.63 8534.12 1715.07 8650.75 1712.60 8767.37 1710.19 8963.16 1706.31 9158.95 1702.58 9354.73 1699.01 9550.52 1695.58 10019.74 1687.81 10488.95 1680.62 10958.17 1673.92 11427.39 1667.63 12054.96 1659.76 12682.54 1652.38 13310.12 1645.41 13937.70 1638.78 14565.28 1632.45 15668.14 1631.58 16522.81 1638.11 17377.48 1646.55 18232.15 1654.31 19086.82 1661.05 19941.49 1667.38 20913.19 1669.25 21884.89 1668.21 22856.60 1666.42 23828.30 1664.85 25050.85 1663.52 26273.40 1662.56 27495.95 1661.88 28718.51 1661.47 30465.65 1661.22 32212.79 1661.36 33959.93 1661.88 35707.08 1662.72 38886.47 1664.94 42065.85 1667.94 45245.24 1671.55 48424.63 1675.76 51604.02 1680.51 55947.60 1687.67 60291.18 1695.42 61402.01 1697.48 62512.85 1694.08 63623.68 1687.89 64734.52 1681.26 66004.34 1674.29 67274.16 1668.07 68543.98 1662.43 69813.80 1657.26 71844.73 1650.02 71899.57 1649.83 71954.40 1649.64 71979.50 1649.55 71996.01 1649.49 72009.28 1651.79 72022.56 1654.35 72035.83 1656.79 72062.23 1661.07 72088.64 1664.84 72115.04 1668.15 72174.39 1674.43 72233.73 1679.21 72293.08 1682.82 72352.42 1685.49 72477.70 1689.04 72602.98 1690.44 72728.27 1690.49 72853.55 1689.70 73071.62 1687.38 73289.69 1684.35 73507.77 1681.07 73725.84 1677.76 74108.25 1672.13 74490.66 1666.80 74873.06 1661.84 75255.47 1657.22 75761.78 1651.54 76268.08 1646.29 76774.39 1641.41 77280.69 1636.85 78061.69 1630.41 78842.70 1624.55 79623.70 1619.17 80404.70 1614.20 81185.70 1609.56 82421.62 1602.83 83657.54 1596.76 84893.46 1591.22 86129.38 1586.14 87365.30 1581.41 88601.21 1577.01 89996.08 1572.39 91390.95 1568.09 92785.82 1564.04 94180.69 1560.21 95575.55 1556.57 97781.29 1551.14 99987.02 1546.06 102192.75 1541.26 104398.48 1536.67 106604.21 1532.24 111218.05 1523.40 115831.88 1515.00 120445.72 1506.92 125059.55 1499.06 131205.84 1488.85 137352.14 1478.85 143498.43 1469.03 149644.73 1459.37 155791.02 1449.85 168657.43 1430.35 181523.84 1411.39 194390.25 1392.95 196073.18 1390.58 197756.10 1388.22 199439.03 1385.87 200000.00 1385.09