HR: 11:05h
AN: PP51D-04    [PDF]
TI: Simulating the Last Half-Millennium
AU: * Tett, S F
EM: simon.tett@metoffice.com
AF: Hadley Centre -- Reading, Meteorology Building University of Reading, Reading, RG6 6BB United Kingdom
AU: Betts, R
EM: richard.betts@metoffice.com
AF: Hadley Centre, Met Office, FitzRoy Road, Exeter, EX1 3PB United Kingdom
AU: Woodage, M
EM: margaret.woodage@metoffice.com
AF: Hadley Centre, Met Office, FitzRoy Road, Exeter, EX1 3PB United Kingdom
AU: Roberts, D
EM: david.roberts@metoffice.com
AF: Hadley Centre, Met Office, FitzRoy Road, Exeter, EX1 3PB United Kingdom
AU: Jones, A
EM: andy.jones@metoffice.com
AF: Hadley Centre, Met Office, FitzRoy Road, Exeter, EX1 3PB United Kingdom
AU: Crowley, T
EM: tcrowley@duke.edu
AF: Dept. of Earth and Ocean Sciences, Nicholas School of the Environment and Earth Sciences, Duke University, Durham, NC 27708 United States
AU: Briffa, K
EM: k.briffa@uea.ac.u
AF: Climatic Research Unit, School of Environmental Sciences, University of East Anglia, Norwich, NR4 7TJ United Kingdom
AU: Osborn, T
EM: t.osborn@uea.ac.uk
AF: Climatic Research Unit, School of Environmental Sciences, University of East Anglia, Norwich, NR4 7TJ United Kingdom
AU: Gregory, J
EM: jonathan.gregory@metoffice.com
AF: CGAM, Department of Meteorology, University of Reading, Reading, RG6 6BB United Kingdom
AU: Lowe, J
EM: ,jason.lowe@metoffice.com
AF: Hadley Centre -- Reading, Meteorology Building University of Reading, Reading, RG6 6BB United Kingdom
AU: Jones, P
EM: p.jones@uea.ac.uk
AF: Climatic Research Unit, School of Environmental Sciences, University of East Anglia, Norwich, NR4 7TJ United Kingdom
AB: To test simulated AOGCM variability and change against proxy reconstructions we have simulated the last half-millennium using the HadCM3 model forced with natural and anthropogenic forcings. The natural forcings used were changes in orbital parameters, volcanic aerosol forcings, and solar irradiance. A simulation (NATURAL) forced with only natural factors and with land-surface characteristics set to 1750 values and well-mixed greenhouse gases set to pre-industrial concentrations was carried out. A second simulation (ALL) with both anthropogenic and natural forcings was started in 1750 from NATURAL. In ALL sulphate aerosols, greenhouse gases, ozone and land surface characteristics also change. The natural simulation shows general agreement between the naturally forced simulation and paleo-reconstructions until the mid- to late-19th century. However simulated surface-temperature response to external forcings (largely volcanic) appears to be too large while simulated decadal variability is significantly smaller than that reconstructed. In the simulations there is an anthropogenic impact on climate by the mid to late 19th century. Comparison with early European instrumental data appears to qualitatively confirm the simulated anthropogenic cooling during the 19th century. Simulated sea-level falls rapidly after large volcanic eruptions (such as Tambora) then recovers over several decades to pre-eruption conditions. A simple diagnostic model shows maximum glacier advance during the maunder minimum and the mid-19th century. Twentieth century sea-level rise is dominated by anthropogenic forcings mainly due to thermal expansion with a moderate contribution from glacier retreat.
DE: 1620 Climate dynamics (3309)
SC: Paleoceanography and Paleoclimatology [PP]
MN: 2003 Fall Meeting