A reconstruction of radiocarbon production and total solar irradiance from the Holocene 14C and CO2 records: implications of data and model uncertainties Climate and Environmental Physics, Physics Institute, University of Bern, Bern, Switzerland
09 Aug 2013
Oeschger Centre for Climate Change Research, University of Bern, Bern, Switzerland
Received: 07 February 2013 – Published in Clim. Past Discuss.: 01 March 2013 Abstract. Radiocarbon production, solar activity, total solar irradiance (TSI) and
solar-induced climate change are reconstructed for the Holocene (10 to
0 kyr BP),
and TSI is predicted for the next centuries.
The IntCal09/SHCal04 radiocarbon and ice core CO2 records, reconstructions of
the geomagnetic dipole, and instrumental data of solar activity are applied in the
Bern3D-LPJ, a fully featured Earth system model of intermediate complexity
including a 3-D dynamic ocean, ocean sediments, and a dynamic vegetation model,
and in formulations linking radiocarbon production, the solar modulation potential, and TSI.
Uncertainties are assessed using Monte Carlo simulations and bounding scenarios.
Transient climate simulations span the past 21 thousand years, thereby considering
the time lags and uncertainties associated with the last glacial termination.
Revised: 05 June 2013 – Accepted: 07 June 2013 – Published: 09 August 2013
Our carbon-cycle-based modern estimate of radiocarbon production of
1.7 atoms cm−2 s−1
is lower than previously reported for the cosmogenic nuclide production model by
Masarik and Beer (2009) and is more in-line with Kovaltsov et al. (2012).
In contrast to earlier studies, periods of high solar activity were quite common not
only in recent millennia, but throughout the Holocene. Notable deviations compared to
earlier reconstructions are also found on decadal to centennial timescales. We
show that earlier Holocene reconstructions, not accounting for the interhemispheric
gradients in radiocarbon, are biased low. Solar activity is during 28% of the
time higher than the modern average (650 MeV), but the absolute values remain
weakly constrained due to uncertainties in the normalisation of the solar modulation
to instrumental data.
A recently published solar activity–TSI relationship yields small changes in Holocene
TSI of the order of 1 W m−2 with a Maunder Minimum irradiance reduction of
0.85 ± 0.16 W m−2.
Related solar-induced variations in global mean surface air temperature are simulated
to be within 0.1 K. Autoregressive modelling suggests a declining trend of solar
activity in the 21st century towards average Holocene conditions.
Citation: Roth, R. and Joos, F.: A reconstruction of radiocarbon production and total solar irradiance from the Holocene 14C and CO2 records: implications of data and model uncertainties, Clim. Past, 9, 1879-1909, doi:10.5194/cp-9-1879-2013, 2013.