Fig. 2A. Actual and reconstructed January-December mean tropical (30°N-30°S)
temperatures with 2 sigma error bars. The shaded histogram denotes the number of coral series utilized through time.
Click image for full figure.
|
Two-hundred-fifty years of reconstructed and modeled tropical temperatures.
Journal of Geophysical Research - Oceans
Vol. 111, No. C10, C10007, doi:10.1029/2005JC003188, 14 October 2006.
Rob Wilson1, Alexander Tudhope1, Philip Brohan2,
Keith Briffa3, Timothy Osborn3, and Simon Tett4
1 School of GeoSciences, Grant Institute, University of Edinburgh, Edinburgh, UK
2 Hadley Centre for Climate Prediction and Research, Met Office, Exeter, UK
3 Climatic Research Unit, University of East Anglia, Norwich, UK.
4 Hadley Centre (Reading Unit), Met Office, Reading, UK
|
ABSTRACT:
Recent large-scale palaeoclimate reconstructions of past temperature
have been essentially biased to the extratropics owing to a paucity of
proxy data in tropical regions. Herein we describe the first coral-based
reconstruction of sea surface temperatures (SSTs) for the whole of the
tropics (30°N-30°S). It was developed from 14 disparate coral records
located in the Indian and Pacific oceans. Over the most replicated period,
the reconstruction explains 57% of the tropical SST variance. However,
the strength of this signal weakens markedly as the number of coral records
decreases. The reconstruction is robust between 1850 and 1993, but some
fidelity is indicated back as far as the mid 18th century. These results
suggest that ambiguities in the low frequency domain of d18O measurements
can be partially overcome by pooling together multiple time series from
different locations around the tropics. Agreement with simulations from
two general circulation models indicates that the late 20th century is
likely the warmest period in the tropics for the last 250 years, and that
this recent warming can only be explained by anthropogenic forcing.
The high frequency variability is dominated by the El Nino-Southern
Oscillation. The reconstruction, owing to the small number of coral
records, is unfortunately restricted both in time and space.
Therefore we hope that this study will spur the palaeoclimate community
to develop new and longer proxy series to improve the current meager
data-base of temperature sensitive series in the tropics.
|