Caribbean coral growth influenced by anthropogenic aerosol emissions

Journal name:
Nature Geoscience
Volume:
6,
Pages:
362–366
Year published:
DOI:
doi:10.1038/ngeo1780
Received
Accepted
Published online

Coral growth rates are highly dependent on environmental variables such as sea surface temperature1, 2 and solar irradiance3, 4. Multi-decadal variability in coral growth rates has been documented throughout the Caribbean over the past 150–200 years5, 6, and linked to variations in Atlantic sea surface temperatures5. Multi-decadal variability in sea surface temperatures in the North Atlantic, in turn, has been linked to volcanic and anthropogenic aerosol forcing7. Here, we examine the drivers of changes in coral growth rates in the western Caribbean between 1880 and 2000, using previously published coral growth chronologies from two sites in the region, and a numerical model. Changes in coral growth rates over this period coincided with variations in sea surface temperature and incoming short-wave radiation. Our model simulations show that variations in the concentration of anthropogenic aerosols caused variations in sea surface temperature and incoming radiation in the second half of the twentieth century. Before this, variations in volcanic aerosols may have played a more important role. With the exception of extreme mass bleaching events, we suggest that neither climate change from greenhouse-gas emissions nor ocean acidification is necessarily the driver of multi-decadal variations in growth rates at some Caribbean locations. Rather, the cause may be regional climate change due to volcanic and anthropogenic aerosol emissions.

At a glance

Figures

  1. Map of the Greater Caribbean region.
    Figure 1: Map of the Greater Caribbean region.

    Mean SST map of the Greater Caribbean region showing the Belize (i) and Panama (ii) sites. Contours give the standard deviation of the mean. SSTs are mean values from the Operational Sea Surface Temperature and Sea Ice Analysis (OSTIA) high-resolution satellite data set (1985–2007)30.

  2. AMO and multi-decadal coral growth anomalies.
    Figure 2: AMO and multi-decadal coral growth anomalies.

    a, The 25-year filtered AMO. b,c, 25-year filtered coral growth anomalies (blue) and observed SST anomalies (red) for the Belize (b) and Panama (c) sites. Coral growth and SST are linearly detrended as per the definition of the AMO.

  3. The influence of anthropogenic aerosols on SSTs and short-wave radiation.
    Figure 3: The influence of anthropogenic aerosols on SSTs and short-wave radiation.

    Modelled SST and short-wave radiation (SW) with time-varying (blue) and fixed (red) anthropogenic aerosols. a,b, SST is shown as Caribbean average (a) and short-wave radiation is shown for the Belize and Panama sites (b). Model ensemble uncertainty is shown bounded by dashed lines and variables are 13-year filtered. Observed Caribbean average SST is shown in black and modelled SSTs have been bias corrected. See Methods for further details on modelling methodology.

  4. The influence of anthropogenic aerosols on coral growth rates.
    Figure 4: The influence of anthropogenic aerosols on coral growth rates.

    a,b, Observational coral growth (black), and modelled coral growth with time-varying anthropogenic aerosols (blue) and with fixed anthropogenic aerosols (red) for the Belize (a) and Panama (b) sites. The 95% confidence intervals of the regression model with time-varying and fixed anthropogenic aerosols are shown bounded by dashed lines. This uncertainty includes HadGEM2-ES ensemble uncertainty. Observations and model variables are 13-year filtered.

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Author information

Affiliations

  1. College of Engineering, Mathematics and Physical Sciences, University of Exeter, Exeter EX4 4QF, UK

    • Lester Kwiatkowski,
    • Peter M. Cox &
    • Theo Economou
  2. Met Office Hadley Centre, Exeter EX1 3PB, UK

    • Paul R. Halloran &
    • Ben B. B. Booth
  3. School of Biological Sciences, University of Queensland, St Lucia Brisbane, Queensland 4072, Australia

    • Peter J. Mumby
  4. Australian Nuclear Science and Technology Organisation, Lucas Heights, New South Wales 2234, Australia

    • Jessica Carilli
  5. Smithsonian Tropical Research Institute, PO BOX 0843-03092, Panama City, Republic of Panama

    • Hector M. Guzman

Contributions

L.K., P.M.C. and P.R.H. conceived and designed the experiments. L.K. performed the experiments and analysed the data. L.K., P.M.C., P.R.H., T.E., P.J.M., J.C., H.M.G. and B.B.B.B. interpreted the data, discussed their implications and contributed to the manuscript.

Competing financial interests

The authors declare no competing financial interests.

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