Aerosol forcing of the position of the intertropical convergence zone since ad 1550

Harriet E. Ridley, Yemane Asmerom, James U.L. Baldini, Sebastian F.M. Breitenbach, Valorie V. Aquino, Keith M. Prufer, Brendan J. Culleton, Victor Polyak, Franziska A. Lechleitner, Douglas J. Kennett, Minghua Zhang, Norbert Marwan, Colin G. Macpherson, Lisa M. Baldini, Tingyin Xiao, Joanne L. Peterkin, Jaime Awe, Gerald H. Haug

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Abstract

The position of the intertropical convergence zone is an important control on the distribution of low-latitude precipitation. Its position is largely controlled by hemisphere temperature contrasts. The release of aerosols by human activities may have resulted in a southward shift of the intertropical convergence zone since the early 1900s (refs,) by muting the warming of the Northern Hemisphere relative to the Southern Hemisphere over this interval, but this proposed shift remains equivocal. Here we reconstruct monthly rainfall over Belize for the past 456 years from variations in the carbon isotope composition of a well-dated, monthly resolved speleothem. We identify an unprecedented drying trend since ad 1850 that indicates a southward displacement of the intertropical convergence zone. This drying coincides with increasing aerosol emissions in the Northern Hemisphere and also marks a breakdown in the relationship between Northern Hemisphere temperatures and the position of the intertropical convergence zone observed earlier in the record. We also identify nine short-lived drying events since ad 1550 each following a large volcanic eruption in the Northern Hemisphere. We conclude that anthropogenic aerosol emissions have led to a reduction of rainfall in the northern tropics during the twentieth century, and suggest that geographic changes in aerosol emissions should be considered when assessing potential future rainfall shifts in the tropics.

Original languageEnglish (US)
Pages (from-to)195-200
Number of pages6
JournalNature Geoscience
Volume8
Issue number3
DOIs
StatePublished - Mar 4 2015

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intertropical convergence zone
Northern Hemisphere
aerosol
rainfall
speleothem
twentieth century
Southern Hemisphere
carbon isotope
human activity
volcanic eruption
warming
temperature
drying
tropics

All Science Journal Classification (ASJC) codes

  • Earth and Planetary Sciences(all)

Cite this

Ridley, H. E., Asmerom, Y., Baldini, J. U. L., Breitenbach, S. F. M., Aquino, V. V., Prufer, K. M., ... Haug, G. H. (2015). Aerosol forcing of the position of the intertropical convergence zone since ad 1550. Nature Geoscience, 8(3), 195-200. https://doi.org/10.1038/ngeo2353
Ridley, Harriet E. ; Asmerom, Yemane ; Baldini, James U.L. ; Breitenbach, Sebastian F.M. ; Aquino, Valorie V. ; Prufer, Keith M. ; Culleton, Brendan J. ; Polyak, Victor ; Lechleitner, Franziska A. ; Kennett, Douglas J. ; Zhang, Minghua ; Marwan, Norbert ; Macpherson, Colin G. ; Baldini, Lisa M. ; Xiao, Tingyin ; Peterkin, Joanne L. ; Awe, Jaime ; Haug, Gerald H. / Aerosol forcing of the position of the intertropical convergence zone since ad 1550. In: Nature Geoscience. 2015 ; Vol. 8, No. 3. pp. 195-200.
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Ridley, HE, Asmerom, Y, Baldini, JUL, Breitenbach, SFM, Aquino, VV, Prufer, KM, Culleton, BJ, Polyak, V, Lechleitner, FA, Kennett, DJ, Zhang, M, Marwan, N, Macpherson, CG, Baldini, LM, Xiao, T, Peterkin, JL, Awe, J & Haug, GH 2015, 'Aerosol forcing of the position of the intertropical convergence zone since ad 1550', Nature Geoscience, vol. 8, no. 3, pp. 195-200. https://doi.org/10.1038/ngeo2353

Aerosol forcing of the position of the intertropical convergence zone since ad 1550. / Ridley, Harriet E.; Asmerom, Yemane; Baldini, James U.L.; Breitenbach, Sebastian F.M.; Aquino, Valorie V.; Prufer, Keith M.; Culleton, Brendan J.; Polyak, Victor; Lechleitner, Franziska A.; Kennett, Douglas J.; Zhang, Minghua; Marwan, Norbert; Macpherson, Colin G.; Baldini, Lisa M.; Xiao, Tingyin; Peterkin, Joanne L.; Awe, Jaime; Haug, Gerald H.

In: Nature Geoscience, Vol. 8, No. 3, 04.03.2015, p. 195-200.

Research output: Contribution to journalArticle

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T1 - Aerosol forcing of the position of the intertropical convergence zone since ad 1550

AU - Ridley, Harriet E.

AU - Asmerom, Yemane

AU - Baldini, James U.L.

AU - Breitenbach, Sebastian F.M.

AU - Aquino, Valorie V.

AU - Prufer, Keith M.

AU - Culleton, Brendan J.

AU - Polyak, Victor

AU - Lechleitner, Franziska A.

AU - Kennett, Douglas J.

AU - Zhang, Minghua

AU - Marwan, Norbert

AU - Macpherson, Colin G.

AU - Baldini, Lisa M.

AU - Xiao, Tingyin

AU - Peterkin, Joanne L.

AU - Awe, Jaime

AU - Haug, Gerald H.

PY - 2015/3/4

Y1 - 2015/3/4

N2 - The position of the intertropical convergence zone is an important control on the distribution of low-latitude precipitation. Its position is largely controlled by hemisphere temperature contrasts. The release of aerosols by human activities may have resulted in a southward shift of the intertropical convergence zone since the early 1900s (refs,) by muting the warming of the Northern Hemisphere relative to the Southern Hemisphere over this interval, but this proposed shift remains equivocal. Here we reconstruct monthly rainfall over Belize for the past 456 years from variations in the carbon isotope composition of a well-dated, monthly resolved speleothem. We identify an unprecedented drying trend since ad 1850 that indicates a southward displacement of the intertropical convergence zone. This drying coincides with increasing aerosol emissions in the Northern Hemisphere and also marks a breakdown in the relationship between Northern Hemisphere temperatures and the position of the intertropical convergence zone observed earlier in the record. We also identify nine short-lived drying events since ad 1550 each following a large volcanic eruption in the Northern Hemisphere. We conclude that anthropogenic aerosol emissions have led to a reduction of rainfall in the northern tropics during the twentieth century, and suggest that geographic changes in aerosol emissions should be considered when assessing potential future rainfall shifts in the tropics.

AB - The position of the intertropical convergence zone is an important control on the distribution of low-latitude precipitation. Its position is largely controlled by hemisphere temperature contrasts. The release of aerosols by human activities may have resulted in a southward shift of the intertropical convergence zone since the early 1900s (refs,) by muting the warming of the Northern Hemisphere relative to the Southern Hemisphere over this interval, but this proposed shift remains equivocal. Here we reconstruct monthly rainfall over Belize for the past 456 years from variations in the carbon isotope composition of a well-dated, monthly resolved speleothem. We identify an unprecedented drying trend since ad 1850 that indicates a southward displacement of the intertropical convergence zone. This drying coincides with increasing aerosol emissions in the Northern Hemisphere and also marks a breakdown in the relationship between Northern Hemisphere temperatures and the position of the intertropical convergence zone observed earlier in the record. We also identify nine short-lived drying events since ad 1550 each following a large volcanic eruption in the Northern Hemisphere. We conclude that anthropogenic aerosol emissions have led to a reduction of rainfall in the northern tropics during the twentieth century, and suggest that geographic changes in aerosol emissions should be considered when assessing potential future rainfall shifts in the tropics.

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Ridley HE, Asmerom Y, Baldini JUL, Breitenbach SFM, Aquino VV, Prufer KM et al. Aerosol forcing of the position of the intertropical convergence zone since ad 1550. Nature Geoscience. 2015 Mar 4;8(3):195-200. https://doi.org/10.1038/ngeo2353