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 language | English (US) |
|---|---|
| Pages (from-to) | 195-200 |
| Number of pages | 6 |
| Journal | Nature Geoscience |
| Volume | 8 |
| Issue number | 3 |
| DOIs | |
| State | Published - Mar 4 2015 |
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All Science Journal Classification (ASJC) codes
- Earth and Planetary Sciences(all)
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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 journal › Article
TY - JOUR
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.
UR - http://www.scopus.com/inward/record.url?scp=84923931135&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=84923931135&partnerID=8YFLogxK
U2 - 10.1038/ngeo2353
DO - 10.1038/ngeo2353
M3 - Article
AN - SCOPUS:84923931135
VL - 8
SP - 195
EP - 200
JO - Nature Geoscience
JF - Nature Geoscience
SN - 1752-0894
IS - 3
ER -