Publication Date:
2022-05-25
Description:
Author Posting. © The Author(s), 2017. This is the author's version of the work. It is posted here under a nonexclusive, irrevocable, paid-up, worldwide license granted to WHOI. It is made available for personal use, not for redistribution. The definitive version was published in Proceedings of the National Academy of Sciences of the United States of America 114 (2017): 6221-6226, doi:10.1073/pnas.1619111114.
Description:
Tropical cyclones (TCs) can have devastating socioeconomic impacts. Understanding the nature and
causes of their variability is of paramount importance for society. However, historical records of TCs
are too short to fully characterize such changes and paleo-sediment archives of Holocene TC activity
are temporally and geographically sparse. Thus it is of interest to apply physical modeling to
understanding TC variability under different climate conditions. Here we investigate global TC
activity during a warm climate state (mid-Holocene, 6,000 yr BP) characterized by increased boreal
summer insolation, a vegetated Sahara, and reduced dust emissions. We analyze a set of sensitivity
experiments in which not only solar insolation changes are varied but also vegetation and dust
concentrations. Our results show that the greening of the Sahara and reduced dust loadings lead to
more favorable conditions for tropical cyclone development compared to the orbital forcing alone. In
particular, the strengthening of the West African Monsoon induced by the greening of the Sahara
triggers a change in atmospheric circulation that affects the entire tropics. Furthermore, while
previous studies suggest that stronger boreal summer insolation and warmer sea surface temperatures
may actually lower TC activity in the Northern Hemisphere, accounting for the Sahara greening and
its associated reduction in dust emissions leads instead to an increase of TC activity in both
hemispheres, particularly over the Caribbean basin and east coast of North America. Our study
highlights the importance of regional changes in land cover and dust concentrations in affecting the
potential intensity and genesis of past TCs, and suggests that both factors may have appreciable
influence on TC activity in a future warmer climate.
Description:
FSRP acknowledges funding from the Swedish Research Council (FORMAS) as part of the Joint
Programming Initiative on Climate and the Belmont Forum for the project “PAlaeo-Constraints on Monsoon Evolution and Dynamics (PACMEDY). KE is grateful for support from the National Science Foundation
under grant AGS-1461517. QZ acknowledges funding from Swedish Research Council VR for the French-
Swedish project GIWA. JCS acknowledge funding by the United States National Science Foundation (P2C2
grant 1358362). JPD acknowledge funding by the United States National Science Foundation and support
from the Dalio Family Foundation.
Repository Name:
Woods Hole Open Access Server
Type:
Preprint
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