Jump to main content
US EPA
United States Environmental Protection Agency
Search
Search
Main menu
Environmental Topics
Laws & Regulations
About EPA
Health & Environmental Research Online (HERO)
Contact Us
Print
Feedback
Export to File
Search:
This record has one attached file:
Add More Files
Attach File(s):
Display Name for File*:
Save
Citation
Tags
HERO ID
1668631
Reference Type
Journal Article
Title
Recent Northern Hemisphere tropical expansion primarily driven by black carbon and tropospheric ozone
Author(s)
Allen, RJ; Sherwood, SC; Norris, JR; Zender, CS
Year
2012
Is Peer Reviewed?
1
Journal
Nature
ISSN:
0028-0836
EISSN:
1476-4687
Volume
485
Issue
7398
Page Numbers
350-354
Language
English
PMID
22596159
DOI
10.1038/nature11097
Web of Science Id
WOS:000304099100038
Abstract
Observational analyses have shown the width of the tropical belt increasing in recent decades as the world has warmed. This expansion is important because it is associated with shifts in large-scale atmospheric circulation and major climate zones. Although recent studies have attributed tropical expansion in the Southern Hemisphere to ozone depletion, the drivers of Northern Hemisphere expansion are not well known and the expansion has not so far been reproduced by climate models. Here we use a climate model with detailed aerosol physics to show that increases in heterogeneous warming agents--including black carbon aerosols and tropospheric ozone--are noticeably better than greenhouse gases at driving expansion, and can account for the observed summertime maximum in tropical expansion. Mechanistically, atmospheric heating from black carbon and tropospheric ozone has occurred at the mid-latitudes, generating a poleward shift of the tropospheric jet, thereby relocating the main division between tropical and temperate air masses. Although we still underestimate tropical expansion, the true aerosol forcing is poorly known and could also be underestimated. Thus, although the insensitivity of models needs further investigation, black carbon and tropospheric ozone, both of which are strongly influenced by human activities, are the most likely causes of observed Northern Hemisphere tropical expansion.
Tags
NAAQS
•
ISA-Ozone (2020 Final Project Page)
Literature Search Results
Literature Search - Included
Citation Mapping
Climate
Title-Abstract Screening (SWIFT-AS) - Included
Title-Abstract Screening (SWIFT-AS) - Included
Full-Text Screening Included
Full-Text Screening Included
Included in ISA First Draft
Integrated Synthesis
Appendix 9
Included in ISA Final Draft
Integrated Synthesis
Appendix 9
Preface
Home
Learn about HERO
Using HERO
Search HERO
Projects in HERO
Risk Assessment
Transparency & Integrity