English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

Comparison of single-forcing varieties of 20th century historical experimentsin a subset of models from the Fifth Coupled Model Intercomparison Project(CMIP5) reveals that South Asian summer monsoon rainfall increases towardsthe present day in Greenhouse Gas (GHG)-only experiments with respect topre-industrial levels, while it decreases in anthropogenic aerosol-onlyexperiments. Comparison of these single-forcing experiments with theall-forcings historical experiment suggests aerosol emissions have dominatedSouth Asian monsoon rainfall trends in recent decades, especially during the1950s to 1970s. The variations in South Asian monsoon rainfall in theseexperiments follows approximately the time evolution of inter-hemispherictemperature gradient over the same period, suggesting a contribution from thelarge-scale background state relating to the asymmetric distribution ofaerosol emissions about the equator.  By examining the 24 available all-forcings historical experiments,we show that models including aerosol indirect effects dominate the negativerainfall trend. Indeed, models including only the direct radiative effect ofaerosol show an increase in monsoon rainfall, consistent with the dominanceof increasing greenhouse gas emissions and planetary warming on monsoonrainfall in those models. For South Asia, reduced rainfall in the models withindirect effects is related to decreased evaporation at the land surfacerather than from anomalies in horizontal moisture flux, suggesting the impactof indirect effects on local aerosol emissions. This is confirmed byexamination of aerosol loading and cloud droplet number trends over the SouthAsia region. Thus, while remote aerosols and their asymmetric distributionabout the equator play a role in setting the inter-hemispheric temperaturedistribution on which the South Asian monsoon, as one of the global monsoons,operates, the addition of indirect aerosol effects acting on very localaerosol emissions also plays a role in declining monsoon rainfall. Thedisparity between the response of monsoon rainfall to increasing aerosolemissions in models containing direct aerosol effects only and those alsocontaining indirect effects needs to be urgently investigated since thesuggested future decline in Asian anthropogenic aerosol emissions inherent tothe representative concentration pathways (RCPs) used for future climateprojection may turn out to be optimistic.  In addition, both groups of models show declining rainfall over China, alsorelating to local aerosol mechanisms. We hypothesize that aerosol emissionsover China are large enough, in the CMIP5 models, to cause declining monsoonrainfall even in the absence of indirect aerosol effects. The same is nottrue for India

Impacts of 20th century aerosol emissions on the South Asian monsoon in the CMIP5 models