Alladi Ramakrishnan Hall

On the Mid-Holocene Hydroclimate Wetness over India - Is the Past a Prelude?

R. Balaji

Unvi. of Colorado

Paleo evidence indicates presence of fairly robust lakes in Northwestern India
(modern day desert) during mid-Holocene (~4000 - 6000 years ago). This led to
the conventional inference that entire India was wet, with estimates varying
upto doubling of existing precipitation, without strong physical mechanisms.
The wetness is assumed to be due to increased solar insolation resulting from
the precession cycle. Two interesting questions ensue:


(i) how much increase in precipitation is needed to sustain the lakes?

(ii) can heating alone lead to increased rainfall?

Mid-Holocene warming is comparable to the impending warmer climate, and hence
insights into monsoon rainfall variability from this past period can help
understand future variability. Interestingly, mid-Holocene period coincided
with flourishing Indus civilization with its decline during late Holocene which
marked the beginning of a drier climate over India. Thus the tantalizing
question - will history repeat itself? Here we explore the above questions and
offer new explanation.