Geoscience Reference
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winter season, and least after the summer monsoon begins
(Shrestha et al., 1999). Consistent with the global trend, temper-
ature is increasing at a faster rate in the higher elevations com-
pared to the lower elevations. Notably, the rate of warming is
greater in the western half of the country compared to the east-
ern half. The former is also significantly drier than the latter.
Unlike temperature trends, no evidence of change in aggregate
precipitation has been noted although studies do point to an
increased variability and intensity of rainfall in some regions
of the country.
If the observed trends of temperature change are overlain on
the prevailing patterns of rainfall of the country, they reveal a
negative association between the amount of rainfall and gen-
eral trends of warming. For example, the Hills and Mountain
regions of the western part of the country, which receive lower
average rainfall, exhibit a higher degree of warming compared
to the central and eastern Hills and Mountain, which are com-
paratively wetter. Theoretically, if this trend continues in the
foreseeable future, the drier regions of the country will become
even more so due to projected increases in temperature. For
farmers, such a prognosis poses a further challenge in their
effort to ensure better rice productivity. A recent study using
general circulation models (GCMs) also projects a consistent
warming of the Himalaya region (Agrawala et al., 2003). While
the study also estimates an overall increase in precipitation,
mostly during the monsoon season, it is not clear how these
changes will affect the timing and period of monsoon rainfall.
Along with maize, millet, wheat, and barley, rice is an
important staple crop, accounting for about 50% of both the
total agricultural area and production in the country (Pokhrel,
1997). Rice is grown in all agro-ecological zones, from the
subtropical climatic region of the Terai and the valleys to
the higher altitudes of 1500 and 3050 m above sea level—the
highest elevations in the world known to grow rice. Most rice-
growing areas of the country have relatively optimal tempera-
ture for rice cultivation except the high Hills and the Mountain.
In India, the total area under rice is estimated to be about 1.55
million hectares (HMGN/MFSC, 2002). The two major rice
cultivation practices found in India are irrigated and rain-fed
wetland (lowland). Both of these practices are common in all
three ecological regions. Where there are irrigation facilities,
rice fields may be irrigated during the rice-growing season to
supplement the rainfall. However, areas under irrigated rice
are extremely limited; so, rain-fed cultivation is the dominant
practice for about 66% of the rice area (Pokhrel, 1997). The
