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Impact of Climate Change on Mountain Ecosystems of India:
Special Reference to the Eastern Himalayas.
by:
Soumit K. Behera*
India ranks 10th in the list of most forested nations in the world
with 76.87 million ha of forest and tree cover. Like other forests
of the world, our forests also provide critical ecosystem goods and
services. However, the significant role of forests in carbon storage
and sequestration has increased their importance manifold and
brought them to the centre-stage of climate change mitigation
strategies. India’s forest and tree cover accounts for about23.4% of
the total geographical area of the country. Over the past decades,
national policies of India aimed at conservation and sustainable
management of forests have transformed India’s forests into a net
sink of CO2.
Why should India be concerned about climate change?
Indians should be concerned about climate change since this
phenomenon might have substantial adverse impacts on them. Not all
possible consequences of climate change are yet fully understood,
but the three main ‘categories’ of impacts are those on agriculture,
sea level rise leading to submergence of coastal areas, as well as
increased frequency of extreme events. Each of these pose serious
threats to India. However, these are long term issues. The
overriding immediate concern for India should be the fast pace at
which negotiations are taking place on the climate front. India’s
main energy resource is coal. With the threat of climate change,
India is called upon to change its energy strategy based on coal,
its most abundant resource, and to use other energy sources (e.g.
oil, gas, renewable and nuclear energy) instead, which may turn out
to be expensive.
Mountain biodiversity and climate change
Mountains are amongst the most vulnerable and hazardous environments
in the world: they also harbour rich repositories of biodiversity.
Some of the world’s most threatened and endemic species are found in
mountain areas. Mountains have been recognised as important
ecosystems by the Convention on Biological Diversity (CBD) and its
special programme on ‘mountain biodiversity’ which aims to reduce
the loss of biological diversity in the mountains at global,
regional, and national levels. There are enormous impediments to
this because of various drivers of global change, including climate
change (Nogues-Bravo et al. 2007). In the context of climate change,
mountains could suffer wide-ranging environmental and socio-economic
impacts, for example on the hydrological cycle, and this in turn
would alter the distribution, seasonality, and amount of
precipitation and result in changes in river runoff, ultimately
affecting not only mountain watersheds but also the lowlands below (Beniston
2003). There is an evident inter-connectedness between climate
change and biodiversity, not just in the impacts of climate change
on biodiversity but also in concomitant changes occurring in the
carbon and water cycles. The Millennium Ecosystem Assessment (MEA)
identified climate change as one of the major drivers having adverse
affects on biodiversity and associated goods and services (MEA
2005). Studies on climate change in mountain areas are incomplete
and scattered (IPCC 2007, Nogues-Bravo et al. 2007),although certain
studies from the Hindu Kush- Himalayas (Shrestha et al. 1999) do
indicate that climate change has an undesirable impact on Himalayan
biodiversity and its services.
The Eastern Himalayas
The Eastern Himalayas (EH hereafter) are counted in the ‘crisis
ecoregions’; ‘biodiversity hotspots’; ‘endemic bird areas’; ‘mega
diversity countries’; and ‘global 200 ecoregions’ (Brooks et al.
2006).. As yet, there are no concrete studies assessing the
magnitude of future warming and its impact on biological resources
in the EH, although considerable efforts have been undertaken to
conserve the region’s unique biodiversity. Three bio geographical
realms meet in the EH Region; namely, the Indo-Malayan, Palaearctic,
and Sino-Japanese, and it contains parts of three of 34 global
biodiversity hotspots, accounting for 39% of the Himalayan hotspot,
8% of the Indo-Burma hotspot, and 13% of the Mountains of Southwest
China hotspot. The complex topography and extreme altitudinal
gradients from less than 300 m (tropical lowlands) to more than
8,000 m (high mountains) have led to a variety of vegetation
patterns.
Climate-Change Scenario, Threats, Vulnerabilities and Potential
Impacts on Biodiversity Climate-change trends and projections
The Himalayan region, including the Tibetan Plateau, has shown
consistent warming trends during the past 100 years (Yao et al.
2006). Current knowledge of the climatic characteristics of the EH
region, however, is limited by both paucity of observation and the
insufficient theoretical attention given to the complex interaction
of spatial scales in weather and climate phenomena in mountain
areas. The analysis of spatial distribution of annual and seasonal
temperature trends (Shrestha and Devkota 2010) shows that annual
mean temperature is increasing at the rate of 0.01°C/yr or more.
Though warming in the winter is much greater and more widespread in
area, the warming trend has been greatest during the post-monsoon
season and at high elevations. An analysis shows progressively
greater warming rates with increasing elevation.
The past trend and change projections suggest that temperatures
will continue to rise and rainfall patterns will become more
variable, with both localised increases and decreases. The figures
for the EH region do not present a drastic deviation from the IPCC
outcomes for South Asia; they reinforce the scientific basis for the
contention that the EH region is undergoing a warming trend (Shrestha
and Devkota 2010).
The analysis of the region suggests the following:
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The Eastern Himalayas are experiencing widespread warming and
the rate is generally greater than 0.01°C per year.
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Using usual seasonal dichotomies, the highest rates of warming
are in winter and the lowest, or even cooling, are in summer.
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There is progressively more warming with elevation, with areas
higher than 4,000 m experiencing the greatest warming rates.
Threats to and vulnerability of biodiversity
Assessing the consequences of climate change in the EH region is
indeed a big challenge mainly due to limited data availability,
uncertainties associated with the climate scenarios, and the
existence of non-linear feedbacks between impacts. Nevertheless,
through various review and consultative processes we have focused on
some thematic indicators such as land-use and land-cover change,
critical habitats and eco regions, bioclimatic zones and phenology,
agro-biodiversity, and threatened and endemic species that throw
light on the potential impacts and vulnerabilities of biological
diversity due to climate change.
Land-use and land-cover changes
Changes in land cover (biophysical attributes of the earth’s
surface) and land use (human purpose or intent applied to these
attributes) are among the most important drivers of climate change
as they relate to carbon sequestration and nitrogen deposition (Lal
2004; Foley et al. 2005). Land-use and land-cover changes contribute
to local and regional climate changes (Chase et al. 1999) and global
climate warming (Penner et al. 1994; Houghton et al. 1999); and they
have a direct impact on biodiversity (Chapin et al. 2000),
influencing the reduction in species’ diversity (Franco et al.
2006). However, there is little documentation on changes over time
(Khan et al. 1997). Land-use change from forest to other usages in
the EH has been quite conspicuous in the last few decades, causing
depletion of natural resources in the Himalayas (Singh and Singh
1992). Shankar Raman (2001) revealed that the North Eastern states
of India lost 378 sq.km. of forest due to human-induced activities
between 1989 and 1991; 488 sq.km. between 1991 and 1993; and 175
sq.km. between 1993 and 1995. Other information from the North
Eastern Indian states from 1991-2005 shows an increase in forest
cover in Assam, Meghalaya and Tripura and either mixed or decreasing
trends elsewhere. The gross forest cover of these seven states
increased by 1,250 sq.km. (0.7%) in total between 1991 and 2001, and
19 sq.km. (0.01%) between 2003 and 2005.
An analysis made of overall land cover in the 1970s and 2000s, based
on six broad categories, using satellite images revealed that
land-cover types in the EH changed significantly over 25 years
between the1970s and 2000s The data revealed a substantial increase
of 17,394 sq.km. (40.4%) of shrub land, which accounts for 3.3% of
the total area of the EH. Forest cover decreased by 9,314 sq.km
(3.4% of the same class and 1.8% of the whole EH) and grassland
decreased by 3,261 sq.km (8.2%), accounting for 0.6% of the EH.
Cultivated area changed by only 594 sq.km. (0.5% of the same class
and 0.1% of the EH). The area of denuded and uncultivated land
increased by 1,369 sq.km (6.1%), accounting for 0.3% of the EH. No
significant change took place in water bodies which show a decrease
of 10 sq.km. Snow cover decreased by 6,756 sq.km. (24.6% of the same
class and 1.3% of the EH).
Vulnerable habitats and eco-regions
The EH region is known for diverse habitats and eco-regions that are
subject to a high level of human-induced threats (Myers et al. 2000;
CEPF 2005; 2007). Conservationists from across the globe have
realized that the prevailing climate change trend and projections
could mean that there will be substantial changes in critical
habitats and the species therein because of the limited scope for
expansion as the habitats outside protected areas are subject to
intense fragmentation (Pounds et al. 1999; Wilson et al. 2007).
Among the 25 eco-regions, 17 protected area complexes, and 41
candidate priority areas in the EH are many which are extremely
important for biodiversity conservation (WWF and ICIMOD 2001). Among
the eco-regions, Eastern Himalayan broadleaved forests, Brahmaputra
Valley semi-evergreen forests, and Himalayan subtropical pine
forests have the greatest conservation values because of the number
of mammals, birds, and plants found in them (WWF and ICIMOD 2001).
Bioclimatic zones and phenology
Although there is no strict compartmentalization of vegetation along
altitudinal gradients in the EH region, elevation has important
implications for its ecology, evolution, physiology, and
conservation and is highly relevant to species’ composition and
phenology patterns (Chettri et al. 2001; Carpenter 2005). As a
result of microclimatic variations, most organisms found in the EH
are confined to specific habitats such as highland pastures,
forests, and so on. This is a special risk factor for highland
species that are sensitive to climate change (Pounds et al. 1999)
and more likely to be at risk of extinction. Globally, there is
evidence of the shift of species towards the north in latitude (Hickling
et al. 2006) or higher elevations (Wilson et al. 2007), especially
for species in the transition zone between subalpine and alpine
which are more vulnerable to climate change as they have limited
scope for movement. Analyses for the EH are few and limited to
certain pockets of areas (Carpenter 2005). Observations have been
made about the change in events related to plant and animal
phenology and also to shifting of tree lines and encroachment of
woody vegetation into alpine meadows. Phenological changes, such as
early budding or flowering and ripening of fruits in plants, and
hibernation, migration, and breeding in animals, could have adverse
impacts on pollination patterns. Consequently, this may have an
impact on the population of pollinators, leading to changes in
ecosystem productivity and species’ composition in high-altitude
habitats (Thuiller et al. 2008).
Recommendations and Future Strategies
While acknowledging the significant diversity of biological
resources in the EH and the existence of a fair understanding of the
important drivers of change, it is recognized that concerted efforts
to monitor and research the impacts of climate change on
biodiversity in the EH region are essential. An enabling policy
environment is essential to support and strengthen community efforts
to cope with change. Documentation and assessments indicate the need
for policy dialogue focusing on areas identified. A clear concern
was the multiplicity of policy actors governing natural resource
management and livelihood support and the need for convergence of
different (often conflicting) policies under one forum for ease of
implementation. There is a critical role for scientific institutions
in regard to policy formulation concerning natural resource
management, livelihood support, and climate change. Policy makers
require authentic data inputs and, more often than not, these are
not available or not in a comprehensible form. Scientific
institutions need to fill this gap so that policy making can be
based on scientific findings.
*Scientist, CSIR-National Botanical Research Institute, Lucknow
(India), <[email protected]> |
