Impacts of Climate Change on Biodiversity in Myanmar

Climate change poses major new challenges to biodiversity conservation, as species will be exposed to climate changes at a rate and magnitude seldom previously experienced, with direct consequences for ecosystem assemblages and the services they provide to humanity (Watson et al. 2011b). The impacts of climate change on biodiversity can be divided into discrete acute impacts, principally extreme weather related events (e.g., storms, droughts, fires, extreme rainfall events), and continuous chronic impacts, such as gradual increases in mean temperatures or decreases in seasonal rainfall, occurring over decades. There is some uncertainty about even the gradual chronic impacts, as possibilities exist for abrupt climate shifts, affecting ecosystem states.

Tropical species may be particularly vulnerable to climate change because they experience minimal fluctuations in annual temperature and are already near their maximum thermal tolerance (Tewksbury et al. 2008; Corlett 2011). Species unable to adapt or move will face local or global extinction and this is more likely to happen to species with narrow climatic and habitat requirements and limited dispersal abilities, such as amphibians and reptiles. In forested areas, birds may be less affected by range-shift gaps than some plants, insects, reptiles and amphibians that are poor dispersers.

There is still much to learn before we can assess accurately the impacts of climate change on biodiversity in Myanmar. Few field studies on the potential impacts of climate change to biodiversity have been conducted in the Indo-Myanmar Hotspot and there are currently no studies on biodiversity and climate change in Myanmar. A global Hotspot analysis estimated that, depending on different modeling scenarios, between 1.9 and 40.5 percent of endemic plant and vertebrate species in the Indo-Myanmar Hotspot may become extinct due to climate change over the next century (Malcolm et al. 2006). Approximately 20 to 30% of plant and animal species assessed so far are likely to be at increased risk of extinction if increases in global average temperature exceed 1.5 to 2.5°C over 1980-1999 levels.

The interactions and consequences of climate change on biodiversity are complex and multidimensional in nature. However, it is possible to represent some of the likely impacts on the three broad realms, terrestrial, freshwater and marine ecosystems.

Climate change impacts and their predicted effects on species

Terrestrial

There are many different ways in which terrestrial ecosystems are impacted by climate change (Fig. 7). As discussed in previous sections, there is considerable uncertainty in the magnitude and rate of the change and consequent impacts, given little knowledge of the resilience of ecosystems and their species to these rapid changes. The synergistic effects of other threats further complicate this but there are some basic generalities and specific examples for impacts on terrestrial ecosystems. Most terrestrial ecosystems are drying, as average high temperatures increase but these changes are likely to be exacerbated by occasional extremely high daily temperatures, which will test physiological tolerances of some species. Climate patterns are already affecting migration patterns of species of birds (Beaumont et al. 2006). Analysis of the elevational distributions of Southeast Asian birds over a 28-year period provides evidence for a potential upward shift for 94 common resident species regardless of habitat specificity (Peh 2007).

Lowland Forest Ecosystems

In the tropical lowlands, there is no source of species adapted to warmer conditions, so species lost as a result of warming will not be replaced (Feeley & Silman 2010). Movements of lowland forest species will be impeded by the cleared and fragmented nature of most lowland forests such that dispersal would require crossing cultivated landscapes and degraded riverine corridors. Under these circumstances, populations of many species may be extirpated. Wetter wet seasons and drier dry seasons could change the structure and composition of terrestrial vegetation communities (Blate 2010), possibly causing declines in food and breeding resources for some species or benefiting others, including the invasion of pest species, and causing a cascade of ecological effects. Most of the high and medium priority KBAs identified in Myanmar are terrestrial forest ecosystems and these can anticipate significant impacts of climate change.

Freshwater

The impacts of climate change on freshwater ecosystems are not particularly well known or understood in most places on earth. Freshwater ecosystems are globally among the most sensitive to climate change, due to predicted impacts to hydrology (Bates et al. 2008). The productivity of large rivers and floodplains is regulated by distinctive seasonal flow regimes. Rivers will be also sensitive to two indirect consequences of climate change.

First, many are impaired already by other pressures with which climate interacts. These include eutrophication, organic pollution, sediment release, acidification, impoundment, urbanization, hydropower development, flood-risk and invasion by exotic species (Ormerod & Durance 2009).

Second, climate will affect river conditions and processes indirectly by changing the human use of river catchments, riparian zones and floodplains. Climate change is anticipated to alter seasonal flow regimes and the timing, extent and duration of flooding, but predictions are confounded by modeling limitations and natural hydrological variability (Kingston et al. 2010).

Hotter and drier conditions, especially toward the end of the dry season, could result in the drying out of small floodplain water bodies and the contraction of shallow-water zones in lakes such as Inle Lake in Myanmar. These habitats support some of the most threatened fauna in the hotspot. For seasonally flooded grasslands such as those in the Hukaung Valley Wildlife Sanctuary, a critically endangered habitat, hotter dry seasons and rising CO2 concentrations could facilitate fire and the invasion of woody plants. Altered seasonal flow levels could impact habitat quality for freshwater populations of Irrawaddy Dolphin Orcaella brevirostris and their prey in the Ayeyawady River.

Climate change impacts in Myanmar’s wetlands are of particular concern given the critical ecosystem services they provide for human populations and biodiversity. Further, climate change impacts in the Greater and Eastern Himalayas can be expected to have repercussions for the flow of the Ayeyawady River and its tributaries that support important rice-growing regions of Myanmar.

Marine

The impacts of climate change on marine ecosystems are reasonably well known, particularly in relation to sea level rise, rising temperatures and acidification (Fig. 7; Grantham et al. 2011). Sea-level rise will exacerbate the impacts of more intense tropical cyclones predicted under global warming (IPCC 2007a). Myanmar is ranked 12 out of 20 countries in terms of population at risk due to sea-level rise. 4.6 million people will be at risk in 2050 (up from 2.8 million in 2008). The Ayeyawady River in Myanmar is one of the “key low-lying river deltas in tropical Asia that are most vulnerable to sea-level rise” (IPCC 2007b).

In the nearer term, sea-level rise and increased water temperatures are projected to accelerate beach and coastal erosion and cause degradation of mangroves and coral reefs. These would in turn negatively influence human communities through impacts on water supply and fisheries productivity. Myanmar hosts 8.8% of the total mangrove forests area of South East Asia with, 46% of the total area of mangroves located in Ayeyawady Region, 37% in the Taninthayi Region and 17% in the Rakhine State (Giesen et al. 2006). They are all considered already under threat from human activities such as pollution, harvesting and coastal development. Problems will be exacerbated for mangrove stands where landward migration is restricted by topography or human developments.

In addition to impacts on mangroves, sea-level rise is expected to impact globally threatened species of migratory shorebirds through the loss of intertidal mud flats (Tordoff et al. 2002; Buckton & Safford 2004; Tordoff et al. 2005). Breeding colonies of seabirds and turtles may be particularly vulnerable to sea-level rise (Duffy 2011).

Global climate change through ocean acidification poses a substantial risk to the biodiversity, ecosystem functioning and productivity of coral reefs in Myanmar and thus threatens their socioeconomic value to dependent human communities. Increasing ocean acidification leads to a reduction in coral calcification and affects coral reefs, which provide habitat for about a quarter of all marine species and are the most diverse among marine ecosystems (Roberts et al. 2002). Coral reefs are extensive on the south west coast of Myanmar and around the islands, extending further south into Thailand, covering 1,870 km², with the majority of coral reefs found in the Myeik Archipelago of the Taninthayi Region. Coral reefs in Myanmar need to be more fully surveyed, better protected and monitored for climate change impacts since they provide many functions, services and goods in terms of coastal protection and sediment retention, nurseries and habitats for aquatic organisms and feeding grounds for economically important species of fish.

By | 2016-01-13T13:00:34+00:00 January 12th, 2015|Climate Change, Threats|0 Comments

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