Sri Lanka, an equatorial island nation of 65,610 square kilometres (25,330 sq mi) and 1,340 km of coastline,[6] is a biodiversity hotspot. It has 480 bird species (25 endemic) and 121 amphibious species (88 endemic).[7]
Temperature and weather changes
A general increase in temperature trends 0.16 C has been traced over the years of 1961–1990 with the highest increase of minimum temperature in Nuwara Eliya by 2.0 C per decade.[8] A vast difference is traced in rising temperatures as the 100 year warming trend from 1896 to 1996 is only 0.003 C per year,[9] meanwhile the 10 year temperature trend from 1987 to 1996 is already 0.025 C per year. This indicates that the warming trend is accelerating. According to scientists this is due to the increase in the greenhouse gasses (global) as well as the rapid urbanization causing the heat effect (local).[10] The mean annual temperature in the country is expected to increase in the near future (2030), and to possibly increase even more in the years surrounding 2050.[11]
Extreme weather events
The island nation of Sri Lanka possesses significant differences in climate across variations in topography. The Northwest region has an annual average rainfall of less than 1 metre, while the Southwest central hills above 5 m. And due to the seasonal variations and topography, Sri Lanka is divided into 3 zones: wet, moderate, and dry. Even though rain helps in supporting the biodiversity of the dense forests covering around 30% of the country, however, the process of deforestation in wet areas contributes to erosion and dangerous landslides.[12] Cyclical pattern of floods and droughts is prompting people to stress and making it difficult for them to cope with their lives . Heavy rain on the other hand, in western and southern regions, leads to major landslides thus killing more than 500 people and affecting 1. 3 million in 2016–2017.[13] Water and vector-borne illnesses can be a direct effect of severe flooding, which can make it even more difficult to maintain sanitation.[14]More than 6 million people have been affected by the drought in the past 30 years.[15] Ironically, in Sri Lanka the number of consecutive wet days decrease while the number of consecutive dry days increased. The most drought vulnerable districts are: Moneragala, Nuwara Eliya, Anuradhapuraand Polonnaruwa.[16] Near future estimates of drought conditions in Sri Lanka are highly uncertain (2030). As for the years surrounding 2050 an increased frequency and intensity of droughts are estimated:[17]thus leading to reduced crop growth exasperated by increased temperatures and evaporation.[18]
Winds and other storms
As for cyclones, the severity has been recorded to be moderate during the past experience. In the months of November and December the northern region of the county is affected by them. As for the near future, future estimates do not have readily available information about the occurrence of cyclones after 2030 and thus are highly uncertain. However, for the future surrounding the year 2050, an accelerated risk of coastal disasters is estimated. For instance, an expected increase of 10-20% in tropical cyclone intensities is triggered by a rise in sea surface temperature, amplification of storm surge heights, and low pressures with tropical storms.[19]
Sea level rise
Sea level rise is another expected consequence of climate change in Sri Lanka's coastal zone in the 21st century.[20]The tidal gauge data of Colombo seasonally adjusted from 2006 to 2017 shows increase in sea level at a rate of 0.288 ± 0.118 mm/month. In the next 50 years, sea level is expected to rise by about 0.1 m – 0.2 m.[21] 25 percent of the population reside in vulnerable to sea level areas (within 1 km of the coast). In Sri Lanka, the coastal zones are the most affected by the uncertain rates of sea-level rise and this could worsen the existing hazards such as tsunamis and cyclones. It is expected that rising sea levels and storm surges erode shorelines, degrade the health of coastal ecosystems, and potentially displace coastal populations. Mangroves and other forms of coastal shrubs and vegetation offer protect shores and reduce vulnerability to tsunamis and cyclones, but only less than one-third of the island is protected by them.[22] Sri Lankan authorities have realized the benefits of coastal vegetation, but more efforts to restore these shrubs and harden unprotected coastlines may be needed.[23][24] Sea levels could rise by 0.13 meters and up to 0.4 meters by 2030 estimated a linear interpolation of end of century global sea level estimated. Meanwhile, a linear interpolation of end of century global sea level by 2050 is speculated to rise by 0.2 meters and up to 0.58 meters. Thus, in turns, inundation is expected to reach approximately to 41 square km for a rise of 0.3 meters, and 91.25 square kilometers for a rise of 1 meter for lowlands along the coastal lines.[25]
Water resources
Climate change threatens both surface water and groundwater sources upon which Sri Lankans depend for domestic use, agriculture, energy generation and industry. The availability of drinking water is the main concern. Nevertheless, increased droughts along with salt water intrusion into coastal aquifers, are expected to seriously deplete freshwater availability. Due to the increased economic activity a high level of groundwater extraction and pollution of existing resources occurs.[26]
Ecosystems
Birds
Twenty five endemic bird species live in Sri Lanka's wet zone, the southwestern part of the island. With 480 bird species on the island, their diversity includes (but is not limited to) waterfowl and migratory birds. Bird species of Sri Lanka are impacted by droughts, prolonged intense precipitation, sea-level rise, increased human interaction, and a lack of corridors which have led to a decline of habitat and range.
The green-billed coucal inhabits the southwestern region of the country's wet-zone forest; its characteristics include its black-brown color, medium-large size and distinctive green beak. In 2010, the species was placed on the IUCN Red List as a vulnerable species due to woodland destruction. Green-billed coucals live in forests containing large trees, shrubs, and bushes which are subject to overexploitation and clearcutting by humans.[27]
Amphibians
Sri Lanka also hosts 121 amphibian species, 88 of which are considered endemic. Severe weather can have a detrimental impact on amphibians, and prolonged droughts and periods of increased intense precipitation have resulted in a decline in amphibian diversity. Twenty-two amphibian species are endangered, and 27 are extinct.[28][29]
The bubble-nest frog is listed as endangered on the IUCN red list. Declining in population, the last count of bubble-nest frogs was estimated at 1,500. They prefer to live on the ground or on low branches near water sources in Sri Lanka's southern canopy-covered forests. The loss of habitatand mating resulting from human interaction and the over-exploitation of dense forests threatens the species.[30]Severe weather also impacts bubble-nest frog populations due to flooding from increased rainfall, which may alter its breeding habitat and force relocation.
Coral reefs
Sri Lanka is a small island nation with rich and various marine ecosystems. Thus, the inhabitants of Sri Lanka rely heavily on fisheries, with approximately a quarter of a million families make their living from fishing.[31] However, climate change in Sri Lanka can impact biodiversity offshore. Coral reefs also provide income for ecotourism and local fisheries, and are important shore barriers and homes for diversified species. Benefits of coral reefs include ecosystem services such as water filtration and shelter and food for species. Over-fishing of coral reefs can negatively impact these communities. Sea-level rise, coral bleaching, ocean acidification and increasing carbon dioxidelevels[clarification needed] also threaten coral-reef communities.
Ocean acidification
The signs of ocean acidification are evident as is deoxygenation, which has damaging effects on biodiversity, marine ecosystems, biomass, and availability of habitats. Specially in low and middle income countries where the inhabitants depend on fishing and reef-based tourism, this could lead to a wide-ranging socioeconomic fall. A new report on ocean deoxygenationreleased by IUCN during COP25 stated the fact that the average amount of oxygen in the oceans has been reduced by 2% globally. Moreover, a 30% decrease of oxygen in waters off the coast of California, and the hypoxic incident in Panama resulting in a 75% loss of coral diversity. Based on a report released by the intergovernmental panel of climate change, since the very 80s, the ocean has absorbed 20% to 30% of emitted carbon dioxide. While others claim that 90% of the heat gained by the planet has also been absorbed by the ocean. There are now calls for the inclusion of blue carbon, but some experts say that it is too little, too late.[32]
Invasive alien plant species
Whereas invasive alien species (IAS) are second to habitat degradation, for human actions have the first and direct effect on that, they (IAS) are still recognized as a major threat to Sri Lanka's native biodiversity.[33]
Sri Lanka lists 12 invasive alien species of animals most of which are vertebrates and least are invertebrates.[34] In developing countries, like Sri Lanka, the consequences of the invasive alien plant species (IAPS) on biodiversity (loss of 75%)[35] have not been adequately tackled. More impacts of IAS on native species could be listed as follows: direct destruction, competitive exclusion, and hybridization.[36] IAS have caused at least 39% of species extinction during the past 400 years.[37] According to ( Kariyawasam, Lalit Kumar, Sujith S. Ratnayake, 2019), specific areas such as the South and the West parts of the country are at high risk of IAPS development due to the high climate suitability for them. Therefore, to combat these plant invaders these researchers concluded that early detection, rapid intervention, effective eradication/control must be taken by land managers.[38][39] Four major bills and three national policies are currently focused on the spread of invasive alien fauna in Sri Lanka, yet more help is urgently needed.
Source:- https://en.m.wikipedia.org/wiki/Climate_change_in_Sri_Lanka
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