Environmental Science Global Warming Effects on Small Melanesian Isla

Question: Discuss about the Environmental Science and describe the report for Global Warming Effects on Small Melanesian Islands. Answer: Summary The islands of Melanesia hold two of the thirty five global biodiversity hotspots with huge number of endemic species. Global warming and climate change are exacerbating the challenges faced by these biodiversity of Melanesia. In this report, the potential impacts of global warming and their harmful effects on the biodiversity of small Melanesian islands have been identified. According to the International Union for Conservation of Nature and Natural Resources(IUCN) more than 305 terrestrial species are threatened by severe climatic changes. Tropical cloud-montane forests, rainforests and dry forests of Melanesia are estimated to completely disappear by the year 2100 with resultant global damages of the endemic biodiversity. Introduction There is now plenty of evidences that climate is changing due to global warming and is impacting global biodiversity. The world is becoming warm. Over the past century, earths average temperature has amplified by more than 1Fahrenheit (0.7 Celsius). There are ten prime indicators of a warming world. If among these indicators seven are rising and three are decreasing, that means the world is becoming warmer. The seven currently rising indicators are humidity, temperature over the ocean, air temperature near troposphere, sea surface heat, ocean heat content, temperature over terrestrial and sea level. The decreasing indicators are glacier retreat, snow covers and sea ice amount. The Pacific Melanesian islands have diverse and complex biogeography history, which have led to the evolution of a unique biodiversity. East Melanesian islands and New Caledonia constitute two global hotspots. But this biodiversity is in the verge of irreversible damages and extinction as a result of global war ming and climate change. Effects on small Melanesian islands Melanesia is a sub-region of Oceania in the western side of Pacific Ocean. Melanesian topography includes the Solomon Islands, Vanuatu,Fiji,New Caledonia and Papua New Guinea. These small islands are biologically diverse and have a very high proportion of endemic species (Taylor and Kumar 2016). According to Bellard et al. (2014), Melanesian islands is in fact without a doubt one of the worlds most vulnerable lands when it comes to the risk of disasters due to global warming and climate change. Warming, El Nio and La Nia Global warming in western tropical Pacific regions will closely follow the proposed global average warming rate of 3.2-7.2Fahrenheit (1.8-4.0Celsius) by the year 2099 (Viles and Spencer 2014). Significant decline in the amount of glaciers in New Guinea has already been observed and current projected warming of 1Celsius suggests that freezing altitudes have now moved upslope with increased temperature and lessened rainfalls (Taylor and Kumar 2016). In Melanesia, El Nio results in drier and hotter terrestrial weather but relatively cold sea temperature. On the other hand, La Nia in Melanesia generates wet conditions on land and much increased temperature of sea surface. El Nio and La Nia cycles which is known as ENSO, have major effects on the climate of Melanesia. Regional climates in the Melanesian islands are strongly influenced by ocean circulation and ENSO (Kingsford et al. 2011). Studies found large-scale changes in ocean circulation patterns, increased temperature, wind direction and speed, rainfall changes, sea-level rise and increased intensity of tropical cyclones as result of global warming. (Allen 2015). Rising of sea-level A study of the International Pacific Research Centre (IPRC) revealed that sea-level in the northern portion of Melanesia have been rising quicker than the mean global sea-level increase and predictions are that sea-level will continue to rise faster than the global average. The Melanesian small landmasses are highly vulnerable to sea-level rise. Sea level rise is causing inundation of coastal habitats for flora and fauna, shoreline erosion and stronger storm surges that can destroy low-lying small islands (Barros et al. 2014). Melanesia contains some of the worlds largest remaining traces of coastal mangrove habitats. As described by Alongi (2014), mangrove ecosystem is extremely affected by the impacts sea-level rise. In unobstructed regions mangrove species zone migrate landward to maintain their suitable environmental conditions. But new colonizing rate gets affected in the presence of obstacles such as seawalls or shoreline protection structures. This causes narrow mangrove density or extirpation of the precious mangrove community. Rising sea-level is also increasing the ground water salinity and pushing salt water further upstream in these islands. This increased salinity is making water undrinkable and harming animals, plants and aquatic plants species which cannot tolerate this increased salinity. Sea level rise holds great threats to coastal ecosystem and the biota that ecosystem supports. With a projected rise of between 0.18 meter and 0.59 meter by the completion of this century, species that depend on low-lying coastal habitats of small Melanesian islands, are particularly at risk of disappearance (Taylor and Kumar 2016). Increase in SST and coral bleaching or damages The worldwide decline of coral reefs is an alarming effect of increased in sea-surface temperature. Sea surface temperature (SST) is warming faster towards the equator and less rapidly near the higher latitudes. In the ocean, temperature rising is about 0.18 Fahrenheit (0.1C). This amplified temperature has transpired from the surface to a depth of about 700 meters (2300 feet), where maximum marine life grow well (Taylor and Kumar 2016). Evidences suggest among all the marine organisms most vulnerable to temperature changes is corals.At even a slight persistent rise in temperature, corals eject their symbiotic algal community (zooxanthellae) and get bleached. It causes loss of many of coral species and reef fishes in Melanesian biodiversity hotspots are at extreme risk from coral species loss (Holbrook et al. 2015). While the entire Melanesian oceans and reefs are becoming warmer, resulting in an increase event of coral bleaching, northern part Melanesia is likely to experience more intense, frequent and persistent coral bleaching event than the southern island regions. Extensive period of La Nia condition due to climate change in Melanesia gives rise to much hotter sea surface temperatures, which results in more frequent and intense coral bleaching. Ocean acidification Ocean water naturally absorbs carbon-di-oxide, but the amount of current human-generated carbon-di-oxide emissions is so enormous that it is altering the chemistry of this planets oceans. Carbonic acid is procedures when ocean water absorbs carbon-di-oxide and thus, oceanic water surface have become more acidic in last decades, causing a reduction of 0.1 pH (Alongi 2014). This type of massive changes have not befallen on this planet for millions of eras, and never on such a short time span. Ocean water acidification decreases the obtainability of calcium carbonate essential for marine creatures like zooplanktons, corals, clams and sea urchins etc. Acidification also hampers the respiratory system in fish and also adversely influence their food source. The most recent scientific findings revealed that calcium carbonate levels in ocean of the Melanesian islands will become minimal by the year 2070 and much earlier in the higher latitudes. Catastrophic events like this will cause slowin g down or reversal of shell and coral reef formation, perhaps bring about major disturbances in marine food webs. Ocean acidification is also an adverse condition for mangrove ecosystem (Alongi 2014). Effects of climate change on terrestrial biodiversity Terrestrial plant and animal species of Melanesia are specifically vulnerable to climate change because of higher levels of endemicity in the islands (Keppel et al. 2014). Researches have evidences that Melanesian island biota are generally at higher risks of extinction and magnitude of extinction is greater than the continental rate for mammals and birds (Loehle and Eschenbach 2012). The species diversity of these islands are limited in their abilities to cope with climate change due to small geographical ranges, narrow genetic variations, reduced species richness and small colonizing population (Jupiter et al. 2014 and Loehle and Eschenbach 2012). The small land areas of these islands offers smaller realized niche pace which generally translates into very small ranges for islands organisms mainly for endemic species. As a result, harmful effects of climate change is affecting the entire habitat of island biota more readily than the continents (Harter et al. 2015). New Caledonia embraces around 3371 native vascular plat species among them 74% are endemics. Increasing atmospheric temperatures are having considerable impacts on those endemic species that are constrained in few regions. Over 20% of gymnosperms and angiosperms in New Caledonia fall into this set. Climate change associated impact like increased frequency and severity of tropical cyclones are immensely affecting the relative abundance of species and supporting disturbance-preferring species and thus, new forest turnover rates (Taylor and Kumar 2016). Species vulnerability modelling showed that organisms of tropical rainforests and dry forests are much more susceptible to climate change than species of other habitats. Tropical dry forests contain many endemic floras with very limited geographic boundaries such as Ancistrachne numaeensis and Diospyros sp. in New Caledonia and highly endangered Guettarda wayaensis and Cynometra falcate in Fiji (Iucnredlist.org 2016). In New Caledonia more than 82% of rainforest organisms are endemic and the changing rainfall regime is imposing immense adverse effects on the ecosystems. Rainforest plants with narrow geographical range such as Lavoixia macrocarpa and Pritchardiopsis jeanneneyi have higher risks of extinction due to altered ecosystem (Cahill et al. 2012). Tropical ectotherms have limited adaptability and environmental temperature has a strong influence on their physiological functions like growth, movement and reproduction. Several species of lizards, snakes and approximately 35 species of frogs of the PNG regions have small populations on islands, making them highly vulnerable to extinction due to climate change related habitat loss (Taylor and Kumar 2016). Mammals of Melanesian regions are directly affected due to changing climates, mainly increased temperature. The native mammal biodiversity of these islands is composed of marsupials, rodents and bats. Temperature elevation and sea-level rise gradually destroying the ecosystems and many vertebrates (37 to 118 endemics) facing the threat of extinction (Wetzel et al. 2013). Mountain-restricted birds with constricted elevational range are specifically vulnerable to the impacts of climate alteration as they have small zones of occupancy. A study a the freshwater and terrestrial bird species of Melanesia indicated that more than 50% were moderate to strong vulnerable species due to climate change impacts (Ã…Å ¾ekercioÄÅ ¸lu et al. 2012). Shifts in normal climatic conditions are also affecting seasonal availability of food and changes in these cycles could affect the entire population of birds. Many small islands of Melanesia provides nesting zones for reproduction and breeding to migratory birds like Numenius tahitiensis. Their nesting ground could be severely affected if increased temperature, elevated sea-level and intense cyclones destroy ecosystems of small islands (Taylor and Kumar 2016). Impacts on human beings Ocean warming, floods, tropical cyclones, droughts are expected to have intense impacts on agriculture system of these islands. Climate change and soil degradation and deterioration of soil fertility as a consequence of amplified precipitation damagingly impacting on agriculture and food security. Systematic evidences shown that due to the lack of adaptation, high islands like Fiji, could undergo damages around USD 23-52 million every year by 2050. In addition, fisheries contribute considerably to the GDP and rural livelihood on many of these islands. More frequent and intense cyclones and increase in sea level is adversely impacting inshore fisheries especially in rural zones (Allen 2015). Water resources in Melanesian island are at risk to fluctuations and changes in climate because of their availability, limited small sizes, geology and topography, specifically in rainfall. With a 2-4 Celsius increase in temperature, projected economic damages aggregated upto one billion USD in damages to water resources. Drinking and agriculture water stresses formed by climate change will have extreme impacts on poor rural society dependent on water resources for their livings (Allen 2015). Conclusion The small Melanesian islands contribute a negligible amount of global greenhouse gas emission but experiencing disastrous consequences of climate change from global warming. These islands contains many endemic species many of which are listed in the IUCN red list of data-book. New extinctions are still being recorded in this part of lands. The unique bio-geographical process on Melanesian islands have given rise to such high level of endemism and also endowed organisms with characteristic traits that make them highly vulnerable to climatic changes. The rapid frequency of weather change, restricted ability for adaptations and limited proportion of fitting habitat on these small landmasses propose that consequences of global warming could be severe for the biodiversity of Melanesian region. 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