**4.5 Climate change and its consequences**

The water, food, health, land, environment, infrastructures are vulnerable affecting by severe consequences of global climate change with irreversible loss of many species around the world. The increasing in extreme weather events damages infrastructures by natural disasters, storms and flooding. According to IPCC 2007, climate has been getting warmer since 1960 and this will continue. Global temperature will be increased at the end of the 21st Century in relative to the end of the 20th Century ranges from 0.6 to 4 °C and 3.3 °C in South Asia with the min-max range as 2.7–4.7 °C. Climate change projections for 1961–1990, in East Asia shows relative to the average for mean temperatures will be 1.9°–2.6 °C higher across the region in 2050, and 3.8°–5.2 °C higher in 2090 [59]. The increasing pressure on natural resources in Asia associated with the rapid urbanization, industrialization, and economic development bringing challenges to protect the degrading environment. Asia comprises 51 countries/regions with land and territories, divided into six sub regions based on geographical position

and coastal peripheries. Forest carbon pools affected by the Climate change in some countries of the region and observed annual mean temperatures over South Asia in the past is increasing significantly about 0.75 °C per century. The physiology, phenology and distribution of plant and animal affecting by the climate change and also increase the risk of mortality and injury from wind storms, flash floods, coastal flooding and expected numbers of vector-borne diseases in the near future.

According to the 2020 edition of Germanwatch's Climate Risk Index, Nepal is ninth hardest-hit nation by climate calamities during the period 1999 to 2018, as one of the most vulnerable countries to the climate change effects [60]. The average annual maximum temperature has been increasing by 0.056 °C per year from 1971 to 2014 [61] and extremely increasing precipitation [62]*.* Similarly, more than 80% property had lost due to water disasters like floods, landslides and glacial lake outburst floods (GLOFs) [63].

Biodiversity is essential for Earths functioning ecosystem but growing human population, habitat loss and over exploitation of resources is the main factors to loss of biodiversity. According to IPBES, more than 1 million IUCN red list threatened species are risk of disappearing which includes 41% of amphibians, 25% of mammals, 34% of conifers, 13% of birds, 31% of sharks and rays, 33% of reef-building corals, and 27% of crustaceans [64]. The issue of global warming is concerned with the raising temperature by trapping earth's emissions in the atmosphere due to exposure of greenhouse gas emissions like carbon dioxide, nitrous oxide, methane, ozone, and water vapor and burning of fossil fuels. Increased lake and stream temperatures have significant implications affecting frequencies of disease in fish species and their altered growth, increased energy expenditures, thermal barriers on adult and juvenile migration, delayed and reduced spawner survival, altered egg and juvenile development, changes in biological productivity and altered species distribution [65].

The living components of ecosystems like plants, herbivores, carnivores, and soil organisms influences by the climate change in their functional ecosystem and characteristics in regards of energy and chemicals flow altering ecosystems properties and species distributions. The major resilience biodiversity in its ecosystems with variation of life on the earth interdepending webs of living organisms and physical environment provides us clean air, fresh water, food, resources and medicine. The humankind activities like air and water pollution, habitat destruction and fragmentation, and the introduction of invasive species likely to be exacerbated ecosystems. The valuable goods and services provided to the human societies by the ecosystem threaten to jeopardize the numerous economic and social values due to climate change effects [66]. The detrimental effects can be mitigated through preserving and maintaining habitat and species to maintaining overall ecosystem structure and species composition together with adapting biodiversity conservation strategy by reducing fragmentation and degradation of habitats, increasing connectivity among habitat blocks and fragments, and reducing external anthropogenic environmental stresses.

Nepal's water resources, public health and terrestrial ecosystems are most vulnerable sectors [67] with associated issues of food security, poverty reduction and environmental degradation. Adaptation of appropriate technology for changing cropping patterns, enhancing mitigation for emerging pests and disease and protection of changing landscapes of Nepal can cope with changing climatic pattern. Nepal's changing climatic pattern as experienced in temperature and mean precipitation, data on temperature trends from 1975 to 2005 showed 0.06 °C rise in temperature annually with significantly decrease in mean rainfall on an average of 3.7 mm (−3.2%) per month per decade. The mean annual temperatures under various climate change scenarios for Nepal has projected to increase between 1.3–3.8 °C by the 2060s and 1.8–5.8 °C by the 2090s with reduction of annual precipitation to be in a range of 10 to 20% across the country [68]. The increased number of glacial lakes

in Nepal exceeds by 11% on an average by 38 km2 per year and 29% about 129 km3 ice reserve has estimated between the period of 1977 and 2010. Nepal is one of the most vulnerable countries to disasters and warming trends of Nepal is increasing as country's averaged mean temperature increases of 1.2 °C and 3 °C projected by 2050 and 2100 [69]. Glacier retreat and significant increases in the size and volume of glacial lakes of Nepal Himalayas making them more prone to Glacial Lake Outburst Flooding (GLOF). Climate change enhance more disaster's like landslides and soil erosion on excavation slopes, drainage disruption, flooding in roads, bridges and airport runways, drinking water sources and infrastructures of lowland areas so that roads, bridges, tunnels and other infrastructures are vulnerable to increased precipitation, groundwater levels, temperatures and winds. Transportation sector is affected by climate change and it contributes to greenhouse gas emissions. The mountain ecosystem and topography is highly affected by the climate events like high rainfall, accelerate surface run-off, increase flows in gullies, drainage channels, streams and rivers expose landslides and flooding, which instable road sections, bridges, and other infrastructures as well as inundations in lowland areas. Design and construction of climate resilient and environmental friendly infrastructures can support to reduce climate change impacts. Local microclimate can adapt through rod site plantation, bioengineering and climate resilient transportation system to reduce GHG level in atmosphere. The GHG emission of Nepal is around 0.027% of total global emissions and increasing GHG trend is from energy sector [70]. As Nepal is a party of UNFCCC supporting to limit temperature rise to well below 2 °C leading to 1.5 °C above preindustrial levels in order to reduce the risks and adverse impacts of climate change.

Climate change and risks associated towards adverse impacts on ecosystems and biodiversity, water resources, food production, and infrastructure with global warming correlates to adapt reducing or avoiding adverse impacts and maximize positive consequences towards the risks. The adaptation process is complex towards risks posed by climate change and variability as Moser & Ekstrom 2010, stated adaptation process is constant of awareness and understanding, planning, implementation and monitoring and review [71]. To mitigate or avoid the projected impacts of climate change, adaptation urgently needed towards extreme changes and impacts that may occur [72]. According to Article of UNFCCC, evaluation of risk associate with climate change refers "dangerous anthropogenic interference with the climate system".

Although, Climate change affects biodiversity and ecosystem services that are not all negative, with some species either thriving or adapting. Climate change and associate impacts is an integrated and integral portion of the major developmental sectors of the nation that can be mitigated through effective implementation of mitigation tools. Environmental assessment a planning application for the development activities mainly propose mitigation measures as obligations within the legal framework for implementation but not fulfilled legal requirement seriously for monitor and implementation. Hence, the assessment strategy to address the likely environmental impacts of the planned sectoral projects is limited on fulfillment of the legal requirement.
