Climate change threat, impact and mitigation

Climate change is a long-term change in the average temperature and weather patterns of the Earth, now mainly caused by human activities that release greenhouse gases (CO₂, CH₄, N₂O, CFCs). The global average temperature is already about 1.1–1.2 °C above pre-industrial levels (IPCC AR6), and the effects threaten the base of human civilisation: food, water, health, settlements and peace.

Why it is a threat to civilisation

Civilisation depends on a stable climate for farming, water supply, settlements and trade. Rapid warming disturbs all of these at once, affects billions of people, and its damage (e.g. glacier loss, extinction) is often irreversible.

Impacts

1. Food security – heat, drought and erratic monsoon reduce crop yields (rice, wheat, maize); pests spread; risk of hunger in South Asia and Africa.
2. Water crisis – melting glaciers (Himalaya, the "water tower of Asia") first increase floods and then reduce dry-season flow; springs in Nepal's hills are drying.
3. Sea level rise – about 20 cm since 1900; threatens coastal cities (Dhaka, Mumbai, Jakarta) and small island countries (Maldives, Tuvalu).
4. Extreme events – stronger heat waves, cyclones, floods and droughts, e.g. 2022 Pakistan floods (about one-third of the country flooded), European heat waves, 2021 Melamchi flood in Nepal.
5. Glacial lake outburst floods (GLOF) – e.g. the Dig Tsho GLOF (1985) in the Khumbu; Imja and Tsho Rolpa are high-risk lakes in Nepal.
6. Health – heat stress, spread of dengue and malaria to higher altitudes (dengue now in Kathmandu and hill districts).
7. Biodiversity loss – coral bleaching, species extinction, shifting tree lines.
8. Economy and migration – damage to infrastructure, tourism and hydropower; climate refugees and conflict over resources.

Mitigation measures

• Renewable energy – hydropower, solar, wind instead of coal and oil.
• Energy efficiency – efficient appliances, buildings and industry.
• Clean transport – electric vehicles, public transport, cycling.
• Forests – afforestation, community forestry, REDD+.
• Sustainable agriculture – less methane from rice and livestock, organic farming.
• Waste management – reduce, reuse, recycle; capture landfill methane.
• International agreements – UNFCCC (1992), Kyoto Protocol (1997), Paris Agreement (2015): keep warming well below 2 °C, aiming at 1.5 °C; Nepal targets net-zero emissions by 2045.

Mitigation must go with adaptation (early warning, resilient roads and bridges, irrigation, Nepal's National Adaptation Plan and Local Adaptation Plans of Action, LAPA).