Unit 2 Global Climate Change Case studies

Negative feedback in Greenland

• Greenland ice sheet’s maximum melt area increased on average by 16% from 1979 -2002

• the northern and north-eastern part of the ice sheet experienced melting up to an elevation of 2,000 metres

• April 2016, ~12% of the ice sheet was melting two months early

  • 10% in 2010

• impacts of greenland ice melt

  • rising sea level

  • threat of very cold winters in Britain

  • could shut off currents of Gulf Stream

  • Britain’s climate could become more like Canada’s (same latitude)

changes due to the retreat of the Swiss glaciers

• change in landscape

• water balance

• glacial outbursts

• mudslides

• debris slides

specifics of changes to swiss glaciers

• glaciated surface of Swiss Alps declined from 1800km² in 1850 to 1300 km² in 1971, loss of 1/3

• surface area as proportion of total land area decreased from 4.4% to 3.15%

Gorner glacier (swtizerland)

• 1882 about 15km long

• 1883 - 1885 glacier grew 4m

• retreated by 26m/yr from about 1890

• retreated more slowly by ~10m/yr until 1920

• retreated by 186m in 1950

• 2007-’08 retreated 290m

• has retreated 2.5km in the last 130 years

Destruction of US forests - wildfires

• dense forest serves as a carbon sink, absorbing ~13% of the greenhouse gases the US emits through burning fossil fuels

• in 2015, >10 million of America’s 776 million acres of forest consumed by wildfires

  • biggest land area burned since 1960

  • cost US government over $2 billion

• fire season increased from 50 days in 1950 to ~125 days now

• by 2036 US forests could become a carbon source

Destruction of US forests - insects

• Insects also caused forest destruction

  • drought-stressed trees lose their ability to repel insects

• since 1990s, 42 million acres of north american pine forest have succumbed to bark beetles

  • warmer, drier weather and milder, shorter winters means insect populations and vulnerable tree populations both increase

• by 2036 US forests could become a carbon source

Mitigation forest destruction effects in US

• more funding required

• 2015 USFS spent more than half its budget on firefighting

• by 2025, USFS predicted to spend 67% of its budget on firefighting

  • less funding to USFS because of Trump administration

• controlled burning becoming more understood (yay)

Climate change in the UK

• temperatures expected to rise at a rate of ~0.2ºC per decade

• ~200km northward biome shift

• annual precipitation over the UK expected to increase by ~5% by the 2020s and ~10% by the 2050s

• UK will be subject to more intense rainfall events and extreme wind speeds

• Gale frequencies will increase ~30%

• exaggerated contrast in UK’s environment, more drought

• sea levels expected to rise ~5cm per decade

  • likely to be increased in southern and eastern England by sinking land

  • Offset by rising land in the north

• potential increase in storm surges

Flooding in Bangladesh

• Bangladesh forms a delta from three main rivers, which regularly flood. Flooding helps soil fertility but has become more intense and prolonged since 1970.

• Climate change will worsen flooding: a 2.6°C rise will cause repeated floods, and sea-level rise makes coastal areas highly vulnerable.

• Monsoon rainfall is projected to increase by 14–40% by the 2030s and 52–135% by the 2090s.

• Government and NGOs have acted to reduce impacts:

• Flood Action Plan (1988) introduced after severe floods.

• Built sluice gates, 5,700 km of embankments (4,000 km along the coast), and 5,000 km of drainage channels.

• Constructed 200 flood shelters on stilts and brick toilets with septic tanks to reduce contamination.

• Despite efforts, people in areas like the Padma River islands remain highly vulnerable, with livelihoods at severe risk.

vulnerability and adaptation in ghana

• climate change impacts include: disease prevalence, food and water insecurity, migration, loss of livelihoods, and social tensions.

• Northern Savanna: Disease, poverty, and migration → strengthened social security, health care, safety nets, and urban social services.

• Transition Zone: Rising demand for resources, food insecurity, and conflict → partnerships in service provision, early warning systems, conflict management, social safety nets, and new livelihoods.

• Forest Zone: Food insecurity, drying water sources, land pressure → improved social services, small-scale irrigation, tenure security, and community-based land management.

• Coastal Savanna: Water shortages, migration, cholera → rainwater harvesting, better safety nets, support for immigrants, economic diversification, healthcare access, and health education.

three amigos summit

• Leaders of USA, Canada, and Mexico agreed on joint climate change initiatives.

• Main pledges:

  • Achieve 50% clean energy by 2025 (requires major expansion of renewables and energy efficiency).

  • Enhance cross-border cooperation and modernize electricity grids.

• Methane: USA and Canada pledged to cut methane emissions by 40–45% by 2025 (North America produces >10% of global methane).

• HFCs (hydrofluorocarbons): All three countries agreed to regulate and reduce their use (major greenhouse gases from refrigerants).

• Transport: Agreed to reduce vehicle emissions, improve fuel efficiency, and align greenhouse gas standards by 2025–2027.