The Impacts of Global Warming

THE ARCTIC: Climate change and its impacts

In the past few decades, average Arctic temperatures have risen at twice the rate of the rest of the world. (3-5 degrees in the last 50 years). Over the next 100 years, this could rise a further 3-5 degrees over land and up to 7 degrees over the oceans. This is leading to the melting of Greenland ice sheets, glaciers and sea ice. Ice and snow reflect a lot of solar energy, so when they melt more energy is absorbed and warming will increase.

The melting of sea ice could make the Arctic ocean less saline and warmer. This could weaken the the formation of the Arctic conveyor, which draws the gulf stream current North.

Water from melting ice sheets and glaciers will contribute to rising se levels globally, this is known as EUSTATIC sea level rise.

Key Terms:PERMAFROST:Permanently frozen ground.

IMPACTS ON NATURAL SYSTEMS

Vegetation Shifts-Vegetation zones are predicted to shift Nortwards, with coniferous forests enroaching on tundra and ice deserts. This shift will destabilise existing food webs. The longer, warmer growing season will benefit to Arctic agriculture although soils will be a limiting factor.

Thawing of Permafrost-Up to 40% of total permafrost is expected to thaw, especially in Sibera. This will release large quantities of of methane-a Greenhouse gas. In some areas leakes and rivers will drain as the frozen ground thaws, while rising river flows could create new wetlands.

Increasing fires and insects-Global warming will increase forest fires and insect caused tree death, this may impact old forest growth.

UV impacts-increased UV radiation will reach the earths surface as snow and ice cover is lost. many freshwater ecosystems are at risk of radiation.

Carbon Cycle changes-The replacement of of Arctoc vegetation with more forests will lead to higher primary productivity and incread CO2 uptake.

Impacts on animal species.

Marine and land species-Marine species dependent on sea ice, including polar bears will decline. some may face extinction. Birds like geese will have different migration patterns. Land species adapted to arctic climates includng lemming, foxes and owls are at risk

North species shift-Species will shift northwards with forests. Some species are likely to sufferent from decline.

Impacts on society

Loss of hunting and culture, need for herd animals to change migratio routes, decline in northern freshwater fisheries, Increased access to marine shipping, but disruption of land based transport due to thawing, enhanced agriculture, Arctic will become more accessible, however, it will become vulnerable for oil, gas and fishing resources.

Africa is most vulnerable to climate change, hiwever it contributes the least to global warming. It is predicted that temperatures will rise 3-4 degrees above mean global average in Africa. Rainfall is likely to increase in the equirorial region but decrease in the north and south of that band.

Water Issues- Life in Africa is regulated by access to water, many of the large rivers are internationally shared, this could create conflict between water users.

Food Insecurity-70% of the population are subsistence farmers, many of whom will not be able to feed themselves should water supplies dry up.

Natural Resources- Poor people, especially those living in marginal environments  depend directly on wild plants and animals to support their way of life. Loss of biodiversity due to climate change willl threaten them.

Health- Vector bourne diseases (malaria) and water bourne diseases (diarrhoea) could increase with climate change. 80% of health services rely on wild plant remidies which are under threat.

Development of coastal zones- Movement of environmental refugees from the countryside puts pressure on the coastal zones. The threat from coastal erosion is likely to increase as the result of rising sea levels. More people are also at risk of flooding if they reside in coastal zones.

Desertification- Majorly destroys grass land, it is increased by lack of rainfall.

Poverty- 2/3 of the LEDC's countries are located in Africa.

A worst case scenario of 15m sea level rise by 2100 would put most areas of the world in peril.

Melting of West Antarctic ice sheet:5m rise

Melting of Greenland ice sheet:7m rise

Collaspe and melting of world glacier systems:2m rise

Continued thermal expansion:1m rise

Eustatic change:Change of sea level due to the amount of water in the oceans. (globally)

Isostatic change:Movement of land in response to loss or gain of mass.

Types of area most at risk to sea-level rise:

River Deltas, Low lying land, Small islands.

Bangladesh: (river delta)

70% of the country consists of floodplains less than 6m above sea level. Bangladesh could lose up to 20% of its land, displacing possibly 40 million people. By 2050 the local sea level could rise by 1 meter. Megacity, Dhaka is at risk of flooding due to being close to floodplains. Solutions are complex as the coast is too long to defend.

Tuvalu: (small islands)

Low lying islands at risk of sea level rise. in 2005 the population was 10,500 spread across 9 islands. It is on the climate change front line, is sea levels rise as predicted, the islands will be classes inhabitable.

The level and nature of economic development particularly in countries like China and India (NIC'S) are still developing, uncertain as to lthe level of GHG emissions being produced until the country is developed.

What degree of international action will be taken to reduce emissions.

The inertia system- even if GHG emissions stabilise, climate change will continue.

The impact of positive feedback, e.g as permafrost thaws global warming will be more powerful , GHG emissions like methane willl be released increasing warming further.