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Consequences of global climate change

Definitions:

Biosphere: it is the part of the earth where life exists, up to a few kilometers into the atmosphere and deep into the earth’s crust or oceans. It is the part where living organisms exist.

Hydrosphere: it consists of the total amount of water on the earth, including underground water (groundwater, wells and aquifers), surface water (rivers, lakes and oceans, glaciers, icecaps) as well as water in the air (water vapor, clouds).

Atmosphere: it consists of the mixture of solids, liquids and gases that are held to the earth by gravitational force.

Cryosphere: refers  to the part of the the earth that is frozen – ice sheets, glaciers etc, most of which is in the Arctic and Antarctica

Global warming: The increase in global average temperature in recent decades, which is believed to be largely caused by anthropogenic or human-produced greenhouse gas emissions

More of terms associated with climate change – Climate Change: What do all the terms mean?

Climate change and the hydrosphere, atmosphere and biosphere, including:

Water stored in ice and oceans, and changing sea levels

Climate change can affect the hydrosphere, particularly ice, in a number of ways: first, high temperatures due to global warming can cause the melting of ice in polar regions, ice on mountain summits, the ocean and many other inland areas with ice.

  • For example, glaciers on the Himalayas, Southern Alps, Rockies and the summits of Mt. Kilimanjaro are all melting at a rapid rate. This releases fresh water for millions of people living along the rivers in the lowlying areas of these mountains, including the Ganges River, fed by melting snow from the Himalayas and passes Pakistan and India.
  • In the polar regions such as the Arctic and Antarctica, including Greenland vast amount of ice is melting rapidly. This releases fresh water into the ocean, thereby increasing the sea levels in many coastal areas around world. Carbon is released from vegetation into the atmosphere and further absorbed by the sea to form carbonic acid. It is estimated that the polar regions release about 30% of carbon dioxide in the atmosphere, which has found its way into the ocean. This acid has the effect of destroying coral reefs including its associated living organisms plankton.
  • The threat of sea level rises is further accentuated by the fact that thermal expansion occurs in the ocean when there is an increase in global temperatures. This means the volume of water in the sea, whether Tropical or Temperate regions, will naturally increase. It is estimated that there is about 3 millimeters of sea level rise each year due to melting ice in the polar regions and thermal expansion of the oceans. Estimates by the Intergovernmental Panel on Climate Change (IPCC) show that by 2100, sea levels will rise about 260 – 820 mm.
  • Changes in sea level: The melting of ice in hydrosphere will result in sea level rises in coastal areas, especially in countries such as the Maldives (just 1meter about sea level with about 311, 000 inhabitants living on 1,196 square meters of land) is likely to be submerged by 2100, and the Ganges Delta in Bangladesh, where river is sinking by 10 millimeters each year. This means its lower basin is likely to be over flooded by sea water. In 2005, the island of Tegua, 100km from the main island of Vanuatu was nearly abandoned due to rising sea levels. Also, two islands have disappeared due to rising sea levels from Kiribati’s several islands. In Tuvalu, there is a threat of rising sea levels and appeals have been made to relocate its inhabitants to other islands (Oakes, 2017).

Carbon stored in ice, oceans and the biosphere

Credit: ARC Centre of Excellence for Coral Reef Studies/ Gergely Torda

Again, carbon is a important component of methane gas. Increasing global temperatures, therefore suggest that ice stored in the polar regions and glaciated areas will release methane as they melt. This will increasing the level of carbon already in the atmosphere. .

Carbon is also stored in the biosphere (vegetation, especially in forest areas). With recent increases in forest fires, the forest, serving as carbon sink (for absorbing global CO2 in the atmosphere) has the tendency of being destroyed. Global warming leads to forests fires by reducing the amount of precipitation, leading to droughts and severe heat waves. Estimates by the IPCC show that by 2050, there will be about 35% increase in the number of days with forest fires in the world.

Incidence and severity of extreme weather events, including drought

Extreme weather conditions or events are weather phenomenon that occur at an unusually high or low levels than the historical record of the weather event. This could be precipitation, drought, temperature or cyclones. Some scientists are a bit skeptical about the direct effects of global warming on extreme weather events.

However, the IPCC believes that “A changing climate leads to changes in the frequency, intensity, spatial extent, duration and timing of extreme weather and climate events, and can result in unprecedented extreme weather and climate events…”(IPCC). Besides, it may also lead to an increase in the frequency of occurrence and possibly the duration of the weather events. Some weather events that may be associated with climate change include;

drought: a period of low rainfall, below the expected average in a given region, leading to severe shortage of water in rivers and underground sources. Examples of droughts include the 2011 drought and heatwaves in the United Kingdom and the 2012-2013 North American drought.

Droughts may result in a fall in agricultural productivity due shortage of water for crop cultivation, affect navigation in rivers by lowering water levels, increasing the risk of bush fires and possibly increase the cost of energy resulting from the use of air-conditioners.

Floods: floods occur when there is an overflow of water beyond normal levels. Rising global temperatures can increase the level of evaporation in rivers and oceans and other sources of overland water, which leads to the formation of clouds. This may lead to increasing rainfall in certain areas of the world especially in tropical areas. Recent floods include Maryland floods in May 2018 and the Kerala Floods in 2018.

Other extreme weather conditions include:

Map of London showing areas at risk of flooding in 2100

Spatial changes in biomes, habitats and animal migration patterns

There is a correlation between climate the type of biome that might be present in a given region. A Biome is simply a large scale collection of plant and animal species (ecosystem) living in a given geographical area, usually covering continents or a wide spatial extent. Examples include the tropical rainforest, tropical savanna, tundra vegetation etc. The vegetation type is determined by the type of climate. Therefore, a change in climatic condition will affect vegetation in a given. For example, due to climate change, the Sahel savanna is becoming a desert due to high temperature and low rainfall result from climate change. The adjacent Sudan savanna is rapidly transforming into a Sahel region, whilst the tropical savanna is transforming into a Sudan region.:

Habitat loss:

Changes to agriculture, including crop yields, limits of cultivation, soil erosion

Impacts of climate change on people and places, including health hazards, migration and ocean transport routes