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Climate Change (Management (Planting trees (Trees act as carbon sinks…
Climate Change
Management
Planting trees
Trees act as carbon sinks removing CO2 from the atmosphere by photosynthesis. They also release moisture into the air which has a cooling effect, reducing incoming solar radiation.
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Carbon Capture
Carbon capture and storage uses technology to capture carbon dioxide produced from the use of fossil fuels in electricity generation and industrial processes. 90% of CO2 is able to be captured which otherwise would've entered the atmosphere.
International Agreements
Climate change is global and needs global solutions. In 2009 world leaders met in Copenhagen to consider international agreements on tackling climate change beyond 2012. It pledged to reduce emissions with financial support for developing nations to help them cope with impacts of climate change. However there was no legally binding agreement.
Impacts
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Water Supply
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In Asia millions rely on snow fed rivers.In Himalayas the 16000 glaciers are disappearing, this threatens long term water supplies there.
As a solution, many are making artificial glaciers
Rising Sea Levels
Sea levels have risen by 20cm since 1900. By 2100 rise by another 28cm-86cm.This could flood low level land such as deltas in India.
Construction of sea walls, stilt raised houses, Artificial island construction, relocation to Sri Lanka are considered by Maldives government as it could be gone by 2070 and unlivable by 2030
Causes
Human
Methane
Very effective in absorbing heat. 20% of enhanced greenhouse effect. Rice farming, keeping livestock, burning biomass for energy and decaying organic matter in landfill sites and compost tips all contribute.
Nitrous oxides
Very small concentrations can be up to 300 times more effective in capturing heat than carbon dioxide. Sewage treatment, car exhausts, agricultural fertilisers and power stations producing electricity all contribute.
CO2 emissions
60% of enhanced greenhouse effect. Global concentration has increased 30% since 1850. Car exhausts, burning fossil fuels and deforestation and burning of wood contribute.
Natural
Change in Earth's orbit
The Milankovitch Cycles
Eccentricity. Path of Earth as it orbits the Sun. The Earth's orbit changes between circular to elliptical. It does a full cycle of this every 100,000 years.
Axial tilt. Currently 23.5 degrees. Over 41,000 years it moves between 21.5 and 24.5.
Precession - natural 'wobble' of the Earth. Complete wobble cycle takes 26000 years.Explains why some regions have really long days or nights at some points in the year.
Solar Activity
Cyclical changes in solar energy output linked to presence of sunspots (a dark patch appearing from time to time on the Sun). Goes from a minimum to a maximum over a sunspot cycle of 11 years.
When sunspot activity is at a maximum the Sun gives off more heat and there are large explosions on the surface of the Sun resulting in solar flares. When it is at a minimum, solar output is reduced leading to lower earth temperatures.
Volcanic activity
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Fine droplets from the conversion of sulfur dioxide to sulfuric acid act like tiny mirrors reflecting radiation from the Sun. This is longer term.
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Eruption of Mount Tambora - 1815, Indonesia. Most powerful in the world for 1600 years. Average global temperatures fell 0.4-0.7 degrees. Harvests failed, food shortages across North America and Western Europe. Food prices rose and there were riots and looting in European cities. 200000 deaths, worst famine in Europe in 19th century.
Evidence
Recent evidence
Glaciers
Many of the world's ice caps and glaciers are melting. Arctic sea ice is also decreasing which is affecting habitats and wildlife such as Polar bears. It is estimated that some glaciers will disappear completely by 2035. Arctic sea ice has thinned by 65% since 1975.
Seasons natural seasonal activities such as tree-flowering and bird migration is advancing. In the mid-1990's, 65 species of bird nested an average of 9 days earlier than in the 1970's.
Sea Levels may rise by 1m by 2100 which will flood agricultural land in Bangladesh and low lying countries such as the Maldives are under threat from sea level rise. The average global sea level has risen between 10 and 20cm in the past 100 years. This is because: when temperatures rise and fresh water ice melts, more water flows to the sea from glaciers and ice caps. Also, when ocean waters warm it expands in volume (thermal expansion).
Historical evidence
During the Quaternary period, temperatures have fluctuated however, there was gradual cooling in this period. Ice used to cover parts of Europe and North America. Warmer parts are called the inter-glacial periods and today's temperature is higher than almost all of the last 400,000 years.
Recently, in the last few decades the average global temperature has increased. This has become known as global warming - an indication of climate change. Since 1880, the average global temperature has risen by 0.85 degrees and most of this increase has been in the mid-1970's.
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