climate

climate

1. climate change

   • natural causes
     • variations in solar output
       • 1. sun emits varying amounts of solar radiation due to changes in its magnetic fields
       • 2. sunspots are cooler regions of the sun's surface
       • 3. periods of intense solar magnetic activity cause an increase in sunspots
         • resulting in higher solar radiation
       • 4. areas surrounding sunspots radiate more energy to make up for the cooler sunspot areas
       • 5. higher solar radiation, earth temp will increase
     • volcanic eruptions
       • 1. when a volcano erupts, large vol of carbon dioxide, water vapour, sulfur dioxide, dust and ash is released into the atmosphere
       • 2. sulphur-based particles, dust and ash reflect solar energy back into space
         • cooling the earth temporarily for months/years
       • e.g eruption of mount pinatubo in the philippines in 1991.
         • eruption released 17m tonnes of so2 into the atmosphere
         • reflected solar energy back into space and lowered temps in NH by 0.6 degree celsius
           • temporarily lowering global temps that lasted for 2 years in some areas
   • greenhouse effect
     • a natural process by which greenhouse gases trap heat in the atmosphere
     • 1. shortwave radiation from the sun passes through greenhouse gases found in atmosphere
     • 2. some of SWR is reflected while most are trapped and absorbed by the earth's surface
     • 3. heated earth's surface emits longwave radiation to the atmosphere
     • 4. greenhouse gases trap LWR, warming the atmosphere
     • enhanced greenhouse effect
       • the inc in conc of greenhouse gases in atmos
       • human activity has released greater GG than natural emissions
       • there will be less LWR that escape into space, thus more LWR trapped & heats up earth's surface
       • human causes
         • deforestation
           • loss of forests due to removal/clearance of trees in forested areas
             • trees absorb co2 (GG) through photosynthesis
           • a) results in fewer trees to absorb co2, leading to an inc in co2 lvls in the atmosphere
           • b) exposes soil to sunlight, increasing the soil's temp & carbon oxidation
             • carbon oxidation : carbon in soil reacts with oxygen in atmos to prod co2
             • soil contains carbon which is accumulated through the decaying of dead leaves & animals
             • inc lvls of co2 in the atmos
           • e.g greatest loss of forests in south america's amazon rainforest
             • betw 2000 & 2010, 52000km2 lost
         • burning of fossil fuels
           • fossil fuels are formed from dead organic matter that has decomposed
             • e.g oils, coals & natural gas
           • to produce energy for industries, transportation, domestic & commercial use
           • prod. large amt of co2
             • e.g china, usa, uk in 2010 released 30.6b tonnes of co2. an inc from of 5.6% from 2009
         • agriculture
           • organic matter, dead leaves & manure prod methane during decomposition
           • rice cultivation : tractors run on fossil fuels, releasing co2
             • use of inorganic fertilisers inc nitrous oxide (GG) in the soil. it is released when the soil is ploughed
           • cattle farming : cattles release methane gas as waste gases
         • industries
           • prod. of goods & services within a country
             • e.g manufacturing involves burning of fossil fuels
               • releases GG as by-products
           • e.g china & india contributes to more global co2 emissions due to rapid industralisation
         • urbanisation
           • an inc in the number of ppl living in urban areas such as cities and towns
             • large fossil fuels burnt to provide energy & high use of transportation
               • results in the release of co2
   • impacts of climate change (SLSX)
     • sea lvl rise
       • the inc in the mean height of the sea's surface betw high tide & low tide relative to land
       • threatens low-lying areas & islands
         • 33% of coastal & wetland habitats are likely to be lost in the next 100 years at current rate
           • e.g majuro atoll in pacific ocean will lose 80% of its land if sea lvl rises by half a metre
     • lengthen the growing seasons in certain regions
       • caused by higher temps
       • e.g inc in the types of crops that can be grown in UK such as blackberries & maize (advantage)
       • e.g in yunnan, china production of fruits (apples & cherries) require cool weather conditions (disadvantage)
     • spread of infectious insect-borne diseases
       • an inc in temps and rainfall
         • insects thrive in these favourable conditions
       • spread of infectious diseases such as malaria & dengue
         • e.g dengue fever had been reported in a cool region such as nepal & bhutan for the first time in 2004
     • extreme weather events
       • severe & rare weather phenomenon that results in significant economic losses & loss of lives
       • e.g heatwaves, floods, droughts, tropical cyclones
       • in aug 2003, europe experienced a heatwave which killed more than 70 000 ppl
   • managing climate change
     • international agreements
       • contracts signed by 2 or more countries
         • 37 DCs & european countries
       • kyoto protocol
         • agreement linked to the united nations framework convention on climate change (UNFCCC)
         • aim to reduce lvls of greenhouse gases
         • came up with measures to address climate change and put them into practice
         • drawn up in 1997, put into action in 2005
       • successes : many countries exceeded their targets
         • encouraging sustainable development
         • clean development mechanisms helped reduce greenhouse gas emissions
         • austria, finland, greece, ireland
       • limitations : countries did not meet target
         • countries that did not sign protocol, continued to contribute significantly to greenhouse gas emissions
         • denmark, sweden, uk
     • national responses (sg)
       • sg green plan 2012
         • launched by ministry of environment in 2002
           • aimed to generate 60% of sg energy needs with natural gas by 2012
         • successes : by 2010, 79% of sg electricity generated by natural gas
         • limitations : needs complex treatment plant. transporting pipelines are buried underground & needs to be regularly checked.
           • high maintenance cost
       • green mark scheme
         • building construction authority launched plan in 2005
           • aimed to encourage more green buildings
         • successes : nlb & standard chartered at changi are green buildings. reported 15% and 35% energy savings
         • limitations : costly to build as materials are recyclable. construction method is environmentally friendly and resource efficient
           • local companies are slower to adopt new construction ideas
       • plant a tree programme
         • started in 1971
           • sg environment council & garden city fund initiated to maintain sg garden city status
         • successes : contributed to 6000 trees planted throughout the island. acts as green lung to remove co2 from atmosphere
         • limitations : trees take time to mature. nparks plant maturing trees like angsana that take at least 25 years to reach its full height