Climate change

Climate change

1. Climate change accounts for any significant change in a region's weather over a period of time of at least several decades. It is constantly changing and for the last 2.5 million years the Earth shifts between cold glacial periods and warmer interglacial periods.

2. 20,000 years ago the Earth was cold however, around 15,000 years ago it started to warm up. Apart from a brief colder period, in the last 1000 years the climate has been warm with minor fluctuations.

3. In the last century there's been a rapid increase in temperature, this is known as global warming. Global temperatures have rose steadily from 13.5° to 14° from the early 20th century to 1940s. Since the 1970s the temperature has rapidly increased again to 14.4° (0.7° rise in the last 100 years) - these changes are said to be caused by human activity.

4. Evidence

   • Biological
     • Pollen analysis - Preserved pollen (found in sediment and peat bogs) can be used to identify the plant it came from. They can also date the time it was deposited (through the age of the sediment). As scientists know what climatic conditions the plants today were formed by through comparisons it can indicate what the climate was like at the time the pollen was produced,
     • Coleoptera beetles - Different species of Coleoptera beetle live in different climatic conditions. When looking at the age of the sediements the remains of these beetles are found, scientists can determine the climatic conditions of when the sediment was laid down.
     • Dendrochronology (tree rings) - This is analysis of tree rings from their cores. Trees form a new ring every year when they're growing. If the ring is thicker then it was a warm wet year whereas thinner rings show a dry, cold climate. Trees can provide reliable dates and visual proof of the climatic conditions in the last 10.000 years.
   • Observations
     • Historical records - Records can indirectly show changes in climate in the past ie. agricultural reports showing changing conditions throughout time. Also, since the 1870s daily weather reports have been taken and kept providing information on how the climate has changed.
       • In tudor times - Frost fairs were held on the Thames river - information found from documenting events.
     • The hottest years have occured since the 1980s (1990s was the hottest decade). This trend has continued through the 21st century - no doubt the world is heating up.
   • Physical
     • Changing sea levels - Changes in sea level indicates the different climates. As the climate warms, ice caps melt causing the sea level to rise (eustatic) or flooding glacial/river valleys creating fjords and rias.
     • Ice core analysis - Glacial ice is drilled into to extract the cores. Carbon dioxide and other gases are a climate indicator as they show the temperature the period would have been when an ice layer was formed. High levels of CO2 suggest warm climates, low levels suggest a colder climate. Different isotopes of oxygen are formed depending on the temperature, high levels of O-18 suggest a cold climate whereas higher levels of O-16 suggest a warmer climate.
       • In Antartica and Greenland there are records that date back 10.000 years
     • Glacial deposits - Records show ice advance during colder periods and ice retreat in warmer ones. They can date the glaciers through looking at pictures and rock deposits, the distance from the rock and the glacier is also an indicator (if the glacier is further away it shows an increase in temperature in that period)
       • Presence of carved glacial lakes in Yorkshire suggest that area was covered in ice during the last ice age
     • Carbon dating - Carbon-14 is an isotope of carbon which decays at a known rate, unlike carbon-12 that doesn't decay. Plants take in carbon dioxide during photosynthesis so by comparing the levels of the two carbons it indicates the age at which the plant died. The vegetation present at the time suggests the climate of that period. Most accurate measure - dates back 50,000 years.

5. Causes

   • It has been agreed by scientific consensus that the raise in global temperature is due to the human enhancement of the greenhouse effect. Increasing amounts of CO2 and methane are the main contributors towards the rise in temperature and humans are increasing the concentration of these greenhouse gases.
     • Greenhouse effect: Greenhouse gases absorb outgoing long-wave radiation, so less gets lost to the atmosphere. This keeps the planet warm however, too much greenhouse gases means too much energy is trapped.
   • Burning fossil fuels - CO2 is released into the atmosphere when fossil fuels (oil, gas and coal) are burnt eg. in power stations or car emissions (nitrous oxide). Since the industrial revolution - atmospheric CO2 levels have increased from 280ppm (parts per million) to 380ppm.
   • Deforestation - Plants remove CO2 from the atmosphere through photosynthesis so when the trees/plants are chopped down they stop taking in CO2. Also, when they're burnt it releases the CO2 into the atmosphere.
   • Farming - The use of nitrogen based fertilisers to help crops grow releases nitrous oxide and livestock produce methane which contributes to the atmosphere.The burning of peat bogs (which stores CO2) releases the gas into the atmosphere.

6. Impacts

   • Rising sea levels - In the 20th century the sea rose an estimated 0.17m with the rate of increase being 1.8mm a year (between 1993 to 2003). These rising sea levels along with higher tides and stormier weather pose a threat to low lying communities.
     • Tuvalu - Comprised of 9 atolls (totalling 10 sq. miles scattered over 500,000 sq. miles of ocean south of the equator, 400m NE of Australia. The land is very low lying (only 5m asl) and could be destroyed within 50 yeears due to global warming.
   • More intense/frequent extreme events - heatwaves, floods, droughts and storms will last longer and increase in intensity due to the higher temperatures. Tropical storms with be stronger and more destructive as the ocean will be a higher temperature giving the storm more energy. (93% of extra heat is stored in the oceans)
     • Typhoon Haiyan travelled over areas in the Pacific ocean that were 5 1/2°F hotter than usual before hitting Tacloban - it was the most destructive storm to make landfall.
   • Areas that experience monsoon climates may see more intense rainfall and more inconsistency (monsoons are getting heavier in recent analysis) - could cause many impacts such as landslides and flash floods due to heavy rain, crop shortages and food insecurity as agriculture is affected.
     • Bangladesh - Population of over 160 million it's very densely populated, also one of the poorest nations and likely to be very affected by climate change. Increase in the frequency and severity in cyclones (warmer temperatures in Bay of Bengal). 20% increase in river discharge (glacial melt in the Himalayas, source of the Ganges, Meghna and Brahmaputra rivers, and increased precipitation). 15% of low lying land will be inundated by the sea (predicted 1m increase in sea level by 2050). Mass migration into northeast India (displaced by flooding and loss of land). Food shortages are likely to occur with a 30% reduction in rice crops.
   • Coastal regions and areas around estuaries may become more vulnerable - increase in frequency and magnitude of storms/storm surges and due to sea level rising flooding may become more frequent. Flooding leads to disruption in the transport, manufacturing and housing sector and can cause long term issues such as damage to agriculture, coastal power stations and salt contaminating water supplies.
     • With sea levels predicited to rise between 13-37cm by 2050 areas in East Anglia, near the Thames estuary and Lancashire will become vulnerable.
   • A rise in temperature could lead to changes in agriculture - cereal crops yields will decrease whilst potato and sugar beet crops increase. New species could be introduced ie. wine and it'll increase the length of the growing season for trees/grasses. Species are likely to migrate northwards and to higher altitudes (where it's cooler) with some becoming extinct if they couldn't adapt. There may also be invasions of new spreading weeds, pests and diseases and foreign species of birds/mammals may come to the UK which may outcompete native species that are already here.
   • The soil could be affected - higher temperatures lead to a lower water holding capacity (soil less easily inflitrated) leading to soil moisture deficits which could affect agriculture. Clay soil with large shrink-well potential could cause a problem when building foundations/structures on top (found central, eastern and southern England)
   • Water/ energy - In the winter there would be a water surplus (wetter winters) however in the summer a water deficit (drier summers). Higher temperatures would decrease the demand for heating however the demand for air conditioning would increase causing a rise in the countries energy consumption.

7. Responses

   • Local (Individual/regional level, locals have developed initiatives to reduce carbon emissions)
     • Recycling - Reduces climate change as more energy is needed to make a product from scratch than recycling it. It also reduces landfill waste that generate gases (ie. methane). Prevents 10-15 million tonnes of CO2 being released every year. BUT... problems such as transporting products to be recycled creates transport emissions (local facilities need building)
     • Using public transport more (or walking/cycling) reduces carbon emissions. The average car produces 2.7 tonnes of CO2 every year so by walking/cycling journeys of less than 5 miles it was reduces emissions considerably. BUT... many prefer using a car as it's more convenient and often faster.
     • Insulating homes properly with double glazing, cavity wall insulation and loft lagging will reduce the amount of energy a household uses in heating. Grants are often available to insulate older housing
     • Choosing energy efficient appliances - reduces fuel consumption therefore emissions from power stations. Products nowadays are around 50% more efficient than previous models (if everyone upgraded their fridges/freezers it would prevent the release of around 3.7 tonnes of CO2 a year) BUT... replacing all these appliances would create a lot of waste, appliances use energy to manufacture and transport emissions to reach the consumer.
     • Use energy wisely - Turning off lights and using energy efficient light bulbs. Wash at lower temperatures (30°). Don't leave appliances on stand-by. Reduces central heating.
   • National (strategies for the UK to reduce CO2 emissions and the impacts of climate change)
     • Changing the energy mix - (current: 73% fossil fuels, 17% nuclear, 8% renewables), replacing fossil fuels with nuclear or renewable energy will reduce greenhouse gas emissions from power stations. Aim to be 30% renewables by 2020. Creating offshore wind turbines and harnessing tidal power, also wave/solar panels. Government encouraging small scale projects ie. by relaxing laws on solar panels. BUT...environmental problems - nuclear creates waste we do not know how to dispose of, tidal damages coastal ecosystems. Have to rely on fossil fuels for the moment as current number of renewables would not meet the energy demand.
     • The carbon trust - granted £65 million from the government over 5 years to help provide loans for small/medium sized businesses investing in improving energy efficiency
     • New technologies to reduce emissions from power stations - Carbon Capture and Storage (CCS) is designed to capture the emission from the power stations (therefore reducing the amount that goes into the atmosphere) and transport it to places it can be stored safely. Potential to reduce emissions by 90%. BUT...still in the developmental stage so there could be problems that arise ie. risk of stored CO2 leaking. Uses fuel/creates transport emissions when transporting.
     • Reducing emissions from transport - encouraging people to buy energy efficient vehicles buy reducing tax of low emission cars, financial incentives to encourage people to buy electric/hybrid cars, encouraging the use of public transport by introducing bus lanes to make journeys quicker and encourage bus use ie. Cambridge. BUT.... still older cars with higher emissions on the roads and producing the technologies for electric/hybrid cars uses a lot of energy which produces emissions.
   • International (Agreements to address the climate change problem and reduce carbon emissions)
     • Kyoto Protocol (1997) - Came into action in February 2005, 162 countries signed and agreed to monitor and reduce their greenhouse emissions. Agreed that industrialised countries would reduce 6 greenhouse gases by 5.2% of their 1990 emission levels - aimed to reduce the atmospheric pollution levels to those of 1990 by 2012.
       • Carbon credits - Countries are set an annual CO2 pollution limit. Major polluting countries can 'buy' carbon credits off less polluting countries who don't reach their quotas. However, if a country still goes above their limit they'e fined, are forced to have to invest more into renewable technology to reduce CO2 emissions or pay for improved technologies/planting trees in developing countries.
       • Countries who signed the Kyoto Protocol succeeded in reducing their emissions, however, the world wide CO2 levels rose 35% from 1997 (2012) due to larger developing countries that were not originally included in the treaty (ie. China and India) which are now the world's largest emitters. Also countries who were some of the biggest emitters at the time ie. USA and Australia refused to sign the agreement as they believed it was potentially damaging to the economy as the targets were unattainable
     • Copenhagen Accord (COP15) (2009) - 192 involved, agreed that the maximum temperature rise was to be kept below 2°C, developed countries to set their own emission reduction targets and to pledge $30 billion for short-term funding for immediate action till 2012. To pledge $100 billion annually by 2020 for long-term financing and to help developing countries.
     • The Paris Agreement (COP21) (2015) - Aims to strengthen global responses to the threat of climate change by keeping the global temperature well below 2°C above pre-industrial levels and try to limit the increase even further to 1.5°C. Also, created new frameworks and financial flows in aims to strengthen the ability to deal with the impacts of climate change, reach these ambitious goals and support developing countries and those most vulnerable. Requires countries to put foerward 'nationally determined contributions' (NDCs) and to strengthen these efforts in the future, they have to regularly report on their emissions and implementation efforts.