Evidence for climate change

Transcription

1 Evidence for climate change

2 Climate change over the quaternary period The quaternary period is the most recent geological time period spanning from around 2.6 million years ago to present day. This is a very recent time period when you compare the age of the earth which is 4600 million years (4.6 billion years old)

3 Before the quaternary the earths climate was warmer and quite stable

4 Temperature change over the last 400,000 years Thousands of years ago During the Quaternary, global temperatures have shifted from cold glacial periods (ice ages) that have lasted around 10,000 years and warmer interglacial periods. The last glacial period ended 15,000 yeas ago. Since then the climate has been warming Global warming is the term used to describe the sharp rise in temperatures over the last century

5 Temperature changes over the last 130 years 1990 s was the hottest decade in the last century was the warmest year on record. Britain s expected weather on occasions is becoming different from the norm

6 Top five wettest years in the UK ,337.3mm ,330.7mm ,309.1mm ,295.0mm ,283.7mm (Source: Met Office) Of the top 5 wettest years recorded in the UK 4 of them have occurred in the last 12 years

7 Rainfall amounts 2012 In 2012 March the rainfall was 61% below average, month later 76% above average, that s a difference of 137% increase in one month.

8 Hockey Stick Graph The Hockey stick graph shows temperature variations over the last 1000 years Grey areas are areas of uncertainty because we use different sources of evidence the temperature readings vary

9 Hockey Stick Graph- evidence FOR! Sustained temperatures for around 1000 years, then a sharp increase around Seen by many as proof that humans have influenced our current climate

10 Hockey Stick Graph RELIABILITY?? HOWEVER... Accurate temperature recordings only go back 150 years Temperature gained from a range of sources such as tree rings ice cores etc.

11 Assessing the Evidence for Global Warming 1. Instrumental readings thermometers have been used to keep a record of temperatures, however the further we date back the less reliable the data maybe. 2. Glacial retreat land ice is retreating however this could be due to reduced snowfall not an increase in temperature

12 Assessing the Evidence for Global Warming 3. Arctic ice arctic ice has thinned to half its thickness. This can speed up warming as less ice will mean less solar insulation reflected and more absorbed The proportion of solar radiation that is reflected by a given surface is called the Albedo Clouds and the ice-covered mass of Antarctica appear bright because they reflect strongly; i.e. they have a high Albedo up to 90% in the case of fresh snow and sea-ice. This reduces the amount of energy from the sun that is absorbed and cools temperatures By contrast, the oceans have a low Albedo (typically less than 5%) and appear dark in this image. Therefore they absorb the energy from the sun and warm temperatures

13 Assessing the Evidence for Global Warming 4. Ice cores when snow falls year on year it builds up a record. Trapped water molecules and air can be analysed to give us an idea of past temperatures and gases present. Restricted to certain areas of the world that have glacial ice 5. Early Spring in the last 30 years there have been signs of seasonal shifts, spring arriving earlier for example. Bulbs such as crocuses and daffodils are flowering earlier.

14 Assessing the Evidence for Global Warming 6. Sea level rise rose 17 cm in last century Due to tectonics moving plates?? 7. Warming oceans degrees Significant amount?? 8. Extreme weather events number of high temp recorded events in USA increased Other places have had cool temp recordings, just because we are noticing them more now due to technology (TV, News) 9. Ocean acidification increased by 30% due to C02 being absorbed Increase pollution from countries particularly developing countries, and due to increase population

15 Natural Causes of Climate Change

16 Variation in Solar energy Evidence suggests that sunspot activity, which occurs in cycles, may affect our climate. A sunspot is a dark patch that appears from time to time on the surface of the sun. These dark patches are caused by magnetic activity inside the sun The sunspot increases from a max to a min and then back to a min over a period of 11 years

17 Variations in Solar Output Models predict that a change in solar output of only 1 percent per century would alter the Earth's average temperature by between 0.5 to 1.0 degrees Celsius. They say sunspot activity was responsible for the warm years of the 1940 s. However since 1970 evidence suggests the sun has cooled slightly, therefore not a cause of recent global warming

18 Orbital Changes: The Milankovitch Cycles Milankovitch was a Serbian Geophysicist who studied the earths orbit while in prison during the war He discovered 3 distinct cycles that he believed affected the worlds climate

19 1. Eccentricity The earth experiences more of the suns energy when the earths orbit is more elongated (elliptical) The earth experiences less of the suns energy when the earths orbit is more circular. The change in cycle from Elliptical to circular occurs every 100,000 years

20 2. Axial Tilt The earth s axis is currently titled to 23.5 degrees. However the earth tilt can vary from 21.5 degrees to 24.5 degrees. The earth s tilt moves backwards and forwards between the two extremes every 41,000 years. The greater the tilt angle the more solar energy the poles receive The lesser the tilt angle the less solar energy the poles receive

21 3. Precession Precession describes the natural wobble of the earth, like a spinning top. A complete wobble takes 26,000 years This wobble affects the relationship between the earths tilt and eccentricity This is the reason why certain parts of the world, such as Norway, experience 24hours of daylight in the summer and 24 hours of darkness in the winter. As the earths precession changes it changes the distance we are from the sun at certain times of the year. Look at examples of the following pages.

22 3. Precession The sun in this example is closer to the earth in January This will mean warmer winters in the northern hemisphere The sun is further away from the earth in July This will mean cooler summers in the northern hemisphere

23 3. Precession The sun in this example is closer to the earth in July This will mean warmer summers in the northern hemisphere The sun is further away from the earth in January This will mean cooler winters in the northern hemisphere.

24 Volcanic Activity It has been accepted that volcanic activity has influenced climate in the past. The increase of dust particles absorbs and scatters incoming radiation. This reduces temperatures on earth. This tends to be a short term impact. Example The eruption of Mount Pinatubo in 1991 is said to have temporally offset the greenhouse effect.

25 Volcanic Activity Sulphur Dioxide is released from volcanic eruptions. When this is mixed with water vapour it creates Sulphuric acid that acts like tiny mirrors reflecting radiation from the sun. This can last a lot longer and effect climate for years Example Mount Tambora 1815 eruption reduced global temperatures by C and 1816 became known as The year without a summer Across the world harvest failed, it was the worst famine in Europe in the 19 th century resulting in an estimated 200,000 deaths

26 Human Causes Of Climate Change

27 Natural and enhanced GHE

28 1. The suns rays reaches the earth as shortwave radiation, known as visible light. The Green House Effect 2. The shorter the wave the higher the energy 3. It is able to get through the greenhouse gas layer Green House gases Carbon dioxide, methane and nitrous oxide

29 1. The shortwave radiation from the sun is absorbed or reflected. 2. If it is absorbed the object that it hits begins to warm. 3. The warm objects then re-emit long wave radiation, known as infra red The Green House Effect Green House gases Carbon dioxide, methane and nitrous oxide

30 1. The Reflected radiation remains as shortwave radiation, this has the energy to escape through the greenhouse gases back The Green into space House Effect 2. The absorbed radiation is now released as long wave radiation that has less energy and so only some will escape. The rest will be re absorbed by the earths atmosphere, keeping us warm, this is GOOD (14deg c rather than -17 deg c) Green House gases Carbon dioxide, methane and nitrous oxide

31 1. Humans are increasing the amount of greenhouse gases in the atmosphere 2. This means that less and less long wave radiation can The Green House Effect escape back into space 3. More and more long wave radiation is absorbed by the atmosphere increasing world temperatures. This is BAD!! Green House gases Carbon dioxide, methane and nitrous oxide

32 Recap Quiz 1. Name of incoming radiation? 2. Wave length? (sort of long?) 3. Name of outgoing radiation? 4. Wave length? 5. How is reflected and absorbed radiation different? 6. Name the 3 major green house gases

33 What am i???? 1. Account for 20% of GHG 2. I have increased by 30% since I come from rice farming 4. Increased fertiliser use produces me 5. I am more effective at trapping heat radiation but here is less of me 6. The more rubbish you throw away the more there is of me 7. I make up 60% of GHG 8. The more electricity you waste, the more there is of me 1. Methane 2. Carbon Dioxide 3. Methane 4. Nitrous Oxide 5. Nitrous Oxide 6. Methane 7. Carbon Dioxide 8. Carbon dioxide, Nitrous Oxide

34 Why is there More carbon dioxide in the atmosphere from October to January?

35 Effects of Climate change

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37 The Enhanced Greenhouse Effect How do these images link to the enhanced Greenhouse Effect? Write a short paragraph explaining the links

38 Have you included the following? Self assess your answer and amend in green pen. Agriculture contributes to approximately 20% of global greenhouse gas emissions. It produces large amounts of methane: cattle produce it during digestion microbes produce it as they decay organic matter under the water of flooded rice paddy fields. As the worlds population increases more food is required, especially in areas such as Asia where rice is the staple diet. When countries increase their standard of living there is almost certainly an increasing demand for meat. Within 10 years the worlds forests could disappear completely. The main reasons for deforestation include: Clearing land for agriculture so farmers have space to plant crops and graze livestock Logging for wood and paper products Building roads to access remote areas Making room for the expansion of urban areas. Trees absorb CO2 during photosynthesis. When trees are burnt to clear an area, such as slash and burn, the CO2 stored is also released.

39 There are two approaches Mitigation reducing GHG or increase carbon sinks (stores) Targets to reduce GHG (e.g. Paris Agreement) Using alternative renewable energy sources (e.g. Wind, Solar or Hydroelectric Power instead of the Fossil Fuels; coal oil and gas) Carbon capture/ carbon credits Adaptation Changing lifestyles to cope rather than to stop climate change Planting drought resistant crops in areas where rainfall is limited Managing coastline erosion/ retreat in areas where sea levels are rising Better quality fresh water provision in drought stricken areas/ periods

40 Mitigation V s Adaptation In order to make a bigger difference both methods have to operate together Ultimately, mitigation is the long-term aim but we wont reduce GHG emissions over night, so in the short term we must adapt Mitigation costs are up front costs meaning they involve a large amount of investment up-front. Higher income countries (HICs) are in a better financial position to do this than lower income countries (LICs) To adapt costs continue over a longer timescale. Ability to adapt is also linked to development. HICs have money and resources to adapt where as LIC s will not.

41 Mitigation V s Adaptation Adaptations need to be linked to the local climate to cope with local impacts Natural systems may not be able to adapt (such as coral reef ecosystems) this in itself is a strong argument that we have to act now.

42 Mitigation Mitigation can operate at a variety of scale Individual consumption choices Local local gvt strategies on cycling, transport. National gvt policies and tax frameworks Global international agreements

43 Mitigation Alternative energy production Switching to renewable energy

44 Mitigation Carbon capture technology Applied to power stations and industry. Carbon dioxide is buried in deep sea or deep under ground in rock.

45 Mitigation Afforestation (planting trees) Large scale tree planting to act as carbon sinks

46 Mitigation Sustainable development Recycling Alternative transport Locally sourced produce

47 International Agreements: Climate Change Mitigation or adaptation? = mitigation strategy = adaptation strategy

48 Without international agreements, the efforts of individual nations would be less effective and potentially unfair. In the Kyoto Protocol of 2005, although 170 countries signed up, 2 major emitters (USA and Australia) refused to sign. This is unfair because: Why should some countries bare the cost of trying to reduce emissions, by developing alternative energies for example, whilst others are not putting in the same time, money or effort, despite being higher income countries (HICs) that could afford to. Emissions are not restricted to the air space over the countries who create the emissions, in the same way that the impacts of increased carbon emissions are not just restricted to those countries who refuse to sign an agreement to reduce their emissions. Ultimately, if some countries continue to emit high levels of carbon it impacts on other countries worldwide, regardless of their own countries individual efforts to reduce emissions. Lower income countries (LICs) can t be expected to cope on their own, when trying to develop adaptation strategies, especially when they have not been the main cause of increased carbon emissions (it has mainly been the result of industrialisation and development in Higher Income countries) So, with 195 countries adopting the first ever universal and legally binding deal in the 2015 Paris Agreement, hopefully, with all these countries working together to achieve the same goal, we can expect to see a quicker and fairer reduction in carbon emissions

49 Adaptation Agricultural systems Moving production to another location due to changing temperatures and extreme weather Increasing irrigation in areas due to changing precipitation. Water harvesting Shade planting Drought tolerant crops or switching to livestock production which tends to have more guaranteed returns.

50 Adaptation Water supply Himalayas artificial glacier project

51 Adaptation Reducing the risk from sea level rising Prevent development in flood risk areas Maldives.

52 Mitigation and Adaptation The best of both worlds 1. Explain why both mitigation and adaptation are needed to manage climate change Mitigation: This is the long-term aim but we can t reduce carbon emissions or increase carbon sinks over night, it s a slow process (e.g. developing new technologies, changing peoples habits etc) Adaptation: This is an immediate, short term necessity the impacts of climate change are already happening, and they will continue to happen whilst we continue to develop further mitigation strategies, so we have a responsibility to adapt now and to reduce the impacts now for the people who are suffering now!

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54 Before attempting to answer the question, remember to BUG it.

55 PEEL your answer Use PEEL notes to structure your answer. This will help you to communicate your ideas to the examiner in the clearest way. PEEL has four stages: Point give three impacts for this question. Use sentences, not bullet points. Explain give reasons for each point. Use sentence starters such as: This is because... One reason is... Evidence include details from names examples to support each point. Link link the impacts to each other. Use PEE sentence starts such as: A second way is.. or Secondly. Finish if off with a onesentence conclusion.

56 Sample exam questions 1. Explain how climate change can bring changes to the frequency and intensity of tropical storms (6 marks) 2. Justify why managing climate change needs to be a combination of mitigation and adaptation strategies (9 marks +3marks SPaG)