Y9 Unit 1.4.pdf

Dr Nyi IIP International School Biology Climate change Dr Nyi IIP International School Biology Weather or climate? When people talk about climate, they mean the weather of a place over a muc...

Dr Nyi IIP International School Biology Climate change Dr Nyi IIP International School Biology Weather or climate? When people talk about climate, they mean the weather of a place over a much longer time, usually more than 30 years. Weather can change in a few hours or even in minutes. Climate information includes the statistics of weather information that tells us about the normal weather as well as the range of extreme weather at that place. Climate is the long-term pattern of temperatures, wind and rainfall on Earth. 9/5/2024 Climate Change 2 Dr Nyi IIP International School Biology 9/5/2024 Climate Change 3 Dr Nyi IIP International School Biology 9/5/2024 Climate Change 4 Dr Nyi IIP International School Biology Global Warming Global warming is a gradual increase in the average temperature on Earth. It is being caused by an increase in ‘greenhouse gases’, which act like a blanket around the Earth. These are gases that can trap heat. Carbon dioxide is a greenhouse gas. Humans burning fossil fuels cause the release of a lot of carbon dioxide. 9/5/2024 Climate Change 5 Dr Nyi IIP International School Biology Greenhouse gases Carbon dioxide and methane are ‘greenhouse gases’. In stage 8, you learnt how carbon dioxide helps to keep the Earth warm. Without any carbon dioxide in the atmosphere at all, the Earth would be a frozen place, unable to support life. Other greenhouse gases ?? 9/5/2024 Climate Change 6 Dr Nyi IIP International School Biology Greenhouse gases But at the moment, we have too much carbon dioxide in the atmosphere. Look back at the carbon cycle diagram in Topic 1.3. You can see that some carbon from the atmosphere ends up in fossil fuels. But if we extract them and burn them, we release the carbon in them back into the air, in the form of carbon dioxide. Carbon dioxide levels in the atmosphere are increasing. This is affecting the climate on Earth. (causing Global warming) 9/5/2024 Climate Change 7 Dr Nyi IIP International School Biology 9/5/2024 Climate Change 8 Dr Nyi IIP International School Biology 9/5/2024 Climate Change 9 Dr Nyi IIP International School Biology Climate change in the past The Earth’s climate has been very different in the past compared to the climate today. 9/5/2024 Climate Change 10 Dr Nyi IIP International School Biology Ice Age About 2 billion years ago The first Ice Age Since then Alternate warm (no ice at the poles) & cold (ice age) Snowball Earth 650 million years ago Earth – covered with ice and snow ‘Slushball Earth’ (Slush is melting ice) 9/5/2024 Climate Change 11 Dr Nyi IIP International School Biology Asteroids colliding with each other 470 million years ago two asteroids collided with one another between Earth and Mars Collision – produced huge quantities of dust light & heat from Sun another Ice age and the Earth became much colder – the ice caps spread from the poles and sea level fell. 9/5/2024 Climate Change 12 Dr Nyi IIP International School Biology Asteroids colliding with Earth 67 million years ago an asteroid collided with Earth near Mexico Collision generated a condition like massive bomb explosion causing a) Very high temperatures near collision site b) Massive tsunami c) Huge amt. of rock and dust less light reaching Earth Plants can’t photosynthesize No food for animals Mass Extinction up to 75% of all the species Disruption of food chains including dinosaurs 9/5/2024 Climate Change 13 Dr Nyi IIP International School Biology Could other objects collide with Earth? Objects in space that are smaller than an asteroid are called meteoroids. When meteoroids enter Earth’s atmosphere they are called meteors. Some people call meteors shooting stars as they appear like stars moving very fast across the sky. They usually present little risk as they burn in the atmosphere due to heat from friction. Some large ones can create shockwaves; in 2013 a meteor exploded over Russia and shattered windows. The parts of meteoroids that do collide with Earth are called meteorites. 9/5/2024 Climate Change 14 Dr Nyi IIP International School Biology 9/5/2024 Climate Change 15 Dr Nyi IIP International School Biology Could other objects collide with Earth? If an object is large enough, it can cause local damage, or even damage that affects the whole planet. In 1998, scientists started making detailed observations of objects that could possibly cause damage to Earth. When assessing the possible risk to Earth, scientists look at: the mass or diameter of the asteroid the closest possible approach to Earth. An asteroid passing further from Earth may be a greater risk than one passing closer if its mass is greater. 9/5/2024 Climate Change 16 Dr Nyi IIP International School Biology Could other objects collide with Earth? For example, a comet less than 100 meters across will explode high in the atmosphere and probably do no harm whatsoever. If the comet is 10 kilometers across or larger (that is, if the impact carries an energy of more than about 100 million megatons), the resulting global environmental damage will be so extensive that it will lead to a mass extinction, in which most life forms die. This is what happened 65 million years ago, when the dinosaurs went extinct. 9/5/2024 Climate Change 17 Dr Nyi IIP International School Biology Keywords slush: partly-melted snow mass extinction: the complete loss of a very large number of species meteoroids: objects in space that are smaller than an asteroid meteors: a meteoroid when it moves through the Earth’s atmosphere meteorite: part of a meteor that reaches the Earth’s surface 9/5/2024 Climate Change 18 Dr Nyi IIP International School Biology Questions 1. You learnt about asteroids in Stage 8. Describe what an asteroid is, and where asteroids are found. An asteroid is a rock, smaller than a planet, which orbits the Sun. 9/5/2024 Climate Change 19 Dr Nyi IIP International School Biology Questions 2. Outline three different ways in which the asteroid collision 67 million years ago would have made it difficult for plants and animals to survive. It produced a lot of heat, which killed plants and animals close to the collision site. It produced a huge tsunami, which killed plants and animals on land that were swamped by sea water. It sent dust high into the atmosphere, so plants died because they could not photosynthesise. Animals then died because there was no food for them to eat. 9/5/2024 Climate Change 20 Dr Nyi IIP International School Biology Climate change today and in the future For the last 2000 years or so, our climate has been fairly stable. People living in different places have become used to having more rain at some times of year than at other times, or temperatures that change in a predictable way during one year. Knowing this helps people to choose the best crops to grow, and to know when they should sow seed and collect the harvest. 9/5/2024 Climate Change 21 Dr Nyi IIP International School Biology Climate change today and in the future Now, however, the mean temperatures on Earth are increasing. This is caused by an increase in carbon dioxide concentration in the atmosphere. Carbon dioxide is a greenhouse gas, which traps heat energy close to the Earth’s surface. When carbon dioxide concentrations increase, more heat is trapped. 9/5/2024 Climate Change 22 Dr Nyi IIP International School Biology The Earth’s mean temperature changed between 1880 and 2016 Y-axis on the graph does not show the actual temperature – it shows how much it differs from the temperature in 1880. 9/5/2024 Climate Change 23 Dr Nyi IIP International School Biology Questions 3. Look at the graph. How much higher was the mean temperature in 2016 than in 1880? 1.3°C 4. Describe the trend in the graph between: 1880 and 1910 and 1910 and 2016. The temperature fell by 0.3°C between 1880 and 1910. It rose by 1.6°C between 1910 and 2016. 9/5/2024 Climate Change 24 Dr Nyi IIP International School Biology Impacts of climate change 9/5/2024 Climate Change 25 Dr Nyi IIP International School Biology More extreme weather events The higher temperatures mean that there is more energy in the atmosphere. This increases the chance of extreme weather events, such as hurricanes and typhoons. Many scientists think that we are already seeing an increase in the number of storms, and in their severity. It is difficult to be certain, because there has always been a lot of variation each year in the number of big storms. 9/5/2024 Climate Change 26 Dr Nyi IIP International School Biology More extreme weather events Tropical cyclone Idai hit the east coast of southern Africa in 2019. It was one of the worst storms ever to affect Africa and killed more than 1300 people. Severe flooding destroyed homes and fields, damaging people’s livelihoods. Was this a result of climate change? We cannot say, because storms like this can happen anyway. However, there seem to be more of them now, and they are more violent. 9/5/2024 Climate Change 27 Dr Nyi IIP International School Biology 9/5/2024 Climate Change 28 Dr Nyi IIP International School Biology Less predictable rainfall The changing climate is also making it more difficult for people in some parts of the world to grow crops. Rains may come late, or might not come at all. Or rain may fall when it doesn’t normally fall – or fall much more heavily, causing flooding. Monsoon rains are usually welcomed, but not when they are so heavy that they cause severe flooding. In 2019, the monsoon rains in Pakistan, India, Nepal and Bangladesh came later and were heavier than usual. Millions of people in these countries were affected by floods. 9/5/2024 Climate Change 29 Dr Nyi IIP International School Biology Less predictable rainfall When rains fail, people may lose their harvests. Long droughts also increase the risk of wildfires. All of these changes affect not only people, but also plants and animals. This wildfire in Australia followed a long period of drought. 9/5/2024 Climate Change 30 Dr Nyi IIP International School Biology Rising sea levels The increase in the Earth’s mean temperature affects sea level. Water expands as it is heated, so if the sea temperature increases, sea level rises. Melting ice caps and glaciers add extra water to the oceans. This glacier is getting smaller (retreating) as temperatures increase. Sea level has been rising at a rate of about 3 mm per year. Scientists estimate that more than 600 million people are at risk from flooding caused by sea level rise by the end of this century. Many megacities are built on the coast – such as Shanghai, Mumbai and Los Angeles – and these are especially vulnerable to sea level rise. 9/5/2024 Climate Change 31 Dr Nyi IIP International School Biology Questions 5. Calculate by how much sea level is predicted to rise by the end of this century. 6. Explain why sea level is predicted to rise. As the mean global temperature increases, more land ice melts and adds extra water to the oceans. Also, higher temperatures cause sea water to expand. 9/5/2024 Climate Change 32 Dr Nyi IIP International School Biology Think like a scientist: How do rising temperatures affect sea level? 1 Melting ice on land and increasing water temperature both increase the water level. Melting ice in the sea does not increase the water level. 2 They indicate how sea level is expected to rise. 9/5/2024 Climate Change 33 Dr Nyi IIP International School Biology 9/5/2024 Climate Change 34 Dr Nyi IIP International School Biology Respiration and combustion increase the level of carbon dioxide in the atmosphere. Photosynthesis decreases it. Plant more trees, because they will photosynthesise and take carbon dioxide out of the air. Stop deforestation (same reason). Stop burning fossil fuels, to reduce combustion. Stop using so much energy, so that we do not need to use as much fuel. Eating less meat (because production and transport of meat uses a lot of energy and produces a lot of carbon dioxide) or reducing air travel. 9/5/2024 Climate Change 35 Dr Nyi IIP International School Biology Check your progress 1.2 a the type of seaweed b the temperature; the light intensity; the size of the piece of seaweed; the time for which the apparatus is left. c the volume of gas collected (after a set period of time). 9/5/2024 Climate Change 36 Dr Nyi IIP International School Biology 1.3 a 4 tonnes per hectare b Adding more than 60 kg per ha gives only a very small increase in yield. It is likely that the cost of the extra fertiliser would outweigh the small increase in income from selling the grain. c The wheat plants use the nitrate to make proteins. The proteins can be used to make new cells, some of which will be used to produce the grains. d In a different place, there might be a different concentration of nitrate in the soil before the fertiliser is added. There might be a lack of other minerals in the soil. The soil might be better or worse at holding water. There might be more shade in one place than another. The temperature might be different. e Magnesium is needed for making chlorophyll. 9/5/2024 Climate Change 37 Dr Nyi IIP International School Biology 1.5 b i Many species of organisms are completely destroyed. ii Look for the idea of long-term reduction in photosynthesis because of dust thrown up into the atmosphere, which reduces light penetration. This in turn reduces food for animals. Other reasons are the immediate results of the impact, including the heat and pressure wave in the vicinity of the impact, and a massive tsunami. 9/5/2024 Climate Change 38 Dr Nyi IIP International School Biology Exercise 1.4 Interpreting graphs about climate change 2 Sea level is rising. Sea level has risen by 230 mm since 1880. 3 Sea ice covered a smaller area in 2017–2018 than between 1979 and 2016. Sea ice appeared later and disappeared earlier in 2017–2018. 4 You would need to collect data for more years after 2017–2018 to see if this is a trend or just a one-off result for this period. 9/5/2024 Climate Change 39 Dr Nyi IIP International School Biology Exercise 1.4 Interpreting graphs about climate change 5 We can correlate an increase in burning fossil fuels with the rise in carbon dioxide concentration. 6 In the northern hemisphere there is more light and higher temperatures in summer than in winter. Plants photosynthesise more in summer, using more carbon dioxide. So carbon dioxide concentration falls in summer and rises in winter when plants cannot photosynthesise as much. 9/5/2024 Climate Change 40 Dr Nyi IIP International School Biology 9/5/2024 Climate Change 41 Dr Nyi IIP International School Biology Meteorological Seasons A/to the meteorological definition, the seasons begin on the first day of the months that include the equinoxes and solstices. In the Northern Hemisphere, for example, spring runs from March 1 to May 31; summer runs from June 1 to August 31; fall (autumn) runs from September 1 to November 30; and winter runs from December 1 to February 28 (February 29 in a leap year). 9/5/2024 Climate Change 42 Dr Nyi IIP International School Biology 9/5/2024 Climate Change 43