The evidence for climate change and its human causes - PowerPoint Presentation

1. The evidence for climate change and its human causes

2. Getting startedYou’ll need a notepad on which to make notes as you go along, or you could make notes, paste images, etc. on your device.You can view these slides:as a slide-show for animations and to follow linksin ‘normal’ view if you want to add call-outs or extra slides to make notes, paste images, answer questions.In this GEO unit you’ll learn about the evidence for climate change, its human causes and how human activities are adding to the greenhouse effect, topics that feature in nearly all GCSE courses.There is a similar GEO unit about the natural causes ofclimate change.

3. About this unit: evidence for climate change and its human causes.In this unit you’ll learn about:the evidence for climate changethe enhanced greenhouse effect and greenhouse gassesthe links between human activities and climate change.ActivityThe rapid melting of Arctic sea ice is important evidence of climate change today. Click on the image to see how the minimum sea ice in August each year has declined, then note down the change in sea ice area.

4. Evidence for climate changeThere is plenty of evidence that Earth’s climate has changed during the last 2.6 million years (the Quaternary Period). It has gone through colder periods, the Ice Ages (right), and warmer periods, the interglacials. Only very recently in history have humans affected the climate. The evidence for climate change includes:evidence found in nature such as tree rings and ice coreshistorical recordstemperature and CO2 data.ActivityRead this Geological Society resource and watch this BBC video. Then list the evidence for the Ice Ages in the landscape.Europe about 20,000 years ago

5. Evidence for climate change: tree ringsMany trees can live for hundreds of years; the oldest for up to 5,000 years. As trees grow they lay down evidence of the climate from year to year in growth rings in their trunk (right). These rings can also be found in old timber, e.g. used in old buildings and ships.ActivityView the video, then label a copy of the image or note down: what tree rings arewhat they tell us about changing climateshow matching rings in different trees can give us a longer record.ResourceWhy Do Trees Have Rings? BBC Earth Lab

6. Evidence for climate change: ice coresIce sheets build up in layers, formed by each year’s snow fall. Greenland’s ice sheet is 1.5km thick and up to 1 million years old. The evidence of past climates is trapped in the layers of ice: traces of pollen from plants, volcanic ash and bubbles of ancient air.Scientists drill deep ice cores (right) to find and analyse this evidence.ResourcesVideo: Scientists drill deep in Antarctic iceWebsite: Ice cores and climate change.ActivityWatch the video and read the first two paragraphs of the web page - make a copy of Figure 2. Then explain how ice cores can show 1,000-year-old climate data.Ice cores have layers, a bit like tree rings

7. Evidence for climate change: historical accountsHistorical documents can also give us evidence of past climates. For example there are many paintings of winter frost fairs held on the frozen Thames and other European rivers in the Little Ice Age. Frost fair on the River Thames, 1683ResourcesWatch: Climate change and the Little Ice AgeRead more on frost fairs here.ActivityWatch the history video to 5:00 minutes. Note down examples of:types of records giving evidence of climate changehow people were affected and how they reacted.

8. Evidence for climate change: dataClimate scientists have measurements of world temperatures from thermometers going back about 150 years.They can stretch the temperature record further back in time using data from tree rings, ice cores and historical sources.The graph shows +/-temperature changes compared with the mid-19th century (markedas 0ºC).ActivityCopy the graph, then add labels with:approximate dates for the Medieval Warm Period and the Little Ice Ageglobal warming since the 19th century.

9. The greenhouse effectEarth’s average temperature is 14.5ºC. Gasses in our atmosphere keep the planet warm: the natural greenhouse effect. Without it heat would be lost into space and Earth would be much colder: around -18ºC.Over the last 250 years humans have added gasses such as CO2 and methane (CH4) to the atmosphere. They absorb more radiation, so less is lost into space. This is the enhanced greenhouse effect, causing the rising global temperatures you saw on the last slide. Resources Investigate the enhanced greenhouse effect with: this introductory NASA video a more detailed video: the science behind the greenhouse effect (watch out: it’s American so uses Fahrenheit)ActivityView the resources until you’re sure you understand the enhanced greenhouse effect. Then go to the next slide.

10. The enhanced greenhouse effectActivityCopy the diagram. Using what you learned from the last slide, add a detailed Label 7 explaining the enhanced greenhouse effect.

11. Greenhouse gas typesThe main natural greenhouse gases are water vapour, carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O).Water vapour is mostly not affected by human activity, although the amount increasesas the atmosphere warms.The amounts of other greenhouse gases in the atmosphere have increased greatly in the last 250 years, since the Industrial Revolution. This change is anthropogenic: caused by human activities.Greenhouse gas emissions, 2018Methane and nitrous oxide are much stronger greenhouse gasses. But CO2 has most effect overall because humans are emitting large amounts of it into the atmosphere, where it can stay for hundreds of years. Find out more here.

12. Sources of greenhouse gasesSources of greenhouse gas emissions 2014The main human activities creating the additional greenhouse gasses that are driving climate change are:burning fossil fuels forenergy – this accounts for about three quarters ofthe emissionsfarming and land use change (especially deforestation) .ActivityWrite a short summary about greenhouse gasses, combining information from slide 11, the text above and examples from the pie chart.

13. Investigate greenhouse gasses – in more detailGreenhouse gas:Carbon dioxide (CO2)Methane (CH4)Nitrous oxide (N20)How it is emittedActivityFind out in more detail about greenhouse gasses and their sources from this Environment Protection Agency webpage.You could copy these tables and use them to make notes.Source:Electricity and heatIndustryFarming and land use changeTransportBuildingsExamples of emissions

14. Investigate where most CO2 emissions are fromClimate change is a global problem, but some countries and regions create more CO2 emissions than others.click on the image for a bigger mapan atlas may help you.Annual share of CO2 emissions 2017ActivityUse the maps and data on this slide and the next to describe the distribution of CO2 emissions; you could copy and label the maps. Include:examples of countries and continents with high and low emissionssome reasons: think about the data on slides 11–12.

15. Country group CO2 emissions (megatonnes) Per capita (tonnes) High-income 12,67010.4Middle-income 20,9483.7Low-income 1680.3Resourcewatch this NASA animation take a screen shot of the parts of the world which are major CO2 sources.

16. Rising world temperatures and CO2Scientists have known about the natural greenhouse effect since the 19th century.In the 1960s climate scientists made the link between rising world temperatures and levels of CO2 in the atmosphere.Data collected from many thousands of sites worldwide is important evidence for climate change and its human causes.The Mauna Loa observatory in Hawaii is one of the most important – it has been collecting data since the 1950s.ActivityVisit the Earth CO2 homepage to find out:today’s CO2 level changes in atmospheric levels of CO2 since 1957.

17. Greenhouse gases and climate changeCO2 is not the only greenhouse gas, but it is the most important one.Graphs like this one are evidence of the link between human activity, greenhouse gases and climate change.Key: temperature, CO2 Carbon dioxide 175019002012Todayparts per million:400Activity copy the table below and complete it using the graph and weblinkuse the graph to describe the trends for temperature and for CO2, then explain how the two are linked.

18. Climate change impactsClimate change is already having an impact on natural systems and on people. Unless humans take action to limit the rise in global temperatures to 1.5ºC the effects on the planet and people will be very serious. Effects on natural systems include:changing weather patterns and more extreme weather such as hurricanesmelting ice sheets and glacierswarming seas and sea level riseloss of ecosystems.Effects on people include:changes to food and water suppliesimpacts on health and economiesincreases in migration and conflict.ResourcesMet Office webpageImpacts in the UK webpage and videoCheck impacts on your UK postcode.ActivitiesWork through resources 1 and/or 2. List the climate change impacts, add some details and explain how they are linked to climate change.

19. Summary Natural climate change has happened often in Earth history, for example during the Ice Ages. Recently the climate was cooler: the Little Ice Age.Scientists find evidence of past climates in tree rings, ice cores and historical records. They can add these to more recent direct measurements of temperature and CO2 data to build a record of climate change.Recently human activities have emitted CO2, methane and nitrous oxide; these gasses trap additional heat in the atmosphere: the enhanced greenhouse effect.As a result global temperatures have risen steadily, at the same time as greenhouse gasses have increased, especially CO2 – the most important and dangerous greenhouse gas. Its main sources are:burning fossil fuels for transport, industry and homes (about 75%)farming and land use change (deforestation).Some countries are responsible for most CO2 emissions, especially China (highest overall) and High Income Countries like USA (high per capita). Next: if you’re studying Eduqas A or WJEC geography (or if you’re just interested) read on to find out about the carbon cycle.

20. The carbon cycleThe carbon cycle is made up of:stores of carbon (e.g. CO2 in the atmosphere, or carbon (C) in the leaves and trunks of trees) andprocesses (e.g. photosynthesis) that result in:flows or movements of carbon from one store to another. ActivityCopy the example text and colour-code the stores, processes and flows, or copy the photo and turn the text into labels or arrows.Explain why this is called ‘the carbon cycle’.Example: The leaves of trees in the Borneo rainforest (below) absorb CO2 from the atmosphere through photosynthesis. The leaves store carbon compounds. Monkeys eat and digest the leaves: carbon enters their bodies. When they breath out (respiration) they return carbon to the atmosphere as CO2.

21. Deforestation and the carbon cycleForests cover about 30% of the Earth’s land area; they are an important part of the carbon cycle:as well as absorbing and recycling CO2, as they grow trees take carbon out of the atmosphere and store it in their trunks: they are a carbon sink deforestation causes about 10% of climate change. It is a double-whammy because: cutting the trees means they can no longer absorb CO2 from the atmosphereif burned, the trees release the carbon they store into the atmosphere as CO2.ActivitiesWatch this National Geographic video.Show how deforestation changes the carbon cycle: adapt your diagram from the last slide, or adapt the graphic above.

22. Fossil fuels and a long-term carbon cycle300 million years ago South Wales was covered in tropical forests like the one on slide 20. Trees died, decayed and were buried underground. The carbon in their trunks turned to coal, stored in the rocks in layers.Today coal is high in carbon from these ancient forests, making it a really good energy source.Burning coal creates CO2, adding carbon from yesterday to the atmosphere today.Read more about coal here.ResourceWatch this 1930 movie of coal mining in South Wales to about 5:00 minutes.ActivityUse what you learned on slides 20–21 to draw a graphic of this long-term carbon cycle, starting in forests 300 million years ago.

23. LinksFrom the awarding bodiesFind out moreTime for geography has a great summary of the human causes of climate change. It uses the term climate forcings.David Attenborough talks about the impact of climate change for all of us.Evidence, causes and impacts of climate change from the Met Office.To finish with, check Bitesize and watch climate change in 60 seconds.TopicAQA3.1.1.4 Climate changeEdexcel A2.3 Climate change and human activityEdexcel B1.3 Climate change and human activityEduqas A5.1.2 Causes of climate changeEduqas B2.4: Climate change - cause and effectOCR A2.3.1/2 Climate changeOCR B2.1 Climate change – human activityWJEC5.1.1/2 Evidence/causes of climate changeCCEAD: Causes of climate change.

24. GlossaryAnthropogenic: originating or caused by human activity (the word is from anthro = people, + gen = be produced).Carbon sink: something that absorbs more CO2 from the atmosphere than it releases.Climate forcings: factors that upset the global energy budget and cause climate change.Enhanced greenhouse effect: the additional warming caused by human activities that release gasses such as CO2 into the atmosphere.Fossil fuels: coal, oil and gas. When they are burned to create energy they emit CO2, as well as other pollutants.Interglacials: periods with a warmer climate in between Ice Ages.Little Ice Age: a period between the 14th and 19th centuries when the climate was about 0.6º cooler than average.Per capita: per person.Quaternary: a period of geological time, from 2.6 million years ago to today.Trend: the overall pattern or change in a set of data or graph.

25. AcknowledgementsThis presentation has been written by John Hopkin, formerly Head of Accreditation for the GA.FiguresSlide 3: NASA image: https://images.nasa.gov/details-iss028e018177Slide 4: https://www.usgs.gov/media/images/glaciers-extended-over-much-europe-during-last-ice-ageSlide 5: Source of image: https://commons.wikimedia.org/wiki/File:Cross-section_of_an_Oak_Log_Showing_Growth_Rings.jpg Slide 6: https://commons.wikimedia.org/wiki/File:The_EastGRIP_ice_core_freshly_cut_2.jpg Slide 7: https://en.wikipedia.org/wiki/Great_Frost_of_1683%E2%80%9384#/media/File:Old_and_new_London_-_a_narrative_of_its_history,_its_people,_and_its_places_(1873)_(14761544406).jpg Slide 8: https://commons.wikimedia.org/wiki/File:2000%2B_year_global_temperature_including_Medieval_Warm_Period_and_Little_Ice_Age_-_Ed_Hawkins.svg Slide 10: Geography 11–14, Geographical Association (2021)Slide 11: Source of data: https://www.epa.gov/ghgemissions/overview-greenhouse-gases Slide 12: Source: redrawn from https://www.statista.com/statistics/270723/distribution-of-global-greenhouse-gas-emissions-by-sector-worldwide/ Slide 14: https://commons.wikimedia.org/wiki/File:Annual_share_of_global_CO%E2%82%82_emissions,_OWID.svgSlide 15: Map: https://commons.wikimedia.org/wiki/File:CO2_emissions_per_capita,_2017_(Our_World_in_Data).svg Data: World Bank https://data.worldbank.org/indicator/EN.ATM.CO2E.KT?view=chart and https://data.worldbank.org/indicator/EN.ATM.CO2E.PC?view=chart Slide 16: https://www.flickr.com/photos/cmichel67/43725689770 Slide 17: https://commons.wikimedia.org/wiki/File:CO2-Temp.png Slide 20: https://commons.wikimedia.org/wiki/File:BorneoRainforest_DSC_9267.JPG