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Xiwai International School Environment Action Club Global Warming

Xiwai International School Environment Action Club Global Warming. February 23, 2011 . Global Warming Basics. What is Global Warming?. Global Warming refers to the recent increase in average global temperatures caused by humans

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Xiwai International School Environment Action Club Global Warming

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  1. Xiwai International School Environment Action Club Global Warming February 23, 2011

  2. Global Warming Basics

  3. What is Global Warming? • Global Warming refers to the recent increase in average global temperatures caused by humans • The idea that humans were heating up the planet used to controversial, but now virtually all serious scientists accept it as fact

  4. This chart is based on actual temperature readings from around the world back to 1858 • The zero line represents the average from 1961-1990 • Lots of year to year fluctuations – even some longer cool periods such as the 1950s and 1970s – but a clear overall trend especially since 1980 • Hottest 10 years on record: 2005, 1998, 2003, 2002, 2006, 2009, 2007, 2004, 2001, 2008 • Source: data from Climate Research Center, Univ. of East Anglia via https://www.planetseed.com/

  5. This chart is based on goes back 2000 years • Green section is the same as last chart; pink section is data taken from tree rings & ice cores • “Little Ice Age” around 1600 and 1700’s • Source: data from Nature Magazine via https://www.planetseed.com/

  6. But Why is the Planet Warming? Our atmosphere blocks certain radiation from coming in – esp. UV radiation But it also has the effect of trapping some of the radiation that comes in and keeping it from escaping back into space … this is the Greenhouse Effect The Greenhouse Effect is caused by Greenhouse Gases (GHGs) Without this, the average temperature would be -19°C and swing from 100°C in the day to -150°C at night vs. average temperature today of about 14°C

  7. For The Science Nerds…

  8. So What’s The Big Problem? The problem is that we’ve knocked the delicate balance out of whack by increasing the amount of GHGs in the atmosphere! But first, what are the GHG’s we’re talking about?

  9. CO2 (Carbon Dioxide) CH4 (Methane) N2O (Nitrous Oxide) Also… Water Vapor (#1 GHG, but not anthropomorphic) Halocarbons (smaller effect) Ozone (smaller effect)

  10. Atmospheric Concentrations Are Shooting Up Like Crazy !! CO2 CH4 N2O 280 => 338 ppm 700 => 1,745 ppb 270 => 314 ppb • PPM or PPB increases are from 1750 to now • Older data comes from sampling ice cores; newer data from direct reading • Each GHG has different properties – strength on greenhouse effect and time in atmosphere • The global increases in CO2 concentration are due mainly to fossil fuel use and deforestation, while those of CH4 and N2O are primarily due to agriculture. • Source: HK Government - http://www.hko.gov.hk/climate_change/

  11. CO2 is the BAD BOY of GHGs… Most CO2 is from Fossil Fuel Data is for the year 2004 Non-CO2 GHGs converted to CO2 equivalent based on IPCC methodology Source: US EPA http://www.epa.gov/climatechange/emissions/globalghg.html

  12. Fossil Fuels Use Up Steadily…

  13. So What Does It All Mean? • Average temperatures already up 0.8°C • We are committed to 0.6°C more no matter what • 0.8°C + 0.6°C = 1.4°C • Scientists say anything over 2.0°C could have a disastrous effects on human civilization • At the last great ice age, the planet was only 5-6°Ccolder than now – a few °C means a lot Remember This Number!

  14. What Happens Above 2.0°C? We’ll get to that in a minute, but first you need to know a little about carbon sinks & the albedo effect

  15. Carbon Sinks (or Sponges) Trees & Plants Trees and plants grow by absorbing CO2 and emitting oxygen … this is why we want to plant trees … however, they are only sinks while they’re growing, and if they are burned they release CO2 Soils & Wetlands There’s more carbon in the world’s soils than in all the plants and the atmosphere combined! … frozen wetlands (e.g. Russia, Canada, etc.) also hold vast amounts of methane… industrial farming can cause soils to release their carbon … warming of tundra can trigger wetlands to release trapped methane Oceans The oceans hold more carbon than trees, plants, soils, wetlands and atmosphere combined … in fact, they absorb about 25% of the carbon we emit … but scientists aren’t sure how much the oceans can take and some say their role as a sink is weakening … the other issue is that as the oceans take up carbon they acidify

  16. The Albedo Effect • Ice & snow are light and tend to reflect sunlight • Water is darkand tends to absorb sunlight • So more ice & snow => weaker greenhouse effect

  17. Melting Ice - Everywhere Problem #1: melting ice accelerates global warming

  18. Melting Ice - Everywhere Problem #2: melting ice raises sea levels We should be alarmed about rising sea levels Feb 18, 2011 Over a couple of centuries, [melting ice] could raise sea levels by six metres: a seemingly unstoppable process that may already be under way.… even a one-metre rise would flood the homes of around 100 million people in Asia, mostly in eastern China, Bangladesh and Vietnam … Megacities such as Shanghai, Karachi, Lagos and Bangkok would have to spend tens of billions of dollars on protecting themselves, or be submerged…

  19. So What Do We Do? • Keep CO2 atmospheric concentration below 350 ppm (or total GHG below 450 ppm CO2e) • Bring annual CO2 emissions to ZERO by 2050 – a 100% carbon neutral planet • BUT HOW?? CAN IT BE DONE?? • First, we need to understand what exactly we’re doing that’s causing the GHG increases! • Plan A: Then either stop doing it…find new and better ways to do it…or find new and better sources of energy to do it… • Plan B: Resort to geo-engineering?? • Plan C: Find a good cave! Remember This Number!

  20. A Picture Is Worth 1000 Words…

  21. How Do You Feel About All This? • DISCUSSION • Is this something that makes you worried? • If yes, what is your main concern? What do you think some of the biggest impacts could be? Could there be positive as well as negative impacts? • If not, why not? • Why do you think so many people refuse to believe in global warming even though virtually all climate scientists say it’s true?

  22. Project For Next Week • Form teams of 3-4 • Pick one of the topics below • Melting sea ice and rising sea levels • Ocean acidification and coral reefs • Extreme weather – floods, droughts, hurricanes • Impact on endangered species • Impact on world food production and hunger • Other topic • Do some web research using resources on the Wiki or other materials you can find on your own • Make a 5 minute presentation to the class to tell us what you learned and what you think

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