3.3 Disturbances And A Changing Environment


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UBC Bio 111 - Intro to Biology

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3.3 Disturbances And A Changing Environment

  1. 1. 3.3 Disturbances and a changing environment Learning Outcomes: 6. Predict the consequences of environmental disturbances on communities Linked articles: How Do Scientists Know They Are Not Wrong? Climate Change: Myth or Menace Reminders: There is a new activity in the Learning Centre each week which you have not seen to help you work through material covered each week in lecture. 5 visits to the learning centre over the semester will result in a 0.5% bonus mark added onto your final grade. Regional and local disturbances Forest fires The frequency of forest fires in BC is increasing every year. The dead organic material on the forest floor (leaf litter) dries and accumulates over longer low rain seasons. This increases the potential for ‘hot’ fires that consume all organic material leaving ash and mineral soil. ‘Cooler’ fires leave patches of vegetation and organic soils that can serve as a refuge for some animals, plant roots, Terrace Mt. fire (north of Kelowna) August 2009 (photo Darryl Dyck) and a seed bank (seeds, fruits, spores) Wind storms In December of 2006 gusts of wind up to 119 km/hour blew across Burrard Inlet and through Stanley Park. Several thousand trees were uprooted or had the trunks snapped off. The immediate impact was the removal of a canopy cover adding more light to the forest floor More dead organic material was added to the forest floor Question: 1. What effect(s) within the carbon cycle does the addition of dead organic matter have? Stanley Park Dec 2006 (photo Steve Pratt) Questions: 2. How are these natural events symptomatic of climate change? 3. How do these events potentially contribute further to climate change? Documented climate change in BC Review this link: http://www.geog.ubc.ca/courses/geog376/students/class05/skcurtis/ QUESTIONS: 4.a)Has the mean annual temperature in British Columbia increased significantly over the last 100 years? 4b) On average how many more frost free days did we have in BC in 1991-2000 compared to 1901-1910?
  2. 2. Global changes in temperature are correlated with CO2 levels Fig 4.7 Evidence from Antarctic ice cores Evidence from monitoring station at Mauna Loa, Hawaii since 1958 Questions: 5. What can explain this trend? 6. Where have the recent increases in CO2 come from? 7. The graph from Mauna Loa shows a steady increase in CO2 levels but what has caused the regular yearly oscillations in CO2 shown on the graph? (There appears to be one increase and decrease each year). Greenhouse effect: -CO2 and H2O in atmosphere act like “glass” Some solar radiation is reflected by atmosphere “glass” Short wave radiation (some visible light) is absorbed Longer wave infrared radiation (from Earth) is reflected back down off “glass” and is retained as heat On Earth there is a balance of greenhouse gases that protect and warm our earth, creating climates suitable for life. Check this link on Goldilocks and the Greenhouse. http://www.livescience.com/common/media/video.php?videoRef=GoldilocksGreen
  3. 3. Greenhouse gases that act as this radiation barrier include: CO2 (1X) fossil fuels, deforestation, respiration CH4 methane (20X more heat trapped than CO2) –from cow farts, coal beds, landfills 350-500mill tonnes/yr last 10 years in atmo added from these processes Cows .5 lb per day X 1.3 billion cows Other sources too N2O(310 X) “laughing gas” released naturally by oceans and soils -from breakdown of fertilizers in soil, sewage treatment, car exhaust, add 7-13 million ton/yr persists >100yrs fluorocarbons: (also many X more than CO2) now mostly banned CFCs which also breakdown ozone layer HFCs hydrofluorocarbons which replaced CFCs in air conditioners and refrigerators (recover coolant when discard these appliances) How carbon cycles through the biosphere: CO2 is assimilated (incorporated into tissue) of plants and other producers by photosynthesis Animals consume plant tissue, respire CO2 and excrete wastes Dead organic matter (plants, animals, fungi, protists, bacteria) is broken down and decomposed by: detritivores and decomposers Organic C can be stored in long-lasting sinks: peat bogs, ocean floor, foraminiferan shells (trees…shorter term) Human use of C-based organic material as a fuel and natural combustion releases CO2 Consequences - Climate Change Scientists are now observing changes in the environment and are trying (to the best of their ability) to predict changes to ecosystems and biological communities. Immediate effect Long term prediction Global Temperature: 8.By how much do you 9. What are the predictions for average global think it has risen in the last 100 years? temperature for the next 100 years? Sea Level. 10. By how much do you think it has 11. What are the predictions for sea level rise for risen over the last 100 years? the next 100 years?
  4. 4. Glaciers and polar ice caps: - The Columbia Many glaciers will be gone and the entire arctic icefields have retreated 1.5 km in the last 100 yrs area is predicted to have completely ice free (shrunk to half size) summers by 2030 in less than 10 years. In Canadian polar ice caps lost 25km3/yr between 2007 they predicted 2050 but the huge melting 95-00. This lost has since accelerated the arctic seen that summer has revised estimates. The ice cap reached its smallest ever size in 2007. IPCC estimates have been too conservative. This year is the third lowest level ever recorded. 12. What is causing the acceleration in ice loss? image of calving glacier at Prince William Sound, Alaska by Len Radin (creative commons) See the Ted talk by nature photographer James Balog who has documented extreme ice loss with time lapse cameras. Pay attention from 11:50 min to 16 min. http://www.ted.com/talks/james_balog_time_lapse_pr oof_of_extreme_ice_loss.html (from T. Homer-Dixon 2008) Homer-Dixon, T. 2008. Climate Change, the Arctic, and Canada: Avoiding Yesterday’s Analysis of Tomorrow’s Crisis. 20th Anniv. Confer. of the Nation Round Table on the Environment and the Economy. Ottawa, ON Oct 30th 2008. Weather patterns: flooding, hurricanes, drought Further increases in extreme weather, permanent prairie dustbowl is predicted even if we change our ways drastically in the next 5-10 years. Locally in the lower mainland, predict drier summers and warmer rainier winters. Water shortages are predicted. Sydney Opera House Wed Sept 23rd 2009 (worst dust storm in 70yrs by Rob Griffith Assoc. Press) (Ironically this new story was on the CBC website right underneath the story about Obama speaking yesterday at the UN about the necessity of global cooperation on many issues including climate change.)
  5. 5. Attempts to mitigate climate change - 1997 Kyoto Accord – an international agreement to reduce green house gas emissions by 5% (below 1990 levels) over 10 years. Canada was one of the first countries to sign on. By 2006 Canada was 20% above 1990 levels. 2009 Copenhagen (this December) The secretary General Ban Ki-moon and US President Obama tried to start negotiations in advance at the current UN summit on Tuesday (Sept 22). Despite the fact that Copenhagen doesn’t start until December it is already known that nations are likely to have problems coming to an effective agreement. - Emissions trading Targets for CO2 emissions are given for regions and companies. Those which are below or have initiatives to significantly decrease carbon emissions can sell credits to those who cannot reduce their emissions by changes in technology alone eg Port Mann land fill traps the methane produced from the decomposing trash and the methane is used to run a nearby factory. They can sell their credits for this initiative. Questions: 13. Do you know of any initiatives today that when you buy a product you can also buy credits to offset the carbon emitted directly or indirectly by that product? -eg WestJet linked to offsetters.ca 14. What does it mean when an organization or event is “carbon neutral”? http://www.davidsuzuki.org/Climate_Change/What_You_Can_Do/carbon_neutral.asp Recent developments -Stern Report by the former head of the World Bank indicating that economically the world cannot afford to not address climate change. -Bill C-31 a federal private members bill to tackle our greenhouse gas emissions was been tabled when parliament dissolved last winter for the previous election call How can we reduce green house gases? – adopt renewable sources of energy (solar, wind, hydro) -using more fuel efficient technology eg Primus cars, fuel cells -trapping methane produced by landfills -adopting agricultural methods that cause less decomposition of soil C (no till) -forestation projects -fertilizing the ocean with iron (a limiting nutrient for phytoplankton) to increase photosynthetic capture of CO2 ***Question: 15. How can you personally reduce greenhouse gas emissions?