Climate Change in. Nicole Brown

Transcription

1 Climate Change in Nicole Brown Picture source: FC E9BB%7DImg100.jpg

2 What is The World Without Us? What scenario does it present? So, let us try a creative experiment: Suppose that the worst has happened. Human extinction by fait accompli. Not by nuclear calamity, asteroid collision, or anything ruinous enough to also wipe out most everything else, leaving whatever remained in some radically altered, reduced state. Not by some grim eco-scenario in which we agonizingly fade, dragging away many more species with us in the process. Instead, picture a world from which we all suddenly vanished. Tomorrow. - The World Without Us, Alan Weisman (pg. 4-5)

3 Slide 1 Notes 2007 book by Alan Weisman Journalist, not scientist (wikipedia) [read quote] If we disappear, what will happen to the climate? Although we aren't around anymore, the planet will still have to deal with our past emissions. Sources: Weisman, Alan. The World Without Us. New York: Picador, Alan Weisman." Wikipedia. 23 Feb 2009 <

4 What climate change scenarios does Weisman present? 1. The world continues to heat up because of CO2 that humans have put into the atmosphere. 2. The Gulf Stream is stopped because Greenland's ice cap melts into it, which could bring an ice age back to Europe and the East Coast of North America 3. The wishful scenario : the two extremes might blunt each other enough to hold temperatures suspended in between Source: The World Without Us (pg 50)

5 Slide 2 Notes Weisman presents three main 'climate visions,' although he offers other ideas as well. Scenario 1: the 'general global warming' scenario wet areas get wetter, dry areas get drier, and there's a northern shift in plant and animal species. Scenario 2: the 'Day After Tomorrow' scenario the Gulf Stream shuts down, which Weisman says could, if not cause a complete ice age, at least cause tundra and permafrost to replace temperate forests. Scenario 3: a combination of the first two scenarios. (For this presentation, we will focus on the first two scenarios.) Sources: Weisman, Alan. The World Without Us. New York: Picador, 2007.

6 What does the IPCC say about Weisman's hypothesized situations? The IPCC says that even if all radiative forcing agents were held constant at year 2000 levels, a further warming trend would occur in the next two decades at a rate of about 0.1C per decade (pg 12) If radiative forcing were stabilized in 2100 at A1B levels, thermal expansion alone would lead to 0.3 to 0.8 m of sea level rise by 2300 (relative to ) (17) Both past and future anthropogenic carbon dioxide emissions will continue to contribute to warming and sea level rise for more than a millennium, due to the time scales required for removal of this gas from the atmosphere (17) Source: IPCC 2007 Summary for Policymakers

7 Slide 3 Notes Warming will continue, which supports Weisman's first scenario. Point two suggests that the planet may not have reached the tipping point for sea-level rise to support Weisman's second scenario; the IPCC elaborates on this point when they later say that contraction of the Greenland Ice Sheet is projected to contribute for sea level rise after 2100 (pg 17). In Weisman's vision the world is suddenly without people the third bullet point is particularly important: Both past and future anthropogenic carbon dioxide emissions will continue to contribute to warming and sea level rise for more than a millennium, due to the time scales required for removal of this gas from the atmosphere Sources: IPCC, 2007: Summary for Policymakers. In: Climate Change 2007: The Physical Science Basis. Contribution of Working Group I to the Forth Assessment Report of the Intergovernmental Panel on Climate Change [Solomon, S., D. Qin, M. Manning, Z. Chen, M. Marquis, K.B. Averyt, M. Tignor, H.L. Miller (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA.

8 If we focus on Weisman's first scenario, what other information (besides the time needed to remove CO2 from the atmosphere) can we find to support it? Lag factor: there s the time-lag factor to consider. Even if we do manage to make significant emissions cuts, it will take decades for the concentration to level off, and many decades more for the temperature to stop rising (The Rough Guide to Climate Change, pg 279) Graphic:

9 Slide 4 Notes For time's sake, we'll focus on one: lag factor. [read quote] from The Rough Guide to Climate Change Lag factor accompanies the idea that it takes time to remove CO2 from the atmosphere, and it also suggests that, if humans disappear tomorrow, the level of CO2 in the atmosphere will continue to rise. Graphic shows that spikes/drops in CO2 can follow temperature changes can be seen particularly in the earlier, less crowded part of the graph. Sources: Henson, Robert. The Rough Guide to Climate Change. 2 nd edition. New York: Penguin Books, Cook, John. "CO2 lags temperature - what does it mean?." Skeptical Science Feb 2009 <

10 In conclusion... Look around you, at today's world. Your house, your city. The surrounding land, the pavement underneath, and the soil hidden beneath that. Leave it all in place, but extract the human beings. Wipe us out, and see what's left. How would the rest of nature respond if it were suddenly relieved of the relentless pressure we heap on it and our fellow organisms? How soon would, or could, the climate return to where it was before we fired up all our engines? - The World Without Us (pg 5)

11 Slide 5 Notes Although Weisman is not a climate scientist, his three scenarios seem to have some basis in science. His first scenario, in particular, is supported by the findings of the IPCC. The implications of this are disturbing they suggest that, even if all greenhouse gas/co2 emissions were stopped, the world will continue warming, and humans have already created a legacy that would remain behind if they disappeared tomorrow. [Read quote] Sources: Weisman, Alan. The World Without Us. New York: Picador, 2007.