Ciências Humanas e Sociais

Acordem e revoltem-se! ( filme animado sobre as alterações climáticas)

Website do filme: http://wakeupfreakout.org/

Guião do Filme

Wake Up, Freak Out – then Get a Grip

It’s much, much later than you think

This really isn’t about polar bears any more. At this very moment, the fate of civilization itself hangs in the balance.
It turns out that the way we have been calculating the future impacts of climate change up to now has been missing1 a really important2 piece of the picture.3 It seems we are now dangerously close to the tipping point in the world's climate system4; this is the point of no return, after which truly catastrophic changes become inevitable.5

Think of it like this: For the past three million years, our planet’s climate has always been in one or the other of two stable states, with small changes in solar radiation providing the energy to push us from one to the other. When we are in this cooler dip, the planet has an ice age; when we are in the warmer one, the planet’s climate is very much as it is now, and has been throughout the whole of human history6.

The problem is that our use of fossil fuels is pushing us further and further out of our little stable dip and up the far slope of this hill. The tipping point is the point at which we cross the peak of the hill, and we no longer need to keep pushing to keep the planet moving towards a much hotter place; it will just keep rolling onwards all on its own. This tipping point exists because of a set of positive feedbacks in the climate systems, mechanisms that can amplify the effects of man-made warming and lead to runaway change.

First, there is the Albedo Effect. White surfaces reflect more solar radiation than dark surfaces, so as global warming from greenhouse gases melts ice and snow7, it leaves behind dark ocean or land; those surfaces now absorb more solar radiation than before - so adding to warming, which melts more ice and snow, and so on8.

Uncondensed water vapour is actually a more important greenhouse gas than carbon dioxide. Although we aren't actually emitting much water vapour directly, as the planet warms, evaporation rates increase, raising humidity and thickening the Earth’s thermal blanket9, which in turn raises temperatures10, further increasing evaporation - etc11.

Normally, about half the CO2 emitted each year from human activities is re-absorbed by a combination of forests, plankton, and the ocean itself12. But the ocean surface is becoming more and more acidic as concentrations of CO2 dissolved in it rise. At the same time the water temperature at the surface is also going up, forming a layer of warm, acidic water that is spreading across the ocean surface, killing off the plankton that lock CO2 out of the atmosphere13. Worse, warm water holds less CO2 than cold water14, so as it heats up it actually starts releasing some of the CO215 it had previously absorbed16.

Just like marine ecosystems, land-based eco-systems normally act as carbon sinks, taking carbon from the atmosphere and using it for growth. But as these eco-systems heat up, their balance is upset; plants become less and less effective at taking in CO217, while micro-organisms in the soil become more and more effective at putting it out18 – causing the eco-system as a whole to go from being a carbon sink19 to being a carbon source20. Eventually, as temperatures rise and rains fail, forests dry out, so when fires start, they don’t get put out21. All of the forest’s stored carbon goes up in smoke, adding to the greenhouse gases in the atmosphere, which increases warming22, which further degrades23 the carbon sinks24.

Up in Siberia, an area of frozen peat bog the size of France and Germany combined that we call the permafrost is melting, and as it melts, it releases huge quantities of methane. Methane is a greenhouse gas with a short lifespan in the atmosphere - but while there it has a warming effect more than 20 times as powerful as carbon dioxide. The more methane is released, the more it adds to warming25, so the more the permafrost melts26, and the more methane is released…27

Unfortunately the arctic tundra is not the only place with large stores of frozen Methane. Lurking under the sea bed there may be as much as 10 trillion tons of Methane stored as frozen crystals at sites around the world. If we raise ocean temperatures by enough - and nobody knows how much is enough - we could trigger the sudden release of this stored methane into the atmosphere.28 The last time this happened29, global temperatures rose abruptly by 10 degrees30.

So these are some of the feedback mechanisms31 that explain why our global climate system has a tipping point32. Each feedback in the system has its own internal tipping point, and it is the relationships within this complex, mutually reinforcing system, that have been missing from our climate prediction models33.

So far we have pushed up global temperatures by only about 0.8 C - but because of the 40 or 50 year time lag between emissions and temperature rise, the emissions already in the atmosphere commit us to raising temperatures by around another 0.6 degrees over the coming decades34 - which could easily place us right at the peak of the hill – or even over it.
If we do pass this critical threshold, global temperatures could soar by as much as 6 degrees.
If this happens, the natural world will suffer a mass extinction event which will wipe out the majority of the plants and animals with which we currently share the planet35 - although there will be a lot more rats, flies, cockroaches and mosquitoes as the world's ecosystems go into meltdown.

The first human impacts will come in the form of steeply declining access to fresh water, as rainfall patterns change, glacier-fed rivers dry up36, and rising sea levels contaminate aquifers. As crops fail37, forests burn38, deserts spread39 and coastal regions flood permanently, people will start to pack up their things in their billions and move on in search of a better life elsewhere40.

But where?

'Humanity' may survive this. But what will 'humanity' mean in a world where countries which remain habitable – like Britain – use most of our remaining resources fighting to keep out the starving millions who can no longer live in their own countries because of what we have done? The world is awash with weapons; enough firearms to arm one in every seven human beings on the planet41. As the Earth's ability to support the huge numbers of people alive today dwindles, we will not die peacefully42 in our sleep43.

OK, here’s the good news: None of this is inevitable – yet.

This is not the time to panic, or to despair. This is the time to act – while we still can. We need to recognize that there is a huge question mark over whether governments and corporations44 are capable of responding to this threat in the time we have left. They have had 20 years already – but still have less than nothing to show for it. This is because they remain committed to a doctrine that prioritises endless short-term economic growth45 over the survival of human life on earth. There is no great mystery about what we need to do to reduce emissions in line with the science; we simply need to consume less.

But that is out of the question in a society which is founded on the ever-increasing consumption of materials and energy.

Nobody has all of the answers; but we do know that this is not the only way to live, and given that it is almost certainly going to kill us all46, we had better start looking urgently at some of the alternatives. It is now very clear that in order to actually win the fight against climate change, making big changes to the way we each live our own lives is not going to be enough; we’re also going to have to actively confront powerful vested interests who will stop at nothing to prevent the changes we need from taking place. We have to be more than just consumers.

These are extraordinary times. Preventing runaway global warming is the single most important task in all of human history – and it has fallen to us to do it. If we don’t, then everything else we work to achieve in our lives will be destroyed, or become meaningless. Those who came before us didn't know about this problem, and those who come after will be powerless to do anything about it. But for us, there's still time! We'd better get a move on though.

1 Hart, J. and Torn, M. S, (2006) 'Missing feedbacks, asymmetric uncertainties, and the underestimation of future warming', Proceedings of the National Academy of Sciences, DOI: 10.1073/pnas.0702737104
2 Brovkin, V., Cox, P. & Sheffer, M. (2006) ‘Positive feedback between global warming and atmospheric CO2 concentration inferred from past climate change’, Geophysical Research Letters, vol 33, p L10702
3 Backman, J. et al. (2006) 'Subtropical Arctic Ocean temperatures during the Palaeocene/Eocene thermal maximum', Nature 441, 610-613 DOI:10.1038/nature04668
4 Lenton, T. M., Held., H. et al. (2008) ‘Tipping elements in the Earth's climate system’, Proceedings of the National Academy of Sciences, DOI:10.1073/pnas.0705414105
5 Hansen et al. (2006) 'Global temperature change', Proceedings of the National Academy of Sciences, vol 103, p14288
6 Pearce, F. (2007) The Last Generation: How Nature Will Take her Revenge for Climate Change, Eden Project Books, London
7 Stroeve, J. (2007) ‘Arctic Sea Ice Decline: Faster than Forecast?’, Geophysical Research Abstracts, Vol. 9, 01362, 2007, European Geosciences Union 2007 Ref-ID: 1607-7962/gra/EGU2007-A-01362
8 Déry, S. J., and Brown,R. D. (2007), ‘Recent Northern Hemisphere snow cover extent trends and implications for the snow-albedo feedback’, Geophysical Research Letters, vol.34, L22504, doi:10.1029/2007GL031474
9 Santer et al. (2007) ‘Identification of human-induced changes in atmospheric moisture content’, Proceedings of the National Academy of Sciences, vol.104, no.39 15248–15253, doi:10.1073:pnas.0702872104
10 Philopona, R. et al. (2005) ‘Anthropogenic greenhouse forcing and strong water vapor feedback increase temperature in Europe’, GEOPHYSICAL RESEARCH LETTERS, VOL. 32, L19809, doi:10.1029/2005GL023624
11 Soden, Brian J. (2005) ‘An Assessment of Climate Feedbacks in Coupled Ocean–Atmosphere Models’, JOURNAL OF CLIMATE, VOLUME 19, 3354, American Meterological Society
12 Friedlingstein, P. (2008) ‘A steep road to climate stabilization’, Nature 451, 297-298 (17 January 2008) doi:10.1038/nature06593
13 Gregg, W. W. et al. (2003), ‘Ocean primary production and climate: Global decadal changes’, GEOPHYSICAL RESEARCH LETTERS, VOL. 30, NO. 15, 1809, doi:10.1029/2003GL016889, 2003
14 Le Quere, C., et al. (2007) 'Saturation of the Southern Ocean CO2 sink due to recent climate change', Science, 316 (5832), 1735-1738
15 Pearce, F. (2007) The Last Generation: How Nature Will Take her Revenge for Climate Change, pp.145-149, Eden Project Books, London
16 Schuster, U., and A. J. Watson (2007), ‘A variable and decreasing sink for atmospheric CO2 in the North Atlantic’, Journal of Geophysical Research, 112, C11006, doi:10.1029/2006JC003941
17 Knorr, W. et al. (2007) 'Impact of terrestrial biosphere carbon exchanges on the anomalous CO2 increase in 2002-2003', Geophysical Research letters, Vol.34, L09703, DOI:10.1029/2006GL029019
18 Lenton, T. M. (2000). "Land and ocean carbon cycle feedback effects on global warming in a simple Earth system model.", Tellus 52B, 1159-1188, doi:10.1034/j.1600-0889.2000.01104.x.
19 Cox, P. M. et al. (2003) 'Strong carbon cycle feedbacks in a climate model with interactive CO2 and sulphate aerosols', Geophysical Research letters, Vol.30, no.9, 1479, DOI:10.1029/2003GL016867
20 Pearce, F. (2007) The Last Generation: How Nature Will Take her Revenge for Climate Change, pp.124-132, Eden Project Books, London
21 Pearce, F. (2007) The Last Generation: How Nature Will Take her Revenge for Climate Change, pp.120-123, Eden Project Books, London
22 Susan E. Page, Florian Siegert (2002) ‘The amount of carbon released from peat and forest fires in Indonesia during 1997’, Nature, vol 420, p 61, doi:10.1038/nature01131
23 Canadel, J. G. et al. (2007) 'Contributions to accelerating atmospheric CO2 growth from economic activity, carbon intensity, and efficiency of natural sinks', Proceedings of the National Academy of Sciences, DOI: 10.1073/pnas.0702737104
24 Friedlingstein, P. (2008) ‘A steep road to climate stabilization’, Nature 451, 297-298 (17 January 2008) doi:10.1038/nature06593
25 Zimov, S. et al. (2006) ‘Permafrost and the Global Carbon Budget‘, Science, Vol.312. no.5780, pp. 1612 – 1613, DOI: 10.1126/science.1128908
26 Walter, K. et al. (2006) 'Methane bubbling from Siberian thaw lakes as a positive feedback to climate warming', Nature, vol 443, p71
27 Pearce, F. (2007) The Last Generation: How Nature Will Take her Revenge for Climate Change, pp.133-143, Eden Project Books, London
28 Leifer, I. et al. (2006) ‘Natural marine seepage blowout: Contribution to atmospheric methane’, Global Biogeochemical Cycles, vol.20 doi:10.1029/2005GB002668
29 Hansen, J. et al. (2007) 'Dangerous human-made interference with climate: a GISS modelE study', Atmos. Chem. Phys., 7, 2287–2312, 2007
30 Pearce, F. (2007) The Last Generation: How Nature Will Take her Revenge for Climate Change, pp.150-161, Eden Project Books, London
31 Knorr, W. et al. (2007) 'Impact of terrestrial biosphere carbon exchanges on the anomalous CO2 increase in 2002-2003', Geophysical Research letters, Vol.34, L09703, DOI:10.1029/2006GL029019
32 Hansen, J. (2008) “Tipping point: Perspective of a climatologist” in E. Fearn and K.H. Redford (eds) The state of the wild 2008 – A global portrait of wildlife, wildlands and oceans, Wildlife Conservation Society/Island Press
33 Lenton, T. M., Held., H. et al. (2008) ‘Tipping elements in the Earth's climate system’, Proceedings of the National Academy of Sciences, DOI:10.1073/pnas.0705414105
34 Hansen, J. et al. (2005) 'Earth's energy imbalance: Confirmation and Implications', Science, June 2005, Vol. 308. no.5727, pp.1431-1435
35 Mayhew, P. J. et al. (2008) ‘A long term association between global temperature and biodiversity, origination and extinction in the fossil record’, Proceedings of the Royal Society B, vol.275 no.1630: pp. 47-53. London: Royal Society
36 Barnett, T. P. et al. (2005) 'Potential impacts of a warming climate on water availability in snow-dominated regions', Nature, Vol.438, 17, DOI:10.1038/nature04141
37 Ainsworth, E. (2007) ‘Rice Production in a Changing Climate: A Meta-analysis of Responses to Elevated Carbon Dioxide and Elevated Ozone Concentration’, Global Change Biology, DOI: 10.1111/j.1365-2486.2008.01594.x
38 Running, Steven W. (2006) ‘Is Global Warming Causing More, Larger Wildfires?’, Science, Vol.313. no.5789, pp. 927 – 928, DOI: 10.1126/science.1130370
39 Scholze, M. et al. (2006) 'A climate-change risk analysis for world ecosystems', Proceedings of the National Academy of Sciences, DOI/10.1073/pnas.0601816103
40 Christian Aid (2007) Human Tide: The Real Migration Crisis, Christian Aid, London
41 Small Arms Survey, Geneva (2007) Small Arms Survey 2007, Cambridge University Press
42 Mabey, N. (2008) Whitehall Papers no. 69:Delivering Climate Security: International Security Responses to a Climate Changed World, Royal United Services Institute for Defence and Security Studies, Routledge
43 Smith, D. & Vivekananda, J. (2007) A Climate of Conflict: The Links Between Climate Change, Peace and War, International Alert, London
44 Dunlop, I. (2007) 'Corporate governance and responsibility', comments at University of Technology Sydney book launch, 5 Dec 2007
45 David Woodward and Andrew Simms (2006) Growth isn’t working, New Economics Foundation, London
46 Lynas, M. (2007) Six Degrees: Our Future on a Hotter Planet, National Geographic Society London

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Ciências Humanas e Sociais