Summary
Dr James Hansen, the world's leading climate scientist, has asserted that to avoid dangerous climate tipping points, we need to stabilise the level of greenhouse gases in the atmosphere at between 300 and 350 parts per million CO2, far below the levels of 450- 550 ppm considered in the terms of reference in the Garnaut report.
In 2007, satellite images showed that the summer ice extent in the Arctic had shrunk to an unprecedented level. This is a 22% loss of the summer ice extent between 2005 and 2007 and is far worse than any of the predictions published by the Intergovernmental Panel on Climate Change (IPCC). Dr Wieslaw Maslowski, of the US Postgraduate Naval School, predicts that on our current emissions trajectory, the summer ice extent in the Arctic could be completely gone by 2013. This could trigger an albedo flip event and climate catastrophe!
A peer-reviewed study published in the Geophysical Research Letters in March 2008, found that only an immediate zero emissions target can prevent a warmer planet. Ken Caldeira (Carnegie Institution for Science, Stanford USA) and Damon Matthews (Concordia University, Canada) "warn that current emissions targets for 2050 are insufficient to avoid substantial future warming. Instead they believe that we need to eliminate emissions, or find a way of actively removing carbon dioxide from the atmosphere". Caldeira said "To reduce emissions enough to avoid this catastrophe, we would have to cut them close to zero — and right away."
1. More of the same
The dramatic climatic events (such as drought, fire, floods, coral bleaching and severe storms) we have seen over the last decade and a half are the results of the greenhouse gases we have already released.
If we were to keep our greenhouse gases at present levels, the best we could hope for is more of the same.
If we want to return our climate to the relatively stable conditions we have experienced in the past (for the last 8,000 years), we will need to reduce levels of atmospheric greenhouse gases to pre-industrial levels. This means reducing our greenhouse gas emissions to near zero and sequestering atmospheric carbon.
2. Lag effects
James Hansen, director of NASA's Goddard Institute for Space Studies, suggests we are already committed to an extra 0.6 of a degree Celsius rise due to the thermal inertia of our oceans. The oceans have reduced the immediate effects of the greenhouse gases we have already released but are still slowly heating up, resulting in a lag effect in climate change.
Paul Brown looked at the issue of the lag effect in his new book 'Global Warning: The Last Chance for Change'.
"Best estimates are that there is a 25-to-30 year time lag between greenhouse gases being released into the atmosphere and their full heat-trapping potential taking effect. That wipes out any feeling of comfort. It means that most of the increase of 0.8˚C seen so far is not caused by current levels of carbon dioxide but by those already in the atmosphere up to the end of the 1970s."
3. Speed
Referring to new ice core data taking climate records back 800,000 years:
"The core shows that carbon dioxide was always between 180 parts per million (ppm) and 300 ppm during the 800,000 years. However, now it is 380 ppm. Methane was never higher than 750 parts per billion (ppb) in this timescale, but now it stands at 1,780 ppb.
But the rate of change is even more dramatic, with increases in carbon dioxide never exceeding 30 ppm in 1,000 years - and yet now carbon dioxide has risen by 30 ppm in the last 17 years."
Original article form the independent.
Source: http://www.commondreams.org/headlines06/0905-06.htm
4. Global dimming
Global dimming is the phenomenon of atmospheric pollution cooling the earth down, by reflecting sunlight and forming sunlight-reflecting clouds.
When all plane flights were grounded for three days in the United States after the September 11th terrorist attack, the temperature in the US jumped one degree. Scientists believe that this increase in temperature was due to the removal of condensation trails - caused by high-flying jet aircraft - which reflect sunlight back out into space.
If condensation trails and other industrial pollution that contributes to global dimming were stopped then we could expect the temperature to jump above the increases we have seen already from global warming.
5. Feedback loops
As the world heats up, elements of the earth's natural systems will respond. Some of these responses may speed up climate change, others might slow it down.
Sadly, we have already experienced feedback events linked to global warming. For example, as the sea ice in the Arctic melts, less sunlight is reflected back out into space and more is absorbed by the dark ocean waters - thus the water gets warmer and more ice melts, and so on.
This type of event is called a positive feedback loop. Other examples of positive feedback loops are the reduction in the area of snow and ice which reflect sunlight, and the thawing of permafrost and consequent release of methane, both causing stress to ecosystems. Stressed ecosystems then release CO2 rather than absorb it. This, in turn, increases the temperature of the oceans, resulting in less carbon absorption.
There are also negative feedback loops that occur, such as the creation of more sunlight-reflecting clouds*, however, the effects of positive feedback loops are believed to outweigh the effects of the negative feedback loops.
If the world temperature increases enough it will trigger positive feedback events so large that our actions will no longer be able to influence the climate and a runaway climate event will occur. This point is called the “tipping point” and it MUST be avoided. Some scientists are speculating we are close to passing the tipping point.
* The exact effects of clouds is under debate: "It's a new science, driven by the fact that everybody doing climate predictions says that clouds are perhaps the single greatest unknown factor in understanding global warming." Taneil Uttal, chief of the Clouds and Arctic Research Group at the Earth Systems Research Laboratory of the U.S. National Oceanic and Atmospheric Administration
John Schellnhuber, research director at the Tyndall Centre for Climate Change Research, has identified 12 tipping points, any one of which could change the climate dramatically. (Guardian article and Mother Jones article looks at human factors for change)
Summary from David Roberts Gristmill
6. Methane hydrates
If global warming is allowed to continue, a mix of methane and water lying frozen on the ocean floor could begin to thaw, and release vast quantities of methane into the atmosphere.
Twenty-one times more effective as a greenhouse gas than CO2, more methane lies trapped on the ocean floor than the total CO2 that could be released from all the oil, coal and gas reserves that exist on earth.
7. Peak oil production - the other problem
Global oil production is expected to peak around 2010. Oil and natural gas are the drivers of our transport systems, agricultural production, and much of our manufacturing.
When global oil production reaches its peak production, world oil prices will jump and our economies will suffer, raising the question, will the billions of dollars needed to move our society to net zero emissions be spent - or even be available to be spent?
More info: Australian Society of Peak Oil, and Global Oil Watch
Why 2020?
Reasons why we have chosen 2020 as a date to have achieved a move to near zero emissions and below.
1. IMPLEMENTATION - How long?
Given that the fastest we could probably do the conversion in would be ten years, 2020 seems a reasonable goal, acknowledging the couple of years it will take to get the implementation going.
2. IMPERATIVE - The situation is already very bad
The faster we move, the less impacts climate change will have and the greater the chance we will have of avoiding the tipping point (some scientists believe we have already passed it, others say we have ten years).
3. FRAMING - Today vs Tomorrow
Given it will take ten years to crash implement a near zero emission plan, 2020 is something you have to start today, while 2030 is something you can do tomorrow or in fact in ten years time. A similar framing problem exists with the 2050 targets.
4. COAL and NUCLEAR - Closing the door
Very importantly for people/campaigns trying to shut down the nuclear and coal industries, the 2020 date closes the door given that both technologies would take over ten years to implement (the nuclear of course argues otherwise).
The 2030 goal opens the door for nuclear power plants and at least the idea of carbon capture and storage for coal plants.
Even if the 2030 date is just used to justify keeping exporting raw materials or to avoid doing something meaningful, it will mean that real solutions are postponed while the debate goes on around nuclear and coal, and this is time we don't have.
5. MESSAGING - Keep it simple and keep it consistent
A number of groups forming together around the Zero Emission Network and campaigning specifically on the Zero Minus goal have chosen a date of 2020 to go for near zero emissions, so it's good that we don't have too many different messages around this concept.
If the groups running "near zero" or "zero minus" targets are all on the the same page, the better it will be for our campaign given the difference of our targets when compared to the mainstream environment groups and the need to compete with them for media, public, political and policy space.
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