Futures Forum: Climate change: tipping point

Previous posts on climate change have referred to a 'tipping point' being reached:
Futures Forum: Climate change: CO2 levels hit 400 ppm
Futures Forum: Climate Change: There is a growing recognition that affordable, scalable solutions are available now that will enable us all to leapfrog to cleaner more resilient economies

Here is a piece from Avaaz, which has also put together a petition calling on the UN meeting in New York to take action:

CLIMATE TIPPING POINTS

There’s a common misconception that climate change is a slow and gradual process. But that’s not actually true -- the last ice age hit in six months. Six months for much of Europe and the Northern Hemisphere to suddenly freeze over for the next thousand years. This is what happens when we hit a climate 'tipping point', and right now we're rushing towards three more of these catastrophic reactions

As the Earth warms it triggers feedback loops which can gradually build until they cause unstoppable and rapid changes. The Earth’s history is punctuated by large changes that occurred over the course of decades or even just several months. And today, scientists are warning that we are perilously close to crossing certain thresholds where these dramatic changes in our climate will become inevitable and catastrophic. Here are the biggest ones they’re raising the alarm about:

Tipping point 1: The Arctic Methane Bomb

Scientists warn that as a warmer climate melts the Arctic permafrost and releases large amounts of methane into the atmosphere, it is creating a feedback loop that is certain to trigger additional warming. A recent study published in the science journal Nature highlighted the risk of a massive amount of methane leaking from beneath the East Siberian sea - which could happen rapidly and speed up global warming at an exponential rate. Experts have already found hundreds of giant plumes of methane bubbling to the surface that are each over 1 kilometer wide! It’s clear this cycle must be stopped before it goes beyond our control.

Tipping point 2: Global Ocean Acidification

Roughly half the carbon dioxide released through human activity dissolves in the ocean. This results in a rise in acidity which is now occurring at a rate 10 times faster than at any point in the earth’s history. Many types of plankton which form the base of ocean food webs could die off - causing the destabilisation of entire ecosystems. The change is occurring so rapidly it raises the possibility that we’ll reach a dangerous tipping point that threatens global food security and significantly reduces the the capacity of the ocean to absorb CO2 from fossil fuel emissions.

Tipping point 3: Melting Ice

Rising temperatures are causing glaciers, ice sheets and sea ice to melt at alarming rates - pushing us towards tipping points that could cause rapid changes in the climate system as well as a dramatic rise in sea level. The geological record shows that catastrophic changes caused by melting ice can happen extremely fast - even in a matter of months. Recent evidence suggests that the last ice age happened within just a few months following the melting of a North American ice sheet.

We’re now seeing signs that similar abrupt changes could occur as a result of recent melting ice in the polar regions. Scientists are now warning that we’ve already reached a dangerous tipping point for a massive slab of ice in Antarctica which will inevitably disintegrate, raising global sea levels by 15 feet - swamping major coastal cities. But cutting carbon emissions now will slow down this process.

The Solution: from Tipping point to Turning Point for climate action

These tipping points aren’t slow, gradual impacts we can adapt to, they are rapid shifts which tip us over into an entirely new reality, and that make life for almost everything impossible. But we can still stop this from tipping over into a nightmare scenario. To do it, we need to take the most important number in the world and make it viral. That number is 100% -- to save the world we need to bring human carbon emissions down to zero in the next 35 years.

It's our moon landing, our generation’s chance to reach for a higher goal that binds us together, and next year’s Paris Summit is our moment for world leaders to give us all that collective sense of purpose. Only world leaders can send the signal that investors, businesses, institutions and the public need to get building. And so beginning with the million march for a 100% clean, and all the way through Paris, Avaaz will be campaigning to put the most important number in the world, on the tip of everyone’s tongue.

SOURCES:

Rapid Arctic thawing could be economic time bomb, scientists say (The Guardian)

http://www.theguardian.com/environment/2013/jul/24/arctic-thawing-permafrost-climate-change

Major methane release is almost inevitable (New Scientist) http://www.newscientist.com/article/dn23205-major-methane-release-is-almost-inevitable.html#.U3tUk-aSypQ

Global change puts plankton under threat (Nature Climate Change)

http://www.nature.com/nclimate/journal/v2/n7/full/nclimate1489.html

Pace of Ocean Acidification Has No Parallel in 300 Million Years, Paper Says (New York Times)

http://green.blogs.nytimes.com/2012/03/02/pace-of-ocean-acidification-has-no-parallel-in-300-million-years-paper-finds/

Big freeze plunged Europe into ice age in months (Science Daily)

http://www.sciencedaily.com/releases/2009/11/091130112421.htm

Antarctic Glacier Loss Is ‘Unstoppable,’ Study Says (TIME)

http://time.com/96173/antarctic-glacier-loss-is-unstoppable-study-says/