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IPCC says abrupt irreversible clathrate methane, ice sheet collapse are unlikely.

Posted By Joanne Nova On October 3, 2013 @ 6:59 pm In Global Warming | Comments Disabled

For years we’ve been warned via the media that there was a risk of irreversible global catastrophe. Is the IPCC stepping back from those forecasts too?  The words abrupt, irreversible, and tipping point didn’t make it into the Headline Points in 2013.

Reader Katabasis at Bishop Hill reports on the Royal Society meeting where abrupt and irreversible changes were discussed. Katabasis notes that in the IPCC Chapter 12 Table 12.4 many of the catastrophic changes being forecast are described as “unlikely” or “very unlikely” or even “exceptionally unlikely”. The only one now considered “likely” is that the Arctic might be ice free 40 years from now (which is a big step back from “ice free by 2013″ as some commentators predicted). Moreover confidence is low.

Will IPCC authors now correct Gore, Flannery, or other commentators when they tell us that CO2 emissions will probably lead to abrupt or irreversible ice sheet collapse, or collapses of the monsoonal circulation or Atlantic currents. Note the IPCC is saying “low confidence” for  long term megadroughts, and monsoon changes, which means, “we don’t know” rather than “unlikely”. But why spend billions to prevent something you have low confidence will happen?

Table 12.4: Components in the Earth system that have been proposed in the literature as potentially being susceptible to abrupt or irreversible change. Column 2 defines whether or not a potential change can be considered to be abrupt under the AR5 definition. Column 3 states whether or not the process is irreversible in the context of abrupt change, and also gives the typical recovery time scales. Column 4 provides an assessment, if possible, of the likelihood of occurrence of abrupt change in the 21st century for the respective components or phenomena within the Earth system, for the scenarios considered in this chapter.

Source: AR5-Chapter 12. Table 12.4 page 78

Katabasis asked Matt Collins:

“What the IPCC says, and what the media says it says are poles apart. Your talk is a perfect example of this. Low liklihood and low confidence for almost every nightmare scenario. Yet this isn’t reflected at all in the media. Many people here have expressed concern at the influence of climate sceptics. Wouldn’t climate scientists’ time be better spent reining in those in the media producing irresponsible, hysterical, screaming headlines?”

Tumbleweed followed for several seconds. Then Matt said:

“Not my responsibility”.

Bishop Hill commenter matthu:

Is that Matthew Collins: Government employee? Joint Met Office Chair in Climate Change?

Is he saying that it is not his responsibility to correct widely held misconceptions about the likelihood of imminent abrupt and irreversible climate change as the result of carbon dioxide?

Even if this is being incorrectly reported by mainstream media in the UK or touted by senior government ministers as a reason for continuing to meet our international obligations i.e. by raising the price of energy?

So if he was asked a direct question about this, say on Newsnight, he would try to bypass his responsibility? No wonder the BBC finds it hard to identify sceptical scientists if even those in full possession of the facts are too cowered to stand up for the truth.

Note the IPCC definitions of irreversible and abrupt are not necessarily irreversible and may take a few decades.

Abrupt climate change is defined in AR5 as a large-scale change in the climate system that takes place over a few decades or less, persists (or is anticipated to persist) for at least a few decades, and causes substantial disruptions in human and natural systems.”

A change is said to be irreversible if the recovery timescale from this state due to natural processes is significantly longer than the time it takes for the system to reach this perturbed state.

Let’s look at that incongruous media coverage:

The Copenhagen Diagnosis November 2009 [NY Times]

Delay in action risks irreversible damage: Several vulnerable elements in the climate system (e.g. continental ice sheets, Amazon rain forest, West African monsoon and others) could be pushed towards abrupt or irreversible change if warming continues in a business-as-usual way throughout this century. The risk of transgressing critical thresholds (“tipping points”) increases strongly with ongoing climate change. Thus waiting for higher levels of scientific certainty could mean that some tipping points will be crossed before they are recognized. The turning point must come soon: If global warming is to be limited to a maximum of 2°C above preindustrial values, global emissions need to peak between 2015 and 2020 and then decline rapidly.

The Guardian,9 November 2011 World headed for irreversible climate change in five years, IEA warns

The world is likely to build so many fossil-fuelled power stations, energy-guzzling factories and inefficient buildings in the next five years that it will become impossible to hold global warming to safe levels, and the last chance of combating dangerous climate change will be “lost for ever”, according to the most thorough analysis yet of world energy infrastructure.

“We could be at a tipping point where the climate just abruptly warms,” said Mark Z. Jacobsen, director of Stanford University’s atmosphere/energy program.

Even after the AR5 release, 30 Sept 2013 Andrew Glickson writes in The Conversation and Business Spectator:

The extreme rates of global warming experienced since about 1975 result in feedback effects from warming oceans, drying land sectors, release of methane from permafrost and Arctic lakes and release of CO2 from fires. A continuation of these processes is bound to bring on a synergy of warming processes and potential irreversible tipping points in the climate system.

“No amount of media and internet spin can alter the essential evidence for runaway climate change presented by the AR5 report…”

David Wasdell, Director of the Meridian Institute:

“The Feedback Crisis in Climate Change highlights the all-too-real possibility of runaway climate change, driven by the naturally occurring positive feedback loops of the biosphere…

Professor of Environmental Change Biology, David Bowmanlink

“Climate change in the 20th and 21st centuries constitutes an unprecedented event horizon – a shift of state in the terrestrial atmosphere. “

The Climate Commission, The critical decade, 2013:

“The most serious risks are associated with potential abrupt or irreversible changes in large features of the climate system, such as the switch to a dry state of the Indian Summer Monsoon (Lenton et al. 2008)..”

“2.5 Abrupt, non-linear and irreversible changes in the climate system

…Some changes in the climate system can be irreversible in any timeframe relevant to human affairs, such as the loss of the Greenland ice sheet.

Some of these quotes will be technically justified with clauses and subclauses. Something “very unlikely” is still possible. But where is the perspective? The IPCC doesn’t seem confident of any abrupt or irreversible changes except for the loss of Summer Arctic Ice (which they admit is not irreversible).

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