vashti (![[info]](http://www.insanejournal.com/img/userinfo.gif){kind=small} vashti) wrote,@ 2007-10-19 04:38:00 |
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Fuck, fuck, fuck: Arctic sea ice
Carbon Equity have released The Big Melt: Lessons from the Arctic summer of 2007.
Summary:
* The standard "safe" warming level of 2 C is much, much too high.
* We lost as much Arctic ice between 2005 and 2007 as we lost between 1979 and 2005 (20% in two years, as opposed to 7% decade on decade).. James Hansen attributes this to us "hitting a tipping point that we have been warning about for the past few years".
Oh, and with regard to the English legal system's attempted discrediting of An Inconvenient Truth, where it was claimed (amongst other things) that significant sea level rise was only going to take place over a millennium, Hansen also has this to say:
I find it almost inconceivable that "business as usual" climate change will not result in a rise in sea level measured in metres within a century... Because while the growth of great ice sheets takes
millennia, the disintegration of ice sheets is a wet process that can proceed rapidly.
... the primary issue is whether global warming will reach a level such that ice sheets begin to disintegrate in a rapid, non-linear fashion on West Antarctica, Greenland or both. Once well under way,
such a collapse might be impossible to stop, because there are multiple positive feedbacks. _In that event, a sea level rise of several metres at least would be expected.
As an example, let us say that ice sheet melting adds 1 centimetre to sea level for the decade 2005 to 2015 [this is less than the current rate - DS], and that this doubles each decade until the West Antarctic ice sheet is largely depleted. This would yield a rise in sea level of more than 5 metres by 2095.
...
The IPCC's latest projection for sea level rise this century is 18 to 59 centimetres. Though it explicitly notes that it was unable to include possible dynamical responses of the ice sheets in its calculations, the provision of such specific numbers encourages a predictable public belief that the projected sea level change is moderate, and indeed smaller than in the previous IPCC report. There have been numerous media reports of "reduced" predictions of sea level rise, and commentators have denigrated suggestions that business-as-usual emissions may cause a sea level rise measured in metres. However, if these IPCC numbers are taken as predictions of actual sea level rise, as they have been by the public, they imply that the ice sheets can miraculously survive a business-as-usual climate forcing assault for a millennium or longer.
There are glaciologists who anticipate such long response times, because their ice sheet models have been designed to match past climate changes. However, work by my group shows that the typical 6000-year timescale for ice sheet disintegration in the past reflects the gradual changes in Earth's orbit that drove climate changes at the time, rather than any inherent limit for how long it takes ice sheets to disintegrate.
Indeed, the palaeoclimate record contains numerous examples of ice sheets yielding sea level rises of several metres per century when forcings were smaller than that of the business-as-usual scenario. For example, about 14,000 years ago, sea level rose approximately 20 metres in 400 years, or about 1 metre every 20 years.
ENVIRONMENTALISTS BRAINWASHING UR KIDS IN UR SCHOOLS OMG.
Carbon Equity have released The Big Melt: Lessons from the Arctic summer of 2007.
Summary:
* The standard "safe" warming level of 2 C is much, much too high.
* We lost as much Arctic ice between 2005 and 2007 as we lost between 1979 and 2005 (20% in two years, as opposed to 7% decade on decade).. James Hansen attributes this to us "hitting a tipping point that we have been warning about for the past few years".
Oh, and with regard to the English legal system's attempted discrediting of An Inconvenient Truth, where it was claimed (amongst other things) that significant sea level rise was only going to take place over a millennium, Hansen also has this to say:
I find it almost inconceivable that "business as usual" climate change will not result in a rise in sea level measured in metres within a century... Because while the growth of great ice sheets takes
millennia, the disintegration of ice sheets is a wet process that can proceed rapidly.
... the primary issue is whether global warming will reach a level such that ice sheets begin to disintegrate in a rapid, non-linear fashion on West Antarctica, Greenland or both. Once well under way,
such a collapse might be impossible to stop, because there are multiple positive feedbacks. _In that event, a sea level rise of several metres at least would be expected.
As an example, let us say that ice sheet melting adds 1 centimetre to sea level for the decade 2005 to 2015 [this is less than the current rate - DS], and that this doubles each decade until the West Antarctic ice sheet is largely depleted. This would yield a rise in sea level of more than 5 metres by 2095.
...
The IPCC's latest projection for sea level rise this century is 18 to 59 centimetres. Though it explicitly notes that it was unable to include possible dynamical responses of the ice sheets in its calculations, the provision of such specific numbers encourages a predictable public belief that the projected sea level change is moderate, and indeed smaller than in the previous IPCC report. There have been numerous media reports of "reduced" predictions of sea level rise, and commentators have denigrated suggestions that business-as-usual emissions may cause a sea level rise measured in metres. However, if these IPCC numbers are taken as predictions of actual sea level rise, as they have been by the public, they imply that the ice sheets can miraculously survive a business-as-usual climate forcing assault for a millennium or longer.
There are glaciologists who anticipate such long response times, because their ice sheet models have been designed to match past climate changes. However, work by my group shows that the typical 6000-year timescale for ice sheet disintegration in the past reflects the gradual changes in Earth's orbit that drove climate changes at the time, rather than any inherent limit for how long it takes ice sheets to disintegrate.
Indeed, the palaeoclimate record contains numerous examples of ice sheets yielding sea level rises of several metres per century when forcings were smaller than that of the business-as-usual scenario. For example, about 14,000 years ago, sea level rose approximately 20 metres in 400 years, or about 1 metre every 20 years.
ENVIRONMENTALISTS BRAINWASHING UR KIDS IN UR SCHOOLS OMG.