Six Degrees

biffvernon · Post by **biffvernon** » 17 Nov 2009, 22:12

http://news.bbc.co.uk/1/hi/sci/tech/8364926.stm

Paraphrasing Professor Corinne Le Quere and the Global Carbon Project, "We're doomed". (Better check that against text.)

But they do come up with lines like

If current trends prevail, global fossil fuel emissions are
expected to rise to between 12 and 18 Gt C per year by
2050 (2 to 3 times the level in 2000).

Good job there's an 'if' in there.

Policy Brief Nov 09 #10

UndercoverElephant · Post by **UndercoverElephant** » 18 Nov 2009, 11:10

A global rise of six degrees is probably enough to set off a chain-reaction "methane burp". In other words, as soon as you get into this sort of territory, six degrees can rapidly become ten and we are talking about a mass extinction on a Permian-Triassic scale: 90% of species lost. To stand any decent chance of avoiding this outcome we need to keep the global rise below five degrees.

RenewableCandy · Post by **RenewableCandy** » 18 Nov 2009, 12:05

My boss at my previous work read "Six Degrees" and it did his head in. Still drives to work, mind. I think what really does people's heads in is they don't realistically have the choice.

biffvernon · Post by **biffvernon** » 18 Nov 2009, 13:38

All too true.

emordnilap · Post by **emordnilap** » 18 Nov 2009, 14:23

RenewableCandy wrote:they don't realistically have the choice.

Tmesis time.

Pre-fecking-cisely, RC.

snow hope · Post by **snow hope** » 18 Nov 2009, 17:03

UndercoverElephant wrote:A global rise of six degrees is probably enough to set off a chain-reaction "methane burp". In other words, as soon as you get into this sort of territory, six degrees can rapidly become ten and we are talking about a mass extinction on a Permian-Triassic scale: 90% of species lost. To stand any decent chance of avoiding this outcome we need to keep the global rise below five degrees.

But on the positive side, 6.5billion of us would become the oil of the future........

fifthcolumn · Post by **fifthcolumn** » 19 Nov 2009, 22:40

UndercoverElephant wrote:A global rise of six degrees is probably enough to set off a chain-reaction "methane burp". In other words, as soon as you get into this sort of territory, six degrees can rapidly become ten and we are talking about a mass extinction on a Permian-Triassic scale: 90% of species lost. To stand any decent chance of avoiding this outcome we need to keep the global rise below five degrees.

Interesting then, that 14500 years ago we got a 22F rise in less than a decade and it didn't end the world.

Post by **clv101** » 20 Nov 2009, 09:06

fifthcolumn wrote:
UndercoverElephant wrote:A global rise of six degrees is probably enough to set off a chain-reaction "methane burp". In other words, as soon as you get into this sort of territory, six degrees can rapidly become ten and we are talking about a mass extinction on a Permian-Triassic scale: 90% of species lost. To stand any decent chance of avoiding this outcome we need to keep the global rise below five degrees.
Interesting then, that 14500 years ago we got a 22F rise in less than a decade and it didn't end the world.

Interesting that you mention that knowing it's irrelevant or just obfuscation. Moving from very cold to quite cold isn't the same as moving from quite cold to warm. The number of degrees is irrelevant. Does it matter if your freezer goes from -40C to -10C? Those 30 degrees aren't half as important as the 15 degrees from -10C to +5C.

fifthcolumn · Post by **fifthcolumn** » 20 Nov 2009, 17:43

clv101 wrote:The number of degrees is irrelevant.

Exactly my point. Thanks for making it for me....

Post by **clv101** » 20 Nov 2009, 19:46

ha, thanks for missing mine!

fifthcolumn · Post by **fifthcolumn** » 20 Nov 2009, 20:49

clv101 wrote:ha, thanks for missing mine!

No I didn't miss it, I ignored it because you left me a perfect opening through which I could slap you.

Now if you please, please explain how rising from today's temperatures to those of today + 20F will screw things up for our current ecosystems which are evolved for today's climate WORSE than a temperature rise of +20F in the ice age screwed up ecosystems which were adapted for the lower temperatures of the day.

Come on chris, enlighten me mate.

Post by **clv101** » 20 Nov 2009, 22:05

fifthcolumn wrote:Now if you please, please explain how rising from today's temperatures to those of today + 20F will screw things up for our current ecosystems which are evolved for today's climate WORSE than a temperature rise of +20F in the ice age screwed up ecosystems which were adapted for the lower temperatures of the day.

Why would every 20F jump have the same impact? I thought my freezer analogy was clear that a small number of degrees over the threshold can be more significant than a larger number of degrees without crossing some threshold.

Why would any impact be linear as you seem to be suggesting?

RenewableCandy · Post by **RenewableCandy** » 20 Nov 2009, 22:33

But it's not even just temperature difference, or thresholds, izzit? It's adaptability. I mean, in the freezer-warming-up scenario, anything that liked life at, say -30degC could migrate (well OK the trees would find it pretty tough as individuals but as a species they'd get there in the end).

But with most landscapes carved up with human-made barriers of one sort or another, and most places already full-to-capacity with people, migration is no longer the simple business of getting from A to B. For people it involves culture, bureaucracy, racism etc, and for wildlife it involves being cut off from where you need to go by roads, dams, cities, etc.

UndercoverElephant · Post by **UndercoverElephant** » 21 Nov 2009, 11:09

fifthcolumn wrote:
UndercoverElephant wrote:A global rise of six degrees is probably enough to set off a chain-reaction "methane burp". In other words, as soon as you get into this sort of territory, six degrees can rapidly become ten and we are talking about a mass extinction on a Permian-Triassic scale: 90% of species lost. To stand any decent chance of avoiding this outcome we need to keep the global rise below five degrees.
Interesting then, that 14500 years ago we got a 22F rise in less than a decade

22 degrees FAHRENHEIT? Do people still measure things in Fahrenheit? Was the six degree of the opening post talking about Fahrenheit? I don't even know what 22 degrees fahrenheit is, but I am highly doubtful that there was a 22 degree fahrenheit rise in a decade, ever. Even under "methane burp" conditions it takes longer than that.

UndercoverElephant · Post by **UndercoverElephant** » 21 Nov 2009, 11:14

clv101 wrote:
fifthcolumn wrote:Now if you please, please explain how rising from today's temperatures to those of today + 20F will screw things up for our current ecosystems which are evolved for today's climate WORSE than a temperature rise of +20F in the ice age screwed up ecosystems which were adapted for the lower temperatures of the day.
Why would every 20F jump have the same impact?

No. Although we should be talking celsius, it is obviously the case that you have to take more into account than just the net rise. For a start it depends how much ice there is on the surface of the Earth (because ice reflects light), second it depends on how much methane hydrate there is that is ready to burp and third it depends on what the starting temperature is.

We know how much methane hydrate there is ready to blow. The current location of the continents happens to mean that there are vast areas of what is currently permafrost (across northern Russia and Canada) which would melt with a 5 degree rise and release vast amounts of methane. And that's not even taking into account the methane hydrate in the seas.

A methane burp is pretty much the ultimate doomer scenario, unless you are including the Earth being sucked into a Black Hole.