Curbing climate change 'unlikely'

[Dead_Parrot]

Another "no shit, Sherlock" moment.

Rising concentrations of greenhouse gases may have more serious impacts than previously believed, a major new scientific report has said.

The report, published by the UK government, says there is only a small chance of greenhouse gas emissions being kept below "dangerous" levels.

It fears the Greenland ice sheet is likely to melt, leading sea levels to rise by seven metres over 1,000 years.

And here's a pricless little gem from the US National Center for Atmospheric Research:

"A stabilisation at 450 ppm CO2-equivalent requires global emissions to peak around 2015, followed by substantial overall reductions in the order of 30%-40% compared to 1990 levels in 2050."

Funny, eveyone set the cliff edge at 400ppm :shrug:

More at http://news.bbc.co.uk/2/hi/science/nature/4660938.stm

[hatrack]

1. Huh, ya think?

:eyes:

[phantom power]

2. No worries. Our climate is no doubt just pining for the fjords.

[Dogmudgeon]

3. The Cliff

We're so close to it, we can't see where it starts.

There's here, and there's the valley below, and all of the sudden, we've gone blind.

The scenario I expect: A "Heinrich Event" starting Any Day Now, followed by a 2-3 thousand year long mini-Ice Age (like the Younger-Dryas), followed by a number of Dangaard-Oeschger and Henrich events in quick succession; all of which will mark the next great glaciation. Humanity will learn to respect the planet they had grown up on in its summer as its autumn passes into winter. The main part of our industry will move into space, followed by civilization in about 100 years.

Then, superintelligent monkeys will fly out of my ass and serenade the chickens dancing the Macarena on my ceiling.

Alternative scenario: Due to continued global warming, the mini-Ice Age lasts less than half a millenium. With CO2 levels nearing 1500 ppm in 2500 CE, the Dangaard-Oeschger warming doesn't stop. As a large amount of the surface water is driven into the atmosphere, the ground becomes arid, and worldwide fires crank the CO2 levels even higher. The planet's atmosphere falls into a Runaway Greenhouse state around 2650 CE. Within 50 years, the final terrestrial human die-off (about 20 billion people) begins; by 2900 CE, the Earth is an outpost for a number of monitoring stations, with human civilization starting to rebuild on Mars. With a global average temperature just below the boiling point of water, the last chordate born on the Earth dies in January of 3001, on the 1000th anniversary of George Bush's swearing-in. Another 1665 years will be required to complete the boil-off of the oceans, and 1831 to force the last of the extremophiles into extinction, but the Earth has effectively been a desert planet since about 2800 CE.

Personally, I'd prefer a lo-o-o-o-ong snow holiday.

--p!

[phantom power]

4. Pretty generous, how we escape to Mars.

At other times in the past, Earth has had CO2 concentrations several times higher than today, and the biosphere lived to tell the tale. This causes me to think that life will have another chance or two at a rennaissance, before the sun starts to heat up in a billion years.

[Dogmudgeon]

5. Yeah, me too

I'm pretty sure that a runaway greenhouse would require a more complex mix of gases. Not that Homo sap isn't capable of it, but I'm thinking we'll be having more snow days than heat warnings.

I also heard that the Sun is heating up even as we speak, and that land animals have about 800-1000 million years left on the clock (maybe more). It would be a lot more beneficial, obviously, if the change was discontinuous.

That's also another 12-15 comet/asteroid impacts on the scale of the K-T/Chichxulub impactor (maybe more). Makes it seem kinda like Christmas morning, dunnit?

:evilgrin:

--p!

[phantom power]

6. I felt robbed, when they downgraded from 4GY to 1GY.

I grew up reading that we had 4 billion years before the sun went off the main sequence. I guess that's still true, but I was disappointed by the new predictions that earth's biosphere would start getting cooked so much sooner.

[Dogmudgeon]

7. I guess it was inevitable

As the astrophysicists began to fill in the gaps in the revised Hertzsprung-Russel sequence, they realized it wasn't just G-zero forever; the Sun probably started as a type-M, and may well heat up to about F0 or even A8 before the reactions occur that cause it to expand to a red giant. (There is still some controversy about whether the final Main Sequence heating will be a jump or a slide, and how much.)

In one billion years, though, we could easily have spread out to 300, 400 million light-years away, and that assumes that the speed of light is the absolute fastest we can go. (Recently, some well-informed doubt has been cast on that.) As a spacefaring civilization, the choice of star won't be quite so critical, though habitat design will be.

But I'd also like to think that we'd also take care of all the planets which we take into our care. We've done a terrible job with our own Earth so far, but we can still reform. We could even reform at a relatively low cost. And if we had started 30 years ago, there would have been a corresponding increase in wealth rather than a cost.

--p!

[phantom power]

8. I'd propose to leave other planets alone. There are so many alternatives.

Or, we could take lifeless planets and give them biospheres. And then leave them alone.

[htuttle]

9. Procreation is a biological imperative...

...whether you're talking about single celled creatures, multi-cellular organisms, or biospheres.

I think we're 'supposed' to spread Earth life anywhere else we can. At least that's what I would want done if I were the biosphere.

'Course, at this rate, it looks like our biosphere might not make it out of puberty...I imagine that happens sometimes.

[blindpig]

12. If we totally fubar this planet

we don't deserve another one. I'd rather see our species extinct than running amuk thru the galaxy fucking up more planets and their lifeforms.

[Odin2005]

10. It's not the Sun's lifespan that was changed.

Stars slowly brighten while on the main sequence as a result of core contrantion speedng up the rate of fusion because fusion decrases the number of atomic nuclei (4 protons become 1 He nucleus). 4 billion years ago the sun was 30% dimmer than it is now, but the Earth wasn't cooler than now because there was a lot more CO2 in the atmosphere than now. as the sun increased in brightness CO2 was gradually removed from the atmosphere since warming increased the rate of erosion, releasing calcim ions from rocks which than reacted with dissolved CO2 to become limestone. The problem is that CO2 lwvels are becoming Dangerously low for plant life, the enzyme that captures CO2 for sugar biosynthesis, RuBisCO, requires at least 160ppm to funtion and the CO2 levels gets very close to that point during glacial periods(about 180ppm). Plants are already trying to get around the limitations of RuBisCO by evolving mechanisms to concentrate CO2 for the enzyme, the so-called C4 system, but even tat will fail when CO2 levels fall below 40ppm. when that happens say hellow to the moist greenhouse effect and Venusian conditions and goodbye biosphere.
:yoiks:

[phantom power]

11. Yes, it was only the lifespan of our biosphere.

[mainegreen]

13. We'll I can think of one alternative to going to Mars...

If we're going to do crazy space scenarios I'd thinks it would be far cheaper to place solar sheilds of micro-thin material in orbit around the earth to provide a shady cooling effect. In fact, that might turn out to be a not so bad solution.
:shrug:

[Nihil]

15. Well BushCo would certainly support that idea ...

... seeing as how it would stop any of those pesky astronomer types
from pointing out scientific facts that confuse the Holy Teachings ...

(From a practical point of view, you would be sending up far too many
shuttles far too often in order to replace the ongoing damage ... even
a bought-off NASA expert would be hard pressed to suggest that this
would result in a net improvement to the situation!)

The best "crazy space scenario" I can think of would be to steer a
moderate sized asteroid into the ocean and give the planet a chance
to start up a more intelligent species.

Alternatively, explode all of the world's nuclear arsenal at an appropriate
altitude that the fallout is largely lost but the EMP will take out all of
the communication command & control capability of the entire globe then see
how well the "civilized" monkeys can survive.

[Dogmudgeon]

16. I actually don't think it's crazy at all

Neither is yours, for that matter, though my solution is for industrialization, not cooling.

It's exotic, sure -- for now. All we have to do is start doing it, and it becomes mundane.

Fact is that we have sufficient technology and expertise to start building automated factories, powered by solar energy (which is far more abundant), in space. Since we can not long sustain on Earth the 2-3% growth per year necessary to keep our economy from collapsing, moving the heavy, dirty stuff into space makes economic sense.

This won't be a very romantic or sci-fi-ish process, though. I'm talking about what would essentially be large automated factories that might require one or two technicians each, who could work there in month-long or year-long shifts "just in case", like the Maytag repairmen we see in the commercials. The factories would be in high Earth orbit, lunar orbit, or at the L4/L5 points. The capture of even one small metal-laden asteroid would contain enough ores to provide the factories with resources for decades. Hauling raw materials from the Earth would not be too expensive, either, using mass-produced (i.e., ten at a time) "big, dumb, heavy lifters". And even generating power in space and sending it down to the Earth via microwaves, or even concentrated reflected light, is possible and economically feasable.

This isn't something we would or should start on tomorrow morning, but it could be started in a few years on a "proof-of-concept" basis, designed to turn a quick enough profit as to not stress governmental or financial resources. It is one part of a long-term plan to continue civilization, which I argue will eventually expand into habitats in space anyway -- unless we kill ourselves off in wars or die-offs.

--p!

[rfkrfk]

14. OK, so what are the odds ?

please enlighten me

'small chance' , is how small ?

how was that determined?