Clearest indication yet that polar ice sheets are melting fast

http://arstechnica.com/science/2012/12/clearest-indication-yet-that-polar-ice-sheets-are-melting-fast

by jfoucher • 14 years ago

42 21 14 years ago

meric• 14 years ago

Also permafrost is melting (irreversibly on human time-scales): http://www.smh.com.au/environment/climate-change/where-even-...

pyre2• 14 years ago

  > (irreversibly on human time-scales)

This comes across as ambiguous and I didn't understand what you meant until I read the article.

"It's happening at a rate that is irreversible on human time-scales"

rdtsc• 14 years ago

I don't know what the original poster meant but I understand it to be that if it is cyclic phenomena and/or was/can be triggered by human activity, it has already entered into a phase that make it unlikely to be reversed no matter what humans do in say one to tens of humans lifetimes (say 100 to 1000 years). The system might correct itself or cycle back but it would be on very large time scales.

The main gist from the articles is that the perma frost echo system is an amplifier for climate change. So it is like positive feedback. For maybe for what seems like a small change contributed by human activity, the permafrost echo system might respond and amplify that by some large factor.

Anyway I don't know enough about the issue but that is what I understood from the article.

genuine• 14 years ago

What good does this do? Should I go into bankruptcy insulating my house with aerogel to protect against severe climate change?

If the weather gets hot or there is a drought, environmentalist scientists tell the media that problem is global warming caused by humans. If the weather gets colder, environmentalist scientists tell the media that problem is climate change caused by humans.

If it gets really damn cold outside, or really damn hot, then we need to make good insulation cheaper. Whining about it doesn't do a damn bit of good.

nitrogen3• 14 years ago

That's not what I've been hearing. I see people saying that no individual weather event or localized change can be attributed to global climate change, but that as more total energy is added to the earth system, more chaotic weather events and localized changes can be expected in aggregate (edit: e.g. http://youtu.be/5EaLVOv8cIk?t=1m49s).

lifeformed• 14 years ago

Well, it's good to have details on the causes and effects of these kinds of problems, so we can better decide how to prevent it from happening more. Our efforts shouldn't be purely reactive, it should also be preventative.

sighagain• 14 years ago

This is what is laughable. The original IPCC report on global warming predicted an average rate of global mean sea level rise of about 6 cm per decade. The reality? 11 mm or less over the last 2 decades! That's over a factor of 100 miss. Nobody seems to notice how the goal posts on this issue are constantly moving. In the end, yes, there is global warming, but it is not even close to what was predicted in the late 1980s and early 1990s.

http://en.wikipedia.org/wiki/IPCC_First_Assessment_Report

nitrogen3• 14 years ago

Science is science because it is allowed to change its mind when presented with new data.

PakG12• 14 years ago

The unfortunate thing happens when incomplete science is used for political posturing and policy.

CamperBob23• 14 years ago

Economics is a bit different. When you make economic decisions based on questionable data, people suffer.

magicalist• 14 years ago

OK, a few things

1) sea level rises have always been one of the trickier predictions to make, and the IPCC has never been cagey about this. It's subject to a large number of secondary and tertiary feedbacks, which can cause huge variances in what the models say, and should not be a proxy for how correct models from the 80s and 90s were. Notice that the Wikipedia article actually summarizes the report as saying "6 cm per decade over the next century (with an uncertainty range of 3 – 10 cm per decade)". In other words, there is a lot of variability here, but the best guess (22 years ago...think of the kinds of computers those models were running on) was that the average rise over the next century would be 6cm per decade.

This is quite different than the current article, which is of course about actual measurements and what they mean for the models, which is presumably exactly the kind of verification (one way or the other) that we should be looking for. If the models were wrong (as undoubtedly some were since there are a number of different models and we have to try to reconcile them) then we can go back and figure out why our models were wrong; not throw the baby out with the bathwater.

2) according to your claim, the reality was 11mm (or less) over the last two decades, "over a factor of 100 miss". Now, I'm an American and the metric system confuses me, but isn't half of 11mm 5.5mm, which is .55cm, which would only be a factor of 10 off from 6cm?

3) According to current data (check here[1] for sources and raw data), the sea level actually rose 3.1mm per year from 1993 to 2003. I don't know where you got your 11mm for the last two decades, but the reality adds up to 3.1cm over that decade, only a factor of two off and well within the prediction from 1990, which has of course been supplanted by several reports since then.

The last IPCC assessment even explicitly stated that they can't be certain if the acceleration of sea level rise seen in the last two decades can be expected to continue or if other dynamics will become dominant, as they don't have enough data (for the current trend) and their models might not be sophisticated enough yet. Their best guess in 2007 was 18 to 59cm by 2100, but I believe that's been revised since then.

Hey, what do you know: scientists being scientists. If you actually take time to take a look, they include their confidence intervals every time.

[1] http://www.climatewatch.noaa.gov/article/2009/climate-change...

uvdiv• 14 years ago

Wrong and wrong. AR1 predicted 5-14 cm over 20 years; the actual rise was 6 cm.

The reality? 11 mm or less over the last 2 decades!

The article claims 11 mm of water solely from melting ice sheets. It says the total increase was five times larger than that.

The increase over the last 19.5 years, 1993 to mid-2012, was between 53-68 mm. The average rate was 3.1 mm/year +/- 0.4.

http://sealevel.colorado.edu/content/2012rel4-global-mean-se...

The original IPCC report on global warming predicted an average rate of global mean sea level rise of about 6 cm per decade.

IPCC AR1 did not predict 6 cm/decade rate for this time; it predicted 6 cm/decade averaged over the century 2000-2100, starting slowly and then accelerating. (Rising CO2 levels accelerate melting; economic growth accelerates CO2 rise).

If you look at AR1's actual forecast,

http://i.imgur.com/2r67Z.png

What it predicted for the near-term, 1990-2010 was (eyeballing the graph): a 9 cm rise, lower range 5 cm, upper range 14 cm. A rate of 2.5-7 mm/year.

The graph is from page 277.

http://www.ipcc.ch/ipccreports/far/wg_I/ipcc_far_wg_I_chapte...

guscost• 14 years ago

Generally speaking, alarmists ignore the issue of falsification. And I'll probably be downvoted into oblivion for pointing it out: http://guscost.com/2012/11/28/global-whining/

retrogradeorbit• 14 years ago

Also ignored is the linear warming trend that started before the large industrial production of CO2 and that accounts for significant amounts of warming. And the multi-decadal pacific oscillation. But you know, alarmism sells.

citation: http://people.iarc.uaf.edu/~sakasofu/pdf/two_natural_compone...

Clearest indication yet that polar ice sheets are melting fast

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