Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

Antarctica loses three trillion tonnes of ice in 25 years

bbc.co.uk

Post reply on HN
Print view View original

31–40 of 58 posts

Re: Antarctica loses three trillion tonnes of ice in 25 years

#31

Post by mkempe »

llccbb wrote: post #29
mkempe wrote: post #12

I don't understand this part: "In total, Antarctica has shed some 2.7 trillion tonnes of ice since 1992, corresponding to an increase in global sea level of more than 7.5mm." If the melting ice of Antarctica contributes only 0.3mm per year to the annual 6mm rise of sea levels, what exactly is causing a 20x larger change? [added] On the other hand a NASA study published in 2015 [1] indicated that Antarctica has been s…

0.3 mm/yr * 26 yr = 7.8 mm Antarctica's contribution to sea level rise per year is fairly small. The largest portion comes from loss of land-ice like mountain glaciers and snow pack. Mass loss from the Greenland Ice Sheet is also substantial, contributing about 2.7 mm/yr to sea level change. Groundwater withdrawal is a measurable component of modern sea level rise. Aside from these mass-transfer mechanisms, there is…

Greenland does not contribute that much to global sea-level rise: "The cumulative ice loss from Greenland from 1992 to 2015 was 3,600 Gt and contributed to global sea level rise by approximately 10 mm" -- that's less than 0.5 mm/year. [1]

Where did you get that Greenland contribution rate?

[1] https://www.eea.europa.eu/data-and-maps/indicators/greenland...

Re: Antarctica loses three trillion tonnes of ice in 25 years

#32

Post by iconjack »

Also NASA:

Antarctic Sea Ice Reaches New Record Maximum (2014) [1]

NASA Study: Mass Gains of Antarctic Ice Sheet Greater than Losses (2015) [2]

  etc etc etc
[1] https://www.nasa.gov/content/goddard/antarctic-sea-ice-reach...

[2] https://www.nasa.gov/feature/goddard/nasa-study-mass-gains-o...

Re: Antarctica loses three trillion tonnes of ice in 25 years

#33

Post by natalyarostova »

kchronic8 wrote: post #30
thinkcontext wrote: post #5

Rather than focusing on the big sounding absolute number in the headline, the more important number is the 3-fold increase since 2012. This means that the losses are accelerating, which is very concerning.

Yeah it's concerning. Now if you'll excuse me, I'll get back to driving my gasoline vehicle and not carpooling.

You don't need us to excuse you, this is an internet comment thread.

Re: Antarctica loses three trillion tonnes of ice in 25 years

#34

Post by nherment »

iconjack wrote: post #32

Also NASA: Antarctic Sea Ice Reaches New Record Maximum (2014) [1] NASA Study: Mass Gains of Antarctic Ice Sheet Greater than Losses (2015) [2] etc etc etc [1] https://www.nasa.gov/content/goddard/antarctic-sea-ice-reach... [2] https://www.nasa.gov/feature/goddard/nasa-study-mass-gains-o...

I think maybe these are worth reading past the title?

[1]: > While the Antarctic sea ice yearly wintertime maximum extent hit record highs from 2012 to 2014 before returning to average levels in 2015, both the Arctic wintertime maximum and its summer minimum extent have been in a sharp decline for the past decades. Studies show that globally, the decreases in Arctic sea ice far exceed the increases in Antarctic sea ice.

[2] "We’re essentially in agreement with other studies that show an increase in ice discharge in the Antarctic Peninsula and the Thwaites and Pine Island region of West Antarctica" ... "“Our main disagreement is for East Antarctica and the interior of West Antarctica" ... "If the losses of the Antarctic Peninsula and parts of West Antarctica continue to increase at the same rate they’ve been increasing for the last two decades, the losses will catch up with the long-term gain in East Antarctica in 20 or 30 years -- I don’t think there will be enough snowfall increase to offset these losses."

Re: Antarctica loses three trillion tonnes of ice in 25 years

#36

Post by acqq »

iconjack wrote: post #32

Also NASA: Antarctic Sea Ice Reaches New Record Maximum (2014) [1] NASA Study: Mass Gains of Antarctic Ice Sheet Greater than Losses (2015) [2] etc etc etc [1] https://www.nasa.gov/content/goddard/antarctic-sea-ice-reach... [2] https://www.nasa.gov/feature/goddard/nasa-study-mass-gains-o...

No, over years, Antarctic loses total ice, 125 GTons per year on average:

https://svs.gsfc.nasa.gov/30880

"Sea ice" from the titles you quote is just a subset of "ice" and "extent" is just one dimension of all its presence, and there's constantly less total ice (minus seasonal variation). Your title selection misuses some people's unawareness of the difference.

Re: Antarctica loses three trillion tonnes of ice in 25 years

#37

Post by coldtea »

LinuxBender wrote: post #6

How many feet above current sea level will I have to reside to be safe in 10 years, 20 years?

If it gets worse, it wont matter how many feet you are above sea level, except to not have your house submerged in water.

But the repercussions, like economic downturns, loss of friends and relatives, climate change created phenomena, food and water shortages, diseases on the raise, and so on, will affect everywhere...

Re: Antarctica loses three trillion tonnes of ice in 25 years

#38

Post by coldtea »

selectodude wrote: post #9
LinuxBender wrote: post #6

How many feet above current sea level will I have to reside to be safe in 10 years, 20 years?

If you’re more than like 150 feet above sea level it will never be an issue.

Water submerging your property wont be an issue. All the tons of others far more important repercussions will still apply...

Re: Antarctica loses three trillion tonnes of ice in 25 years

#39

Post by coldtea »

mkempe wrote: post #25
Retra wrote: post #18

Earlier quoted context omitted.

That's also average sea level. If hurricanes get more powerful or more frequent, then you're going to want to account for the storm surge as well.

The historical record shows that hurricanes have gotten neither more frequent nor more powerful. [1] [1] https://www.wsj.com/articles/the-hurricane-lull-couldnt-last...

The historical record talks about what (a) happened in the past, (b) is on record. Neither applies to a rapidly changing climate landscape.

Re: Antarctica loses three trillion tonnes of ice in 25 years

#40

Post by kaybe »

mkempe wrote: post #23
kaybe wrote: post #19

Earlier quoted context omitted.

Water expands when it gets warmer.

On the other hand, "In the most recent estimate, for 1993–2008, the contribution from land ice increased to 68 percent, the contribution from thermal expansion decreased to 35 percent". [1] Something is not right. Either ice melting has been contributing 4mm/year to recent decades of sea rise, or the contribution is slightly negative (in the largest ice sheet, over Antarctica). Thermal expansion of ocean water on its…

https://ipcc.ch/pdf/assessment-report/ar5/wg1/WG1AR5_Chapter...

Check page 291 for an overview of components and time lines. This is still the current scientific consensus AFAIK (no major updates).

Post reply on HN