Graphing The Icy Actuality


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Visitor Publish by Willis Eschenbach

As we speak I noticed some scary headlines. I put up them up together with snippets of the tales. First, from the BBC:

Earth’s nice ice sheets, Greenland and Antarctica, are actually shedding mass six occasions quicker than they had been within the 1990s due to warming circumstances.

“That’s not a excellent news story,” mentioned Prof Andrew Shepherd from the College of Leeds within the UK.

Subsequent, from the NASA Jet Propulsion Laboratory (JPL)

The 2 areas have misplaced 6.four trillion tons of ice in three a long time; unabated, this charge of melting might trigger flooding that impacts a whole lot of thousands and thousands of individuals by 2100.

Lastly, from LiveScience:

The fast ice loss places the world proper on observe for the ‘worst case’ local weather situation.

Hmmm, sez I, the dreaded “worst-case” local weather situation … so I went to seek out the information. The articles are in Nature journal, hyperlinks are right here (paywalled, I obtained the DOI and used it over at SciHub to get the papers). The research is completed by a bunch of scientists who’re a part of a undertaking known as the “ice sheet mass steadiness inter-comparison train” (IMBIE).   

Right here is their cash graph concerning Antarctica:

Determine 1. From Mass steadiness of the Antarctic Ice Sheet from 1992 to 2017. The purple on the backside is the general complete loss for Antarctica

And right here’s the corresponding graph for Greenland:

Determine 2. From Mass steadiness of the Greenland Ice Sheet from 1992 to 2018. Click on to develop. Darkish blue is the general complete loss for Greenland

OK, each of these look scary sufficient.

So I downloaded the information. Kudos to the Imbie people who did the research. The info’s all accessible on two Excel spreadsheets, freely accessible right here. Determine three reveals my graph of their information comparable to the “Antarctica” a part of Determine 1:

Determine three. Cumulative ice mass loss, Antarctica. The photograph is penguins on surreal ice.

And Determine four reveals the corresponding information from Greenland:

Determine four. Cumulative ice mass loss, Greenland. Word the totally different vertical scales. Greenland loses extra ice than Antarctica.

YIKES! The ice loss appears to be like prefer it’s falling off of an ice cliff … 

So these agree with the IMBIE research, and they’re each adequately terrifying.

Having seen that, I assumed “how does this examine to the full ice mass within the Greenland and Antarctica ice sheets? Their ice volumes aren’t precisely recognized however are on the order of thirty million cubic kilometres in Antarctica and a tenth of that, three million cubic kilometres, in Greenland.

Now, one cubic kilometre is about zero.95 gigatonnes of ice. Utilizing these figures, I added the month-to-month Greenland ice mass loss proven in Determine four to the full mass of the ice in Greenland. That provides me the month-to-month complete quantity of Greenland ice. Determine 5 reveals that consequence.

Determine 5. Month-to-month change in Greenland ice mass as calculated however not graphed by the IMBIE staff.

See the blue/black line throughout the highest? Yep, that’s the change in Greenland ice. The web change is so small that you would be able to’t actually see it even in 1 / 4 century plus of knowledge. It’s about five-thousandths of 1 % (zero.005%) of the full Greenland ice mass per yr … be nonetheless, my beating coronary heart.

And right here’s the corresponding plot for Antarctica:

Determine 6. Change in Antarctic ice mass as calculated however not graphed by the IMBIE staff.

As earlier than, the blue/black line throughout the highest is certainly the change within the complete ice mass of Antarctica. The factor is, all of that terrifying ice loss proven in Determine three represents a complete lack of three ten-thousandths of 1 % (zero.0003%) of the Antarctic ice mass per yr … misplaced within the noise.

Subsequent, the media, and to a lesser extent the scientists, waste a bunch of ink hyperventilating in regards to the impact on sea-level rise. They suggest, however don’t state, that that is rising the general charge of sea-level rise. Nonetheless, what they fail to notice is that in suits and begins, the polar ice caps have been melting since we got here out of the final glacial interval … so the impact of polar meltwater is just not new. Meltwater has been included within the sea degree rise information for hundreds of years. And as I’ve proven right here, we’re not seeing any acceleration within the charge of sea-level rise within the longest and greatest tide gauge data we’ve. 

Lastly, right here’s most likely the most important factor that the research revealed. Determine 7 reveals the month-to-month ice loss from Greenland and Antarctica mixed.

Determine 7. Whole mixed month-to-month ice loss from Antarctica and Greenland

Discover something interested by that chart? I imply, apart from the actual fact it has a map of Greenland, Antarctica, and the US within the background?

Yep, you’re proper. In 2011, it began going the opposite means. The good ice caps had been shedding an increasing number of ice every year from 1992 to 2011. By 2011 they had been shedding about fifty gigatonnes of ice every month.

In that yr, one thing modified. Since 2011, Antarctica and Greenland have recovered to the place the loss is lower than half of the utmost lack of fifty gigatonnes monthly. Appears to me that issues are getting colder, not hotter as all of the headlines are shouting. Most just lately the loss is simply on the order of twenty gigatonnes monthly.

And why is that? Why is the speed altering? Why is even the signal of the speed altering, from extra ice misplaced every month to much less ice misplaced every month? And why did that change happen 9 years in the past, and never seven years or eleven years in the past?

Easy reply. We don’t know. 

Oh, they inform you within the research that it’s from “ocean-driven melting” or the “North Atlantic Oscillation” or ” atmospheric circulation favoured cooler circumstances” or that the “spatial sample of accelerating mass modifications displays the geography of NAO-driven shifts in atmospheric forcing” … however these are simply mechanistic correlations and relations. After they say “ocean-driven melting”, they’re simply saying that when the water is hotter the ice melts extra. Which is trivially true, and doesn’t reply the straightforward query—why did the pattern reverse 9 years in the past, and never eleven years in the past, or seven years in the past, or in no way?

We don’t know.

My greatest to all,

w.

As Is My Wont: I ask people who when you find yourself commenting please quote the precise phrases that you’re discussing. This fashion, we will all perceive simply who and what you might be referring to.

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