Greenland's melting ice raised global sea level by 2.2mm in two months | Hacker News Reader

Greenland's melting ice raised global sea level by 2.2mm in two months

theguardian.com

106 pointsperfunctory89 comments

Has anyone considered the albeit short term emissions impact of grounding flights due to COVID-19? Airlines have in some cases experienced over 70% reduction in volume in the past weeks[0].

Not to mention, so many companies have been forced to adopt remote working practices and social life has been forced into a sedentary routine. I wonder what the inertial impact of this pandemic will be on emissions over the coming years.

[0] https://www.economist.com/business/2020/03/15/coronavirus-is...

If humans continue to raise and eat massive amounts of land animals, nothing will change. The emission won't change in the slightest. Maybe a blip from less cars on the road but overall, nothing big. As someone pointed out, planes are a fraction of the source of emissions, animal agriculture is far more devastating than anything else.

You could cut your agricultural megafauna emissions in half by switching from cattle to bison. https://mrdrscienceteacher.wordpress.com/2019/09/21/bison-vs...

That's interesting, but not a solution. It's inefficient to raise an animal for years and feed it plants (and have to deal with feces and other output) for a few million calories of output.

What percentage reduction would you consider to be a solution? Since AFAICT you already moved the goalposts from "methane emissions" to "resource usage".

Air travel makes up for 2.5% of global carbon emissions. Not really worth micro optimizing a lot in those 2.5% if you asked me. At least not if you can focus efforts in energy production and cars instead.

This is a pretty common fallacy that I read every few days on HN. Air transportation is a major contributor to CO2, if you limit the scope to the people who use it. It is estimated that about 80% of the world's adults have never taken a flight, and 94% of the world's adults have not taken a flight in over a year.

So, the real picture is that this 2.5% of global CO2 emissions are caused by as few as 6% of the population, who also are incidentally the richest and bear a high personal carbon footprint in other domains than transportation.

Also please remember that the aviation sector is growing, and therefore its global contribution to GHG emissions will grow as well in the future. Discounting the carbon footprint of the aviation sector based on today's numbers is a mistake.

If you do not want to impede on your ability to travel, you shouldn't object to it for the 94% of the population that want the same thing as you, and when it becomes available to them the aviation sector's emissions will increase 15-fold.

There is much more benefit in focussing in energy production and heating. Coal makes up for 40% of carbon emissions. Nobody will care whether their electricity comes from coal or renewables. We can get rid of those 40% of emissions without imposing restrictions on people.

> Nobody will care whether their electricity comes from coal or renewables.

They will once their taxes start going up.

> We can get rid of those 40% of emissions without imposing restrictions on people.

Without imposing restrictions on _the people_ who are generating the most CO2 emissions per capita. How do you think this is gonna hold? Air travel should be restricted, or at the very least taxed in proportion to its emissions, because it's cheap, easy to implement, and doesn't impact the survival of millions of people, whereas increasing the price of electricity in developing countries does.

> They will once their taxes start going up.

We can use a relatively small amount public funds to make targeted investments in electric grid infrastructure and scaling PV solar and storage. That will drive costs down and coal will disappear without any need for new taxes.

Heck, even if we don't make any public investments to accelerate the process, it will happen soon (< 10y). Coal is on its way out as a fuel for electric powerplants.

> Air travel should be restricted, or at the very least taxed in proportion to its emissions, because it's cheap, easy to implement, and doesn't impact the survival of millions of people, whereas increasing the price of electricity in developing countries does.

Soon enough, either microgrid PV solar and storage or utility-scale PV solar and storage will be cheaper than coal, even in developing countries. Microgrid PV solar and storage is especially attractive in developing countries where the electric grid is typically unreliable.

I do agree that the emissions costs of air travel should be internalized to the ticket price, but the regulation needs to leave enough room to allow airlines to avoid emission taxes by using carbon-neutral fuel.

> the regulation needs to leave enough room to allow airlines to avoid emission taxes by using carbon-neutral fuel.

Where exactly do you expect this carbon neutral fuel to come from?

Fuel=energy, and energy doesn't grow on trees. Well technically biofuel can grow on trees but whatever.

What seems to be forgotten by many "optimistic" folks is that we NEED to cut emissions TODAY, and reduce them by ~7% a year for the next 30 years, to avoid catastrophic warming and feedback loops. By many measures, today is already too late.

Now tell me how we are going to turn these planes carbon neutral today, or even next year, without turning to hypothetical abundant solar energy that will turn atmospheric CO2 into fuel, or turning half of Indonesia's rainforest into palm trees (note that this is not CO2 neutral at all, land change use is one of the biggest culprits today).

The only solution available today is grounding some of those planes. They can take off again when magical carbon neutral fuel is abundant enough that we can afford using it to fly at 850km/h.

we don't necessarily have to restrict anything. start by pricing in the cost of cleaning up after <activity>, and see what happens.

everyone has that one thing that they don't want to give up to help reduce emissions. I'll admit for me it's fast cars. for a lot of people on HN, it seems to be that they don't want to sacrifice travel or visiting that distant family member. I've seen people go so far as to argue that the holistic benefit of seeing other places is worth the cost in emissions.

I suspect if emissions were priced into air travel, we would start to see a lot of businesses realizing that video can replace a lot of in-person meetings. we might also see people start to place more value in living close to the people they care about.

Really we ought to price in the genuine cost of countering whatever emissions a product or service causes. My guess is that the effect that would have on demand for different product and services would surprise us, in that I don't think we understand very well where people would cut when externalities are priced in, partly because we're bad at estimating what value people put on different things, and partly because we're bad at assessing what impact different things has when e.g. factoring in supply lines.

Ya think?

"Unless market constraints are put in place, growth in aviation emissions will result in the sector's emissions amounting to all or nearly all of the annual global CO 2 emissions budget by mid-century, if climate change is to be held to a temperature increase of 2 °C or less."

(from: https://www.wikiwand.com/en/Environmental_impact_of_aviation)

The article you quote validates my point by assuming other emissions can be decreased to a minimum. If all emissions we have to worry about in 2050 was air travel, that would be spectacularly good news!

That's in the scenario where fossil fuel use elsewhere is essentially eliminated; eliminating it for air travel is obviously particularly challenging.

The same links says:

"The central case estimate is that aviation's contribution could grow to five percent of the total contribution by 2050 if action is not taken to tackle these emissions, though the highest scenario is 15 percent."

So which is it? 5%/15% or 100% by 2050?

once you get rid of other big thing, this now small thing becomes big, relatively speaking.

Getting rid of air travel completely would give 0.03 degree tep benefit

That assumes vast reductions in emissions from every other sector except air travel, for physical energy density reasons.

Air travel alone is not sufficient to affect climate much... if we were to get rid of fossil fuels on the ground.

Growth is not something that continues forever. There's already constraints on the aviation industry (lack of pilots, congested routes) that will anyway slow down the growth significantly as time goes.

when you break up carbon emissions by industry, you get a lot of buckets that make up <10% individually. you can't ignore all of them because they're too small to be worth optimizing.

also, instead of focusing on optimizing emissions per mile, why not ask how many flights are actually necessary? at the same time that we invest in electric vehicles, cleaner power generation, and public transit, we might also ask if it's really necessary to vacation overseas. we might ask if video chat could replace flying to meet the board or a client.

What problems do we tackle if everything is just "a small percentage" of the big issue?

Also, would you give up 2.5% of your net worth?

According to https://ourworldindata.org/co2-and-other-greenhouse-gas-emis..., the biggest sources are electricity and heat production, transport, and manufacturing (I suspect livestock is part of the manufacturing stat). So for CO2 emissions, switch to renewables; for methane and nitrous oxide, do something about agriculture.

But please don't mention going vegan; that MIGHT only improve the situation by 0.000000001%. It can only be done if on a national scale meat production and consumption is reduced, or we find a way to capture / sequester methane / nox emissions. Factory farming shouldn't have an excuse in that regard, they keep their animals indoors anyway.

Ground transportation is so much larger of an emitter that drops in commuting have a bigger effect.

Certainly air quality in major cities has dropped significantly, look at the satellite images from China. https://www.youtube.com/watch?v=6DWBhp-oKOI

edit, INCREASED. I'm tired yo.

> Certainly air quality in major cities has dropped significantly

Your link shows the exact opposite of what you're claiming - air quality has increased significantly.

too early in the morning, you know what I meant :)

I'm really curious to see the data in a couple months. There should be a slowing of melting, right? I'm not sure what lag there is between emissions and temperatures. If there isn't a change in rate, what do we do then?

Remember that any improvement we make will immediately make the situation worse temporarily because of the aerosol masking effect. The temperatures are lower than they should be because of our emissions blocking out the sun, once the emissions improve the temperature will jump up.

Thinking about this, COVID-19 both reduces CO2 emission in terms of transport, and increases energy demand on other ends (people working from home, using more electricity). It would be interesting to see a detailed breakdown of those effects.

I don't use more electricity at home than in the office.

But you do more video conferencing, buy/order stuff etc., which all generates energy consumption too.

> people working from home, using more electricity

Wait, how does this work? The electricity I use in the office comes from the same place as the electricity I use at home. I'm probably using a little less, as I have a smaller monitor at home.

But you communicate with other people over e.g. video-conferences, which consumes more power than talking to them in real life.

Electricity is always produced with a large buffer (which is why you have lower electricity prices at night to encourage people to use it more, otherwise it's wasted capacity) - so I doubt there's any real increase in electricity production.

No, electric capacity has the built-in buffer you describe. But the main driver for ongoing GHG emissions from electricity generation is, of course, generating the electricity.

I'm sure there are no formal studies yet as to whether these work from home policies are a net increase in GHG, either within the utility industry specifically (i.e., excluding savings on cars) or overall, but my gut instinct is that it will be a net increase. Distribution to where residential homes are tends to be less efficient, and it's certainly less efficient to heat, cool, and light 1000 houses all day than 1 office building.

I can't find 2.2 mm mentioned anywhere in the study they refer to. Where is that number coming from?

https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1029/2020...

I can't find it either. I only see gigatonnes. Even with a naive calculation that assumes no ice reclaimed elsewhere, I get 1.8mm. https://docs.google.com/spreadsheets/d/1zC2c30kIkbx39v0gyY1P...

Why is that naïve?

Because in the opposite hemisphere, water is turning to snow and ice.

The ocean freezing anywhere is irrelevant: the mass of water in the ocean stays the same regardless of its phase.

The problem discussed here is the Greenlad ice cap melting, which we can assume increases the mass of water in the ocean.

The nature of ice caps in both Greenland and Antarctica is that they are in deserts that go for years with zero precipitation. Ice accumulates steadily through what we can think of as layers of frost every morning over centuries until it covers entire continents kilometers deep. On the other hand, surface melt due to increased seasonal insolation usually doesn't result in much runoff: these are not glaciers that slowly flow out to sea, either.

Just to make sure the context is clear, my main question is why the article headline says this particular melt caused a 2.2mm global rise in sea level. The melting described in the article would only account for a 1.8mm rise, in isolation. If anything happening in Antarctica had an effect, it would lower that number even further, making it more different from the headline. Does the 2.2mm number include other melting that the article and cited paper don't mention?

I see, good point.

However, it seems insignificant, since that process happens relative to the surface of the ocean, not to the bottom of the ocean. Assume that the top 1cm of sea water in the southern hemisphere evaporates, turns to clouds, and lands on Antarctica in the form of snow. If that top 1cm of the ocean is 2.2mm (or 1.8mm) further from the ocean bottom, I don't see why that would increase (or decrease) evaporation.

The source of the article does mention Antarctica: https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2020...

"In Antarctica, ongoing high mass losses in the Amundsen Sea Embayment of West Antarctica, the Antarctic Peninsula, and Wilkes Land in East Antarctica cumulate to 2130, 560, and 370 Gigatonnes, respectively, since 2002. A cumulative mass gain of 980 Gigatonnes in Queen Maud Land since 2009, however, led to a pause in the acceleration in mass loss from Antarctica after 2016."

Sure, Antarctica affects sea level even if it doesn't affect brlewis' computation. My point is just that brlewis' arithmetic doesn't seem naïve.

I was curious on the math for all this.

Surface area of earth = 510,064,472 km2

70 percent water = 357,045,130 km2

2.2mm = 0.0000022 km

volume = 785.499 km3

GIS area 1,710,000 km2

div vol by area = 459.3 mm

melting 1kg of ice from 0C = 333.55kJ

density of ice = 919kg/m3

785,499,000,000 m3 x 333.55 = 262,003,191,450,000 kJ

1J/s = 1w

2 months = 5,184,000s

= 50,540,739 kJ/s

= 50.540 GJ/s

= 181,944 GWh

making it the 24th largest electricity producer in the world (if it were all electricity).

That's pretty incredible!

I got inspired by your calculation to fact check the article's claim of the 2.2mm see level rise. They apparently base this on the reported melting of 600 Billion tons of ice as stated in the article.

600 Billion (metric?) ton = 600000 Billion kg (or liter water) = 600 km3

This doesn't quite add up. I wonder where they got the 2.2 mm from ..

Just been checking http://grid.iamkate.com and in the UK as a country it seems to me that we're about 7% down on power usage week on week as a result of people WFH.

The reduction in fossil fuels, the fact people are not necessarily able to get their favourite foods (and there was already a backdrop of a rise in plant-based diets in the UK anyway), the lack of commuting and travel, it all adds up to me thinking our emissions are going to be much, much lower this year, at least in the UK.

I'll be fascinated to see how much of that sticks, and whether we start to see any reversals on data like this.

Doubtful, but if habits change in the next six months for good, well, it's a silver lining. We can dream.

Can somebody explain to me what the big problem of sea levels rising is.

Sure, at that rate, or even at that 100 times that rate, at some point in the not-so-close future the coastline will move inward significantly. Beach properties will become diving attractions.

I don't think I care. Tell my why I should care.

Well, it seems folk weren't impressed with the technical aspects of your question, but I'll give it a shot and ignore the moral aspect entirely.

What would happen at "100 times that rate"? That's about 10cm a month, or four inches a month for Americans.

Firstly, the coast does not slope back at a constant angle from the sea, so you can't just move uphill a few yards and think that everything will be fine. Even if you could, try it now: try moving to an area that's, say, 20 yards uphill from where you are. Today. Do you see the immediate problem?

But let's say you're already a fair height above sea level, so you've got a few years, and you live in a coastal town. What is going to happen? Well, after a few months, you're going to start having issues with high tides. Sewers will flood, so you'll literally have a river of shite flowing in the streets below. The piers down at the harbour will become dangerous at high tide. Breakwaters will become ineffective. Warehouses will flood.

You've probably got a coastal road out of the town. With the higher tides, you've got increased erosion, so after a particularly bad storm, there's a major landslip, and you lose not only the road but the rail link out as well. Goods can't get in or out of your town now.

The higher parts of the town are now islands, and you don't have a functional slipway so it's difficult to even use boats. The shape of the coastline is now in constant flux; it changes with every tide as mud and sand gets sloshed around, which means that tides are completely unpredictable. Sometimes you get a massive tide as more water is funnelled in, and other times it's barely noticeable as mudbanks cut off whole areas of water.

Now, all this might even be manageable, if you have access to plenty of money to rebuild, but who is going to rebuild when they'll have to do it all again next year? And you're not going to get help from anywhere else, because this is happening to every coastal town all at once.

Of course, this is based on your extreme case of 10cm per month, so the real question is "at what stage does this become unmanageable?". Is it 10cm per year? 1cm per year over the course of a decade? Somewhere inbetween?

At the current rate of melt, how long is it until Greenland is out of ice and we don't have to worry about it contributing 1.1mm of sea level rise a month?

I dunno, a 1000 years or so? It doesn't seem worthwhile even roughly calculating since it's rather obviously going to accelerate as it gets warmer. It would be bizarre if it didn't!

If you only have yourself to take into consideration, I assume you have the luxury to relocate and have the economic bandwidth to do so.

But I challenge you to widen your viewpoint; there are so many people out in the world where 1cm would mean becoming environmental refugees.

If you don’t care about that, there isn’t much I can do.

Finally, I want to point out what that means; you lack empathy for those people.

> But I challenge you to widen your viewpoint; there are so many people out in the world where 1cm would mean becoming environmental refugees.

See, I don't believe that to be true.

Sea levels already rose 7.5cm in the past 30 years, where are all these "sea level refugees" specifically?

> Finally, I want to point out what that means; you lack of empathy for those people.

Of course I don't have empathy for people that I do not believe exist. I also have trouble developing empathy for hypothetical people that may have to migrate in 100 years time.

People are going to have/want to migrate, no matter what. So did my recent ancestors, as well as my ancient ancestors. I don't see that as a big problem, I don't believe in ethnostates of any kind.

Refugees welcome!

Sea levels are an easy way to measure the effects of global warming. Since the ocean has so much water, massive changes need to happen for it to rise even a little (for example 2.2mm).

Moreover Antarctica has an estimated ice volume of around 26.5 million cubic kilometers (most recent estimation - I believe). I estimate that cumulative melting since 1992 (2325 gt) has reduced that volume by 0.001%. Info & data at http://imbie.org/news/publications/ and http://imbie.org/data-downloads/

I'm not buying this. Someone please explain, in detail, how 2.2mm of sea level can be measured precisely? What kind of tolerance are we talking about? 2.2mm +/- 5mm?

If you have volume and divide by surface area you'll get height.

How do you accurately (down to mm precision) determine volume of a moving target?

... and what's the precision on the volume? How many significant digits?

So is the sea level being measured or estimated?

Is it even solid science to measure sea levels over 2 months? How do you measure "sea level"? It seems normal that ice melts as summer comes around. So there would be fluctuations in sea level? How do they account for all the possible variations to establish a sea level number?

> How do you measure "sea level"?

A lot of places around the world have rulers that are fixed to the ground and have been regularly read for many decades.

The process is basically that one person reads the level at regular intervals for several minutes throughout the day (every 5 seconds for 4 minutes, once every hour for 8 hours, starting 4 hours before high tide in my case, not sure if it's exactly the same everywhere). The place is sheltered from waves.

Since tide effects are very well known and there are a lot of such stations, it is actually easy to get an accurate image of the global sea level from all these measurements.

Nowadays, they are also complemented by GPS-based measurements, and the stations themselves are also GPS-monitored in order to prevent long-term ground movement from adding bias to measurements.

Since the measurements are done on a global scale (in my case, I performed those while I was stationed on Kerguelen island) and since they have been done for so long in always the same way, they do allow to compare current results to any previous results with much better precision than 2mm.

I have no issue believing you can measure sea levels at certain places. The question is, how do you mix all those measurements together to determine a global sea level number?

Afaik many things affect local measurements, like storms and tides.

For example, if you measure at three points in the US, and one point in Japan, how are the measurements weighted?

Suppose a storm is blowing in the US, increasing the measurements by 1m. How is it being accounted for?

Well actually, the total amount of ocean water stays constant during a storm. The quantity of rainwater that falls is absolutely negligible, and the surge caused by wind means the water level falls very slightly in the areas that are not affected by the very localized surge.

That's why you don't measure "three points in the US and one point in Japan". You measure thousands of points all around the world, so if storms affect two or three of them for a day, the global result isn't significantly affected. For instance, just the French observation network is made up of 90 stations that cover enough of the globe to be enough on their own for measuring a 2 mm rise over two months (near real-time data available on ftp://ftp.sonel.org/tidegauge/rmsl/Demerliac/RAW/).

It's really not as complicated as you think it is, the basic science behind global sea level measurements was established in the 18th century.

I suppose they measure the missing ice, and deduce the sea level.

They don't measure the missing ice either. They estimate it based on all kinds of things (mostly models based on what they guess the answer should be). Some of the actual measurements include the deviation in satellite orbit as it passes over Greenland, from which they estimate the change in gravity, which leads directly to an estimate of the change in mass. Since the rock is unlikely to be changing on the time scale of a year or so, they assume it's a change in ice mass. Given a typical annual precipitation of zero in central Greenland, it's a safe bet that any change is mass is due to ice melt.

And how is sea level defined - the average over the year? So more ice has melted than usually? Even then, it seems normal that not the same amount of ice would melt every year?

This, and satellites don't have millimeter-level precision of sea level measurement. Not even close.

We also don't have nano meter precision calipers and yet we managed to measure the size of atoms...

Perhaps less funding for the researchers or clickthroughs for the journalists would accompany a failure to provide such a conclusion?

It’s hard to get excited about 2.2mm.

I’m not saying it isn’t a problem, I’m just saying it’s not a scale humans are likely to panic about.

If it were 2.2m in one month you can bet your left shoe we’d panic.

Well, it's global sea level. It's pretty significant and just shows how fast the sea level could change if larger chunks of ice would slip into the water and melt.

If it's exponential growth, then that's pretty scary.

If all of the world's ice were to melt the oceans would rise by only 70 meters.

Warmist National Geographic offers that it would take 5000 years for all of the world's ice to melt.

https://www.nationalgeographic.com/magazine/2013/09/rising-s...

"Only" 70m.

The sea raises and lowers by up to 16000mm every day in parts in of Canada during spring tides

That would be over 600 meters, impressive :p. EDIT: the parent author corrected his entry to still impressive 16 meters.

And of course tides/sea level is almost the same duality as weather/climate.

> And of course tides/sea level is almost the same duality as weather/climate.

I tried to argue for the same point but lacked the word “duality” in my corpus. Thank you, will use in the future!

16000mm is 16m. Still impressive.

Edited to 16000. No idea what I was typing!

Up to 16 meters.

“It’s snowing today so global warming is a hoax.”

weather ≠ climate

It blows my mind that to some people, 2.2mm isn’t a big deal. Seriously, the size of earth, the amount of coastlines, the amount of rivers connecting to the ocean, the snowballing effect on increased melting?

What is it that people don’t get?

I suspect people think that along the lines of

A high tide causes floods, but that's like a 4000mm tide. What difference does it matter if it's 4002mm?

And they'd be mostly right - if it was just 2mm higher that wouldn't be an issue.

What's missing is

1) 2mm is average, some places it's far higher 2) 2mm in 2 months is 12cm in a decade, or 30cm after a 25 year mortgage

Where did I say it was? Can you perhaps quote the part?

I’m just saying the mention / comparison you are making is very similar to that kind of rhetoric. Also, it doesn’t relate to the actual problem but can be used to undermine the seriousness if these values are true.

2.2mm is an average. What happens is that in some places high tides are higher than that, along with the low tides.

Geologists studying glaciers have determined we're in an Interglacial Period, where glaciers are contracting and it's also cyclical [1]

There's also natural wonders like the Great Blue Hole, a marine sinkhole off the coast in Belize, which show this has been going on for some time. It was "formed during several episodes of Quaternary Glaciation when sea levels were much lower.. as the ocean began to rise again, the [124M] cave was flooded" [2]

[1]https://en.m.wikipedia.org/wiki/Quaternary_glaciation [2]https://en.m.wikipedia.org/wiki/Great_Blue_Hole#cite_note-NA...

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