Melting ice may change shape of Arctic river deltas

Melting ice may change shape of Arctic river deltas
Yukon Delta, AK. Landsat natural color satellite image. May 17, 2002. Credit: USGS

Thawing ice cover and easily erodible permafrost may destabilize Arctic river deltas, according to new research.

A new study in the AGU journal Geophysical Research Letters finds sea ice and permafrost both act to stabilize channels on Arctic river deltas.

"Your channels tend to stay in one place when you have really thick ice or when you have permafrost that's really hard to erode," said Rebecca Lauzon, environmental educator at the Rochester Museum and Science Center's Cumming Nature Center in New York and the lead author of the new study.

Ice cover on Arctic deltas is expected to thin while permafrost is expected to thaw along the banks of Arctic rivers due to climate change.

The new study finds these changes could destabilize deltas in the far north of the globe, making them less resilient to rising sea levels. Less stable deltas could also impact Arctic ecosystems, creating winners and losers among delta species and even affecting the global carbon cycle.

Changing deltas

The new study examined how ice cover and permafrost affect sediment transport in Arctic deltas and provides insight as to how coastal dynamics may change in a warming Arctic. Sediment movement is important because it defines the shape river deltas take. It also provides food and habitat for delta species and oceanic creatures that feed off the organic matter which makes it out to sea.

Melting ice may change shape of Arctic river deltas
Kolyma Delta, Russia. Landsat natural color satellite image. May 30, 2013. Credit: USGS

Previous research on Arctic river deltas found that permafrost along the banks of rivers affected riverbank erosion rate, and thick ice covers resulted in constricted and faster river flow.

Lauzon, who was working an internship at Los Alamos National Laboratory during the time of the research, and her co-authors, created two versions of a model: One to predict the effects that ice thickness might have on Arctic river deltas and another to predict the effects of permafrost strength.

The study's authors found that when ice cover is thicker on rivers, or with more stable permafrost along the banks, river deltas tended to be characterized by deeper, more stable channels which acted as funnels, carrying sediment out to the ocean.

But thinner ice or more easily erodible permafrost along the banks caused the deltas to destabilize, with shallower water channels cutting through shifting sediment banks.

Part of the reason these channels become less stable is due to a loss of overbank flooding, which decreases with thinner ice and more erodible permafrost. Overbank flooding, which happens with thick and more resistant permafrost, causes sediment to be deposited along the tops of channel banks. Over time this results in higher riverbanks, which increases the stability of deltas.

Melting ice may change shape of Arctic river deltas
Lena Delta, Russia. Landsat natural color satellite image. June 4, 2015. Credit: USGS

But with less overbank flooding, deltas may become more vulnerable to the effects of , according to Anastasia Piliouras, an earth scientist at Los Alamos and a co-author of the new study.

"They then might be less resilient to sea level rise," she said.

Ecological, carbon cycle impacts

Piliouras said changes to the geography of river deltas could have ecological impacts and create winners and losers among species which live in the delta, favoring those that prefer more frequent flooding while negatively impacting species that prefer dry land.

Lauzon said there could also be impacts on the carbon cycle as more organic material could be released from the delta areas, though more research is needed to determine the overall effects thinner ice and unstable permafrost would have on carbon release.

Melting ice may change shape of Arctic river deltas
Lena Delta, Russia. European Space Agency Proba-V satellite image. July 27, 2014. Credit: ESA

The study's authors hope to use their model to help understand what might happen to real deltas such as those of the Yukon or Mackenzie rivers in Canada or the Lena River in Russia. Piliouras said they have done some follow up research to check if real river deltas exhibit the characteristics they predicted from their models, and that future research should now look at tracking how less stable permafrost and thinner ice affects river deltas.

Furthermore, they are also working on research which shows how both factors taken together may affect river stability rather than only looking at or ice thickness in isolation as they did in this study.


Explore further

Tides stabilize deltas until humans interfere

More information: Rebecca Lauzon et al. Ice and permafrost effects on delta morphology and channel dynamics, Geophysical Research Letters (2019). DOI: 10.1029/2019GL082792
Journal information: Geophysical Research Letters

Provided by GeoSpace
Citation: Melting ice may change shape of Arctic river deltas (2019, July 26) retrieved 24 August 2019 from https://phys.org/news/2019-07-ice-arctic-river-deltas.html
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Jul 26, 2019
oh god what happens when the wind blows all the loess away? the horrors.

Jul 26, 2019
Another steaming load of AGW Cult bullshit.
Gobble up, Chicken Shites.

Jul 26, 2019
As the Grand Solar Minimum continues and its associated cooling and heavy rains continue, be prepared for the new climate models that "predict" the change and link it to CO2!

Jul 26, 2019
Gobble up, Chicken Shites
Squawk squawk denier trolls. You can't change the facts.
https://www.bloom...n-normal

Jul 26, 2019
We invite all scientists to sign a short article on climate change

If you are a scientist from any scientific discipline, we invite you to sign our Viewpoint article "World Scientists' Warning of a Climate Emergency" by Ripple et al. 2019, which is now in press with Bioscience Magazine.

http://scientists...ate.edu/

Jul 26, 2019
As the Grand Solar Minimum continues and its associated cooling and heavy rains continue, be prepared for the new climate models that "predict" the change and link it to CO2!

The fraud that predicted the solar minimum has been exposed, so don't get your hopes up.

Interestingly, the difference in solar forcing between the recent solar maximum (~1950) and the Maunder Minimum was ~0.35 W/m2. The increase in heating due to AGW since the Industrial Revolution is ~2.3 W/m2 (most due to recent increases in greenhouse gases). And that keeps increasing. So even if we did have another minimum, it wouldn't stop the current warming. But since 2019 is on track to being much warmer than 2018 (and since you think short term trends are relevant here), the "grand solar minimum" is over. ;)

Jul 26, 2019
So even if we did have another minimum, it wouldn't stop the current warming.


But banks still give out 30 year mortgages in Miami.

So banks think you're full of chit too.

Jul 26, 2019
ZZ the GSM has nothing to do with the sun's heat output and everything to do with the increase in cosmic rays hitting the earth due to the lack of sunspots.

Jul 27, 2019
But banks still give out 30 year mortgages in Miami.

So banks think you're full of chit too.

The banks require flood insurance in Miami, and the premiums are going up.
https://www.miami...440.html

Jul 27, 2019
ZZ the GSM has nothing to do with the sun's heat output and everything to do with the increase in cosmic rays hitting the earth due to the lack of sunspots.

Unfortunately for this hypothesis, there are multiple lines of evidence showing that cosmic rays have little effect on the earth's climate. And, again, since the earth continues to warm that also seems to disprove the whole hypothesis.

Jul 27, 2019
Climate change denial has come full circle to where only stupid folks still deny.

Those that embraced it (for whatever reason) now have it shoved in their faces that denial is beyond stupid.
Well...what are they gonna do, hang their head and apologize for their stupid stance?
Negative, no admitting nothing, in fact you may notice them getting louder and more incoherent in their denial.
No arguing, there is too much to list showing the warming. And the denial excuses have gotten too absurd to take seriously.
Sheesh.

Jul 28, 2019
Scrotist, goaticle, and "M. R." sticky-sick.

Right out of the gate, with a barrage of their debunked, out-worn chicanery.

Such deliberate, knowing, intransigence is actually painful to behold.

A very special kind of stupidiosity, cave-cured by years of dwelling in Mommy's basement.

Jul 29, 2019
Indeed, antisciencegorilla and his sockies got smacked over the head one too many times when hi was a kid... but wait.. he still is... lol, mommy keeps him in the basement for fear of embarrassment.

Jul 29, 2019

The banks require flood insurance in Miami, and the premiums are going up.
https://www.miami...440.html


FEMA confirmed to the Miami Herald that it is looking into switching to risk-based pricing in 2020,

You liar, they aren't going up, the article says they're looking into it.
Alarmist fool.

And the only photo the Article has, is a 2013 King Tide flood in Miami, with cars driving through a few inches of water. It was a super high tide. Fools.

Jul 29, 2019
No Dumbty it is going up and keeps going up ! it has already risen 8% this year !
"That means insurance is about to become very expensive, and it kind of sounds the bell that these are high-risk areas," said Wayne Pathman, a Miami-based land use attorney and chair of the city's Sea Level Rise Committee.

Premiums through the National Flood Insurance Policy are already rising an average of eight percent this year; the first wave of pricier policies started in April. That brings the average annual price (including surcharges) for a policy holder to $1,062.

Jul 29, 2019

The banks require flood insurance in Miami, and the premiums are going up.
https://www.miami...440.html


FEMA confirmed to the Miami Herald that it is looking into switching to risk-based pricing in 2020,

You liar, they aren't going up, the article says they're looking into it.
Alarmist fool.

And the only photo the Article has, is a 2013 King Tide flood in Miami, with cars driving through a few inches of water. It was a super high tide. Fools.

"Premiums through the National Flood Insurance Policy are already rising an average of eight percent this year; the first wave of pricier policies started in April."
Maybe you would have understood it better if there were more pictures

Jul 29, 2019
from the miami article , concludes
"This doesn't have to be a doom and gloom thing. These are solvable and manageable things in the foreseeable future," he said. "If you look at the economics and you look at whats coming and you look at what's already happening, it's all about risk. The risk is already here even if the water isn't."
''

Aug 09, 2019
@snoosebaum.
from the miami article , concludes
"This doesn't have to be a doom and gloom thing. These are solvable and manageable things in the foreseeable future," he said. "If you look at the economics and you look at whats coming and you look at what's already happening, it's all about risk. The risk is already here even if the water isn't."
''
All well and good...but who pays? And where is the alternative land etc to retreat to when all the globe is struck with disastrous floods, droughts, salt-water-intrusion into fresh water aquifers, more extreme wind/cold storms and unseasonal extremes which kill crops, and insect/disease spreading towards the poles, etc etc. Such blithely naive/self-serving analyses/approaches as that you quoted is not a way out of this mess, and you know it, mate. Be honest for a change; not only with yourself and your intellect but with your family/friends who will pay for your silliness if you and those like you don't wake up to yourselves.

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