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Messages - mitch

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1
Arctic sea ice / Re: "Stupid" Questions :o
« on: April 18, 2020, 08:26:40 PM »
The big problem for a fleet of AUV's measuring ice thickness is the energy expended to ping on the subsurface of the ice.  This take significant energy, and batteries don't release energy well when they are cold. So, one has to work out how to recharge the AUV's.

The 2nd problem is tracking the AUV depth, since any depth error translates into an ice thickness issue.  It is possible to use pressure as a depth measure, but must correct for the salinity of the water, since adding salt to fresh water makes about a 3% difference going to ocean salinity. 

2
Antarctica / Re: What's new in Antarctica ?
« on: March 13, 2020, 09:39:53 PM »
About the Antarctic core collection now at Oregon State University.  It was an archive facility at FSU. Most of the cores were collected off the USNS Eltanin, run by Lamont Doherty Earth Observatory of Columbia University and funded by the National Science Foundation's Office of Polar Programs.  The cores were taken by dropping weighted pipes into the bottom to collect layers of sediments. The ship also did large numbers of water sampling as well as mapping the ocean bottom by geophysical methods.

https://www.ldeo.columbia.edu/research/office-of-marine-operations/history/eltanin

3
Science / Re: Where are we now in CO2e , which pathway are we on?
« on: February 03, 2020, 11:37:32 PM »
You don't actually get around the GWP20 vs GWP100 issue using Co2 equivalents.  Here is the NOAA website explaining how they calculate them:
https://www.esrl.noaa.gov/gmd/aggi/aggi.html

The CO2e depends on a calculation of forcing. 

4
Science / Re: Carbon Cycle
« on: January 25, 2020, 10:30:45 PM »
During upwelling season along the west coast of the US, pCO2 in the water responds very strongly to the recycling of nutrients--particulate matter from the water moving offshore at the surface falls into the incoming water and degrades there.  This drives pCO2 to very high levels, sometimes > 1000 ppm

https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2010JC006625

5
The politics / Re: The Koch Watch Thread
« on: January 13, 2020, 09:08:39 PM »
At least Pompeo is out of the Kansas senate race. However, a lot of money are going to other GOP fringe candidates:
https://www.rollcall.com/news/money-flows-to-kansas-senate-campaign-with-pompeo-out-of-the-race

6
If ferromanganese nodules are mined, it will be for the Co, Ni, Cu primarily, with a side of rare earth elements.  It will end up in a huge oversupply of Mn, which will have to be disposed of somehow. 

I doubt if the prices are such that a sustained mining operation could succeed. One mine of 2 million tons of nodules per year would produce roughly 2 times the current world supply of cobalt, assuming about 0.2% Co in a nodule.
https://www.tandfonline.com/doi/full/10.1080/1064119X.2017.1319448?scroll=top&needAccess=true 

If there are a bunch of operations, there would likely be wild swings in prices. Furthermore the mining is essentially strip mining--the nodules took millions of years to grow. The sediment plume would be a major environmental problem of unknown consequences.

7
Science / Re: Carbon Cycle
« on: November 16, 2019, 05:12:35 PM »
I haven't read the Notz and Stroeve paper in detail, but they apparently relate sea ice area to cumulative CO2 emissions. I find that puzzling because the effects of current emissions are offset by a couple of decades. 

I think the paper is overly optimistic.  Incidentally, total CO2 emissions since 1750 is about 600 Gt C

8
Antarctica / Re: Where is D-26 headed?
« on: October 17, 2019, 08:20:23 PM »
An iceberg as big as D-26 will stick down 300 m or more into the sea.  Currents at that depth are not necessarily going where the wind is blowing.  As for thinning, the temperature at 300 m is most likely warmer than the surface water, so most melting will occur from the bottom. However, being a tabular berg, it will just sink lower--the freeboard will remain about 10% of the total thickness.

9
Arctic sea ice / Re: 2019 sea ice area and extent data
« on: September 23, 2019, 07:24:23 PM »
No matter how good the processing power, the inherent instability in weather systems means that you are limited by how many observations you can make. If I remember correctly, even if you observe 99% of the surface today, by 10 days out you would only have reliable information about 50% of the surface.  You are trying to predict where the next bubble will form in a boiling pot of water a minute or so after the boiling started.  Here's a paper I located:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3270390/

10
Consequences / Re: Hurricane Season 2019
« on: September 20, 2019, 08:19:46 PM »
The person is wrong about history. A hurricane hit San Diego in 1858:
https://en.wikipedia.org/wiki/1858_San_Diego_hurricane

11
Science / Re: 2019 Mauna Loa CO2 levels
« on: August 24, 2019, 07:57:18 PM »
The change in annual atmospheric CO2 buildup depends strongly on the Amazon. If the Amazon is growing, CO2 is sucked into the forest but if it is not the terrestrial CO2 sequestration drops strongly. With a strong dry season and fires in the Amazon, as well as in the subarctic, we will probably see significant CO2 increases this fall.

12
Policy and solutions / Re: Greta Thunberg's Atlantic crossing
« on: August 16, 2019, 08:25:37 PM »
Once Greta gets south of the Bay of Biscay, the seas don't look too bad. Here's a wave height forecast for the Atlantic:
http://www.stormsurfing.com/cgi/display.cgi?a=atla_ortho_height

13
Science / Re: Small changes can cause transition to a Pliocene climate
« on: August 04, 2019, 07:16:17 PM »
Going back to the Tierney paper--what they showed is that small changes in CO2 (280 to 400 ppmV) could make a model match the observations made by the paleoclimate community.  Despite what Tierney says, it does not say how easy it would be to convert from an interglacial to a warm climate. 

What impresses most paleoclimatologists is how long it takes before a change happens. Glacial-interglacial cycles happen because the world with northern hemisphere glaciations have two endpoints (cold and warm) that are hard to move past.  We are currently in a low albedo interglacial, so it is unclear how long and what CO2 will be needed to drive the world to the Pliocene state.

I just wanted to add a final point of information.  The PRISM (Pliocene Research, Interpretation and Synoptic Mapping) interval was chosen when the Central American Seaway was essentially closed and the Bering Strait was open, but before the initiation of Northern Hemisphere glaciation. Tectonic reconfigurations of ocean circulation are minimized.  Here's a recent report that will allow tracking back:
https://pubs.er.usgs.gov/publication/ofr20181148

https://pubs.er.usgs.gov/publication/ofr20181148
 

14
Science / Re: Small changes can cause transition to a Pliocene climate
« on: August 02, 2019, 06:02:54 PM »
The Tierney article said that the higher CO2 plus other feedbacks was sufficient to make a model look like the Pliocene, not that it would change the world into the Pliocene. You have to understand that the Pliocene deep ocean was about 2°C warmer than modern, a huge heat reservoir.  There will be several hundred years needed to warm the deep ocean by that extent.  If the ocean warms faster then the surface is kept more temperate.

There is inertia caused by the arrow of time--warm to cool is not the same is cool to warm.

15
Policy and solutions / Re: Why people don't listen to experts
« on: July 30, 2019, 06:04:50 PM »
We are in paranoid times when people think that experts are determined by "centralized power".  Instead, we find that groups pushing agendas tend to produce alt-experts that ignore facts.

16
Glaciers / Re: Glaciers worldwide decline faster than ever
« on: June 09, 2019, 06:14:08 PM »
That most of the alpine glacier mass is in Alaska makes sense, since it sets next to a relatively warm water mass (the North Pacific), so has a major water source.  However, significant parts of the new deposition melt out every summer. Now that the temperatures have warmed, there is net loss along the glaciers.

17
The rest / Re: Archaeology/Paleontology news
« on: May 28, 2019, 07:51:13 PM »
I tried to check out the paper, and found that all the data was in another that I couldn't access.  There is a problem when astrophysicists try to do geology--they don't seem to understand that the recording system is imperfect.  So the speculation without a tie to the actual sediment cores that they worked on is very untrustworthy.  Furthermore, they string together Fe-60 data from unknown sources to a dubious calculation of change in lightning frequency to disappearance of forests in Africa via lightning-caused fire. 

The likelihood that they are right is probably less than 10%.

18
The rest / Re: SpaceX
« on: May 27, 2019, 06:39:29 PM »
I am always frustrated by people that say that space exploration is a solution to earth's climate change.  It is not, and means only that a few hundred people at a cost of 10^9 dollars per person will be delivered into an environment that is much worse than the worst environments on earth. 

Spend a few trillion and we can fix earth. 

19
Consequences / Re: Widespread Ocean Anoxia to be Noticeable by 2030
« on: April 14, 2019, 06:05:02 PM »
Thanks for the second paper as well. I need to look into the systematics of U-isotopes, but would expect that the isotope anomaly would also match a low in U/Ca.  The main problem with the Paleozoic studies is that essentially all the preserved material is from shallow water--plate tectonics has wiped out Ordivician age sea floor.  So, significant confirming evidence is needed before the hypothesis is accepted. 

It is very hard to make the whole ocean anoxic, since cutting off oxygen to the deep prevents recycling of nutrients to the surface. Shelf areas are most susceptible, like the anoxia that now appears off Oregon, e.g.:
https://journals.ametsoc.org/doi/full/10.1175/JPO-D-15-0119.1

20
Science / Re: 2019 Mauna Loa CO2 levels
« on: March 18, 2019, 11:57:56 PM »
pre-industrial CH4 was about 700 ppb vs about 1800 ppb today:
https://earthobservatory.nasa.gov/features/MethaneMatters

One should be able to make a pre-industrial CO2e.

21
The fundamental difference between the Pleistocene and the rest of the Cenozoic is that deep waters are 3-10 degC warmer before 3 million years ago. The huge heat reservoir of the deep ocean meant that heat brought up from below ended the smaller cold perturbations. Right now the deep ocean is at a cold extreme, which helps to ameliorate warm perturbations. 

Between the deep ocean and the remaining ice sheets, it is harder to push warming  despite the energy imbalance, sort of like walking up hill rather than on a flat surface.

22
Consequences / Re: Hurricane season 2018
« on: May 24, 2018, 06:07:43 PM »
You never see hurricanes in the 10 deg S region off South America because that is in the the east Pacific cold tongue, the currents that bring polar waters into the region.  Sea surface temperatures are too cold to maintain strong convection. Currently at 90W, the 10degS temperature is 25, versus 29 at 10degN. I would expect that the same is true of the Atlantic. 

23
Arctic sea ice / Re: Abrupt sea ice loss
« on: April 21, 2018, 06:39:45 PM »
A year round ice free Arctic requires a couple of things: (1) relatively warm water coming into the Arctic Basin and sufficient stirring by storms to bury the large fresh water runoff into the basin, (2) relatively high greenhouse gases to provide a heat cap, and (3) development of winter cloud cover to trap outgoing heat. 

If it truly was ice-free in the early Pliocene, the estimated atmospheric CO2 content was about 400 ppm, like the last couple of years. However, the Pliocene oceans were a huge heat reservoir because the deep ocean was much warmer then.

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