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Messages - mitch

Pages: 1 [2]
51
Science / Re: Ocean temperatures
« on: January 06, 2019, 05:47:54 PM »
There seems to be confusion about what the Gebbie and Huybers paper said. First, Atlantic deep circulation takes a few hundred years to complete, and Pacific deep circulation takes more like a thousand years.  The Atlantic circulation is warming up because it is surface water derived, and average deep ocean temperature is going up. However, the Pacific abyss is still cooling off on average because of the lag time in deep Pacific circulation. This cooling reduces the net amount of heat stored below 2000 m.

Incidentally, fellowships are usually given to students/post docs from endowments set up at the university. The donors typically have no ability to decide who gets them.


52
Science / Re: Ocean temperatures
« on: January 05, 2019, 09:19:49 PM »
Roemmich et al (2012; Nature Climate Change 1 April) give the precision of challenger thermometers to 0.1 F (0.06 C).  The cooling is at the edge of the observations. However, it matches the model prediction of a long lag time for cooling in the Pacific.

53
Science / Re: Precipitation trends
« on: January 02, 2019, 05:40:23 PM »
My experience in College Station Texas:  At night in summer the air would cool down nearly to the dewpoint, about 70 deg F, so would be near 100% relative humidity.  Late afternoon the temperature would be around 103 deg F, and the relative humidity would be about 30%. The air was fed from the Gulf of Mexico, so there was plenty of water vapor.

54
Consequences / Re: Heatwaves
« on: January 01, 2019, 05:37:32 PM »
Half of the atmospheric CO2 increase has occurred since 1985, so CO2 emissions have been decoupled from coal.  Sulfur from coal did have a significant cooling effect prior to the  Acid Rain fix, but that has largely been eliminated from the US and Europe

I wonder how much warming will result from China cleaning up its air pollution. 

55
Policy and solutions / Re: Space colonization
« on: December 20, 2018, 06:16:30 PM »
Orbiting sun screens will play hell with photosynthesis. The aerosols are relatively benign and much cheaper than space junk.

 Also, the cost of terraforming earth after the fossil fuel crisis will probably be about a million times cheaper than terraforming another planet in the solar system. 

56
Policy and solutions / Re: Nuclear Power
« on: December 20, 2018, 06:05:14 PM »
Uranium reserves will be a problem without breeder reactors. U-235 fission supplies the energy for most reactors (0.75% of total U). Breeder reactors are needed to convert U-238 to the more fissile plutonium species, or to convert Th-232 to U-233. 

There will be concern about these nuclear fuels going forward. 

57
Science / Re: ECS is 2.5
« on: December 01, 2018, 05:46:37 PM »
When worrying about heating it is important to remember the other greenhouse gases. If you go to NOAA:

"...In terms of CO2 equivalents, the atmosphere in 2017 contained 493 ppm, of which 405 is CO2 alone. The rest comes from other gases..."
https://www.esrl.noaa.gov/gmd/aggi/

Another factor is that coal-burning in China and India is partly blocking solar insolation, so that there will be a warming associated with control of sulfate emissions in Asia. 

58
Policy and solutions / Re: Carbon Capture and Storage (CCS)
« on: November 28, 2018, 07:20:14 PM »
Plastics make up a small amount of fossil fuel use, roughly 3-5%
http://large.stanford.edu/courses/2010/ph240/hamman1/

So, people could still build plastics from fossil fuels if the other uses were curtailed. However, the problem of plastic pollution would still be around.

59
Consequences / Re: Global Surface Air Temperatures
« on: November 06, 2018, 05:09:32 PM »
La Niña doesn't cool the earth but preferentially stores heat in the ocean.  The east Pacific cold tongue gets colder and collects sensible heat from solar insolation, but because it is cold does not have much evaporation (latent heat loss from the ocean). In the west Pacific evaporation from 30 degree water causes significant heat loss, and rainfall, and hurricanes.  during el Niño, 30 degree water sloshes back to the east, producing a much larger area where evaporation occurs and movement of heat to the atmosphere.

The aerosols over China may affect the El Niño cycle and thus how heat moves around the surface ocean, but only indirectly. However, they also block incoming solar radiation and help to hide some of the greenhouse gas effects.   

60
Policy and solutions / Re: Geoengineering, another rush for money?
« on: October 31, 2018, 06:38:35 PM »
There will be environmental damage from switching to renewables--it just will be less than continuing to use fossil fuels. The amount of power needed is too large not to have costs. Efficiency should be a major part of the switch

Geoengineering is one of the costs to keep using fossil fuels.  Unfortunately, we do not have a good handle on the climate or environmental impacts of the different geoengineering options. Again, because the problem is large, the impacts will be large as well. The costs will continue to go up the longer we delay.

61
Policy and solutions / Re: Oil and Gas Issues
« on: October 22, 2018, 06:35:10 PM »
The major issue is that Trump has bought (or been flattered/bribed) into the idea that Iran is the great Satan in the Saudi-Iran conflict.  So, that means that the US has to stick to Saudi Arabia no matter how stupid and vicious they behave. 

It will be interesting to see how long other countries will continue to sanction Iranian oil. 

62
Consequences / Re: Global Surface Air Temperatures
« on: September 21, 2018, 05:59:26 PM »
Just wait until the 2018-2019 ENSO shows up. Right now there's another warm kelvin wave sweeping from W to E in the equatorial Pacific. Odds are 65-70% for el Niño in Dec-Jan-Feb this year.

63
Policy and solutions / Re: Oil and Gas Issues
« on: August 31, 2018, 06:42:35 PM »
New article in Science Magazine "Global carbon intensity of crude oil production"
http://science.sciencemag.org/content/361/6405/851

Canada has 4th highest carbon intensity (total CO2 emissions per unit energy), US is at the average, and Saudi Arabia 2nd from bottom. Watch out for heavy crudes...

64
Arctic sea ice / Re: Northern Sea Route thread
« on: August 27, 2018, 08:49:10 PM »
At 72°N, there are only 34 km per degree of longitude, so many of those decimals are superfluous. The 6th decimal place is roughly 3.4 cm vs 11 cm in the latitude direction.

65
There is one other pathway for freshwater to be exported: down. Mixing by storms in the summer time can exchange relatively fresh surface water with saltier Atlantic water at depth. This also increases the heat reservoir needed to be overcome in fall/winter for ice to form. 

66
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.

67
Policy and solutions / Re: Oil and Gas Issues
« on: August 01, 2018, 06:14:40 PM »
While plastics are needed for a variety of purposes, the total oil production to make all the plastics, if the 8300 million Mt is correct, is equivalent to about 58 billion barrels of oil. This is a little over 1/2 of the current annual oil production for all the plastics ever made. Plastics aren't driving oil extraction. 


68
The rest / Re: Wildlife
« on: June 03, 2018, 07:22:25 PM »
Lots of shipping containers lost at sea every year. Here is a blog on them:
https://www.tjocargo.com/how-many-containers-are-lost-at-sea-and-what-happens-to-them

He estimates in the several thousand container range. This is on top of the huge amount of plastics that washes down rivers every year, especially in Asia.

69
Policy and solutions / Re: Oil and Gas Issues
« on: May 26, 2018, 06:38:31 PM »
On the LLNL charts--I expect that all hydro, wind, and solar have little rejected energy since they are reported as electricity generated. However, coal and gas have a maximum efficiency of about 40% because of thermodynamics of the steam cycle.  I am not certain how nuclear is counted.

Rejected energy is an important factor, because 1 unit of efficient electrical generation can replace 2.5 units of fossil fuel input. If you find more out on how the rejected energy is determined it would be good to know. 

70
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. 

71
Consequences / Re: Ice-free Arctic
« on: May 21, 2018, 07:14:40 PM »
McKenzie River is moving along in its spring breakup--flowing water to the east edge of the delta, and some of the river water tunneling to the shelf fast ice.  We'll see how fast the river water spread out into the Beaufort Sea.

72
Here is one of the best graphics out of anywhere in the US to show climate vs weather. It shows the seasonal cycle, the averages, and the current year's temperature/precipitation. It is out of College Station TX, not Houston, but close enough.
https://www.weather.gov/hgx/climate_cll

So far this year, the temperatures are running near average. It is not nearly as bad as 2011/2012.

73
Science / Re: Precipitation trends
« on: May 16, 2018, 06:10:57 PM »
On China rain--by the time that the air mass gets to the Tibetan Plateau there is basically no way to add much additional water vapor. If the cloud seeding actually works, which I question, it will dry the air mass and make it less likely to rain downstream. However, this dry air mass will be interacting with wet ones coming from off the ocean over China. 

Ultimate answer is that it is complicated to what extent it will affect rainfall in other regions.

74
Arctic sea ice / Re: What's new in the Arctic ?
« on: May 11, 2018, 05:33:29 PM »
Thanks for the link--very well written. Fundamentally what we observe is that the weakening of the pycnocline increases the heat buffer in the Arctic, lengthening the ice-free season, and reducing ice thickness. I wonder if the winter heat loss keeps the system relatively linear. 

75
Policy and solutions / Re: Renewable Energy
« on: May 08, 2018, 05:09:32 PM »
I think the increase in gas reflects replacement of coal power plants, so is not entirely bad news.  At least it helps to cut out environmental mercury. 

76
Science / Re: 2018 Mauna Loa CO2 levels
« on: May 07, 2018, 06:09:40 PM »
Here is another site to get GHG time series:
https://www.esrl.noaa.gov/gmd/dv/iadv/index.php?code=brw

Northern hemisphere has higher CO2 and methane because of the fossil fuel source. The southern hemisphere lags by about a year because of the time it takes air parcels to work across the equator. 

77
Arctic sea ice / Re: Latest PIOMAS update (May)
« on: May 06, 2018, 06:55:47 PM »
A question about the Fram export numbers. Is the export east of Svalbard included in the Fram export, since it is not actually Fram Strait?  A lot of ice has been coming into the Barentz Sea between Nova Zemlya and Svalbard and then melting out. 

78
Policy and solutions / Re: Renewable Energy
« on: May 06, 2018, 06:26:16 PM »
You can get good deals on shipping containers on the US west coast--probably a good indicator of trade disparity.  We just bought a 1-use container for $3100 delivered.

79
Policy and solutions / Re: Ships and boats
« on: May 02, 2018, 05:03:51 PM »
I found it interesting that the Silent Yachts didn't give a range for their boats. Looking at the specs, they had a second diesel engine as well as an electric one--or I might have been reading wrong.

80
Policy and solutions / Re: Renewable Energy
« on: April 25, 2018, 05:25:37 PM »
$105M is not very much for a program.  This would fund roughly 200 3-year research projects, assuming no overhead at the agency.  And I am talking one faculty member, 1-2 graduate students as the research project.

81
Arctic sea ice / Re: Abrupt sea ice loss
« on: April 22, 2018, 06:18:14 PM »
On Pliocene ocean heat content--the data are pretty sparse prior to the Pleistocene.  What I can find has bottom water temperatures around 4-5 deg C prior to 4 million years ago versus about 2 deg C today.  This would represent the temperature to about 2 km depth, so roughly 3/4 of the ocean.  The Pliocene ocean had a very large ocean heat content that would stabilize the system. 

82
Arctic sea ice / Re: 2018 sea ice area and extent data
« on: April 21, 2018, 06:42:09 PM »
The Chukchi Sea region is still cold enough to resurface itself with ice when big open ocean areas form.  This will stop soon, so I expect to see major drops in ice extent soon.

83
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.

84
Glaciers / Re: Glaciers worldwide decline faster than ever
« on: April 18, 2018, 05:32:04 PM »
At some point the glacier mass loss will drop. Unfortunately that comes about because the total glacier volume has decreased to a small number. Do you know of any site that is trying to track alpine glacier volume?

85
Consequences / Re: 2018 ENSO
« on: April 09, 2018, 06:50:46 PM »
There's a big warm kelvin wave coming across the Pacific that has reached 115W (only 4000 km more to the coast).  When that starts surfacing there will be some major changes in eastern Pacific temperatures.

86
Permafrost / Re: Northern Hemisphere snow cover
« on: April 06, 2018, 05:28:09 PM »
The snow cover is definitely high this year. However, glaciers grow by the net remaining snow cover, the difference between winter snows and summer melt. Temperate glaciers tend to get more snowfall, but also get more summer melt.

87
Policy and solutions / Re: Seaweed and Seashell Farming
« on: March 10, 2018, 12:14:35 AM »
I would expect that seaweed farming should draw down pCO2 in the ocean where it grew, which would then raise pH some in the surrounding water. However, unless it is buried on land, it will not affect atmospheric CO2.

88
Policy and solutions / Re: Coal
« on: February 18, 2018, 06:22:46 PM »
I disagree that the 2 Chicago coal plants were closed solely by political pressure.  If they lasted through the 80's, they had to be significantly cheaper to run than replacing them.  Now, not so much. 

I do agree that political pressure made the job easier.  The least cronyist of the political pressures that can be applied would be to have a reasonable carbon tax. And, we could use part of  the revenues to repair infrastructure. 

89
Arctic sea ice / Re: Stupid Questions :o
« on: February 13, 2018, 05:12:49 PM »
Yes, ocean circulation is complicated. Here is a great animation made by the ECCO (Estimating the Circulation and Climate of the Ocean) consortium with NASA: https://www.nasa.gov/topics/earth/features/perpetual-ocean.html

90
Policy and solutions / Re: Oil and Gas Issues
« on: February 03, 2018, 07:23:11 PM »
Important thing to note is that Exxon price has been range-bound since 2007 (high of $103, low of $56). The reserves that Exxon actually owns are dropping. And, fracked oil is not cheap--it would not have been developed 25 years ago even if the technology existed. It is evidence that recoverable oil is dropping. 

91
Policy and solutions / Re: Energy Efficiency: The “First Fuel”
« on: January 27, 2018, 06:06:02 PM »
Why should there only be one solution? Increasing aggregate efficiency by 5% means that the equivalent energy isn't used. If the energy is produced by fossil fuels then those fossil fuels aren't burned.  Efficiency achieves the biggest returns when the energy production is relatively fossil-fuel rich. 

Efficiency also helps renewables, because it means that less energy needs to be replaced by clean sources.

92
Consequences / Re: Conservative Scientists & its Consequences
« on: January 21, 2018, 04:02:34 PM »
ECS was developed as a model metric in the 1970's, to compare responses of different climate models to the same forcing. It then began to be applied to the world in general when it appeared that humans would potentially double CO2 in the atmosphere. It is state dependent, since the feedbacks are state dependent. It is not useful to think of it as a constant, and it is useful to realize that the total earth system response will probably be more than the purely physical responses that make up ECS--in other words, Earth System Sensitivity. 

93
Arctic sea ice / Re: 2017 sea ice area and extent data
« on: January 01, 2018, 06:10:38 PM »
The fundamental oscillation is that of the polar front.  Since there are 4-6 waves along the front, if it is cold on the US east coast (trough), there will tend to be a ridge over Europe and the US west coast.  Warming oceans tend to lock the waves along the polar front in place.

94
Arctic sea ice / Re: Stupid Questions :o
« on: December 28, 2017, 04:40:31 PM »
The Gulf Stream is a western boundary current for the North Atlantic Gyre.  The gyre is driven by westerlies along the Polar Front, and trade winds down near the equator.  At the last glacial maximum, the westerlies blew much more in an E-W direction, so the boundary between the subtropics was roughly along the 45N parallel.  It moves more northerly as AMOC removes subArctic waters from the surface in the GIN and Labrador seas. 

95
Policy and solutions / Re: Cars, cars and more cars. And trucks, and....
« on: November 27, 2017, 05:53:07 PM »
On backing trucks--
Probably the easiest would be to have a belly box to remotely control the truck, while the trucker stands outside and watches.  This technology already exists for cranes.

96
Permafrost / Re: Arctic Methane Release
« on: November 04, 2017, 04:20:25 PM »
The most important event to warm the Arctic shelves is not the present global warming but the flooding of the shelves, which ended at roughly 6000 BP. Average temperature then changed from roughly -15C to -1C. That temperature change must diffuse downward through the sediments to warm either the permafrost or the hydrate layer.   

If we wanted to see the current warming, we need to take temperature measurements in the upper 10 m of the sea floor. Once we do that, we can evaluate how fast heat is diffusing down. However, most of the response right now is caused by early Holocene shelf flooding.

97
Policy and solutions / Re: The Hyperloop
« on: July 21, 2017, 06:21:23 PM »
You don't want to go down too deep with a tunnel.  Typical temperature gradient in the earth is about 30 deg C per km. Also, more issues develop with sidewall pressure in a big open space, so have to worry about collapse. They will stay in the near surface.

98
Arctic sea ice / Re: The 2017 melting season
« on: June 04, 2017, 05:42:14 PM »
Another feature to watch:  Mackenzie River has broken up and 'warm' water from the south is building up in the delta behind shore fast ice.  This adds to significant warming in the Beaufort Sea.
https://www.jpl.nasa.gov/news/news.php?release=2014-069

99
Policy and solutions / Re: Carbon Capture and Storage (CCS)
« on: April 12, 2017, 06:35:26 PM »
The reduction in research most likely reflects priorities by the funding agencies. Very little research funding is internal to the universities. 

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