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Messages - Ken Feldman

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551
Policy and solutions / Re: Nuclear Power
« on: April 13, 2018, 06:54:18 PM »
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I believe Canada has a few reactors that have, or had been running for many decades, possibly in excess of 60 years?
Canadian reactors actually have had terribly short lives before having to be shutdown for refurbishment. Candu refurbishment seems to take tons of money and many years. I think the Bruce reactors took 18 years of refurbishment. Point Lepreau needed 4 years of refurbishment after running for about 10 years and needed refurbishment again in less than 10 years.

The newer reactors in Ontario have a better record - they require major refurbishment at closer to 30 years of age. The Darlington refurbishment is planned to run from 2016-2026.

Funny how capacity factors for nukes never count the many years of shutdown they need for maintenance.

I don't know about the Candu reactors, but US reactors average 90% capacity factors because they only refuel once every two years and schedule the major maintenance during the refueling shutdown.

https://www.forbes.com/sites/jamesconca/2015/05/11/when-should-a-nuclear-power-plant-be-refueled/#161525c93d95

Quote

An outage usually takes only 40 days, so once every two years means the plant operates just under 100% of the time – 98% in the case of this nuclear plant. When Columbia Generating Station starts up again at the end of June it will produce even more electricity, more efficiently and more reliably.

...

There are many other reasons to shut down a power plant - for maintenance, repair and replacing components - but if everything is running perfectly, you can do all of those things during the occasional refueling outage.

During the outage, more accurate ultrasonic instruments will be installed for measuring the water flow through the reactor core, producing more electricity and saving water. A new Power Range Neutron Monitoring system will be installed for better fuel use, replacing analog circuit controls with more reliable and redundant digital controls. In addition, three new 175-ton power transformers will be installed.

The benefits of these improvements will allow for a more efficient use of nuclear fuel, an increase in the overall efficiency of reactor operations, and increased equipment reliability.

A refueling outage is also very good for all the other businesses in the area. For this refueling, 1,500 new out-of-town workers will descend upon the plant to supplement the 1,100 permanent Energy Northwest employees, something that local businesses look forward to with every outage (NEI).

The outage will replace 248 of the plant’s 764 nuclear fuel assemblies (see figure). Fuel is replaced after being in the core for six years, so every two years a third of the fuel is replaced and the other two thirds are moved around to make for even burning.

Many smaller maintenance projects will occur at the same time - 13,000 separate tasks in only six weeks. Sawatzke says, “The team has worked hard and we are well prepared and ready to execute.”

If the past is any clue to the future, this outage will go smoothly and on schedule, returning this super-efficient power plant to operation in time for the Fourth of July.



552
Policy and solutions / Re: Renewable Energy
« on: April 13, 2018, 06:04:14 PM »
Good story on renewables with battery storage here:  https://oilprice.com/Energy/Energy-General/The-Supersized-Future-Of-Energy-Storage.html

An excerpt (note the part I bolded):

Quote
... Another project, however, is not: A British billionaire is building a 120 MW/140 MWh installation not far from Tesla’s installation in Australia.

Sanjeev Gupta, owner of Australian steelworks Whyalla, is building the battery to use both as storage for electricity produced by a solar farm, and in construction at the steelworks site. What we’re seeing there is likely just the beginning of ever-bigger battery storage systems that will accompany every large-scale solar or wind project.

A recent Moody’s report on energy storage supports this forecast. It found that investors are getting more and more interested in energy storage projects as their commercial viability improves. Moody’s calculated that a kWh of electricity from a battery storage installation currently costs around US$0.133. That’s based on a price of US$400 per kWh of storage (a high-price estimate) for a fully installed system divided by 3,000 charge/recharge cycles per battery over a lifetime of 10 years.

Now, Moody’s notes that this cost per kWh is still higher than conventional electricity, but adds that things are changing fast as batteries become cheaper and cheaper, so soon we may actually have renewable electricity that costs less than the output of fossil fuels power plants.

There is the question of battery life spans, of course, when compared to the life span of the average gas-fired power plant. Also, there are some unique challenges, Moody’s vice president and senior credit officer Rick Donner said in the report, especially with regard to operating risks. Still Donner said, on the whole, battery storage projects carry the same risks as conventional power generation projects.

Costs are falling, in the meantime. Moody’s estimates that by 2020-2022, the cost per kWh of storage will drop to US$100. This will make even bigger projects than Crimson viable. If things continue moving in the same direction as they have been for the last decade, it won’t be long before a 100 MW storage system becomes the lower end of renewable storage capacity.

553
Policy and solutions / Re: Nuclear Power
« on: April 12, 2018, 08:38:38 PM »
In the article I linked to above, it linked to a more detailed report available here:  http://esi.nus.edu.sg/docs/default-source/esi-bulletins/esibulletinvol10-issue-6-(1).pdf?sfvrsn=2)

The report has about two pages on the recent past failures to commercialize SMRs.  Here are the relevant paragraphs:

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There is a further hurdle to be overcome before these large numbers of SMRs can be built. For a company to invest in a factory to manufacture reactors, it would have to be confident that there is a market for them. This has not been the case and hence no company has invested large sums of its own money to commercialise SMRs. An example is the Westinghouse Electric Company, which worked on two SMR designs, and tried to get funding from the U.S. Department of Energy (DOE). When it failed in that effort, Westinghouse stopped working on SMRs and decided to focus its efforts on marketing the AP1000 reactor and the decommissioning business. Explaining this decision, Danny Roderick, then president and CEO of Westinghouse, announced: “The problem I have with SMRs is not the technology, it’s not the deployment -- it’s that there’s no customers... The worst thing to do is get ahead of the market”.4

Given this state of affairs, it should not be surprising that no SMR has been commercialised. Timelines have been routinely set back. In 2001, for example, a DOE report on prevalent SMR designs concluded that “the most technically mature small modular reactor (SMR) designs and concepts have the potential to be economical and could be made available for deployment before the end of the decade, provided that certain technical and licensing issues are addressed”. Nothing of that sort happened; there is no SMR design available for deployment in the United States so far.

Similar delays have been experienced in other countries too. In Russia, the first SMR that is expected to be deployed is the KLT-40S, which is based on the design of reactors used in the small fleet of nuclear-powered icebreakers that Russia has operated for decades. This programme, too, has been delayed by more than a decade and the estimated costs have ballooned.5

South Korea even licensed an SMR for construction in 2012 but no utility has been interested in constructing one, most likely because of the realisation that the reactor is too expensive on a per-unit generating-capacity basis. Even the World Nuclear Association stated: “KAERI planned to build a 90 MWe demonstration plant to operate from 2017, but this is not practical or economic in South Korea” (my emphasis). Likewise, China’s plans for constructing a series of High Temperature Reactors (HTR-PM) appear to have been cancelled, in part because the cost of generating electricity at these is significantly higher than the generation cost at standard-sized light water reactors.

The final paragraph in that article states:

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Meanwhile, other sources of electricity supply, in particular combinations of renewables and storage technologies such as batteries, are fast becoming cheaper. It is likely that they will become cheap enough to produce reliable and affordable electricity, even for these remote and small communities never mind larger, grid-connected areas, well before SMRs are deployable, let alone economically competitive.

554
Policy and solutions / Re: Nuclear Power
« on: April 12, 2018, 08:23:55 PM »
There are also people who think SMRs wont be commercially viable:

https://www.greentechmedia.com/articles/read/interest-in-small-modular-nuclear-grows#gs.6semL=g

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In the December 2017 edition of the National University of Singapore’s Energy Studies Institute Bulletin, for example, Canadian academic Professor M.V. Ramana provided a detailed argument for why SMRs could never be a viable technology.

Nuclear plants in general require high levels of capital, he noted, and high construction costs mean the electricity they provide ends up being more expensive than coal, gas and, more recently, wind andsolar 

SMRs may be able to overcome the first problem, said Ramana, who is a professor at the University of British Columbia's School of Public Policy and Global Affairs.

But SMRs could end up with even higher energy costs because the smaller reactors can't take advantage of economies of scale unless they're manufactured “by the thousands, even under very optimistic assumptions about rates of learning.”

Experience indicates such rates of learning may be rare in the nuclear industry. In France and the U.S., according to Ramana, reactor construction costs have historically risen rather than falling.

Also, mass production would need the industry to settle on a single SMR design. As of 2016 there were 48 listed by the International Atomic Energy Agency.

Finally, said Ramana, for all the interest in SMRs, no country has yet got behind the technology enough for it to be commercialized. This likely indicates demand for the reactors is not as solid as proponents imagine.

555
Policy and solutions / Re: Nuclear Power
« on: April 12, 2018, 08:18:45 PM »
NuScale Power is hoping to have a set of 12 50 MW SMRs operational in Utah 2026.  They need additional investors though.

https://www.bloomberg.com/news/articles/2018-04-10/first-small-scale-nuclear-reactor-may-be-just-eight-years-away

Quote
NuScale Power LLC, which is leading global efforts to build a so-called small modular reactor, is seeking as much as $120 million in equity investment to accelerate design of a matching power generator. The company has already spent more than $700 million, and has “hundreds of millions of dollars more to spend,” Chief Financial Officer Jay Surina said in an interview on the sidelines of the Bloomberg New Energy Finance Future of Energy Summit in New York.

“We could use another investor or two,” he said. Backed by Fluor Corp., NuScale is casting a wide net that includes “deep-pocketed individual investors,” Surina said, noting it’s “too early yet for private equity.”

556
Policy and solutions / Re: Nuclear Power
« on: April 12, 2018, 06:51:16 PM »
To get back on-topic again: It's been a long time since I looked into GenIV nuclear, about 10 years or so, when I concluded that it was the only acceptable form of nuclear. I remembered that I really liked the aspect of scalability, ie that smaller, mobile modules could be built for residential areas, etc (I believe Toshiba was working on that). Can someone give me a brief update on how far has the technology progressed since then?

And likewise for Bob Wallace's question: How will Gen-future nuclear be able to close the very large price gap between nuclear and wind/solar enough to get nuclear back into the game?

Gen IV nuclear is still in the developmental stage.  In the US, deployment is still 10 to 15 years away: 
Quote
Accordingly, the Department has provided substantial support to the development of light water-cooled SMRs, which are under licensing review by the Nuclear Regulatory Commission (NRC) and will likely be deployed in the next 10-15 years.

ref: https://www.energy.gov/ne/nuclear-reactor-technologies/small-modular-nuclear-reactors

There is also a Generation IV International Forum (GIF) looking at six different potential Gen IV reactor types.  In December 2017, the GIF stated:

Quote
At least four of the systems have significant operating experience already in most respects of their design, which provides a good basis for further R&D and is likely to mean that they can be in commercial operation before 2030.

More info here: http://www.world-nuclear.org/information-library/nuclear-fuel-cycle/nuclear-power-reactors/generation-iv-nuclear-reactors.aspx

Given the rapid decrease in prices for solar, wind and batteries, I doubt that Gen IV reactors will be deployed before they become priced out of the market.

557
Policy and solutions / Re: Oil and Gas Issues
« on: April 11, 2018, 11:29:13 PM »
This is a potentially very big decision if upheld: PA court challenges the rule of capture:

http://www.ehn.org/pennsylvania-fracking-trespassing-2555983611.html

sidd

Whoa!  It's worth reading that article.

Basically, someone with natural gas on their property didn't want to sell the mineral rights, so the extraction company set up a well on an adjacent property and did a horizontal well, fracced the shale, and took the gas without paying the property owner that didn't sell the mineral rights!  And the lower court upheld it as  legal.  It was overturned at the state superior court.

558
Policy and solutions / Re: Nuclear Power
« on: April 10, 2018, 07:51:40 PM »
Two new reactors for the Turkey Point site near Homestead, FL: https://weather.com/news/news/2018-04-09-turkey-point-nuclear-reactor-expansion-homestead

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On Thursday, the U.S. Nuclear Regulatory Commission (NRC) approved a pair of new reactors at the Turkey Point Nuclear Generating Station, which is owned by Florida Power & Light, the Palm Beach Post reported. If the reactors are built, they could cost as much as $21.8 billion and wouldn't be ready until at least 2031, the report added.
 
In a 2014 investigation, weather.com and the Huffington Post identified the Turkey Point plant as one of the eight U.S. power plants most vulnerable to flooding from sea level rise by the end of the century. It showed that in worst-case projections, nearly all of the plant could be flooded by a tropical system in 2033, if current sea level rise projections materialize.

I'm surprised that anyone is even proposing to build new nukes in the US after the Westinghouse bankruptcy.  If the current estimated cost is $21.8 billion, the probably cost will be over $40 billion.  And with the rapid growth of renewables and battery storage, does anyone think that there will be a need for these plants in the 2030s?

559
Policy and solutions / Re: Aviation
« on: April 10, 2018, 07:42:30 PM »
Battery powered commuter planes could be operational on regional air routes up to 650 miles by 2021.  Story here: https://www.fastcompany.com/40549048/world-changing-ideas-transportation-eviation-alice-commuter



Quote
In five years, if you want to take a trip from San Francisco to San Diego, it may be possible to do it on a small electric plane–and with a ticket that costs less than driving or taking the train. The Israel-based startup Eviation, which is building a new all-electric, nine-seat airplane, called the Alice Commuter expects to begin making its first commercial flights in 2021 and scale up to hundreds of routes across the U.S. over the next few years.

560
Policy and solutions / Re: Renewable Energy
« on: April 06, 2018, 01:53:40 AM »
More money was invested in solar in 2017 than in any other energy technology.  Story here:  https://oilprice.com/Alternative-Energy/Solar-Energy/Solar-Attracted-More-Investment-Than-Any-Technology-In-2017.html

From the story:

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The proportion of world electricity generated by wind, solar, biomass and waste-to-energy, geothermal, marine and small hydro in 2017 was 12.1 percent (up from 5.2 percent in 2007).

Since 2004, the world has invested $2.9 trillion in these green energy sources.

Falling costs for solar electricity, and to some extent wind power, is continuing to drive deployment, the study claims. Last year was the eighth in a row in which global investment in renewables exceeded $200 billion — and since 2004, the world has invested $2.9 trillion in these green energy sources.

561
Policy and solutions / Re: Renewable Energy
« on: April 05, 2018, 06:42:46 PM »
Solar power’s greatest challenge was discovered 10 years ago. It looks like a duck.

https://www.vox.com/energy-and-environment/2018/3/20/17128478/solar-duck-curve-nrel-researcher

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Back in 2008, a group of researchers at the National Renewable Energy Laboratory (NREL) noticed a funny-looking shape in their modeling.

They were starting to take solar photovoltaic (PV) panels seriously, running projections of what might happen if PV were deployed at scale. They noticed that large-scale deployment had a peculiar effect on the electricity “load curve,” the shape that electricity demand takes throughout the day.

That's  a variation on the "sun doesn't always shine, wind doesn't always blow" argument.  The solution is the same, storage.  From the article you linked:

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The holy grail: affordable energy storage

David Roberts

It is frequently argued that a system based on wind and solar will need an enormous amount of storage — not just hourly, but daily or even seasonal storage — and that batteries aren’t up to the task. So we’ll either have to limit the scale of renewables or find some other cheap, large-scale, long-term storage. What’s your take?

Paul Denholm

We spend a huge amount of time talking about this topic here around the lunch table — a lot of calories are spent on it. So I’ll tell you what I’d say is the informal general consensus about ultra-high-penetration renewables scenarios.

The consensus is emerging that we can probably do 80 percent [renewables] with some combination of spatial diversity and short-duration storage.

We can deal with diurnal shifts with short-duration storage, and not too much of it. When we did our Renewable Electricity Future study back in 2012, we got up to 80 percent renewables with only about 100 GW of additional storage. It’s not that much.

In the US, we currently get about 19% of our electricity from nuclear and 5% from hydro-power, so we could go carbon free with battery storage, some of which could come from smart electric vehicle charging.

562
Policy and solutions / Re: Renewable Energy
« on: April 05, 2018, 06:25:07 PM »
Those numbers are quite a bit higher than what Lazard puts out, across the board. I wonder where their methodology differs.

Regardless, the consilience is a good thing.

They're using Leveled? Cost of Energy (LCOE), which takes into account the capacity factor and the operating and maintenance costs.  The previous numbers were the bid cost of installing the systems.

563
Arctic sea ice / Re: Abrupt sea ice loss
« on: April 05, 2018, 06:03:54 PM »
Over at the Ice Free Arctic  thread Ken Feldman posted this

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A 2011 study estimated that the albedo effect of an ice-free arctic for a month in late summer would increase from the current forcing of 0.11 watts per meter squared (W/m-2) to 0.30 W/m-2.  Using current estimates of climate sensitivity, that would lead to a global temperature increase of 0.15 degrees C. Here's the abstract from the study:

https://forum.arctic-sea-ice.net/index.php/topic,1886.msg145111.html#msg145111


So if the ice is gone for the last month of every year, over ten years the world is more than 1C warmer. I imagine that's where the number comes from.

That said, those calculations use local and temporal forcing changes and apply them to global yearly forcing changes. That misses the whole point. That global, annual .15C become several degrees at the local level of the Arctic. That's significant because it delays the onset of the freezing season.

It's 0.15C total, not an additional 0.15C every year.  Don't forget the planck (or blackbody) feedback, which is that the temperature increase leads to more heat being shed into space.

However, over time, that 0.3 W/m-2 (about a month of nearly ice free conditions) eventually grows to 0.7 W/m-2 (the whole spring and summer ice-free) as the Arctic continues to lose ice earlier during the summer, allowing for the Arctic Ocean to warm more.  Other studies have shown that it will take decades to go from the first nearly ice free September to the whole summer being ice free.

564
Policy and solutions / Re: Renewable Energy
« on: April 04, 2018, 06:29:51 PM »
We're nearing the tipping point now.  This article is on the Oilprice.com blog:  https://oilprice.com/Alternative-Energy/Renewable-Energy/Renewables-Are-Closing-In-On-Fossil-Fuels.html

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However, the economics are pretty dire for fossil fuels. The LCOE for onshore wind currently stands at about $55 per megawatt-hour (MWh), which is a global comprehensive average that incorporates equipment, construction, financing, operating and maintenance costs, and average run time. That cost is down 18 percent from the first six months of 2017, an impressive and significant decline.

Solar LCOE costs without tracking comes in at $70/MWh, which is also down 18 percent from the first half of 2017.

These averages obscure some truly low-cost wind and solar potential in certain parts of the world. BNEF says that onshore wind in India averages $39/MWh, down by nearly half from 2017. Solar PV in India only costs $41/MWh. That compares favorably to the $68/MWh for coal and $93/MWh for natural gas. In fact, clean energy is cheaper than coal and gas in both China and India.

The analysis was done by Bloomberg New Energy Finance for a report here: https://about.bnef.com/blog/tumbling-costs-wind-solar-batteries-squeezing-fossil-fuels/

With sources like Bloomberg and Oilprice.com reporting that renewables plus storage are cheaper than new fossil plants, I think the transformation of the energy supply from fossil fuels to renewables is finally on the launch pad.  Investors are going to be putting their money into renewables and batteries, not fossil fuels.  There aren't going to be many new fossil fuel plants built in the future and a lot will be prematurely retired due to their operating costs.

565
Consequences / Re: Ice-free Arctic
« on: March 31, 2018, 12:54:49 AM »
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The thickness maps show ice 3 to 4 meters thick in areas north of 80N

That's mostly due to multiyear ice accumulating yearly excess ice.

I'll ask again, because you are making it sound like temperatures don't matter for ice formation, when I believe it is the major component of ice formation. Yet you are not saying it straight up, you are simply dancing around it. I'm very confused.

To your understanding, does it matter how cold it gets or is it simply enough to reach the minimum freezing point? If it does matter, what percentage of the ice is made through bottom growth and what percentage is made by snow/rain/ridging.

Both are important, but ridging and rafting is obviously capable of adding more thickness than thermodynamic processes.  This is from a site on the Antartic sea ice, but the physical processes are the same:

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Analysis of the pack shows that deformation, rather than basal freezing, is the dominant mechanism for increasing ice thickness beyond 0.2-0.4 m. This results in an increase in local ice thickness whilst at the same time opening leads where, during the growth season, new ice is able to form. The net effect is increased ice production resulting in an increase in the total mass of ice within the pack, and subsequent changes in the ice thickness distribution.
 

Here's a link to the site:  http://aspect.antarctica.gov.au/home/about-sea-ice/ridging-and-rafting

And here's a follow-up to the paper on storms in the North Atlantic helping the ice to grow:

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As the Arctic sea ice cover continues to thin, convergent sea ice motion can more readily pile up ice into large ridges. Such ridges can be hazardous to marine activities in the Arctic. Divergent ice motion produces openings in the ice called leads, where new ice can readily grow. Winds are the main driver for both ridging and lead formation. A single storm event can lead to significant redistribution of sea ice mass through ridging and new leads. As part of the Norwegian Young Sea ICE (N-ICE2015) expedition, colleagues at the Norwegian Polar Institute made detailed sea ice thickness and ice drift observations before and after a storm in an area north of Svalbard (Figure 5). Results showed that about 1.3 percent of the level sea ice volume was pressed together into ridges. Combined with new ice formation in leads, the overall ice volume increased by 0.5 percent. While this is a small number, sea ice in the North Atlantic is typically impacted by 10 to 20 storms each winter, which could account for 5 to 10 percent of ice volume each year.
  The source for that story is the NSIDC website at this link: http://nsidc.org/arcticseaicenews/2018/02/




566
Policy and solutions / Re: Renewable Energy
« on: March 30, 2018, 09:17:53 PM »
Another article on how solar and wind are becoming (and in some cases, already have become) cheaper than coal and gas:  https://thinkprogress.org/solar-wind-power-prices-are-beating-natural-gas-c9912054400c/

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Prices for solar, wind, and battery storage are dropping so rapidly that renewables are increasingly squeezing out all forms of fossil fuel power, including natural gas.

The cost of new solar plants dropped 20 percent over the past 12 months, while onshore wind prices dropped 12 percent, according to the latest Bloomberg New Energy Finance (BNEF) report. Since 2010, the prices for lithium-ion batteries — crucial to energy storage — have plummeted a stunning 79 percent (see chart).

567
Consequences / Re: Ice-free Arctic
« on: March 30, 2018, 08:51:24 PM »
Quote
This statement is incorrect.  Ice formation is a binary function of below freezing and not below freezing.  Once seawater gets below the freezing point, -1.8 C, ice crystals will form.  It's basic physics.

Are you arguing that temperatures have no significant bearing on ice formation rate?

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After that, sea ice thickness is determined by other factors, including wind and snow.  Wind and snow help thicken the ice sheet.  The wind by allowing more heat to dissipate through the ice, and snow by weighing down the ice and allowing more snow ice to form.

Woosh. Most ice formation is due to bottom growth. That growth is completely dependent on the gradient of temperature of the water with the atmosphere. The colder it is the larger the gradient producing more ice.

Of course, snow and frozen rain do add to the total but that number is much smaller than bottom growth.

Quote
Snow also helps to protect the ice during the melt season through it's higer albedo.  Here's a link to a paper about observations of snow on ice during the 2015 spring:


Did you even read that abstract to the end? Read the last sentence.

Quote
So a few degrees of warming during the winter, provided that the temperatures stay below freezing (resulting in new ice crystals forming in leads and snow falling on that ice), don't prevent new ice from forming.  That's why models predict that the Arctic will become a seasonal ice sheet (similar to Antarctica or the Sea of Okhotsk), not ice free all year.

Sure a few degrees will of course result in almost unnoticeable effects but the warmer it gets the less growth you get through bottom melt.

The thickness maps show ice 3 to 4 meters thick in areas north of 80N, where the temperatures have been been warmer in winter.  So I'm arguing that the effects of rafting, ridging and snow ice formation can offset the slower bottom growth from the above average temperatures and delay the complete melt out of the Arctic ice.  These mechanisms will also allow the Arctic ice the reform in winters after it eventually goes ice-free in summers, becoming a seasonal ice sheet, like the Antarctic sea ice.

And I did read the entire article, not just the abstract.  With more storms, you get more snow on the thinner ice.  That leads to more snow-ice formation and the protective albedo effect.  From the discussion section of the article that explains the last sentence of the abstract (emphasis added):

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Mean precipitation from 1980 to 2016 shows the highest precipitation in the Atlantic sector of the Arctic (Figure S2b). This region is characterized by a larger number of autumn and winter storm events (Graham, Rinke, et al., 2017; Graham, Cohen, et al., 2017; Rinke et al., 2017; Woods & Caballero, 2016; Zhang et al., 2004). This is largely due to the influence of North Atlantic Ocean. High precipitation in this region is supported by the deep (>50 cm) snowpacks observed in this region during spring field campaigns in 2015 (Merkouriadi, Gallet, Graham, et al., 2017) and 2017 (M. Granskog; M. Nicolaus, personal communication, 2017). Given the recent observations of thicker snow cover and thinning of the ice cover in the Atlantic sector
of the Arctic (Renner et al., 2014; Rösel, Divine, et al., 2016; Rösel, Polashenski, et al., 2016), we surmise the potential for snow-ice formation in this region is the largest in the Arctic Ocean but can become imminent in larger areas when the ice is thinning.

In autumn and winter of 2014–2015, frequent storm events brought heavy precipitation and positive air temperature anomalies to our study region (Figures 1a and 1b). These storms are also associated with sustained 6-hourly wind speeds above 10 m s1, according to the ERA-I reanalysis (Merkouriadi, Gallet, Graham, et al., 2017). These strong winds initially come from the south and advect warm and moist air from the North Atlantic into the Central Arctic, resulting in heavy precipitation and positive temperature anomalies (Cohen et al., 2017; Kayser et al., 2017; Woods & Caballero, 2016). It is clear from our results that these storm events, and associated precipitation and temperature changes, play a crucial role in the growth, development, and structure of FYI. The impact of these storms in relation to the growth onset of FYI needs to be considered in sea ice modeling studies.

568
Consequences / Re: Ice-free Arctic
« on: March 30, 2018, 06:06:04 PM »
What I want you to understand is that ice formation is not a binary function "below freezing", "not below freezing". Ice formation speeds up the colder it is. FDD's as illustrated by Tealight show how Arctic winter temperatures increased over time.

This statement is incorrect.  Ice formation is a binary function of below freezing and not below freezing.  Once seawater gets below the freezing point, -1.8 C, ice crystals will form.  It's basic physics.

After that, sea ice thickness is determined by other factors, including wind and snow.  Wind and snow help thicken the ice sheet.  The wind by allowing more heat to dissipate through the ice, and snow by weighing down the ice and allowing more snow ice to form.

Snow also helps to protect the ice during the melt season through it's higer albedo.  Here's a link to a paper about observations of snow on ice during the 2015 spring:  https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1002/2017GL075494

From the introduction of the paper: 
Quote
Snow on sea ice is a critical physical parameter that modulates the growth and decay of sea ice (Maykut, 1978; Sturm & Massom, 2010). In spring, when solar insolation is high, even little snow fall on Arctic sea ice can significantly slow down surface melt, due to the snow’s high albedo (Perovich et al., 2017). In winter, when sea ice grows in the absence of solar insolation in the high Arctic, the role of snow is twofold. Snow insulates the sea ice surface from cold air temperatures, hindering thermodynamic growth of sea ice (Ledley, 1991; Maykut, 1978). However, snow can also contribute to the sea ice mass balance through the formation of snow-ice (e.g., Leppäranta, 1983). Snow-ice forms when seawater floods and refreezes at the ice/snow interface, due to excessive snow load that pushes the ice surface below sea level. Snow-ice is a common process in seasonally ice-covered seas but has not been prevalent in the Arctic, where thick perennial sea ice has dominated (Sturm & Massom, 2010).

So a few degrees of warming during the winter, provided that the temperatures stay below freezing (resulting in new ice crystals forming in leads and snow falling on that ice), don't prevent new ice from forming.  That's why models predict that the Arctic will become a seasonal ice sheet (similar to Antarctica or the Sea of Okhotsk), not ice free all year.

569
Consequences / Re: Ice-free Arctic
« on: March 30, 2018, 01:23:38 AM »
Quote
It just might be because even as "warm" as the previous winters have been, they haven't come close to reaching the melt point of ice:

The thermodynamic ice thickness growth rate is a function of time and temperature. The metric used to calculate that function is the Freezing Degree Day. You can read about it here:

 https://nsidc.org/cryosphere/seaice/processes/thermodynamic_growth.html

 Tealight has a nice set of graphs describing FDD behavior over the last several years here:

https://sites.google.com/site/cryospherecomputing/fdd

Quote
Volume has increased despite the warmer winters:

Do you mean 2017/2018 volume increased relative to 2016/2017? Of course. See the FDD graphs above. 2016/17 was the warmest winter on record, so it follows that that it had a very low volume gain. Luckily, 2017 had the second smallest volume loss since 2014. That left the volume minimum in a good position to overtake 2017/2018 even if it was almost as warm.

2017/2018 my yet surprise. If the Bering situation results in a chukchi/beufort/ess situation, Volume Maximum might reach record low.

Tealight's graphs seem to undercalculate the thickness of the ice.  Compare the graph, which calculates a current ice thickness of 150 cm to the map showing the current ice thickness:

Tealight's graph.

Current ice thickness and volume from DMI

It seems that the simple formula leaves out a lot of real life situations.  Here's what NSIDC says on the page you linked: 
Quote
The ice thickness increases at a rate roughly proportional to the square root of the cumulative FDD. Formulas such as this are empirical, meaning they are calculated only with observed data, so they really are simplifications of the ice growth processes. The formulas assume that the ice growth occurs in calm water and is reasonably consistent, and they do not take into account sea ice motion, snow cover, and other surface conditions.

NSIDC has a good page summarizing how sea ice forms.  Here's a link:https://nsidc.org/cryosphere/seaice/characteristics/formation.html

The wind and waves can cause forming ice sheets to raft over each other (becoming thicker) and crash into each other, forming ridges. From the link above:

Quote
If the ocean is rough, the frazil crystals accumulate into slushy circular disks, called pancakes or pancake ice, because of their shape. A signature feature of pancake ice is raised edges or ridges on the perimeter, caused by the pancakes bumping into each other from the ocean waves. If the motion is strong enough, rafting occurs. If the ice is thick enough, ridging occurs, where the sea ice bends or fractures and piles on top of itself, forming lines of ridges on the surface. Each ridge has a corresponding structure, called a keel, that forms on the underside of the ice. Particularly in the Arctic, ridges up to 20 meters (60 feet) thick can form when thick ice deforms.

570
Consequences / Re: Ice-free Arctic
« on: March 29, 2018, 07:37:33 PM »
Quote
The sea ice extent in 2012 bottomed out at 3.39 million square kilometers.  In 2013 the minimum was 5.05 million square kilometers.

The 2012-2013 freezing season had the record volume gain at the time at 19.063 x 1000km^2. Then it lost 17.04 during the melting season for a total volume gain of 1.79, year over year. In that cycle the Arctic grew. The 2013-2014 freezing season was much weaker at 17.726 but the melting season was the weakest since 2007 for a net year over year gain of 1.42.

In both years the gains exceeded the losses thus we had two years in a row of volume growth. But only in one of those years was record gains obtained.

Both 2016 and 2017 had similarly low volumes but they only gained 17.031. For both seasons winter temperatures remained highly anomalously warm for the whole season.

Volume has increased despite the warmer winters:



It just might be because even as "warm" as the previous winters have been, they haven't come close to reaching the melt point of ice:


571
Consequences / Re: Ice-free Arctic
« on: March 28, 2018, 11:41:04 PM »
My assumptions justifying thinking the gulf stream will find its way into the arctic ocean.

1. A BOE will let the stratification of the arctic ocean be disrupted by wave action.

2. when the sun sets and things cool off with the stratification a thing of the past you get bottom water production rather than ice.

3. what drives the currents around Greenland and the CAA currently is the Earth's rotation the warmth coming up from the equator (gulf stream) and the large freshwater input from ice melt and run off.

4. it is the cold reduced salinity run off water plus ocean water surface water current that pushes the gulf stream away from the east coat of north America.

The freshwater mixes with surface water, if that becomes bottom water then the surface water needs to be replaced.  The cold water would sink rather than stay on the surface.  So instead of a current coming out of the arctic ocean past Greenland you would have a current going in instead.

No current pushing the gulf stream east.  So it would go north into the arctic ocean.

With 20C water coming into the arctic basin you could see 20C air temps over the water and storms like there was no tomorrow.

Climate models show that a slow down of the Gulf Stream (actually the Atlantic Meriodonal Overturning Current, or AMOC) is more likely due to global warming.  There's a good summary of it here:  https://e360.yale.edu/features/will_climate_change_jam_the_global_ocean_conveyor_belt

Quote
A huge amount of heat is moved around our planet by a single ocean current system — the Atlantic Meridional Overturning Circulation (AMOC) — which accounts for up to a quarter of the planet’s heat flux. The system is driven by density: waters that are cold or salty are denser and so dive down to the ocean floor. As a result, today, cold waters sink in the North Atlantic and flow southwards, while warm tropical waters at the surface flow northwards in the Gulf Stream, making northern Europe unusually mild for its latitude. But if northern waters get too warm, or too fresh from melting ice, then they can stop being dense enough to sink. That causes a major traffic jam for the water attempting to move north, and the system grinds to a halt.

...

If the North Atlantic current slows dramatically, then the entire Northern Hemisphere would cool; a complete collapse of the current could even reverse global warming for about 20 years. But the heat that ocean currents fail to transport northwards would make parts of the Southern Hemisphere even hotter. And a cooler north isn’t necessarily good news. Should the AMOC shut down, models show that changes in rainfall patterns would dry up Europe’s rivers, and North America’s entire Eastern Seaboard could see an additional 30 inches of sea level rise as the backed-up currents pile water up on East Coast shores.

572
Consequences / Re: Ice-free Arctic
« on: March 28, 2018, 11:27:58 PM »
I don't care if an article is peer reviewed. It it contradicts my perception of reality I'll challenge it. This models predicts extraordinary growth that no one has ever witnessed before.

 I'll tell you exactly the mistake of the model.

The model assumes that after November, Arctic temperatures return to average. The average temps remain average even while generating record ice growth until April.

That's the opposite of the observations. So far the surface temperature anomalies last until April and ice has not grown at the incredible rate required by this model. There is something seriously wrong with it. The part of my reply that you didn't address explains why, let me repeat their assumption:

Quote
For SAT a large positive anomaly occurs between October and February after the initial perturbation, with a peak of almost 11 K in November (Figure 2). After February, there are no further SAT anomalies stronger than natural variability.

We are already at 5-8 K winter anomaly that last until April.  Yet you want me believe that after the first BOE all that extra heat will be vented out to of the arctic system? That makes no sense.

The record low ice extent to date was in 2012.  Here's how the 80N temperatures responded (note the below average temperatures in February):



The sea ice extent in 2012 bottomed out at 3.39 million square kilometers.  In 2013 the minimum was 5.05 million square kilometers.  So somehow, 1.66 million square kilometers of exceedingly thin first year ice survived.

573
Arctic sea ice / Re: Abrupt sea ice loss
« on: March 28, 2018, 06:33:58 PM »
It's important to read how they run the simulations in the models.  Here's what they did in the paper above:

Quote
The loss of Arctic sea ice during the whole year that we examine here only occurs under the large radiative forcing of the RCP8.5 simulations. In these simulations, the CO2 concentration is prescribed and shows an accelerating increase until the year 2100 (implying a radiative forcing from well-mixed greenhouse gases of 8.5 W m−2), followed by a stabilization period with a decelerating increase (Meinshausen et al. 2011). In the year 2250, the CO2 concentration reaches its final level of almost 2000 ppm.

If we continue on a high emissions path as described by the paragraph above, loss of the winter Arctic sea ice will be the least of our worries.  Note that the current goals of international agreements are to stabilize concentrations at 450 ppm and that some organizations are work toward an eventual reduction to 350 ppm by studying ways to take CO2 out of the atmosphere and sequester it.

574
Consequences / Re: Ice-free Arctic
« on: March 28, 2018, 12:00:14 AM »
Quote
After the first BOE, the ice will struggle to return.

I've pasted links and excerpts of several peer-reviewed scientific papers that refute this argument.  Do you have any peer-reviewed studies that support it?

Why would the Arctic behave differently than other bodies of water that melt out and then refreeze seasonally?  It's much colder and in the dark much longer than they are.

575
Consequences / Re: Ice-free Arctic
« on: March 23, 2018, 10:21:30 PM »
Quote
...  because chances are I'm wrong about an irreversible state change

I'm glad you're open to new information.  Here's something you may be happy to read:

https://journals.ametsoc.org/doi/pdf/10.1175/JCLI-D-14-00654.1

Abstract: 
Quote
Record lows in Arctic sea ice extent have been making frequent headlines in recent years. The change in
albedo when sea ice is replaced by open water introduces a nonlinearity that has sparked an ongoing debate
about the stability of the Arctic sea ice cover and the possibility of Arctic ‘‘tipping points.’’ Previous studies
identified instabilities for a shrinking ice cover in two types of idealized climate models: (i) annual-mean
latitudinally varying diffusive energy balance models (EBMs) and (ii) seasonally varying single-column
models (SCMs). The instabilities in these low-order models stand in contrast with results from comprehensive
global climate models (GCMs), which typically do not simulate any such instability. To help bridge
the gap between low-order models and GCMs, an idealized model is developed that includes both latitudinal
and seasonal variations. The model reduces to a standard EBM or SCM as limiting cases in the parameter
space, thus reconciling the two previous lines of research. It is found that the stability of the ice cover vastly
increases with the inclusion of spatial communication via meridional heat transport or a seasonal cycle in
solar forcing, being most stable when both are included. If the associated parameters are set to values that
correspond to the current climate, the ice retreat is reversible and there is no instability when the climate is
warmed. The two parameters have to be reduced by at least a factor of 3 for instability to occur. This implies
that the sea ice cover may be substantially more stable than has been suggested in previous idealized
modeling studies.

Here's a plain language summary of the article: https://scripps.ucsd.edu/news/research-highlight-arctic-sea-ice-loss-likely-be-reversible

Quote
Research Highlight: Arctic Sea Ice Loss Likely To Be Reversible
   
Scenarios of a sea ice tipping point leading to a permanently ice-free Arctic Ocean were based on oversimplified arguments

New research by Till Wagner and Ian Eisenman, scientists at Scripps Institution of Oceanography, UC San Diego, resolves a long-running debate over irreversible Arctic sea ice loss.

Ever since the striking record minimum Arctic sea ice extent in 2007, the ominous scenario of a sea ice tipping point has been a fixture in the public debate surrounding man-made climate change and a contingency for which Arctic-bordering countries have prepared.

For decades, scientists have been concerned about such a point of no return, beyond which sea ice loss is irreversible. This concern was supported by mathematical models of the key physical processes (known as process models) that were believed to drive sea ice changes. The process models forecasted that increased global warming would push the Arctic into an unstoppable cascade of melting that ceases only when the ocean becomes ice-free.

...

Wagner and Eisenman resolve this discrepancy in the study in an upcoming Journal of Climate article,  “How Climate Model Complexity Influences Sea Ice Stability.”

They created a model that bridged the gap between the process models and the GCMs, and they used it to determine what caused sea ice tipping points to occur in some models but not in others.

“We found that two key physical processes, which were often overlooked in previous process models, were actually essential for accurately describing whether sea ice loss is reversible,” said Eisenman, a professor of climate dynamics at Scripps Oceanography. “One relates to how heat moves from the tropics to the poles and the other is associated with the seasonal cycle. None of the relevant previous process modeling studies had included both of these factors, which led them to spuriously identify a tipping point that did not correspond to the real world.”

“Our results show that the basis for a sea ice tipping point doesn’t hold up when these additional processes are considered,” said Wagner. “In other words, no tipping point is likely to devour what’s left of the Arctic summer sea ice. So if global warming does soon melt all the Arctic sea ice, at least we can expect to get it back if we somehow manage to cool the planet back down again.”

576
Consequences / Re: Ice-free Arctic
« on: March 23, 2018, 10:04:56 PM »
One of the weaknesses with just projecting from recent trends is that the natural variability inherent in the climate system could be missed.  For example, it's estimated that the Atlantic Multidecadal Oscillation (AMO) and the Pacific Decadal Oscillation (PDO) both influence the transport of heat from the tropics to the Arctic.  Recent studies estimate that natural variability is responsible for 30% to 50% of the recent losses in Arctic sea ice are due to natural variability.

Some studies are showing that the AMO is shifting from a positive phase, as it has been since the 1990s, to a negative phase.  During a positive phase of the AMO, more warm Atlantic water is transported to the Arctic than during a negative phase.  This could lead to a slow-down in the loss rates of the Arctic sea ice, which wouldn't be captured by projecting trends.

Here's an article explaining the link between the AMO and Arctic sea ice:  http://adsabs.harvard.edu/abs/2016EGUGA..18.1978D

Here's the abstract:
Quote
The Arctic and North Atlantic have experienced pronounced changes over the 20th and early 21st centuries, including a rapid loss of Arctic sea ice over the last several decades, prominent multidecadal variability in both ocean temperatures and sea ice, and decadal-scale change in tropical storm activity. We use suites of coupled climate model simulations to probe some of the factors responsible for the observed multidecadal variability in the Atlantic/Arctic system. In our models we show that multidecadal fluctuations of the North Atlantic Oscillation (NAO) induce multidecadal fluctuations of the Atlantic Meridional Overturning Circulation (AMOC). A positive phase of the NAO is associated with strengthened westerly winds over the North Atlantic. These winds extract more heat than normal from the subpolar ocean, thereby increasing upper ocean density, deepwater formation, and the strength of the AMOC and associated poleward ocean heat transport. In model simulations the observed negative phase of the NAO in the 1960s and 1970s led to a weaker than normal AMOC, reduced poleward ocean heat transport, a cold North Atlantic, and an increase in Arctic sea ice extent in both winter and summer. The NAO strengthened from the 1970s to the mid 1990s, leading to an increase of the AMOC and a warming of the North Atlantic. The increased heat transport extended throughout the North Atlantic, into the Barents Sea, and finally into the Arctic, contributing to a rapid reduction of sea ice in the 1990s through the 2000s. Feedbacks involving shortwave radiation are an important component of the overall changes. The NAO-induced AMOC increase also led to hemispheric-scale atmospheric circulation changes and increased Atlantic hurricane activity, as well as atmospheric teleconnections to the Southern Ocean. Since the mid 1990s the strong positive phase of the NAO has weakened to a more neutral phase. Climate projections for the next decade that take into account recent behavior of the NAO as well as anthropogenic radiative forcing suggest a weakening of the AMOC and associated ocean heat transport, which would tend to moderate the rate of Arctic sea ice loss over the next decade. This effect is superimposed on the persistent and growing effects of anthropogenic climate change.

And here's another article about the possibility of a slow down in the sea ice loss: http://www.pnas.org/content/112/15/4570

Abstract: 
Quote
Satellite observations reveal a substantial decline in September Arctic sea ice extent since 1979, which has played a leading role in the observed recent Arctic surface warming and has often been attributed, in large part, to the increase in greenhouse gases. However, the most rapid decline occurred during the recent global warming hiatus period. Previous studies are often focused on a single mechanism for changes and variations of summer Arctic sea ice extent, and many are based on short observational records. The key players for summer Arctic sea ice extent variability at multidecadal/centennial time scales and their contributions to the observed summer Arctic sea ice decline are not well understood. Here a multiple regression model is developed for the first time, to the author’s knowledge, to provide a framework to quantify the contributions of three key predictors (Atlantic/Pacific heat transport into the Arctic, and Arctic Dipole) to the internal low-frequency variability of Summer Arctic sea ice extent, using a 3,600-y-long control climate model simulation. The results suggest that changes in these key predictors could have contributed substantially to the observed summer Arctic sea ice decline. If the ocean heat transport into the Arctic were to weaken in the near future due to internal variability, there might be a hiatus in the decline of September Arctic sea ice. The modeling results also suggest that at multidecadal/centennial time scales, variations in the atmosphere heat transport across the Arctic Circle are forced by anticorrelated variations in the Atlantic heat transport into the Arctic.

None of this is to deny the impact of greenhouse gas emissions and the warming climate.  If we don't reduce are emissions and lower the concentrations in the atmosphere, the Arctic will eventually become ice free.  It's just a question of how soon.

577
Consequences / Re: Ice-free Arctic
« on: March 23, 2018, 09:43:02 PM »
Here's a good article on the sensitivity of trend analysis with Arctic sea ice:  http://www.mdpi.com/2072-4292/10/2/230

Here's an extract from the article:
Quote
Using an inter-calibrated satellite sea ice product, this article examines the sensitivity of decadal trends of Arctic sea ice extent and statistical projections of the first occurrence of an ice-free Arctic summer. The projection based on the linear trend of the last 20 years of data places the first Arctic ice-free summer year at 2036, 12 years earlier compared to that of the trend over the last 30 years. The results from a sensitivity analysis of six commonly used curve-fitting models show that the projected timings of the first Arctic ice-free summer year tend to be earlier for exponential, Gompertz, quadratic, and linear with lag fittings, and later for linear and log fittings. Projections of the first Arctic ice-free summer year by all six statistical models appear to converge to the 2037 ± 6 timeframe, with a spread of 17 years, and the earliest first ice-free Arctic summer year at 2031.


578
Arctic sea ice / Re: The 2018 melting season
« on: March 23, 2018, 07:55:42 PM »
A bit off topic (apologies!) but can anyone point me to a good site for the Gulf Stream and changes over time in the Gulf stream?

There's a good overview at carbon brief, link here:https://www.carbonbrief.org/the-atlantic-conveyor-belt-and-climate-10-years-of-the-rapid-project

Here's a link to the RAPID project, which measures the Atlantic current at 26N:  http://www.rapid.ac.uk/background.php

Here's a picture from the site of the flows from the first decade of the Rapid project:


579
Consequences / Re: Ice-free Arctic
« on: March 21, 2018, 11:15:03 PM »
First let me be very clear. Your post and my post are talking about two very different things.

you talked about:

When will the Arctic be sea ice free in the summer for the first time?

I talked about:

What happens after the first ice free Arctic, if anything?


There are some short-term negative feedbacks that occur after the ice melts out.  This article describes them: http://pubman.mpdl.mpg.de/pubman/item/escidoc:2461121/component/escidoc:2461125/PAGESmagazine_2017_14-19_Notz.pdf

Here's an excerpt:

Quote
Annual variability: The importance of negative
feedbacks
In addition to seasonal forecasts on time scales of a few
months, also forecasts on time scales of a few years
have made some headlines over the past decade. These
headlines were usually related to claims that the Arctic
would lose its remaining summer sea ice within just a few
years. The underlying reasoning of such claims was often
related to a discussion of a possible ’tipping point’ that is
related to the ice-albedo feedback. Given the substantial
loss of Arctic sea ice in the past few years, the ocean
could potentially absorb enough heat to rapidly melt the
remainder of the sea ice cover.
However, our current understanding of the Arctic climate
system strongly suggests that this reasoning is unrealistic.
A first indication for this finding derived from model
experiments in which all Arctic sea ice was synthetically
removed from the Arctic Ocean at the onset of summer,
thus maximising the possible ice-albedo feedback
(Tietsche et al., 2011). Despite such maximised feedback,
the ice cover recovered in these experiments within
just a few years. This is because on annual time scales,
negative feedbacks dominate the evolution of the Arctic
sea ice cover. Three negative feedbacks are particularly
important: First, the open ocean very effectively releases
its heat to the atmosphere during winter, causing a rapid
loss of much of the heat that was accumulated in the icefree
water during summer. Second, the thin ice that forms
during winter can grow much more rapidly than ice that
survived the summer, because heat can more effectively
be transported from the ocean to the atmosphere when
the ice cover is thin (Bitz and Roe, 2004). Third, as ice
forms later in the season, it will carry a thinner insolating
snow cover as any snow fall occurring before ice
formation simply falls into the open ocean (Notz, 2009).

580
Policy and solutions / Re: Seaweed Farming
« on: March 09, 2018, 10:43:24 PM »
How about including seashells as well in a new and broader title with even more focus on CO2 drawdown:

Seaweed and seashell farming

Good suggestion.  I made the change.

581
Consequences / Re: Ice-free Arctic
« on: March 09, 2018, 10:27:16 PM »

I post a response.  Initially, the ice will regrow and then melt again in summer.


Yes, but:

 1. Initial conditions in October will be very different from initial conditions of the past. To begin with there won be a giant slab of ice keeping the waves down and the humidity locked in the oceans. The water will be very warm from all the incoming radiation. The atmosphere will be very warm too.

2. Before ice can form all the extra heat and humidity must be vented and the waves calmed. That means that refreezing will begin late and from 0.

3. Winter temperatures are already crashing. After A BOE Arctic growth is bound to be anemic.

4. Come the melting season of the following year the ice will be thinner than ever, with a record low extent.

5. This means that the year following  the first ice-free year will be ice free again but much sooner, gathering more heat than ever.

6. See 1.

Quote
Eventually, if the Arctic warms enough, the Arctic will be ice free for more and more of the year.


Yep

Quote
However, when the Arctic cools, the ice will grow back.


And there is not reason for it to cool until GHG levels in the atmosphere are significantly lower. It can be centuries or millenia. Eventuall, regardless of CO2, milankovitch cycles guarantee that it will return.

The arctic gets really, really cold in winter.  Even when it's warmer than usual, it's still below freezing.  That's why most scientists who study the arctic don't think we'll see ice-free (less than 1,000,000 square km of ice) Septembers until the 2050s at the earliest.  And even then, if we reduce our emissions, the Arctic will refreeze every winter and the loss of sea ice will plateau.

Quote
This paper addresses the specter of a September ice-free Arctic in the 21st century using newly available simulations from the Coupled Model Intercomparison Project Phase 5 (CMIP5). We find that large spread in the projected timing of the September ice-free Arctic in 30 CMIP5 models is associated at least as much with different atmospheric model components as with initial conditions. Here we reduce the spread in the timing of an ice-free state using two different approaches for the 30 CMIP5 models: (i) model selection based on the ability to reproduce the observed sea ice climatology and variability since 1979 and (ii) constrained estimation based on the strong and persistent relationship between present and future sea ice conditions. Results from the two approaches show good agreement. Under a high-emission scenario both approaches project that September ice extent will drop to ∼1.7 million km2 in the mid 2040s and reach the ice-free state (defined as 1 million km2) in 2054–2058. Under a medium-mitigation scenario, both approaches project a decrease to ∼1.7 million km2 in the early 2060s, followed by a leveling off in the ice extent.

Full article in the Proceedings of the National Academies of Science (2013) here: http://www.pnas.org/content/110/31/12571

And here's a more recent article about the duration of ice-free portions of the Arctic during summer:  https://pubag.nal.usda.gov/catalog/5405017.  Here's the abstract:

Quote
Global warming and continued reduction in sea ice cover will result in longer open water duration in the Arctic, which is important for the shipping industry, marine mammals, and other components of the regional ecosystem. In this study we assess the length of open water duration in the Alaskan Arctic over the next few decades using the set of latest coupled climate models (CMIP5). The Alaskan Arctic, including the Chukchi and the Beaufort Sea, has been a major region of summer sea ice retreat since 2007. Thirty five climate models from CMIP5 are evaluated and twelve are selected for composite projections based on their historical simulation performance. In the regions north of the Bering Strait (north of 70° N), future open-water duration shifts from a current 3–4months to a projected near 5months by 2040 based on the mean of the twelve selected climate models. There is considerable north–south gradient in projected durations. Open water duration is about 1month shorter along the same latitudes in the Beaufort Sea compared with that in the Chukchi Sea. Uncertainty is generally ±1month estimated from the range of model results. Open-water duration in the Alaskan Arctic expands quickly in these models over the next decades which will impact regional economic access and potentially alter ecosystems. Yet the northern Alaskan Arctic from January through May will remain sea ice covered into the second half of the century due to normal lack of sunlight.


582
Policy and solutions / Seaweed and Seashell Farming
« on: March 09, 2018, 07:06:37 PM »
I read "Atmosphere of Hope" by Tim Flannery recently and came across a topic I didn't know about, seaweed farming.  Apparently it's a way to reduce ocean acidification and draw down CO2 from the atmosphere.  It's been growing exponentially in the past decade and people are making money and producing food from it.

Quote
Globally, around 12 million tonnes of seaweed is grown and harvested annually, about three-quarters of which comes from China. The current market value of the global crop is between US$5 billion and US$5.6 billion, of which US$5 billion comes from sale for human consumption. Production, however, is expanding very rapidly.

Seaweeds can grow very fast – at rates more than 30 times those of land-based plants. Because they de-acidify seawater, making it easier for anything with a shell to grow, they are also the key to shellfish production. And by drawing CO₂ out of the ocean waters (thereby allowing the oceans to absorb more CO₂ from the atmosphere) they help fight climate change.

Here are a couple of links to articles about it:

https://theconversation.com/how-farming-giant-seaweed-can-feed-fish-and-fix-the-climate-81761

https://www.washingtonpost.com/lifestyle/food/seaweed-is-easy-to-grow-sustainable-and-nutritious-but-itll-never-be-kale/2015/10/26/1d1719b8-7750-11e5-b9c1-f03c48c96ac2_story.html?utm_term=.ddbbc9294451

https://e360.yale.edu/features/new_breed_of_ocean_farmer_aims_to_revive_global_seas

583
Consequences / Re: Ice-free Arctic
« on: March 08, 2018, 08:00:39 PM »
It's very difficult to predict how the atmosphere will respond to climate change, which makes it even more difficult to make predictions of regional responses to climate change.  That's because some of the responses will be offset.  For example, there is evidence that when anthropogenic aerosols are reduced in the atmosphere, organic aerosols increase.  Will it be enough to offset that warming effect, at least partially?  We don't know.

For an ice free arctic, some of the effects are predictable, such as the increase in the ice-albedo affect.  Some can only be speculated about, such as changes to the atmospheric circulation.  Part of the reason for this is that global warming is expected to shift the Hadley cells poleward, however, melt of the Arctic sea ice is expected to oppose this effect.  Here's an article about the issue:  http://onlinelibrary.wiley.com/doi/10.1002/2017GL076096/full  The key conclusion is:
Quote
The warming of sea surface temperatures (SSTs) and the direct radiative impact of CO2 have been shown to favor the poleward shift of midlatitude circulation (Grise & Polvani, 2014). However, in the Northern Hemisphere (NH), this process might be opposed by the loss of Arctic sea ice and the associated polar amplification of global warming (e.g., Blackport & Kushner, 2017; Harvey et al., 2015; Shaw et al., 2016). By analyzing the intermodel spread in the future projections from the Fifth Phase of the Coupled Model Intercomparison Project (CMIP5), evidence of this “tug-of-war” between tropical and polar forcing has been identified for the future response in the latitude of the North Atlantic jet (Barnes & Polvani, 2015), the strength of midlatitude storm tracks (Harvey et al., 2014), and the speed of midlatitude westerlies (Manzini et al., 2014; Zappa & Shepherd, 2017).

And we haven't considered changes to the ocean currents.  They may respond to changes in atmospheric pressure or wind patterns over time, and in the long run, they carry most of the heat from the tropics toward the poles.

That's why regional predictions of responses to climate change are difficult.  Estimating global temperature responses is easier because it's based on an overall response to multiple forcings over a long time.

584
Consequences / Re: Ice-free Arctic
« on: March 08, 2018, 07:05:26 PM »
Quote
Using current estimates of climate sensitivity, that would lead to a global temperature increase of 0.15 degrees C.

 If the global, annual temperature is increased by .15C, how much will be the local, monthly temperature increase in the arctic?

How does that local increase in temperature and humidity affects atmospheric and ocean currents?


Then you start october with 0 ice and much higher temperarures than normal. What is the most ice the Arctic has grown in a year? 

How thick will that ice be by april of the next year?

How quick will the thin, very low extent ice reach 0 again? August? July?

Rinse and repeat.

Arcmid,

I post a response.  Initially, the ice will regrow and then melt again in summer.  Eventually, if the Arctic warms enough, the Arctic will be ice free for more and more of the year.  However, when the Arctic cools, the ice will grow back.

Rinse and repeat.

585
Consequences / Re: Ice-free Arctic
« on: March 08, 2018, 01:54:46 AM »
For a good article outlining some of the possible impacts of the loss of Arctic see ice, go here: https://www.nature.com/news/arctic-2-0-what-happens-after-all-the-ice-goes-1.21431

In the article, they note that the loss of sea ice is not irreversible, provided we stop warming the planet:

Quote
If the future of the Arctic seems dire, there is one source of optimism: summer sea ice will return whenever the planet cools down again. “It’s not this irreversible process,” Stroeve says. “You could bring it back even if you lose it all.”

Unlike land-based ice sheets, which wax and wane over millennia and lag behind climate changes by similar spans, sea ice will regrow as soon as summer temperatures get cold enough. But identifying the exact threshold at which sea ice will return is tricky, says Dirk Notz, a sea-ice researcher at the Max Planck Institute for Meteorology in Hamburg, Germany. On the basis of model projections, researchers suggest that the threshold hovers around 450 parts per million (p.p.m.) — some 50 p.p.m. higher than today. But greenhouse-gas concentrations are not the only factor that affects ice regrowth; it also depends on how long the region has been ice-free in summer, which determines how much heat can build up in the Arctic Ocean.

Notz and his colleagues studied the interplay between greenhouse gases and ocean temperature with a global climate model8. They increased CO2 from pre-industrial concentrations of 280 p.p.m. to 1,100 p.p.m. — a bit more than the 1,000 p.p.m. projected by 2100 if no major action is taken to curtail greenhouse-gas emissions. Then they left it at those levels for millennia.

This obliterated both winter and summer sea ice, and allowed the ocean to warm up. The researchers then reduced CO2 concentrations to levels at which summer ice should have returned, but it did not regrow until the ocean had a chance to cool off, which took centuries.

586
Consequences / Re: Ice-free Arctic
« on: March 08, 2018, 12:13:56 AM »
Can anyone help me detail positive feedbacks amplified by the new arctic state?

Albedos
Methane release
oceanic warming/Water vapour
downward radiations increasing related to temperature inversion


And any negatives... if there are any worth speaking of.

A 2011 study estimated that the albedo effect of an ice-free arctic for a month in late summer would increase from the current forcing of 0.11 watts per meter squared (W/m-2) to 0.30 W/m-2.  Using current estimates of climate sensitivity, that would lead to a global temperature increase of 0.15 degrees C. Here's the abstract from the study:

Quote
A simple method for estimating the global radiative forcing caused by the sea ice–albedo feedback in the Arctic is presented. It is based on observations of cloud cover, sea ice concentration, and top-of-atmosphere broadband albedo. The method does not rely on any sort of climate model, making the assumptions and approximations clearly visible and understandable and allowing them to be easily changed. Results show that the globally and annually averaged radiative forcing caused by the observed loss of sea ice in the Arctic between 1979 and 2007 is approximately 0.1 W m−2; a complete removal of Arctic sea ice results in a forcing of about 0.7 W m−2, while a more realistic ice-free summer scenario (no ice for 1 month and decreased ice at all other times of the year) results in a forcing of about 0.3 W m−2, similar to present-day anthropogenic forcing caused by halocarbons. The potential for changes in cloud cover as a result of the changes in sea ice makes the evaluation of the actual forcing that may be realized quite uncertain since such changes could overwhelm the forcing caused by the sea ice loss itself, if the cloudiness increases in the summertime.

The study can be read here:  http://onlinelibrary.wiley.com/doi/10.1029/2011JD015804/full


587
Consequences / Re: Near Term Human Extinction
« on: March 07, 2018, 09:01:44 PM »
Seriously, what's with all the climate change deniers on this forum?  Aren't you people supposed to be over at Alex Jones's message boards?

There's a lot of very interesting responses in this thread, but the deniers (you know who you are) tend to say "I don't think, or that can never happen, or humans are invincible".

The baseline temp is wrong, we're at 1.5C over baseline, not 1 or 0.8 or whatever you're using.  1.5C.  Stick to the facts.  Baseline is PRE Industrial.  We're measuring changes that have occurred since industrialized civilization, not since some date ranges two centuries later.

I've argued with climate deniers on other forums and haven't seen any here.  What this argument we've been having is how soon the climate impacts are going to occur and how severe the impacts are going to be.

I've used scientific studies, the IPCC reports and observed facts to support my arguments that we're not heading to a near term human extinction or a collapse of human society.  If you disagree with these studies, find some peer-reviewed scientific studies that support your arguments and post them here. 

As to the temperature increase, the IPCC AR5 published in 2013 concluded:
Quote
The globally averaged combined land and ocean surface temperature data as calculated by a linear trend, show a
warming of 0.85 [0.65 to 1.06] °C3, over the period 1880 to 2012, when multiple independently produced datasets exist.
The total increase between the average of the 1850–1900 period and the 2003–2012 period is 0.78 [0.72 to 0.85] °C,
based on the single longest dataset available4 (see Figure SPM.1). {2.4}
The past 5 years have been warmer still, bring us up another 0.3 degrees (maybe slightly less when you consider the effects of the large El Nino we experienced in 2015-2016).  So we are at about 1 degree C warmer than preindustrial.  That's according to those deniers at NASA and the IPCC. ;D

588
Consequences / Re: Near Term Human Extinction
« on: March 07, 2018, 07:55:50 PM »
I've yet to see anything from the doom and gloomers that leads me to believe we'll see large decreases in the human population, much less a collapse.
Darfur, Somalia, Syria, Yemen. When ecocide and (sui)genocide go hand in hand and form a feedback loop of death and destruction. Just small examples, yet...

The Arab Spring riots were fuelled by rising prices of bread, after Russia stopped exporting due to drought and fires.

Problem is, people just can't starve peacefully.

For some optimistic counter examples from e.g. Ethiopia and Rwanda see John d Liu's films https://knaw.academia.edu/JohnDLiu
Let's hope the agricultural enlightenment he documents happens quick enough -  and does not get steamrolled by rapid climate disruption.

All of the examples you site are situations that could've been avoided.  For example,
Quote
The Arab Spring riots were fuelled by rising prices of bread, after Russia stopped exporting due to drought and fires.
  Why did Russia stop exporting?  Why didn't some other country fill the need?  I don't think it was climate change.

In fact, the hypothesis that climate change will lead to more conflict is unproven.  The evidence currently doesn't support it:

Quote
It is true that impoverishment and human insecurity may arise as a result of climate change, if preventive measures are not undertaken. But there is missing evidence that global warming directly increases conflict. The temperature has risen in the last three decades, but the number of conflicts has significantly dropped since. A prominent study by scholars from the International Peace Research Institute, Oslo, claims that “the causal chains suggested in the literature have so far rarely been substantiated with reliable evidence

Here's a link to the article that quote is from: https://www.brookings.edu/blog/africa-in-focus/2017/01/20/does-climate-change-cause-conflict/

589
Consequences / Re: Near Term Human Extinction
« on: March 07, 2018, 06:40:51 PM »
The idea that 400+ nuclear reactors are going to melt down at once is just pure fantasy.  Most of the reactors operating today will have been shut down for economic reasons long before climate change impacts start reducing the human population (if that ever happens).  The fuel rods will have been cooled in temporary ponds and moved to longer term dry storage casks which can contain the spent rods for a century or more before needing to be replaced.  There wont be a lot of radiation leaking or Chernobyl/Fukushima events happening. 

Humans are the most adaptable species on the planet.   Climate change will cause disruptions and perhaps slow population growth when impacts above 1.5 C to 2 C (such as long term droughts wiping out a lot of crops) start happening, but even those events will take a long time to occur and people will adapt.  Although some people don't like GMO crops, they are being developed and will be used when the alternative is massive famines.  Drought resistance, heat tolerance, the ability to grow in areas where salt water intrusion occurs, are all things that can be bred into plants.  And people will eat less meat which will allow our crops to feed more people.

Yes, some coastal areas will flood due to rising sea levels later in this century, but people will just rebuild on higher ground.  Hurricanes like Maria and Katrina will cause devastation in their paths, but they're not extinction events.

I've yet to see anything from the doom and gloomers that leads me to believe we'll see large decreases in the human population, much less a collapse.

590
Consequences / Re: Near Term Human Extinction
« on: March 05, 2018, 07:41:55 PM »
There's a new paper on aerosol emissions that has been accepted for publication in the peer-reviewed journal Environmental Research Letters.  It's available here: http://iopscience.iop.org/article/10.1088/1748-9326/aab1b2/pdf

Here are the findings related to near term and long term increases in temperature due to reductions of fossil-fuel aerosol emissions:
Quote
We found that aerosol emission reductions associated with the co-emissions with CO2 have a significant warming effect during the first half of the century and that the near-term warming is dependent on the pace of aerosol emission reductions. The modeling results show that these aerosol emission reductions account for about 0.5◦C warming relative to 2015 on top of 1◦C above pre-industrial levels that have been already reached in 2015.

Quote
Aggressive aerosol control due to air quality legislation impacts the peak temperature which is 0.2-0.3◦C above the 1.5◦C limit even within the most ambitious CO2/GHG reduction scenario.

So a mid-century impact of 0.5 degrees C due to the loss of cooling and a long-term impact of 0.2 to 0.3 degrees C due to the loss of cooling being offset by the reduced carbon emissions from retiring the fossil fuel plants.

And it's possible that the decrease in anthropogenic aerosols may lead to an increase in natural aerosol productions and/or that climate change will lead to increases in natural aerosol production.  Here's a good summary of the current science: https://link.springer.com/article/10.1007/s40641-018-0086-1 

The key point is: 
Quote
In regions where anthropogenic aerosol loads decrease, the impacts of climate on natural aerosol variabilities will increase. Detailed knowledge of processes controlling aerosol concentrations is required for credible future projections of aerosol distributions.

There's a lot of uncertainty about this subject, but I have yet to read any peer reviewed science that supports a huge temperature increase due to a reduction in fossil fuel produced aerosols.

591
Consequences / Re: Near Term Human Extinction
« on: March 05, 2018, 06:28:59 PM »
http://arctic-news.blogspot.com/p/aerosols.html

Some of you will ignore this because it is ´alarmist´. But there is some actual scientific papers tagged on this post.

I have come to my conclusion. Humanity is screwed. Near term we are gonna see billions die and populations decrease to pre- Industrial levels. This will likely be the last time posting on this thread due to the back and forth arguing on who is right and wrong.

Good day to all!

That blogger can't do math.  In his write up, he indicates that the IPCC AR4 report attributes a cooling effect of 2.7 W/m-2 to aerosols.  He then indicates that James Hansen believes the climate sensitivity is 0.75 degree/W/m-2.  He comes to the conclusion that removal of aerosols would lead to a temperature increase of 2.5 degrees.

However, 2.7 * 0.75 = 2 degrees.  And that's assuming all aerosols disappear overnight.  They won't.  It will take decades to eliminate the fossil fuel plants that produce most of the human caused aerosols and there is no indication that the natural aerosols (from ocean organisms, volcanos, dust, etc...) are going to disappear in the near future.  As I noted above, a temperature change of an order of magnitude less, 0.2 degrees, is what the science currently supports for loss of the aerosol cooling effect.

592
Consequences / Re: Near Term Human Extinction
« on: March 02, 2018, 11:19:32 PM »
Quote
-and it will not take decades for the aerosol effects to be removed.  Aerosols do not enter the stratosphere, they stick to the troposphere, and are removed from precipitation events.  This process would only take, at most, a couple of months.

But new aerosols are being produced from burning fossil fuels and biomass.  There won't be an instantaneous reduction in aerosols, because of the new production.

And the current IPCC reports estimates that the cooling effect of aerosols is 0.35 w/m-2.  However, 0.13 w/m-2 comes from dust and organic sources, so the amount caused by "apes" is about 0.22 w/m-2.  If you assume a climate sensitivity of 3 degree increase due to a doubling of CO2 (mid-range of current estimates), removing the cooling effect of aerosols results in about a 0.2 degree temperature increase.  Compared to the 2.5 degree increase (in a decade no less), that's pretty minor.

Edit.  Corrected assumed climate sensitivity and calculation of cooling effect.

593
Consequences / Re: Near Term Human Extinction
« on: March 02, 2018, 09:09:51 PM »
<snip>

So again, the feedbacks from increased arctic methane release are much closer to zero than what's shown on that table.
We aren't seeing a zero methane feed back loop now.  The arctic is currently 10% higher than the rest of the world and that is climbing.

I said close to zero, and I meant over the decade from 2016 to 2026, which is what we're discussing.  And science backs me up on this. The radiative forcing from methane hasn't increased much in the past decade.  Here it is in graphical form:






594
Consequences / Re: Near Term Human Extinction
« on: March 02, 2018, 08:04:00 PM »
https://guymcpherson.com/2016/08/the-politics-and-science-of-our-demise/

I recommend giving this a chance
I recommend to avoid it. I am sorry to use such generalities on this fine forum, but this is alarmist claptrap posing as science.

Trying to fight the claims one by one is futile,  this is pure troll feeding. I will refrain. Take my word for it, global temps will not rise 8 degrees C in the next 10 years. (The headline says 10 but never mind the details). I'm just a nobody , but at least I'm not a liar like these folks, so my word might be good for something.
Note: I dislike anyone who bends science on purpose, whether it's deniers or alarmists, both of whom make a good living out of their evil. I recmmend to avoid reading such sources,  and stick to the actual science.

I am open to disscussion because I think thats what science is all about, but if you could provide me with proof to explain why 8 degrees wont happen. That would be of great help. I personally think we are headed for about a 4 C rise by 2050.

On that chart, the top two effects have already occurred, resulting in an estimated warming of 1.9 degrees C since pre-industrial. 

Further down the chart, the aerosol masking is not going to go away in an instant, it will take decades to reduce it, as fossil fuel use and wood burning are not going to be instantly reduced to zero.  Also, the increased black carbon from forest fires and other impacts of climate change will probably offset the cleaning up of smokestack emissions and the reductions in coal use.  So that 2.5 degree change will be closer to zero.

As to increasing CO2 emissions, they tend to take effect slowly (sometimes referred to as the"in the pipeline amount").  The more instantaneous effect has been estimated by climate scientists such as James Hansen as 0.1 to 0.2 degrees per decade.

This chart relies on older estimates of methane release.  More recent articles show that even in periods of much higher global warming than we're currently experiencing, such as the Younger Dryas near the last warming maximum from the previous ice age (about 8,000 to 10,000 years ago), the arctic sea ice clathrates didn't melt. Abstract of article is at this link: https://www.nature.com/articles/nature23316.   So again, the feedbacks from increased arctic methane release are much closer to zero than what's shown on that table.

As to the increase in temperature from the albedo changes in the arctic, 1.6 degrees in the next decade seems extremely unlikely.  Research in 2014 showed that increases in Arctic Sea surface temperature from 2000 to 2012 was 0.58 degrees per decade.  (Article here: http://onlinelibrary.wiley.com/doi/10.1002/2013GL058951/full).  During that time, global temperatures, calculated by NASA, increased much less, roughly 0.1 degrees C (data here: https://data.giss.nasa.gov/gistemp/tabledata_v3/GLB.Ts.txt.

And the water vapor feedback tends to equal the CO2 increase at about a 1:1 ratio.  So that 2.1 degrees in the chart should be about 0.1 to 0.2 degrees.

In short, we're much more likely to see a slight increase over current warming (0.1 to 0.2 degrees per decade) in the near future, maybe even a doubling to 0.2 to 0.4 degrees by 2026; not an additional 8 degrees C.  So an extinction event (due to climate change) by 2026 is not going to happen.  If we continue on the "business as usual" emissions guidelines, an extinction event in a century or so is possible.  However, so much progress in renewable energy, battery storage, and other technologies to decarbonize our economies has been made that it's clear that we'll emit far less carbon than the business as usual model assumes.

Even so, the effects of our previous and future emission have lead to climate change and it will get worse over the next few decades.  Call me an optimist, but I believe that even with the upcoming troubles ahead, the human race will survive.  And posting extremely alarmist articles like the McPherson one just gives ammunition to deniers who will use it to discredit legitimate science when the alarmist projections don't pan out.

It's helpful to read some of the background science and do your own analysis rather than just accept something that shows up on the internet.  You can start with the IPCC reports.  The latest, AR5, is available at this link:  http://www.climatechange2013.org/report/full-report/.

Edit:  Corrected link to IPCC AR5 report.

595
Antarctica / Re: PIG has calved
« on: February 17, 2018, 12:13:42 AM »
Solartim,

What is the scale on that photo?  Can you tell how far back from the edge the new rift is?

Also, are dots that appear to be small holes melt ponds?  If so, that's a troubling sign.

596
Policy and solutions / Re: Renewable Energy
« on: February 16, 2018, 10:45:48 PM »
Here's another story on batteries plus solar replacing peakers (power plants that operate to supply peak loads): https://oilprice.com/Energy/Energy-General/Big-Batteries-Are-Becoming-Much-Cheaper.html

Quote


Big Batteries Are Becoming Much Cheaper

By Irina Slav - Feb 15, 2018, 3:00 PM CST
  Tech

Huge battery arrays are undermining peakers—the gas-fired power plants deployed during peak demand—and could in the future completely change the face of the power market.

Batteries are hot right now. Energy storage was referred to as the Holy Grail of renewables by one industry executive, as it would solve its main problem: intermittency. No wonder then that everyone is working hard on storage.

They are working so hard, it seems, that prices, which used to be a major obstacle along the path toward renewable energy storage gaining ground, have fallen much lower than the price of traditionally generated and stored energy, the Wall Street Journal notes in a recent story on giant batteries.

One Minnesota utility, Xcel Energy, not long ago, carried out a tender for the construction of a solar + storage installation, receiving 87 bids whose average price per megawatt hour was just US$36. This compares with US$87 for electricity generated by peakers, with the price including the cost of construction and fuel purchases for the plant.

597
Policy and solutions / Re: Renewable Energy
« on: February 14, 2018, 10:26:49 PM »
Do you have a cite on the price? The story says solar+battery won but doesn’t say it was cheapest, just “competitive”.

They didn't announce a price.  More details are available here:

https://www.utilitydive.com/news/aps-to-install-50-mw-135-mwh-solar-shifting-battery/516850/

Here is some cost information from other recent solar plus battery projects cited in the article:

Quote
The APS project comes on the heels of a pair of high-profile solar-plus-storage projects announced last year. In January, a Hawaii co-op signed a deal for a 28 MW solar array with a 100 MWh battery system for $0.11/kWh, below the retail rate of electricity there. And in May, Tucson Electric Power signed a deal for 100 MW of solar and a 120 MWh battery for "significantly less than $0.045/kWh over 20 years," the lowest publicly available price for such a project.

APS did not release pricing information for its new project, but charging the battery mostly with solar power could allow it to qualify for a 30% federal investment tax credit for solar facilities.

598
Policy and solutions / Re: Renewable Energy
« on: February 13, 2018, 11:35:47 PM »
Solar plus battery storage is now cheaper than natural gas in Arizona:

https://www.bloomberg.com/news/articles/2018-02-12/a-powerful-mix-of-solar-and-batteries-is-beating-natural-gas

Quote
Natural gas is getting edged out of power markets across the U.S. by two energy sources that, together, are proving to be an unbeatable mix: solar and batteries.

In just the latest example, First Solar Inc. won a power contract to supply Arizona’s biggest utility when electricity demand on its system typically peaks, between 3 p.m. and 8 p.m. The panel maker beat out bids from even power plants burning cheap gas by proposing to build a 65-megawatt solar farm that will, in turn, feed a 50-megawatt battery system.

It’s a powerful combination for meeting peak demand because of when the sun shines. Here’s how it’ll work: The panels will generate solar power when the sun’s out to charge the batteries. The utility will draw on those batteries as the sun starts to set and demand starts to rise.

Just last week, NextEra Energy Inc.’s Florida utility similarly installed a battery system that’ll back up a solar farm and boost generation. In California, regulators have called on PG&E Corp. to use batteries or other non-fossil fuel resources instead of supplies from gas-fired plants to meet peak demand.

599
Consequences / Re: Global Surface Air Temperatures
« on: August 15, 2017, 10:38:08 PM »
I think there might be something amiss with the GISS numbers.  Typically they run ~.15 higher than HADCRU.  A difference of almost 0.3 is unheard of in the temperature database.

Bill showed the HadSST (sea surface temperatures) as fourth highest, not the HADCRU global.  NASA's land only value for July is 1.10, the highest for July, which is balanced by the SST being the fourth highest.

Edit:  HadSST uses a 1961 - 1990 baseline for their anomaly reports while NASA uses a 1951 - 1980 base period.  In addition, NASA uses the ERSSTv5 for the SST is in the global number.  I don't know how the ERSSTv5 anomaly for July compares to the HadSST anomaly.

600
Policy and solutions / Re: Boring, boring ol' Elon Musk...
« on: August 12, 2017, 02:07:12 AM »
Boring is boring much smaller diameter tunnels so feet per day averages from other tunnels won't apply.

If you look at the size of the Boring machine it wouldn't take months to dig an entry hole.  I'd say a short number of days.

From Wiki
Quote
As of February 2017, the company has begun digging a 30-foot-wide (9 m), 50-foot-long (15 m), and 15-foot-deep (4.6 m) testing trench

Quote
At the end of April 2017, a TBM was seen at SpaceX with the company's name on the side.

Given that they have already drilled to the edge of their property (350 feet), several months does seem a little excessive, I doubt they have proceeded as fast as they could if they were already fully knowledgeable about what they are doing and besides they have also done car elevator and doubtless other work.

They started work on the launch pit in January and installed the TBM in May.  That's four months just to get started.  Musk tweeted that the first segment of the tunnel was complete on June 29th.  There were no details about how long the segment was.  If we assume that it's the 350 feet you mention in the quote above, that's a month to go 350 feet, or 12 feet a day.  That's about right for a TBM and crew working up to speed on a new tunneling project.

In another another article, Boring's representative estimates that it will take 8 months to bore the 2 mile long test tunnel in Hawthorne. 

Quote
Horton also told the council members that the tunneling process, which should take just eight months, would prove the company can build “safely, reliably, and for significant cost savings to traditional tunneling projects.”

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