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09-14-2019, 04:44 PM #1451Banned
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09-14-2019, 05:08 PM #1452
- Maybe we're not looking at the same chart in the same way but multidecadal variability does look externally forced principally by changes in the frequency and amplitude of volcanic forcing. Location matter too. The series of 1800 era volcanic eruptions, for example, were mostly tropical.
A lot of this is addressed in the previously cited paper. If you're asking why there are exceptions then there are other natural forcings independent of volcanic activity. Asking why volcanic activity is not a perfect analog is not addressing the point because, per our previous discussion, the focus was specifically on the end of the Little Ice Age during the late 1800s.
-- So, per my previous comment early 1900's warming appears to be due to:
1. Natural forcing: Early 20th-century Arctic warming intensified by Pacific and Atlantic multidecadal variability, sun activity, etc.
2. A relative lack of volcanic activity
3. Humans played a role as well
--- If you want to argue that anthropogenic forcing was small that's ok but keep in mind you are also arguing the greenhouse effect is logarithmic so according to your argument the initial greenhouse effect might be greater than the later effect. Lots of CO2 and Methane were pumped into the atmosphere:
---- Also keep in mind that along multi-decade timescales, natural internally-driven warming should go back to the equilibrium determined by any external factor. Instead, what we are seeing is a planet that once experienced lots of internal variability giving way to a slow-varying warming trend.
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09-14-2019, 05:09 PM #1453
What? Your fingers have so much cherry juice on them it is hard to read your writing. I am glad to see you accept that the last five years globally have been the hottest on record however.
To bring context to the global goal of limiting warming to 2°C, we compare the global temperatures to an earlier, pre-industrial 1880-1910 baseline. 2018’s global temperatures were 1.90°F (1.06°C) above that baseline — more than halfway there. This made 2018 the second-warmest year on record without an El Niño event, behind only 2017. (El Niño can enhance warming, but it can’t explain all of it). Only 2016 and 2015 were warmer years, and 2014 rounds out the top five. With the five warmest years on record happening during the past five years — and the 20 warmest occurring over the past 22 — a consistent warming trend couldn’t be clearer. Meanwhile, monthly averaged atmospheric CO2 concentrations have risen to 411 ppm at Mauna Loa Observatory, thanks in part to an estimated 2.7 percent increase in global CO2 emissions from fossil fuels.
As Mark Twain said, "Climate is what we expect, weather is what we get."
Global warming doesn't mean every place every day is warm. July 2019 was the hottest year on record in human history, but it was quite cool here in Montana (where did you say you live again?). Do you understand the word global?
As for your growing glacier, "A Greenland glacier is growing. That doesn't mean melting is over.
A pulse of cooler water at its edge let part of the glacier gain some mass. But overall, the melting across Greenland continues apace."
IT’S MELTING AND it’s not coming back. That’s something we often hear about our shifting climate and the ice that, in a sense, holds it together. Throughout the Arctic, glaciers are shrinking, right?
Maybe not quite the way we think.
NASA's Oceans Melting Greenland (OMG) project has revealed Greenland’s Jakobshavn Glacier, the island’s biggest, is actually growing, at least at its edge. In research published Monday in Nature Geoscience, researchers report that since 2016, Jakobshavn’s ice has thickened slightly, thanks to relatively cool ocean waters at its base—which have caused the glacier to slow down its melt. This reverses the glacier’s 20-year trend of thinning and retreating. But because of what else is happening on the ice sheet, and the overall climate outlook, that’s not necessarily a good thing for global sea level.
That's because, despite the fact that this particular glacier is growing, the whole Greenland ice sheet is still losing lots and lots of ice. Jakobshavn drains only about seven percent of the entire ice sheet, so even if it were growing robustly, mass loss from the rest of the ice sheet would outweigh its slight expansion.
It may sound a bit confusing, but that’s because the reality of climate change isn’t a straight line, say NASA researchers.
“The thinking was once glaciers start retreating, nothing's stopping them,” explains Josh Willis, an oceanographer at NASA’s Jet Propulsion Laboratory and OMG’s lead scientist. “We've found that that's not true.”
Other Arctic glaciers may be undergoing similar growth. That suggests the ebb and flow of glaciers in a warming world may be more complicated and harder to predict than previously thought, says Willis.
One important factor is that it’s not just about a warming atmosphere. “The water is warming, too,” says Willis. “Oceans are doing a huge part of the work in terms of driving Greenland's ice melt.”
“All this is an indicator of how sensitive glaciers are to ocean temperatures,” says the study’s lead author, Ala Khazendar, a glaciologist with OMG.
Why is Jakobshavn growing? The scientists point to a recent influx of unusually cold water from the north Atlantic pushing into the Arctic. This has been particularly marked in Disko Bay, which spills over into the Illulisat Icefjord, the glacier’s home. At a depth of 820 feet, temperatures have dropped two degrees Celsius since 2014. And that colder water has helped the glacier slow its melt and even grow slightly.
This influx of cold waters isn't an isolated event: Thanks to a natural cycle in the Atlantic Ocean that switches back and forth between warm and cold about once every 20 years, cooler waters are penetrating far up the western coast of Greenland. But the phase will switch again at some point and warmer waters will return.
So, while the overall melt on the continent isn’t on hold—and the overall ice balance of the ice sheet is still declining as the world warms—these cycles show that climate change isn’t necessarily creating impacts in a straight line. It also means that conditions might be a bit more complicated than previously thought for Greenland’s 200-plus glaciers throughout the continent-sized island.
Complex interactions
Glaciers like Jakobshavn extend out into the ocean, which explains how water temperature can impact their size and movement and may mean that the overall melting trend—while still happening—may be happening slower than we thought.
Between 2000 and 2010, Jakobshavn contributed the largest solid ice discharge in all of Greenland’s ice sheet, equivalent to nearly a millimeter to global sea rise. Greenland holds 10 percent of the world's freshwater in a deep freeze. If it melted completely, it could raise oceans about 25 feet (see what would happen if all the world’s ice melted).
Willis says experts had thought the shape of the seafloor is what largely controlled a glacier’s retreat, because the ice can get stuck on undersea ridges that delay its movement. “We found you also have to pay attention to what the ocean’s doing,” he says. And as ice melts on the surface, the water drills through the ice sheet and comes down at the bottom of the glacier.
This mix of fresh and ocean water under the glacier drives melting and increases calving, the real hard-luck consequence of the findings. So, while the glacier is growing, the ice sheet is still losing tremendous mass and contributing to sea-level rise.
“That’s how the warming of the ocean translates,” Khazendar says.
It’s also why despite serious implications for Greenland’s near future ice loss, researchers caution the findings don’t mean we’ve found a magic climate reverse. It’s in fact akin to a pendulum. Jakobshavn had periods of fast retreat in the 20th century, followed by thickening, then retreat, Khazendar says—but on average the air and sea are warming, and that means retreats are always going to be bigger than advances, adds Willis.
Retreating “even faster than it was before”
“Over 90 percent of the heat that’s trapped from greenhouse gases are warming the oceans,” he says. “So we know in the long run, this cooling is going to pass. When it does, the glacier is going to retreat even faster than it was before.”
NASA’s OMG, which began in 2016 to track the ice’s seasonal ebb and flow to help predict global sea-level rise, now plans to determine if that hypothesis is accurate. One way the team determines ice thickness is by flying above the glacier and using an airborne topographic mapper, which employs radar to scan and measure the ice cap at an accuracy of about three feet. Much climate research studies the air. OMG, which is also tagging narwhals to measure ocean depth and temperature, studies the water and the glaciers themselves.
Later this year, NASA’s Grace Follow On mission, which tracks earth’s water in motion, will reveal how much mass Greenland has lost the last two years, which Willis says “may help us learn if this ocean effect is more widespread and could affect mass balance in a positive sense in less ice loss in previous years. We don’t know how to put the Jakobshavn results in context of the whole of Greenland until we get that extra data.”
“I think the story is basically correct,” says David Holland, a New York University professor who was not involved with the research but who has studied ice-ocean interaction at Jakobshavn for 12 years. He thinks this type of ocean interaction could be widespread, from the Arctic to Antarctic.
“You can see in the summer, Jakobshavn’s advancing, not slowing down,” Holland continues. “I think the question is why does the glacier do what it does and I’m of the opinion that the ocean is a dominant player controlling it.”
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09-14-2019, 06:50 PM #1454
Can you specify a referfence for the Greenland ice sheet growing?
Here it says it's shrinking over all despite the Jakobshavn growing: https://www.nationalgeographic.com/e...d-ice-growing/
A pulse of cooler water at its edge let part of the glacier gain some mass. But overall, the melting across Greenland continues apace.
…
That's because, despite the fact that this particular glacier is growing, the whole Greenland ice sheet is still losing lots and lots of ice. Jakobshavn drains only about seven percent of the entire ice sheet, so even if it were growing robustly, mass loss from the rest of the ice sheet would outweigh its slight expansion.
...
So, while the overall melt on the continent isn’t on hold—and the overall ice balance of the ice sheet is still declining as the world warms—these cycles show that climate change isn’t necessarily creating impacts in a straight lineMerde De Glace On the Freak When Ski
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09-14-2019, 06:52 PM #1455
This is like the claim that there was no evidence of collusion with Russia or evidence of obstruction of justice on the part of the Trump administration.
No matter how many times one points out the data, some people just can't get there.Merde De Glace On the Freak When Ski
>>>200 cm Black Bamboo Sidewalled DPS Lotus 120 : Best Skis Ever <<<
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09-14-2019, 07:46 PM #1456Banned
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1050-1100 is already going into a cooling trend before any volcanic forcing, same for 1400-1450.
A lot of this is addressed in the previously cited paper. If you're asking why there are exceptions then there are other natural forcings independent of volcanic activity. Asking why volcanic activity is not a perfect analog is not addressing the point because, per our previous discussion, the focus was specifically on the end of the Little Ice Age during the late 1800s.
For the record, the Little Ice Age isn't solely attributed to volcanic activity. Orbital cycles, solar activity, and ocean circulation have all been theorized to have played a role.
-- So, per my previous comment early 1900's warming appears to be due to:
1. Natural forcing: Early 20th-century Arctic warming intensified by Pacific and Atlantic multidecadal variability, sun activity, etc.
2. A relative lack of volcanic activity
3. Humans played a role as well
--- If you want to argue that anthropogenic forcing was small that's ok but keep in mind you are also arguing the greenhouse effect is logarithmic so according to your argument the initial greenhouse effect might be greater than the later effect. Lots of CO2 and Methane were pumped into the atmosphere:
---- Also keep in mind that along multi-decade timescales, natural internally-driven warming should go back to the equilibrium determined by any external factor. Instead, what we are seeing is a planet that once experienced lots of internal variability giving way to a slow-varying warming trend.
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09-14-2019, 08:10 PM #1457Banned
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Instrumental record sure, I don't take issue with that.
Global warming doesn't mean every place every day is warm. July 2019 was the hottest year on record in human history, but it was quite cool here in Montana (where did you say you live again?). Do you understand the word global?
As for your growing glacier, "A Greenland glacier is growing. That doesn't mean melting is over.
A pulse of cooler water at its edge let part of the glacier gain some mass. But overall, the melting across Greenland continues apace."
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09-14-2019, 08:28 PM #1458Banned
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09-14-2019, 08:32 PM #1459Banned
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09-14-2019, 08:34 PM #1460
Huh
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09-14-2019, 08:42 PM #1461
The entire global ocean is warming, but some parts are changing much faster than others — and the hot spot off Uruguay is one of the fastest. It was first identified by scientists in 2012, but it is still poorly understood and has received virtually no public attention.
https://www.washingtonpost.com/graph...?noredirect=on
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09-14-2019, 08:43 PM #1462Banned
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That has nothing to do with our current argument. I'm claiming that I don't think that it's a coincidence that the highest (mostly natural) warming rate by far of the past 2,000 years shows up as soon as the data switches from proxy to instrumental. You were trying to make a case for it being a coincidence.
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09-14-2019, 08:47 PM #1463
sarcasm??!! because anyone with functioning brain cells knows "collusion" isn't a actual offense, it's obstruction of justice
https://www.vox.com/policy-and-polit...ustice-summary
https://www.washingtonpost.com/polit...n-you-tell-us/
https://www.newyorker.com/news/news-...on-helps-trump
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09-14-2019, 08:48 PM #1464
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09-14-2019, 08:49 PM #1465
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09-14-2019, 09:29 PM #1466Banned
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I think you understand what I'm saying, but none of your responses relate to the point I'm trying to make, so I'm not sure if you do understand. To be clear, I am saying that it is a stretch to be able to make bold conclusions about 20th/21st century warming rates compared to the warming rates of the previous 2,000 years because of the differences in proxy records vs instrumental records. I don't think that it is a coincidence that as soon as we start using instrumental records to look at warming rates, we start seeing the highest warming rates of the past 2,000 years. The authors of the Neukom paper would not begrudge me for this perspective.
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09-14-2019, 09:47 PM #1467Banned
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09-14-2019, 09:50 PM #1468
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09-14-2019, 09:50 PM #1469Banned
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09-14-2019, 09:54 PM #1470
Again, this is an instance of claiming that perturbations in the overall trend is evidence that the trend is invalid. Which I just don't understand as being significant mathematically or scientific.
From the first link:
Note, the SMB doesn’t take into account the breaking off, or “calving” of icebergs from the ice sheet’s edge, which we’ll come to later. Calving losses have averaged around 500bn tonnes of ice per year this century. This means the ice sheet has been losing mass overall across recent years
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We must wait for data from the GRACE-Follow On (GRACE-FO) satellite mission before we know how the total mass budget has fared this year – which includes calving and melting at the base of the ice sheet. However, it is likely that the relatively high end of season SMB will mean a zero or close-to-zero total mass budget this year, as last year.
Likely?
Again, the argument that anomalies occur in data sets does not invalidate the observed overall trends.
In addition, one effect of warming is more moisture in the atmosphere which will account for more snow in areas not yet sufficiently affected to prevent freezing. So it actually makes some sense that certain areas will receive more snow until those areas warm sufficiently to preclude freezing.
So. I'm still not only unconvinced by the conclusions, but am mystified that the approach is considered even remotely sensical.Last edited by Buster Highmen; 09-14-2019 at 10:17 PM.
Merde De Glace On the Freak When Ski
>>>200 cm Black Bamboo Sidewalled DPS Lotus 120 : Best Skis Ever <<<
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09-14-2019, 10:06 PM #1471
In a nutshell. you're claiming that the fundamental assumption that these records are valid is incorrect. OK.
I disagree.
I'd be all for a paradigm shift, I'm ready for pregnant polemics, but all this position does is attempt to nullify a theory with no replacement.
For example, I value greatly the work of Henrik Svensmark, it' an interesting theory.
But one thing I really don't understand is the cost argument to reacting to the AGW theory. I'd think it's a fantastic opportunity for technological growth, for new markets and upheaval in the financial status quo. People who see a threat to the status quo are not the people who lead new technologies, new ideas or growth.Merde De Glace On the Freak When Ski
>>>200 cm Black Bamboo Sidewalled DPS Lotus 120 : Best Skis Ever <<<
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09-14-2019, 10:11 PM #1472
Just the opposite is true. While acknowledging limitations inherent in the proxies themselves, their finding that modern era climate change is unprecedented in the common era still stands:
"Neukom et al. weave all of this evidence into a detailed global portrait of surface temperatures that spans the past two millennia.
...
Even when we push our perspective back to the earliest days of the Roman Empire, we cannot discern any event that is remotely equivalent — either in degree or extent — to the warming over the past few decades. Today’s climate stands apart in its torrid global synchrony." -- Scott St. George, University of Minnesota
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09-14-2019, 10:23 PM #1473
In instance, the presumed absence of valid data destroys a theory (climate change).
In another, it supports it (Neukoms position).
This is dumb.Merde De Glace On the Freak When Ski
>>>200 cm Black Bamboo Sidewalled DPS Lotus 120 : Best Skis Ever <<<
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09-14-2019, 11:28 PM #1474
The whole last dozen pages of this thread are dumb
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09-15-2019, 09:43 AM #1475
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