Natural period for recession of glaciers

[Toronado3800]

Its been about 12,000 years since the end of the last ice age. During that ice age ice extended all the way down to Wisconsin. Now obviously its limited to further north regions. (Odd the southern hemisphere seems less affected. Moderating effects of their higher percentage of ocean?)

So apparently ice has been retreating for at least 12,000 years. We can argue the finer points of how far and from where to where but between 1,000 and 2,000 miles seems certain. I'll use 1,500 miles for my math. That's maybe .125 mile per year on average. To mess up the ease of using math to determine what's "normal" ice should probably retreat slower from areas near the poles and quicker from Wisconsin.

None the less (and even if anti-man made global warming folks don't point out that ice has been retreating for some time), I think it may be natural for ice to be retreating.

Does anyone have evidence of something like "where the ice has historically stopped retreating between ice ages"

Last Ice Age

Current

PS, don't think this means we need to be lazy and just keep dumping CO2 in the atmosphere. My opinion on that is we don't need to be liberal with our stewardship of the earth and find the environmental tipping point of no return.

 

[Old Rocks]

By the controlling factor of the Ice Ages, the Milankovic Cycles, we should be starting the slow descent into another ice age. In other words, our glaciers should be growing right now. As they were in the little ice age.

But we are not growing our glaciers, they are in rapid retreat. In fact, the curve for the decline in the North Polar Ice looks far more like a catastrophe curve than the line predicted by the "alarmists" of the IPCC.

Here is where you can read about the latest studies on this matter;

The Copenhagen Diagnosis

 

[Toronado3800]

Interesting and thanks for the link.

Still though, how little ice at the poles have we ever had before between cycles?

 

[Toronado3800]

I still haven't found this. Darn it. I like having a point of comparison. Something like "well for a 200,000 mile car them ball joints are pretty darn tight" or "for xxx years after the end of an ice age the ice caps usually do retreat up to this point"

 

[waltky]

Glaciers act as protective caps...

Alpine glaciers 'protect mountain peaks from erosion'
2 August 2013 > Instead of wearing mountains down, evidence from Europe's high Alps shows that glaciers shield summits from erosion, acting as a protective lid.

French scientists studied erosion on Mont Blanc, western Europe's highest peak, below and around its glaciers. Cold ice at the highest points froze to the mountain rock and played little part in erosion, the team said. In contrast, water and rain eroded glacier-free areas 10 times faster than areas protected by the glacier. The research was part of Cécile Godon's doctoral research at Université de Savoie, located on the edge of the French Alps, and appeared in the journal Earth and Planetary Sciences Letters. The study focused on the Bossons glacier, which flows down the northern face of Mont Blanc towards the French town of Chamonix. Rock debris, carved from the mountain at the toe of the Bossons glacier and sediments washed out in high mountain streams were compared with erosion in nearby glacier-free areas. The researchers found that the cold glacial ice protected the mountain from erosion, rather than promoting it.

Rising ice

These results may explain the high altitude of the Alps. Driven by the tectonic collision of Europe with Africa, the high alpine bedrock is rising about one millimetre each year. Glacier-free areas of the Alps erode at a similar rate but where the mountains are protected by ice, the peaks wear away at one tenth that rate.

Mont Blanc's Bossons glacier protects the peak from rain

Fritz Schlunegger, from Bern University, Switzerland, was not involved in the work and commented: "This group has used sediments at the end of Bossons glacier to determine where erosion is happening beneath the ice. "Most material has been derived from the non-frozen part the glacier, while higher up towards (the summit of) Mont Blanc - where the glacier is frozen to the ground - erosion is much less," he told BBC News. "This is really the first time, according to my knowledge, where this has been convincingly shown in a quantitative way and using a natural example. "However, mountains don't grow to infinity, so there must be another mechanism which has lowered the summit of Europe. According to (Dr) Godon's findings, this erosion is not related to glaciers, so we still have to think about other possibilities."

Around the globe, mountain glaciers - especially those at low latitudes - are retreating in response to climate change, scientists say. Reports earlier this year indicated that glaciers around Mount Everest had lost more than one eight of their area in the past 50 years, and the snowline had retreated 180 metres up the mountain sides. Dr Godon's results suggest that changes like these could change the shapes of the world's highest mountains, and that climate and mountain landscape are intimately linked.

BBC News - Alpine glaciers 'protect mountain peaks from erosion'

 

[waltky]

How Glaciers Around the World are Melting...

Then and Now: How Glaciers Around the World are Melting
April 04, 2017 - Over the past decade, scientists and photographers keep returning to the world's glaciers, watching them shrink with each visit. Now they want others to see how a warming planet is melting masses of ice in a series of before-and-after photos.

In the Geological Society of America's GSA Today journal , a group of ice researchers and a photographer-filmmaker published pictures showing how much five of the world's glaciers have thinned. "There is something fundamentally compelling about the approach they take. For all our emphasis on models and math, seeing is still believing," said University of Colorado ice scientist Ted Scambos, who wasn't part of the team.

Under natural conditions, glaciers at times melt and retreat while others grow and advance. But measurements from Earth's 5,200 glaciers show warming temperatures have increased the number of melting glaciers and the speed of glacial retreat, according to the study. Scientists primarily blame man-made global warming from the burning of coal, oil and natural gas. "There is something that touches the heart more profoundly when you see it in pictures than when you see it in maps or reports or graphs," said photographer James Balog, who founded the nonprofit Earth Vision Institute . "It certainly brings it alive."

Frozen areas of the planet, like the Mendenhall Glacier in Alaska, are warming at twice the global average.​

Iceland

The Solheimajokull glacier has shriveled by about 2,050 feet (625 meters) between 2007 and 2015.

Alaska

The forward edge of the Mendenhall glacier outside of Juneau has receded about 1,800 feet (550 meters) between 2007 and 2015.

Switzerland

The Stein glacier has shrunk about 1,800 feet (550 meters) between 2006 and 2015. The Trift glacier has retreated nearly three quarters of a mile (1.17 kilometers) between 2006 and 2015.

Peru

Ohio State ice scientist Lonnie Thompson has visited the Qori Kalis glacier since 1974. Between 1978 and 2016, it has shriveled 3,740 feet (1.14 kilometers). Thompson described his regular expeditions to the Peruvian glacier "like visiting a terminally ill family member."

Then and Now: How Glaciers Around the World are Melting