I've come across a few climate articles reporting warm temperatures and high sea levels just several millennia ago. A long time to us, just a blink of the eye in the geologic timeframe. The most interesting reports come from the Swiss Alps, but reports from Greenland and Peru suggest that the glacial retreat was worldwide.
A common theme of these articles is to report how anomalous our current temperatures are compared to the past. (Warmest in 7,000 years! Disaster is near!) Surprisingly absent is speculation that there may be more botanical and archaeological remains to be found should glaciers retreat further. The report on glacial wood does point that out. It would be refreshing to read an article looking why it was so warm then. I haven't gone looking for any, I'm sure I'll find one soon enough.
This includes a ruined settlement left by the Independence I Culture in North Greenland abandoned at least 4,000 years ago.
Uniquely old tree remains have recently been uncovered by the thawing of the rapidly shrinking Kårsa Glacier west of Abisko in Lapland, in northernmost Sweden. The finds show that in the last 7,000 years it has probably never been so warm as during the last century.
"If the area hadn't been covered by a glacier all these thousands of years, these tree remnants would never have made it. The finds yield information indicating that the 20th century was probably the warmest century in 7,000 years. The fact that the climate is so unique during the last century means that we must question whether this could be 100 percent the result of natural mechanisms," says Leif Kullman, professor of physical geography, who is directing the project.
Pines and birches grew on the site of the glacier during parts of or perhaps the entire period between 11,800 and 7,000 years ago. This is shown by carbon 14 dating of the remains of trees that have now been uncovered. During that period, the glacier did not continuously exist, and the climate was warmer than at any time afterward.
The radiocarbon dates seem to be the same around the world, according to Koch. It's important to note that there have been many advances and retreats of these glaciers over the past 7000 years, but no retreats that have pushed them back so far upstream as to expose these trees."
The central figure in this article is Ulrich Joerin, lead author of a 2008 paper above. A similar article is Green Alps instead of perpetual ice about work by Juerin collaborator Christian Schluechter.
his recent observations that suggest that the entire [Peruvian Qori Kalis] glacier [in the Quelccaya ice cap] may likely be gone within the next five years, providing possibly the clearest evidence so far of global climate change.Ancient plant beds have been newly uncovered as the ice retreats. The first were discovered in 2002, more are uncovered each year, and carbon dating indicates that most have been buried for at least 5,000 years.
(See the 2008 Oct 12 entry above.)
In late 2012, photos show little change, so perhaps the current retreat is slowing down. At any rate, the glacier "may likely" be there for several more decades.
The lake's bacteria and other microbial inhabitants get by on carbon that seawater left behind thousands of years ago, researchers report in the April AGU Advances. The find adds to existing evidence that, during a period of warming about 6,000 years ago, the ice sheet in West Antarctica was smaller than it is today. That allowed seawater to deposit nutrients in what is now a lake bed buried under hundreds of meters of ice.This study is among the first to provide evidence from beneath the ice that the ice sheet was smaller in the not-so-distant past, geologically speaking, before growing back to its modern size, says Greg Balco, a geochemist at the Berkeley Geochronology Center in California.
"Most of the perishable artifacts were manufactured from wood, including birch bark containers, projectile shafts, and walking staffs," researchers said. Other artifacts were made "using animal remains include a stitched hide boot and carved antler and bone tools."
The research area is Mount Edziza Provincial Park. Claims that the paper is open source appear wrong, but try Ice Patches and Obsidian Quarries...
A 5900-year-old whitebark pine forest has been discovered due to the melting of alpine ice in the Rocky mountains. Scientists found more than 30 trees approximately 3100 metres [10,200 feet] above sea level - 180 metres [590 feet] higher than the present tree line - while carrying out an archaeological survey on the Beartooth plateau in Wyoming.
This "offers us a window into past conditions at high elevations", says Cathy Whitlock at Montana State University. Whitebark pine (Pinus albicaulis) don't grow at this elevation now, so these ones had to grow at a time when the climate was warmer, she says.
See the paper at PNAS: Dynamic treeline and cryosphere response to pronounced mid-Holocene climatic variability in the US Rocky Mountains. From the abstract:
Results suggest that mid-Holocene forest establishment and growth occurred under warm-season (May-Oct) mean temperatures of 6.2 °C (±0.2 °C), until a multicentury cooling anomaly suppressed temperatures below 5.8 °C, resulting in stand mortality by c. 5,440 y BP. Transient climate model simulations indicate that regional cooling was driven by changes in summer insolation and Northern Hemisphere volcanism. The initial cooling event was followed centuries later (c. 5,100 y BP) by sustained Icelandic volcanic eruptions that forced a centennial-scale 1.0 °C summer cooling anomaly and led to rapid ice-patch growth and preservation of the trees.
Semi off topic links:
I hadn't looked hard, but I hadn't come across an information source for North American glaciers. I found Glacier Mass Balance in a blog entry. The site concentrates on the North America's North Cascades, but has links to mass balance information from wider areas. The data thins out going before 1980, so most of it covers the warming phase of a PDO cycle and no data is included from before 1890 or so. However it is a good source of modern glacier information.
A very good reference site for Swiss glaciers is maintained by the Swiss Federal Institute of Technology - Zurich. Its data goes back to the late 1800s when glacial flow first began to be studied.
Contact Ric Werme or return to his home page.
Last updated 2025 January 17, originally written 2008 December 6.