If Global Warming is Happening, Will Frost Lines become Less Deep?

Question

Is there any research showing that frost lines (the depth at which the ground freezes in a given area, typically each zone has its own depth) decrease as the world temprature increases? Is this another way to prove/dis-prove the theory that global warming is happening at an alarming pace?

I dont mean almost permently frozen land such as the antarctic. I was referrring to the frost line in parts of the world that freeze during winter, then thaw during the summer. Construction standards for footer depths use the frost line as a standard depth to dig footers for building. Are these frost lines less deep now than they were 100 years ago? Can this measurement be another way to prove the earth is warming?

Answer 1

Permafrost occurs when there is a mean annual soil temperature of 0°C (32°F) or lower. According to a report on Alaska rangelands by the University of Alaska Fairbanks:
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"Over the past 50 years the average temperature in Alaska has risen about 2°C. The impermeable permafrost layers that underlay much of the shrub/grasslands may melt as much as 9 m (30 ft.) over the 21st century (Parson 2001). In several places this means standing surface water will infiltrate leaving the upper soils much dryer than in the past (Smith and Smith 2001)."
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Melting permafrost is causing some problems with structures in Alaska that depend on the stability it provides for support on land that would otherwise be swamp-like. As permafrost melts, the early results are not so much a loss of thickness or areal extent, but a softening of the ice itself as it becomes slushy.

Some of this may be in part due to normal cycles like the Arctic Oscillation, so drawing absolute conclusions about the causes and future course of this pattern would be premature.

In the Midwestern USA, well, spring, and cave temperatures have risen slightly, something like 1° or 2° F if I recall the conversation with a hydrologist in Missouri correctly. This could be from a variety of reasons; global warming, removal of vegetation, increased use of ground source heat, increased removal of groundwater, and many other factors could be involved.

Friends in the construction industry who regularly excavate year round indicate frost in the Midwest does not penetrate as deeply as a few decades ago, rarely reaching depths of over 12" when twice that used to be common in my area. These are of course anecdotal reports and not to be confused with scientific study.

For building codes, footer depths and water line burial codes need to provide for the maximum seasonal frost depth. Climate change would affect permafrost much more directly as the driving force behind it is average yearly temperature, while seasonal frost depths are affected by much shorter periods, more on the order of average temperature over a few days, so maximum frost depths in temperate zones would be a poor indicator for global climate change. No hypothesis involving global warming that I have heard of precludes seasonal cold snaps, the focus is on the yearly average temperature .

But all in all, average maximum frost depth might be directly affected by the warming climate. The root cause of that warming and what it means for the future is a matter for debate, but until more research is completed on the subject it's an irresolvable debate. However, not supporting funding for such research is akin to closing your eyes while driving towards an intersection because you're sure the light will be green when you get there.

Answer 2

Permafrost in the Arctic extends hundreds of feet into the soil. Summer melting only occurs in the top several feet. So, it is unlikely that this would be a viable way to measure the effect of any temperature change.

One thing that people tend to overlook is that the average temperature in the Arctic is well below freezing. Winter temperatures can go as low as -100F. The average global temperature has increase a couple of degrees since the end of the Little Ice Age in the mid-1800s. It may have gone up a bit more in the Arctic. Frozen is frozen and it won't likely matter much if the coldest temperatures rise to -95F. There is a lot of room to maneuver between the average Arctic temperature and melting.

Additional:

No one disputes that the earth has warmed up a couple of degrees in the past 150 years. There are too many other variables that would make your frost line indication theory meaningless. Think wind, ground cover, sunlight, humidity, evaporation, etc.

Answer 3

Well it will not prove that the earth is warming .Here in Texas we had a cold day that broke a record that had been in place for 100 years. All over in the north east was very cold . This data if we were heating up at such an alarming rate I don't see it. We would not be setting new lows that the last record was 100 years ago.

Answer 4

here is a link for an article about reserch that some professors have done at Texas A&M pertaining to your question. It has some search words that you can google for more info

(yes, I wrote the article during college for some extra $$$)