Scientists: Less ice on Great Lakes during winter
CLEVELAND — Ice cover on the Great Lakes has declined more than 30 percent since the 1970s, leaving the world's largest system of freshwater lakes open to evaporation and lower water levels, according to scientists associated with the National Oceanic and Atmospheric Administration.
They're concerned about how the milder winter freeze may affect the environment. But they're also trying to come to terms with a contradiction — the same climate factors that might keep lake ice from freezing might make freezing more likely if lake levels drop due to evaporation.
Scientists at the Great Lakes Environmental Research Laboratory in Ann Arbor, Mich., say global climate change can be at odds with regional climate patterns. Accurately measuring ice cover across a lake system that spans 94,000 square miles in two countries is no small task, they say.
Their studies show that although the amount of ice cover can vary substantially from year to year, the overall coverage on the world's largest system of freshwater lakes is diminishing, especially in the deepest, middle portions of Erie, Huron, Michigan, Ontario and Superior.
"The deeper the water, the greater the heat storage from summer, and it freezes later than the shallow areas," research Ray Assel told The Plain Dealer. "Now, increase the air temperature and the lake takes in more heat and stores it longer, to the point that many of the midlake areas are freezing over less."
Assel's records indicate that ice formation at nearshore areas has decreased less than on the deepest parts.
Evaporation from open water can cause heavy lake-effect snow inland.
Researcher Jia Wang said ice loss can cause other problems, including the destruction of the eggs of fall-spawning fish by winter waves from an open lake, erosion of coastal areas unprotected by shore ice and less winter recreation on the lakes such as snowmobiling or ice fishing.
The Coast Guard has estimated it cost more than $245,000 to rescue 134 fishermen from a huge ice floe off Ohio last month. The fishermen became stranded Feb. 7 when a miles-wide chunk of ice broke away in Lake Erie.
There might be one short-term advantage to decreased ice: Shipping may someday be more possible in the winter months. The locks at Sault Ste. Marie now close each year in mid-January and reopen in late March. But shipping companies might haul less cargo to pass through low-water areas.
Mar 30, 2009 at 1:04 p.m.
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The fact that there has been some slight global warming is not (generally) in dispute. The idea that this warming is primarily the result of human burning of fossil fuels, as opposed to radiation levels from the sun or other natural phenomenon, is what is disputed. Just a point of clarification.
Mar 27, 2009 at 12:31 a.m.
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“i never claimed it was mine ?? it's directly from the EPA website and any 2nd grader could have figure that out.”---You did post it with no quotes and no reference, so then are all your posts cut and paste from someplace else also?
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“didn't they teach you anything in the air force or could you just not get into college ??”--- Correct they taught me nothing and I never even finished pre-school.
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“you NEVER explain why you think global warming is not real. i answered your drought question,”--- I never stated the world temperature was rising or falling. My specific comments were directed to your obtuse answer; “when it gets warmer more water evaporates and as a result more water comes down in the form of snow or rain. we had record breaking snow last year and lots of flooding.”. And then pointed out your conclusion is drawn from this region of the world alone. As we know California has been in drought conditions for the past three years so your previous answer is proven false. As is your quote (not referenced or quoted) from the EPA site. If you took the time to read the last line of the paragraph (you did not post that sentence); it refers to NASA’s information that predicts the most of the California region under global warming should be experiencing +5% increase in precipitation in the summer months, the south and southwestern parts should experience a -10% to -20% drop in precipitation during the winter months, and the northern area should be +5% or more all the time…Yet none of this is true.
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“but you just call names and state no facts”---Wrong on both counts. Never once called you a “name” and did provide you with facts.
Mar 25, 2009 at 8 p.m.
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To clarify (don't know if this was taught in 2nd grade). There are 4 seasons in a year; 3 years makes 12 seasons. 1-2 seasons is seasonal, 12 seasons is not.
Mar 25, 2009 at 7:57 p.m.
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So it is more than 2nd grade math? Nice to see you try to justify your remark by cut&paste from a website and pretending the answer was yours. Funny how your cut and past answer of seasonal droughts does not answer why 3 years of drought in California when we have had the opposite.
Mar 25, 2009 at 1:24 p.m.
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to not think there is not some level of global warming going on is just dopey.
Mar 25, 2009 at 1:13 p.m.
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Here's some more 2nd grade math: when the sun gets hotter, global temperatures rise. The sun has been warming up for the last few hundred years, as a result of which the little ice age started coming to an end. People take minor trends (such as lake water) which are more likely the result of sun temperatures returning to their previous highs in the middle ages, and think it means a global warming catastrophe.
Mar 25, 2009 at 1:18 a.m.
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Guess your second grade math equation did not take into account the extended drought (going on three years) in California. So as you were saying "as it gets warmer water evaporates...record breaking snow and lots of flooding". For this to be true (your 2nd grade therory on global warming) we in the upper midwest are under global warming and those on the west coast are not? I guess if California is not getting enough rain and snow it must be global cooling out there; more 2nd grade math.
Mar 24, 2009 at 12:05 p.m.
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Oh wait, I get it: warmer temperatures cause more heat storage from summer leading to less freezing; more evaporation means shallower water level and therefore not as much heat is stored from summer leading to more freezing. Got it.
Coincidentally, I wonder why they compare to 1970? Could it be that prior to 1970 the global temperatures were on the decline? Although this article is not as direct as others, it still has hints of global warming hysteria, and is somewhat (intentionally?) misleading.
Mar 24, 2009 at 11:59 a.m.
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"But they're also trying to come to terms with a contradiction — the same climate factors that might keep lake ice from freezing might make freezing more likely if lake levels drop due to evaporation."
I'm not sure I understand the contradiction.
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