Northern Hemisphere Lakes And Climate Change

For non-scientists like myself, trying to observe the effects of climate change can be daunting. Which dataset should we trust for temperature measurements? Should we jump on board the lower estimates of sensitivity provided by observation-based analyses or stick with the models that have not performed well at all over the past decades?

Should we follow the melting of glaciers, despite the low numbers that are analyzed? Should we put a lot of stock in GRACE satellite measurements of the great ice caps of the world? The hoops you have to jump through to really get a handle on ocean heat content are intimidating–is the very slight warming of very deep water really happening due to surface warming of the past 50 years?

One underlooked resource is measurements of the lakes of the Northern Hemisphere. They are contained and easier to watch and measure. They are in the part of the world where climate change is noticeable. There are a lot of data points to look at. For example, Lake Erie’s lowest maximum of ice cover since 1973 was in 1998, the famous El Nino year. But one of its highest maximums was in 2014.

Lake Erie max ice cover

Data for most Connecticut lakes is scattered, but summertime measurements at Candlewood Lake show a clear warming trend, with average surface temperatures increasing about 1.2 degrees Celsius, or near 2.2 degrees Fahrenheit, since the Candlewood Lake Authority began monitoring in 1985.”

Lakes in Canada are some of the fastest-warming in the world, a new study shows. A “study looked at 235 lakes on six continents representing half the world’s freshwater supply. Their surface temperatures between 1985 and 2009 had been measured both directly and using satellites. The lakes had different sizes, depths, locations and other characteristics, but despite their variability, “over 90 per cent of them had a clear signal of warming.” …”The study found that on average, lakes were warming at a rate of 0.34 C per decade — faster than either the ocean (increasing 0.12 C per decade) or the air (warming by 0.25 C per decade), the researchersreported in the journal Geophysical Research Letters and announced at the American Geophysical Union meeting San Francisco Wednesday.”

Of course, nothing is ever simple. “a couple of factors are having a particularly strong effect on lakes like Superior. One is that lakes that are normally ice-covered in winter are melting earlier in the spring, exposing the lake to warmer air temperatures for a longer period of time. Another, ironically, is that decreased pollution in North America is leading to less smog and cloud cover. “So more solar radiation is hitting the lakes and water temperatures are warming faster than you’d just expect simply [from] climate change.”

And then there’s this, from June 2014: “With summer just around the corner, the Great Lakes are officially free of ice for the first time in seven months. While only weeks ago, chunks of ice could be seen floating on the lakes as residents and visitors flocked to the waters for Memorial Day, as of June 6, the lakes were classified as ice-free.

“This year is the longest we’ve seen ice on Lake Superior in our 40 years of records,” Physical Scientist with the National Oceanic and Atmospheric Administration George Leshkevich said.” But… wasn’t 2014 a record hot year, the year that killed the pause?

Sigh… Ah, well, at least I’m trying to think outside the box:

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4 responses to “Northern Hemisphere Lakes And Climate Change

  1. Did you ever read about geothermal gradient measurements? I would love to run a well funded paleo temperature project using geothermal transient measurements. II think we may be able to get signals going back over 10 k years.

    • I know–how much of the change that we’re seeing now was initiated by something that happened back in the time of Charlemagne?

    • Fernando,

      Are you referring to borehole temperature profiles? There are already thousands of those. From what I’ve read, the time and temperature resolution are poor, especially if you try to go back more than a few centuries. And interpreting the data requires a lot of assumptions. So is there some reason you think it can be done much better?

      • Mike, I think the answer is improved borehole temperature profiles. I guess you know the instruments we run aren’t as refined as the latest technology allows.

        I’ve been thinking about this issue, and I conclude we have to fund phased research to identify the extreme boundary of what can be achieved. If my ideas pan out, we need to follow up to develop borehole drilling and coring techniques which allow getting down 1500 meters into granite while minimizing the temperature impact of the coring itself, as well as developing sensor strings which minimize the borehole signal distortion.

        What I have in mind may allow us to dig out very old signals, but to be honest I don’t see much written about the subject.

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