Western Lakes Warming Up Rapidly

Craig Miller

Lake Tahoe from above Emerald Bay. Photo: Craig Miller

Some lakes in Northern California and Nevada are warming twice as fast as the surrounding air temperature, raising concerns that climate change may be affecting aquatic ecosystems more rapidly than terrestrial ones, according to a recently published study.

Researchers from the Tahoe Environmental Research Center, UC Davis and NASA’s Jet Propulsion Laboratory in Pasadena, studied Lake Tahoe, Lake Almanor, Clear Lake, and Mono Lake in California, and Nevada’s Pyramid and Walker Lakes, by analyzing 18 years of temperature data from satellite sensors.

Long-established instrument buoys provided a flow of temperature data for Tahoe, dating back to 1968, which allowed the team to calibrate satellite readings, raising confidence in data gathered from the other lakes. Previous studies have documented the warming of Lake Tahoe but John Reuter, associate director of the Tahoe Environmental Research Center (TERC), says the new study takes that information one step further.

“This study really shows that this phenomenon is happening on a much larger scale than just Lake Tahoe,” said Reuter.

All of the lakes studied showed a strong warming trend among summer nighttime temperatures between 1992 and 2008.  The two lakes that warmed the most during that time, Almanor and Mono, warmed 4.3 degrees (F).  During that time Lake Tahoe’s surface waters warmed 3.7 degrees, averaging .23 degrees annually.  In contrast, Tahoe City’s air temperature increased just .1 degree each year.

TERC director Geoffrey Schladow, who co-authored the study, said there is no doubt in his mind that rising lake temperatures are related to climate change, and he expects that it’s happening across the world, not just in Northern California and Nevada.

“The significance of this study is that across the western United States these very different lakes are displaying signs of warming.  It’s not just a Tahoe issue, it’s a regional issue.  And in all likelihood, it’s a global issue,”said Schladow.

Over the next six months, researchers will be using the remote sensors to extend the study to 50 lakes across the world to evaluate whether or not large lakes everywhere are warming at similar rates.

Warmer temperatures can affect water circulation, which influences the amount of oxygen and nutrients available throughout the lake.  A 2008 study from TERC predicts that warming due to climate change could dramatically affect the amount of mixing in Lake Tahoe, which would deplete the bottom water of oxygen and drastically disrupt the food web.

“Temperature is one of the conditions that dictates who lives in the lakes,” said Schladow. “Warmer temperatures may make the lakes more hospitable to invasive species and put native species under stress.  I’m not saying this is happening yet, but it could.”

In his article about the study, Matt Weiser of the Sacramento Bee has some examples of how warmer temperatures can affect lake ecosystems. And KQED news editor Dan Brekke has assembled an interactive map (below), showing the locations and some temperature data for lakes in the study.


View California’s Warming Lakes in a larger map

  • http://ncvoices.us Anna Haynes

    Hey Gretchen, could we have a once-a-week “Ask Climate Watch” feature, where y’all’s blog post topic would would be commenter-driven?

    e.g. (speaking of driving) what are the ski resorts doing to educate visitors about climate change, and about meaningful vs feel-good ways for people to make a difference?
    (word of mouth says they’re stuck at the personal-action “drive a Prius” stage, when the important efforts are elsewhere)

    and fyi, a review article that Steve Bloom pointed out (in Stoat comments) –

    – for #16, A to my Q about Sierra skiing, linking to:

    http://tenaya.ucsd.edu/~dettinge/Lundquist_UUPress09.pdf

    Variability and Trends in Spring Runoff in the Western United States – Jessica D. Lundquist, Michael D. Dettinger, Iris T. Stewart, and Daniel R. Cayan

    (Content appearing in Wagner, F. (ed.), 2009, Climate warming in western North America—Evidence and environmental effects, University of Utah Press, 63-76.)

  • http://ncvoices.us Anna Haynes

    s/would would/would/
    s/.*Sierra skiing.*//
    (no Preview!)

  • http://ncwatch.typepad.com/ Russell Steele

    This last year I did some research on Lake Tahoe air temperatures, which was sparked by a UC Davis Tahoe: State of the Lake Report 2008. I recalled reading about lake surface temperatures in that report:
    “Surface water temperatures have been recorded at the mid-lake station since 1968. Despite year-to-year variability, water temperatures show an increasing trend. The average temperature in 1968 was 50.3 degrees F. For 2007, the average surface water temperature was 51.9 degrees F.: 
    According to this report in 39 years the surface temperature only went up 1.6 degrees F.

    Here is the graphic from the 2009 Report: http://ncwatch.typepad.com/media/2009/12/will-lake-tahoe-soon-reach-boiling-point-.html

    See if you can see the Lake Tahoe Warming in the graphic, based on actual measurements not satellite scanning. As you can see, except for 2006, the temperature has been going down since 2002.

  • Steve Bloom

    I thought I’d check into things and see exactly where Russ went wrong.

    It turns out that the graph he points to uses data from the “mid-lake station,” a single location near the center of the lake. Are its measurements a good proxy for the entire lake surface (what the satellites are measuring)? Maybe, maybe not, but that’s an issue that someone could inquire about. Until then, there’s no evidence for a discrepancy.

  • Craig Miller

    Guys, I’ll see if I can Geoff Schladow or one of the other authors to shed some light here.

  • Steve Bloom

    Thank you, Craig.

  • http://www.kqed.org/climatewatch Gretchen Weber

    Hi Anna,
    We actually have been talking about trying to do an “Ask Climate Watch”-type feature, but with limited staff, weekly might be a bit ambitious. We are always looking for ways to make our coverage more audience-inclusive.

    Did you have a specific idea for a post topic? We welcome ideas both here on the blog, and you can always email ideas to climatewatch@kqed.org.

    In terms of the ski industry idea, we are actually working on story related to that subject right now. While many resorts do seem be making very minor efforts towards addressing climate change, there are examples of some that have made larger efforts such as converting vehicles and equipment fleets to biodiesel, and others that are generating on-site renewable energy.

    Here’s a starting point for some ski industry information that you might find useful:
    http://www.skiareacitizens.com/

  • Steve Bloom

    I’ll repeat this story suggestion from an older thread since I’m not entirely sure it will be seen otherwise:

    Speaking of future temperature projections, Craig, I wanted to draw your attention to Robinson (2009), a recent paper with major implications for the Arctic and California. The focus of the paper is on Arctic warming, but note the other major feature of the SST reconstruction on page 7. With lags due to the time needed to warm up the oceans and melt a substantial part of the ice sheets, that reconstruction is our climate future given *current* CO2 levels, let alone the 500 ppm+ that more and more seems unavoidable. (Also see Lunt et al, a just-published companion paper, for discussion of the larger implications.)

    While we should not lose track of the main concern, which is the huge danger posed by melting the Arctic’s stock of frozen carbon too quickly for the climate system to buffer it, this seems like a good opportunity for you to do a California-centric story tieing in these results with the recent Montanez paper.

  • James Mayeau

    This sentence is the tell.
    “All of the lakes studied showed a strong warming trend among summer nighttime temperatures between 1992 and 2008.

    The main determining factor for lake temp is water volume, not the ambient air.
    All of the lakes in the study are highly regulated for ag, recreation and domestic drinking water, by dam.
    Tahoe drains into Pyramid Lake via the Truckee River.
    If this study were worth a hill of beans the scientists would list the lake water level by year, average summer flow of the river by year. When were the drought years if any? Did Reno go on water rationing? When and for how long a duration?
    For that matter they wouldn’t have restricted it to summer months.
    The fact is between 1992 and 1998 we had extraordinary wet seasons. Since 1999 when the PDO shifted we have had less snow in the Sierra.
    This is due to cool dry storms coming in off the Pacific, not global warming.

    The main thing I find from this study is a distressing rush to push their invalid conclusions forward to other less studied regions of the world.

  • Steve Bloom

    Now all you need is a scientist who agrees with any of that James. Good luck. Re your PDO fantasy in particular, see here.

  • http://ncvoices.us Anna Haynes

    > “all you need is a scientist who agrees with any of that”

    Heck, Steve, you forgot we’re all in a conspiracy and could never break ranks – did you miss that class?
    (D-K note: this is a joke)

    re Gretchen’s “there are examples of some [resorts] that have made larger efforts [towards addressing climate change] such as converting vehicles and equipment fleets to biodiesel”

    GRRRR. They’re illustrating my point. The #1 most important thing they can do is educate their still-clueless customers, a) about what C.C. will do to the sport, and b)about personal-carbon-footprint action *not* being enough – that the **MOST IMPORTANT** thing is to build political will, and to build public awareness that working on that trumps any “take the bus” stuff, since without govt action we’re hosed. “We’re all on the same ship and what we do in our individual cabins is of almost no consequence in terms of the direction the ship is going.”

    Do the resorts know this? Do they try to communicate that personal “going green” is a great first step, but not enough?

    The climate nihilists proselytize up a storm – it’s like an adjuvant, that Rush administers somehow, when vaccinating his listeners against sanity – but most of us don’t. That needs to change.

    and some info re skiing – Romm reposted this from CAP today –
    http://climateprogress.org/2010/01/06/skiing-global-warming-science/

  • James Mayeau

    I wouldn’t characterize Schladow any higher then activist.

    Here’s a report from Aug 2004,

    Water Authority to Tap Drought Reserves
    Reno is starting to run low on water and, for the first time in a decade, the Truckee Meadows Water Authority plans to dip into its drought reserves to keep taps flowing in the Reno-Sparks area.”

    “The authority’s general manager, Lori Williams, said nobody’s panicking, but after five dry years, the drought plan is needed. She added that there is plenty of water to serve the area even if the drought extends for several more years.”

    “The region has received below-normal amounts of precipitation since the winter of 1999-2000, with the Truckee River Basin getting 82 percent of normal this year, according to the National Weather Service.
    The outlook is for stream runoff in the Truckee River Basin to be 58 percent of normal and utility officials expect Lake Tahoe to dip below its natural rim in late September or early October at the latest, cutting off the primary flow into the Truckee River.”

    Who needs scientists to agree with me, when reality is doing the job so well?

  • Craig Miller

    James, I’m not seeing what your excerpt has to do with Schladow’s credibility as a scientist. Let’s try to avoid personal attacks here and stay focused on the arguments (that goes for everybody, btw). Thanks.

  • Steve Bloom

    Speaking of the Arctic’s stock of frozen carbon, things looked a bit more melty (and bubbly) this summer. There’s no quantification in the article, but the methane was not breaking through to the surface in prior years.

  • http://ncvoices.us Anna Haynes

    Yow, Steve, that is disturbing.

    “I would like to see a stake driven into the heart of this “you can make a difference” meme; or into the notion that we can do this through voluntary or community action.”

    “I’d like clear direction about the most active, high leverage political and social initiatives that deserve immediate focus. There is so much information, so many initiatives, so many causes…but surely the 80/20 rule applies, and we would be well served by focusing on the very few events where we get the greatest impact for our effort.”

  • Geoff Schladow

    Let me try to address the two main lines of comment – an “apparent” inconsistency with the UC Davis State of the Lake Report (terc.ucdavis.edu) and the impact of droughts and lake levels. There is no inconsistency, and lower water years have a negligible impact on surface temperatures of Lake Tahoe.

    Both reports (the UC Davis State of the Lake 2009 and the NASA report) used the same general Lake Tahoe database. However, they used slightly different parts of the database.

    First, the State of the Lake data (page 8.4) is the annual average surface water data. This is compiled of temperature measurements we have been taking approximately monthly at the same location on Lake Tahoe since 1968. The measurements are typically taken around the middle of the day.

    The NASA report uses something slightly different. Let me give you the background first. Since about 1998 NASA and UC Davis have operated 4 buoys on Lake Tahoe. These record the surface temperature (a few inches down actually) every 15 minutes. They do this 24 hours a day, 365 days a year. If you look at the graph on page 8.5 of the State of the Lake Report you will see what these data like. If you look at the graph on page 8.6 you will see what the July measured temperatures like when these 15 minute data are averaged for just one month. Note that there is about a 3 degree increase in the last 10 years (but that is a separate issue). The reason why NASA has been collected these data is that they need them to calibrate sensors that are on their satellites. By comparing what the satellites record the skin temperature to be (the long wave radiation that is emitted by the water surface) they can relate this to the bulk temperature of the water (what is being measured by the buoys). This was done for 10 years and we now have a very good relationship between the satellite measurements and the bulk water temperature.

    Now the interesting part. The satellite data goes back for longer than the buoy data (to 1992 in fact). But by applying this relationship we can use the satellite data to estimate what the temperature change was between 1992 and 2008. To try and simplify the data, the decision was made to calculate an average temperature for July, August and September. This period is often used to characterize summer conditions. The satellite generally passes over these lakes twice daily, around midday and midnight. Only the midnight data were used. During the day, the solar heating tends to warm up the very surface of the lake and it can give a lot more variability to the data. At night the cooling of the lake tends to make the surface layer more uniform. In theory for the 3 month period the average temperature would have been computed from about 90 satellite measurements, but because there were clouds on some nights the actual number is somewhat less, but still more than enough to compute a very robust average.

    So the numbers reported in the NASA report are really the mid-night average surface water temperature for July, August and September. The rate of change is greater than the annual average day-time temperature. That is because the winter time temperatures at Tahoe have remained fairly constant over time (looking at page 8.5 of the State of the Lake Report you will see that the bottom of the cycle shows very little trend, while the top does show an upward trend).

    As to the impact of lake level and drought, this is really irrelevant for the case of Lake Tahoe. With a 600 year average residence time, an average inflow year bring in less than 0.2% of the water in the lake (regardless of level). Furthermore the stream inflows generally plunge down below the water surface as they are colder and denser. Finally, the surface of the lake will equilibrate with the atmosphere heat balance very quickly.

  • James Mayeau

    There is no inconsistency, and lower water years have a negligible impact on surface temperatures of Lake Tahoe.

    Strange that in a teapot, bathtub, wading pool, stream, river, or pond, in fact in any other body of water, the shallower it is the faster it warms.
    But not in lake Tahoe you say?

    That’s some special lake. Some lakes are more equilibriated then others, you might say.
    But you just turned your regional issue back into a Tahoe issue.

  • Craig Miller

    Steve: Thanks for the reminder on the UCD study. I did see your prior comment and will look into it (it’s one of those “So many stories, so little staff” situations). We’re also interested in the black carbon/snow albedo studies being done in Yosemite.
    http://www.recordnet.com/apps/pbcs.dll/article?AID=/20091226/A_NEWS/912260310#STS=g3rj0zub.22jm
    Honestly there is way more going on out there than we could possibly cover and–apropos of Anna’s request–we’re looking at ways to involve our readers and listeners more in those decisions. Look for more on that in the weeks to come.

  • Steve Bloom

    Thanks, Craig. I was suggesting a single story on the two papers in the hope that it would be more efficient on your end. I’m curious about the evidence for the strikingly hot California shown in the Robinson paper, as it was news to me that it would be that bad, plus as far as I can tell the near-contemporaneous Lunt et al PRISM paper doesn’t show it. I’ll email Robinson to find out and will forward whatever I come up with to you.

    But speaking of our hot and dry future, today this paper popped up:

    “Contrary to conventional belief, as the climate warms and growing seasons lengthen subalpine forests are likely to soak up less carbon dioxide, according to a new University of Colorado at Boulder study.”

    And thanks to Geoff for those details.

  • Dixon Cruickshank

    I have to agree with James, being from Fla I have extensive first hand experience with water temps in lakes, bays and the Gulf. Rainfall, and especially runoff from rivers will have a huge impact, is the Truckee River below 50′ and that cold water then sinks, rivers flow over and around land usually are warmer, all our tropical fish run up river in the winter. As for depth a major effect as he stated, the shorelines will certainly always be warmer, so Russ’s using a bouy in the middle is probably a better indicater than scanning the whole lake.

    I know none of this fits with the lake is getting so much warmer but these lakes are also in geo-thermal areas, which may also have an afeect. I will also throw in for a lake with an average temp in the 50’s a couple degree’s sounds rather – so what.

    As to Anna – I agree on the ski resorts, those people are there to have fun and escape, can’t have that – they should have to go through a political indoctrination class before getting that lift ticket LOL
    I thought I heard they all opened early this year but maybe not, its a dying sport I guess.

  • James Mayeau

    Dixon here is the Tahoe SOTL report 2009.

    The portion I want to draw your attention to is ch. 7, meteorology.

    On ch 7.5 annual precipitation, we find that from 94-99 the average precip for Lake Tahoe was ~ 39.5 inches. From 00-08 the ave is ~ 28 inches.
    In 2004 the Tahoe stopped feeding the Truckee river sometime during the summer.
    I can’t tell from their report if this is a regular event, but since it is pivotal to their contention that there is a global warming going on, I can say that the omission of this information is the dividing line between scientist and activist.

    Other then that the ch 7 shows air temp squigglies from the Tahoe City HCN station, claiming that T-minus has increased 4 degrees since 1909, while T-max has increased a little less then 2 degrees (perfect signature of the UHI effect btw).
    No word on when the hotel was built. Ditto the tennis court. But from ch 7.2, number of freeze days, you can take a good guess.
    There’s a break point around 1960, when the hotel was built, and another around 1980.
    I’m guessing that’s when the tennis court was installed.

  • James Mayeau

    Re: Craig Miller on January 6th, 2010 6:19 pm

    I wasn’t basing my assessment on that Reno news report, but rather on the AGU abstract in the body of your (KQED) report.

    Here’s the first sentence:
    Large lake temperatures are excellent indicators of climate change; however, their usefulness is limited by the paucity of in situ measurements and lack of long-term data records.

    Any reading of it shows it begging the question; not looking for the truth, but rather looking to prove their version of the truth, without any caviates or room for analysis of what might make their assertions false.

    That’s why I say activist rather then scientist.
    But I didn’t get all the information, just the abstract.
    Perhaps the body of the report give mitigating details.

  • http://warming101.com Anna Haynes

    Gretchen, re ski resorts –
    > Here’s a starting point for some ski industry information that you might find useful:
    http://www.skiareacitizens.com/

    it illustrates my point. They grade ski resorts on “addressing global climate change”, and what are the criteria?
    (see here: http://www.skiareacitizens.com/index.php?nav=how_we_grade#criteria8 )

    Answer: carbon-footprint actions by the ski resort, and encouragement by the resort to visitors, to take carbon-footprint actions.

    Do you agree that – by educating the customer that personal-footprint-reduction is the way to address climate change – this is insane?

  • Gretchen Weber

    Hi Anna,
    I’m not exactly sure what you’re asking.

    It looks like they grade resorts on how well they: conserve energy by avoiding snow-making, use energy efficiently, use renewable energy, and offer transportation alternatives.

    There is also a section on advocacy under Section D, if you are interested in how they are graded in those areas.

    I’m not endorsing this scorecard, I’m simply offering it as a starting point for some information about specific ski resorts and what they are doing in these areas.

  • http://ncvoices.us Anna Haynes

    Zero points for educating their customers a) that climate change is real, and will likely kill the sport in the Sierras; b) about what action is most needed to control it.

    In other words, the resorts get points for doing the most ineffectual things, but none for doing the most important ones.

    This is CYA environmentalism only.

  • James Mayeau

    I give the ski industry high marks for not foolishly badgering their customers with quasi-religious liberal dogmas.

    At least a B+.

    They could have done better by ignoring the “ineffectual things” as well.