Summer drought: Comparison of years

Just like the comparison of "winter" this year and previous ones, it's interesting to look at the condition of this year's drought conditions. The front lawn area is where this year's drought is most evident. The brown lawn looks more like something one sees in California than what one would expect in southeastern Michigan.

From Thursday morning (July 25, 2012):


Compare it with July 23, 2011:


September 7, 2010 (couldn't find a photo from the end of July):


July 23, 2009:


And although the lake appears to continue to be nice and blue and stable, it actually has continued to drop quite precipitously (considering that it's a spring fed lake and all). To wit:

On Thursday afternoon (July 25, 2012), you can see the matted bottom starting to show through the algal mat:


whereas two months ago (May 25, 2012) it was a channel deep enough for it to be a usable fish passage:

Buckeyes growing in the forest

Living through this summer of far-hotter-than-normal days in Ann Arbor - home to the University of Michigan Wolverines - and working in environmental and natural resource management, I am thinking about the on-the-ground effects of climate change more than often. (Maybe more than is healthy.)

I hope for rain. I hope for cool winds. I hope for clouds even.

We get heavy sun that heats up asphalt, withers trees, and browns the grass. We get hot gusts of dry wind that buffet you into sweat-stained submission. We get few clouds, and those we get rarely carry rain for us.

It's the largest drought area ever declared, but some people are wondering if this is a forecast of things to come, or even the new normal. However, people from Mississippi River managers to Michigan cherry crop farmers to almost anyone paying attention in much of the country is recognizing that there is a massive drought happening and that weather has gone haywire (unless you happen to be Newton Leroy Gingrich).

And these are just the things that are happening right now. For University of Michigan fans, things could well get much worse.

According to research done in 2007 by Daniel McKenney and colleagues, the Ohio buckeye - which is the state tree of Ohio as well as the mascot to Ohio State University - will be shifting northward over the next 100 years. This means they will be shifting into Michigan, moving from its current distribution and possibly into Michigan (according to the CSIROmk35 A1B prediction model).

This will turn Michigan into the new "Buckeye State", and in Saginaw Forest, there are already many buckeye saplings that have been growing quite happily over the past number of years. Take a walk near the tree-tee-pee and see for yourself. (Here's the Ohio DNR's handy identification page.)

Will this growth get a lot of Michigan (and Michigan State) fans quite angry about the whole thing, and maybe start to think of climate change as something real? Yes, it's a strange way to introduce people to the effects of climate change, but many people have visceral attachments to sports, and for many people this includes university sports (even if they never attended that particular university).

What might make this an even greater blow for University of Michigan fans is that the last known wolverine living in the state died in 2011. With the local extirpation of the wolverine - the UofM mascot - and the encroachment of their largest rival's mascot onto home territory, could there be some sort of climate change education and action that come out of this? True, it was tried back in 2008, when the implications of McKenney's paper became recognized, but maybe the time is ripe again?

While part of this is written as tongue-in-cheek, another part of me is trying to think of ways to get people latched onto simple fact that climate change is not just happening right now, but has been happening for decades already; that the time to act is not tomorrow, but yesterday; and that the fact we haven't done a lot is only going to require us to work all the harder down the line.

Unexpected cool morning

The morning is unexpectedly cool. After reaching 100F in town yesterday, and having an expected low temp of only 75F, I wake up to quite comfortable temperatures. The windows are now open and I'm attempting to pull in as much cool air as possible.

Hopefully, the weather won't get too hot today.

Warming temperatures leading to additional lake complications?

This past winter, Third Sister Lake didn't get a complete freeze, and it was possible, as the spring approached, to see algae growing in some of the ice. In March, while we were experiencing temperatures normally part of June weather, I wrote about some of the possible impacts that such weather might bring if they become the norm. I also wrote about some of the possible impacts to Third Sister Lake that such warming might bring.

Well, add to all that one more impact brought on by warming: decreased lake turnover. In a new paper out in the journal Climate Change, Swiss scientists have shown how increased warming in Swiss lakes have decreased lake turnover, and this has brought about increased levels of Burgundy blood algae.

The paper's abstract states:

Anthropogenic-induced changes in nutrient ratios have increased the susceptibility of large temperate lakes to several effects of rising air temperatures and the resulting heating of water bodies¹. First, warming leads to stronger thermal stratification, thus impeding natural complete water turnover (holomixis), which compensates for oxygen deficits in the deep zones^{2, 3}. Second, increased water temperatures and nutrient concentrations can directly favour the growth of harmful algae^{4, 5, 6}. Thus, lake-restoration programmes have focused on reducing nutrients to limit toxic algal blooms⁷. Here we present evidence that the ubiquitous^{8, 9, 10} harmful cyanobacterium Planktothrix rubescens has become the dominant species in a large lake during the past four decades, although the phosphorus content of the ecosystem decreased fivefold. However, the nitrogen input was not diminished concomitantly, favouring this non-N₂-fixing cyanobacterium owing to increased N:P ratios¹⁰. P. rubescens contains gas vesicles that allow for buoyancy to accumulate within the depth of optimal irradiance¹¹. As the toxic cyanobacterium has low consumption by predators¹², water turnover represents the main mechanism of seasonal population control. Thus, unidirectional lake-restoration measures¹³ in parallel with recurrent absence of holomixis owing to lake warming may lead to similar undesired effects that have formerly emerged from fertilization.

This type of impact is problematic for Third Sister Lake, not because of Planktothrix (or because of other cyanobacteria, at least to my knowledge), but because Third Sister Lake is already a lake that doesn't completely turn over. From a 2001 paper by Bridgeman et al., the finding of lake stability (i.e., the resistance to turnover) in Third Sister Lake was that:

Salt-laden water entering Third Sister Lake [during the winter] from [the business lots to the southeast] could eventually lead to the formation of a chemocline. Large vertical gradients of salinity may potentially prolong stratification or altogether prevent mixing. ... If Third Sister Lake follows a similar pattern [to First and Second Sister Lakes], the contribution of a chloride gradient to stability would reach a maximum in March or April ... and the lake ... will remain [thermally stratified] until mid-November.

The paper also reported that - due to forest growth from 1904 - Third Sister Lake didn't fully turn over in the spring (i.e., following ice-out), even back in 1986. The authors of the 2001 paper concluded that:

Given that the lake is now more sheltered [than in earlier decades] and may require about 60% more wind energy to overcome a chlorine gradient, complete spring mixing, which was a common event at least into the 1940s and occurred occasionally until the early 1980s, is now probably rare.

And it's likely to remain rare if increased temperatures become the norm. (That is, unless a significant number of trees fall down, thus increasing the lake's wind exposure.)

Are vines growing faster?

Walking through Saginaw Forest this summer, I have noticed far more vine growth than I recall there being in previous years. Is this just my imagination? Confirmation bias? Or could it have something to do with the really warm winter that we had? (Too, could it have something to do with the differential rates of growth between vines and trees?)

What we know for sure is that the winter of 2011/2012 was a really warm one and March, May and June have been uncharacteristically warm, as well. There has also been less rainfall than usual.

Now, what I'm guessing at is that, since vines require less resources to maintain themselves and grow compared to trees, it seems possible to me that vines have been able to quickly take advantage of the warm spring and start their growth while also being able to continue growing during these more parched months. However, this is just a guess on my part.

What I know is that there are a lot of trees with vines growing on them; the vines themselves are very dense, and there's a lot of poison ivy, too. This radically warm winter, spring, and summer seem to correspond with the basic message of a 2006 paper by Mohan et al. Their abstract reads, in part:

Contact with poison ivy (Toxicodendron radicans) is one of the most widely reported ailments at poison centers in the United States, and this plant has been introduced throughout the world, where it occurs with other allergenic members of the cashew family (Anacardiaceae). ... Rising CO2 is potentially responsible for the increased vine abundance that is inhibiting forest regeneration and increasing tree mortality around the world. In this 6-year study at the Duke University Free-Air CO2 Enrichment experiment, we show that elevated atmospheric CO2 in an intact forest ecosystem increases photosynthesis, water use efficiency, growth, and population biomass of poison ivy. The CO2 growth stimulation exceeds that of most other woody species.
So, poison ivy is expected to be more abundant and a greater lover of the high CO2 future than trees. And this is likely also a cause for the increase vine abundance in general.

We heard news a few months back that the atmospheric concentration of CO2 has increased past 400ppm, which doesn't correspond to the elevated CO2 chambers of Motan et al's study, but as the Motan paper discusses previous studies on increased CO2 and vine growth:

With an increase in CO2 concentration and a corresponding increase in photosynthesis, vines can allocate more photosynthate to additional photosynthetic tissue, because of a low allocation to support tissue relative to other woody growth forms (13, 14, 18, 19). Increasing abundance of woody vines is causing increased tree mortality and reduced tree regeneration in forests around the globe (18, 20–23), potentially resulting in shifts in community composition that may impact carbon cycling and biodiversity (23). Although it is unclear how elevated CO2 will affect the growth of vines in forest environments, the contemporary increase in woody vine abundance may be the result of rising atmospheric CO2 concentrations (19, 23).

The Motan et al paper doesn't discuss the impacts of warmer winters, springs, and summers on poison ivy growth (nor on the growth of other vine species). However, I am going to guess that a large part of the vine growth this year is likely due to the ever increasing CO2 levels and have been exacerbated this year by the unnaturally warm seasons.

Morning temps cooled off

The morning temperatures have really cooled off these past two mornings. Yesterday it was enough to bring the inside-cabin temperature all the way back down to 70F and today I woke up to an inside temperature of 66F, and - walking outside - I was greeted with what had to be in the low 60s or high 50s.

Too, the rising sun was showing off the steam rising from the lake, and as I walked down to the dock, I startled a great blue heron that jumped out of its standing place and slowly sailed to the far side of Third Sister, squawk-honking all the way; no doubt annoyed at being disturbed.

Nice morning.

Cabin climate

As mentioned previously, the cabin does not have an A/C system, and these past days of record and near-record heat has meant a challenge in keeping the inside from being like a sauna. Thankfully, the cabin is almost entirely shaded and I don't use the stovetop very much nor use many heat-producing items (i.e., few appliances and no incandescent bulbs). This means that - combined with the thick stone walls - the cabin only slowly gains heat, even in this summer weather.

To wit, since yesterday morning (when I last had opened the windows), the inside-cabin temperature has gone up from 75F to 83F, slowly climbing through yesterday's 101F and today's 97F. Thanks to the dehumidifier and fans, the inside humidity stays below 65%. However, I've had to empty out at least 4 gallons of water from the dehumidifier over the past 36 hours!

Happily, I'll be able to cool off the cabin tonight, since the overnight low will doubtless be lower than 83F, and it's expected to be as low as 65F. Phew, I was getting to the point when I was starting to think about purchasing an A/C unit...

Cold showers also help.

UPDATE (2012-July-08): Thanks to the cool temperatures of last night, the inside cabin temperature has come down to 70F. Based on the forecast for tonight, I might even be able to get the temperature down to 60F; a good way to start a week that is expected to climb slowly back up to 100F by next weekend by some forecast.

Swelteringly hot in the forest... implications for a future Saginaw Forest?

Although the rains of the hard rains of the past two days have helped (a very little bit) with the longer-term lack of rain, the constant heat isn't helping with temperatures in the forest.

Today, when walking outside, I felt the steaming heat of the outside. Humidity seemed to be at or near 100% and the temperatures were pushing 90F at 11am; what happened to the low 70s from just three hours earlier?

Many scientists are saying that this summer is a glimpse of a world under conditions of global warming. If this is what a 2C rise in global temperature means in Ann Arbor, we'll have much to look forward to in Saginaw Forest, including:

* more deer flies and horse flies
* more vine growth (including poison ivy)
* fewer raspberries due to a comparative lack of water
* a smaller Third Sister Lake (which is already at its lowest level that I remember), which means little use of the dock that was put there and - due to the steep grade of the lake - less and less suitable nesting habitat for the fishes that are already in there
* a lowered water table due to a combination of increased evapotranspiration, diminished recharge, and diminished retention capacity
* more tree death, since the existing trees may suffer from heat stress and a lack of water due to a lowered water table
* a different tree mix - including many more Ohio and Indiana species - that is more suited to hotter summers

In other words, a future Saginaw Forest is likely to be far more sparse in tree cover, will have - in upland areas - younger trees that are better adapted to warmer and drier conditions, and will have a smaller lake with far fewer fish. The lawn in front of the cabin may well be dry throughout the summer months, and the raspberry canes will be producing smaller and more sour berries.