Climate Change and the Northern Appalachian Forests

[Fiddleback]

Climate Change Complexities in the Northern Hardwood Forests
"... until now, there has been no exhaustive study conducted to see how the climate change will affect the biosphere of the northern hardwoods." http://www.enn.com/wildlife/article/45248

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FB

[prain4u]

The "study" in the this article examines just 50 years of climate data. That is not a long enough period of time when we are looking at potential "climate change"

I talk to lots of OLDER people--in their 80s and 90s. They remember having weather (like we are having in recent years) back when they were younger. A quick look at some climate data going back to 1925 for the Adirondacks confirms that weather was warmer in the Adirondacks in the early 1930s and also in the late 1940's and early 1950s. (Both of those periods are outside the 50 year period covered in the study in the article). Much of the current weather conditions have nothing to do with "climate change". It is just the typical CYCLICAL change in weather.

The article mentions a decline in maple syrup production. The Spring of 2012 was a horrid year for maple syrup production in most of New England. Yet, 2011 was a near record year for production. That 2011 data pretty much shoots down the theory that maple syrup production is declining. (We need to remember that market forces also impact how much syrup is produced),

[Pedaling Fool]

It's not just the Northern Appalachian Forests. http://news.yahoo.com/upon-further-review-giant-sequoia-tops-neighbor-185737665.html



Upon further review, giant sequoia tops a neighbor



FRESNO, Calif. (AP) —

"Deep in the Sierra Nevada, the famous General Grant giant sequoia tree is suffering its loss of stature in silence. What once was the world's No. 2 biggest tree has been supplanted thanks to the most comprehensive measurements taken of the largest living things on Earth.

The new No. 2 is The President, a 54,000-cubic-foot gargantuan not far from the Grant in Sequoia National Park. After 3,240 years, the giant sequoia still is growing wider at a consistent rate, which may be what most surprised the scientists examining how the sequoias and coastal redwoods will be affected by climate change and whether these trees have a role to play in combatting it.

"I consider it to be the greatest tree in all of the mountains of the world," said Stephen Sillett, a redwood researcher whose team from Humboldt State University is seeking to mathematically assess the potential of California's iconic trees to absorb planet-warming carbon dioxide.

The researchers are a part of the 10-year Redwoods and Climate Change Initiative funded by the Save the Redwoods League in San Francisco. The measurements of The President, reported in the current National Geographic, dispelled the previous notion that the big trees grow more slowly in old age.

It means, the experts say, the amount of carbon dioxide they absorb during photosynthesis continues to increase over their lifetimes.

In addition to painstaking measurements of every branch and twig, the team took 15 half-centimeter-wide core samples of The President to determine its growth rate, which they learned was stunted in the abnormally cold year of 1580 when temperatures in the Sierra hovered near freezing even in the summer and the trees remained dormant.

But that was an anomaly, Sillett said. The President adds about one cubic meter of wood a year during its short six-month growing season, making it one of the fastest-growing trees in the world. Its 2 billion leaves are thought to be the most of any tree on the planet, which would also make it one of the most efficient at transforming carbon dioxide into nourishing sugars during photosynthesis.

"We're not going to save the world with any one strategy, but part of the value of these great trees is this contribution and we're trying to get a handle on the math behind that," Sillett said.

After the equivalent of 32 working days dangling from ropes in The President, Sillett's team is closer to having a mathematical equation to determine its carbon conversion potential, as it has done with some less famous coastal redwoods. The team has analyzed a representative sample that can be used to model the capacity of the state's signature trees.

More immediately, however, the new measurements could lead to a changing of the guard in the land of giant sequoias. The park would have to update signs and brochures — and someone is going to have to correct the Wikipedia entry for "List of largest giant sequoias," which still has The President at No. 3.

Now at 93 feet in circumference and with 45,000 cubic feet of trunk volume and another 9,000 cubic feet in its branches, the tree named for President Warren G. Harding is about 15 percent larger than Grant, also known as America's Christmas Tree. Sliced into one-foot by one-foot cubes, The President would cover a football field.

Giant sequoias grow so big and for so long because their wood is resistant to the pests and disease that dwarf the lifespan of other trees, and their thick bark makes them impervious to fast-moving fire.

It's that resiliency that makes sequoias and their taller coastal redwood cousin worthy of intensive protections — and even candidates for cultivation to pull carbon from an increasingly warming atmosphere, Sillett said. Unlike white firs, which easily die and decay to send decomposing carbon back into the air, rot-resistant redwoods stay solid for hundreds of years after they fall.

Though sequoias are native to California, early settlers traveled with seedlings back to the British Isles and New Zealand, where a 15-foot diameter sequoia that is the world's biggest planted tree took root in 1850. Part of Sillett's studies involves modeling the potential growth rate of cultivated sequoia forests to determine over time how much carbon sequestering might increase.

All of that led him to a spot 7,000 feet high in the Sierra and to The President, which he calls "the ultimate example of a giant sequoia." Compared to the other giants whose silhouettes are bedraggled by lightning strikes, The President's crown is large with burly branches that are themselves as large as tree trunks.

The world's biggest tree is still the nearby General Sherman with about 2,000 cubic feet more volume than the President, but to Sillett it's not a contest.

"They're all superlative in their own way," Sillett said."

[joshuasdad]

This post was deleted by the author, because it is now out of context, as several posts have been deleted from this thread.

[Alligator]

This thread is about a research paper that discusses possibilities of changes to Northern Hardwood forests in a changing climate. If you would like to discuss, it will require that you actually read the research paper, not just the article about the paper. So the thread is going to have a narrowed focus. Rants and raves will be removed, and continued off topic posting can result in lack of access to the thread.

I will see about getting the actual article or if someone has the off post it.

[Creek Dancer]

Why they heavy moderation? This is not a straight forward thread. I enjoy reading the viewpoints, even if they are not exactly as you dictate.

[joshuasdad]

I would like to see the paper, as it looks to be consider atypical factors such as land use. I hike the AT to escape from the politics of environmental issues--in fact I was given express permission to hike the AT to do so. So when I see two spins on studies posted in a short time--without links to the actual studies--this is an unwanted jolt to reality.

I was actually more responding to the second paper, as the hidden message is that one needs to go to extraordinary measures to remove CO2 from the air. Again, all of the attention to CO2 distracts from the other issues that affect our hikes, like the acid rain that kills our forests, the toxins that pollute the water we drink, the ozone that causes that blue haze, etc.

[joshuasdad]

Why they heavy moderation? This is not a straight forward thread. I enjoy reading the viewpoints, even if they are not exactly as you dictate.

I am more than a little concerned about the heavy moderation as well. I think about 6-8 posts were deleted. True, one of them was a pithy (but somewhat enjoyable) "overgeneralism" by LW, but I did not see anything inappropriate for a General posting.

[Alligator]

Problem is, climate change/global warming threads here on WB have degenerated into stupidity on multiple occasions. Some members get a kick out of this but from a moderation standpoint it's a PITA so these threads generally get closed. Part of the problem is the intertwining of politics. From a scientific standpoint, changes in this forest would affect the AT. Therefore, the topic is being left open and posts will be expected to be on topic and to adhere to the user agreement.

Also threads do not have be in Straight Forward to be held on topic,
Do not post inflammatory messages, spam, “off topic” posts, or hijack topics.

[fcoulter]

It's difficult to talk about the original paper when the title of the original paper isn't mentioned in the article. Also, there's no guarantee that the paper is available outside the academic community. (I lost access to the academic paper databases when I finished my second Masters. I'm not planning on starting a Ph.D. for at least a year. That leave me out of the loop.)

However, my concern about these studies is that, in general, there's an assumption that recent (50-100 years) history is the norm. While I don't agree with prain4u about the strong cyclic view of climate, there is plenty of evidence that the climate for the last 100 years does not represent "normal" climates. In the last 2,000 years there have been two periods with significantly hotter temperatures than current times (specifically during Rome [0 AD] and medieval [1000 AD]). It's also been significantly colder than current time [Little Ice Age 1350 AD].

If you look out much farther -- and, yes, the farther you look the more questionable the data becomes -- the farther back you go, the more the temperature record varies. It has been argued that the rise of civilization was due to a decrease in climactic variability during the last 10,000 years. But the last 10,000 years is a blip in the 4.5 billion year life of the Earth. There is no guarantee that our current relatively stable climate will remain stable into the future. And even during the relatively stable recent times, there are multiple stories of civilizations which vanished due to climactic changes.

So, back to the article.

Climates have changed in the past and ecosystems have adapted. Climates will change in the future, and I see no reason why ecosystems won't adapt. Isn't that fundamentally the definition of evolution? Adaption to changing circumstances?

If temperatures rise a little more, maybe Baxter State Park will remain open longer. Maybe more people will hike into Canada.

I don't see the start at Springer Mountain becoming too hot too hike, although the hiking season may start sooner. That's good news for us old fogies, who have been told that it's much harder for us to through hike the entire trail in a year once you've reached 65.

As for Florida where I normally hike: I use hiking as a way to acclimate myself to the summer. If I hide in the airconditioning at the beginning of summer, I really FEEL the heat. But the summers I've been in the woods -- with LOTS of water -- I am far more comfortable in general. A one degree difference (which is all the IPCC predicts for the rest of my life) won't do anything to my hikes.

[JAK]

Read the article in the OP, but not whatever it is referencing. Some sketchy bits, like about deer and moose, which could be confused with what happened to woodland caribou. Nonetheless I do agree with the general assertion that climate change models are limited in their complexity, as are all models, but they are still useful.

I would like to see a study on how much soil loss has occurred over past 200 years. Even without climate change, it does not appear that we are even yet managing our forests sustainably. We just keep changing the goal posts of what we consider to be normal, and that is not sustainability.

[Prime Time]

Climate change is a serious problem, and to the extent that humans are contributing to it should be a concern to us all. Proponents of taking action to slow, stop, or reverse these effects, however, do their cause a disservice by jumping on every severe storm or unusually mild winter or hot summer as further evidence of the reality of man made climate change. Here in Northern NH the winter of 2011 was one of the snowiest and coldest in several decades. The following winter, 2012 was one of the mildest, driest on record. The mild winter was declared "proof positive" that the planet was getting warmer because of man. One year made that much of a difference? Really? It shifts the argument away from asking what we can do to reduce emissions, pollution, and generally destroying our planet over to is or isn't climate change caused by man? We're guilty of rearranging the deck chairs on the Titanic as it sinks. Crazy.

[prain4u]

I like what fcoulter wrote, above. I think the comments are pretty much on target.

Some of us in my small town were talking about this stuff just the other day. Climate changes have come--and gone for billions of years. Animal species have become extinct and new ones have come into existence. Water levels have risen and fallen. Coastlines have changed. The planet has survived.

A century or two ago, people heated their houses with coal fires and wood fires. Coal fires powered many factories. Some of the paintings and photos of the smoke / smog of that era are almost unbelievable It is hard to imagine that the emissions from the dirty coal and wood fires of a century or two ago did not impact the climate of that era as much (or more) than the emissions of today. Even if humanity suddenly became extinct today---and there was no more man-made global warming--good old Mother Earth would continue to experiences climate shift--just as it has for billions of years.

Yes, humans play a role in this--and we need to do whatever we can do (within reason) to limit our impact upon the environment and climate. However, at the end of the day, the climate will continue to change no mater what we humans do.

(Climate) Shift happens!

[JAK]

It's going to be a very interesting century.

[Alligator]

It took some time, but I was able to acquire the article under discussion. I do not think it is at all unreasonable to ask people to actually read something before commenting on it. If it was a piece of gear a solid review of the item should include actually using the item. If it was book, one should generally actually read the book before issuing a review. Eat at the restaurant before eviscerating the chef. Too often in science, the scientist or scientists publish a paper and the general media then places their own spin on the science. Go to the source and form your opinions, don't just spew out what the talking heads (both sides) tell you to. I'm not suggesting you have to agree or disagree with the article but please try to read it. In academia, there is a format called a seminar where sometimes a paper or study is presented then the participants discuss (collegially;)). So try that without trying to score cheap points and do please focus in on the core issue of possible change to Northern forests as that is the reason the thread is still open.

The manuscript is still in the uncorrected proof stage. This means that it is just about to be published in final form. The article has gone through peer review and passed the editor and they would simply be looking for graphical and other minor errors in formatting, etc.

[Slo-go'en]

^^^ An interesting if not some what difficult read. As I suspected, as our winters become shorter with less snow pack, we'll start to loose the confiers, which will be replaced by the hard woods making our woods look much like those much farther south.

It was 50 degrees and raining here in the Whites at 2 AM this morning.

[prain4u]

O.K. I have now read the entire article. My comments remain essentially the same as they were when I had only read a synopsis of the article. (Except, that I am even less impressed with the "study" after reading the entire article).

Except for the authors looking at some old surveyor's records and selectively using those old records to bolster their conclusions, this less-than-impressive study pretty much looks at climate and weather factors from just a 30-50 year period--primarily in a very localized area. A nice start--but certainly not an extensive period of time in terms of the study of climatology. The authors come to the "cutting edge" conclusion that any weather changes (even from year-to-year) impact vegetation type, vegetation distribution and vegetation vitality--and all of this (in turn) impacts wildlife. Thanks for the newsflash, Captain Obvious! The authors also reveal to the readers the "groundbreaking" discovery that the forest vegetation patterns and the animal populations and animal distribution patterns have changed in New England the past 200-300 years. (Gee, until I read this article I always thought that the New England forests of today were EXACTLY like they were 300 years ago. Thanks to this study I am now more enlightened!)

The article uses a great many important and impressive sounding words and phrases--but (overall) this article (in my opinion) was not great science nor does it break any significant or earth shattering new ground. It is pretty much an 8th Grade Science Fair project written with a PhD-level vocabulary. These researchers pretty much started out with an assumption (conclusion) regarding climate change and it's impact upon a local area in a Northern region and they then set out to PROVE and support their CONCLUSION. Sure enough, the data that they self-selected supported their conclusion (Surprise! Surprise!)

I was even less impressed by their secondary conclusion--which (loosely paraphrased goes something like this: "We need to have more studies like this one--because we think such studies are important". (I am guessing that the authors are trying to fund their ongoing research--and if you keep telling people how important such studies are--eventually someone might pay for your ongoing study).

This concludes my "book report" regarding the article entitled: "Long-Term Integrated Studies Show Complex and Surprising Effects of
Climate Change in the Northern Hardwood Forest" which appeared in the December 2012 edition of BioScience Magazine. I trust that this latest post of mine is infinitely more acceptable than my previous posts on this same thread because I have now read the entire article and this latest post confines its focus to discussing the glaring inadequacies of this less-than-stellar article in a semi-obsure quarterly publication.

[WingedMonkey]

"cutting edge" conclusion
"groundbreaking" discovery

After reading the short fourteen pages twice, I can not find the words "cutting edge" or "groundbreaking" anywhere in the report.
I'll assume that's part of your editorial opinion.

[prain4u]

After reading the short fourteen pages twice, I can not find the words "cutting edge" or "groundbreaking" anywhere in the report.
I'll assume that's part of your editorial opinion.

Definitely my editorial opinion. However, my sarcastic and satirical response is a somewhat tongue-in-cheek" reaction to the lengthy title of this article, which states (in part): "....Surprising Effects of Climate Change in the Northern Hardwood Forest". I sure didn't read anything "surprising" in this article.

[fcoulter]

It took some time, but I was able to acquire the article under discussion.

Thanks for getting the article. I'll be reading it this weekend, and may have more pertinent comments at that time.

Or I'll just be grumpy about the whole thing.

[Alligator]

Thanks for taking the time to read it Prain4u.

I went back and reread your original comments as they had not changed so that I might better understand your opinion. You mention climate data from the Adirondacks in NY but Hubbard Brook is in the White Mountain National Forest in NH. Perhaps older climate data is the same in both locations but they are separated by VT. You also placed an emphasis on the memories of weather of 80-90 year olds. Personally, I wouldn't use that in any sort of rigorous analysis, but you are free to call them better. The daily and weekly 50 year records from Hubbard Brook are pretty solid though wouldn't you think? Probably considerably so and less subject to memory issues. The two data points you used to illustrate your maple syrup argument are perhaps too (two) few. The authors relied on two separate studies for their Figure 4, and both did not include your two dates but might include several more. Hard to say whether you have the better conclusion on that one.

Eighth graders do not perform the types of analysis that is used on page 5, L35. The language is by no means abnormal for this type of research. Granted, it is written by scientists for scientists but I don't see for example other words for evapotranspiration. Every discipline has concepts and language that do not readily transfer to laymen's terms.

Bioscience was rated 10 out 84 in the category of Biology in 2011. That's not obscure that is in the top 10.

I found several of the findings to be interesting. The reduction in snowpack and potential impact on recreation is important, perhaps even economically if the snowmaking is affected. The dynamics between moose and deer is something I was unaware of, I suspect hunters might have some interest there. The maple syrup studies were from other sources but that's yet another economic concern. Particularly striking was that the holding line for hemlock wooly adelgid may not occur in that area due to increased winter temperature. Hemlock forests are interesting forest types and it is unfortunate they are dying out.

In the conclusions (around page 10 line 57 on), the authors mentions the several ecological processes for which the data apply from Hubbard Brook. Long term data like that is rare and particularly important for ecological research involving time studies.

[prain4u]

Gator--We will just have to agree-to disagree--agreeably.

You find this topic (and this particular research) to be interesting and important. You also find the article and this "journal" to be good. You belive the article provided you with some good and interestng information that might be of value to other people.

Conversely, I find the research to be (relatively) inconsequential. I believe the research premise and the research methods are sloppy and slanted toward a pre-selected conclusion. (That pre-selected conclusion is one that many of the "peers" in the "peer review" process support. Thus, I don't really see the "peers" significantly challenging the study, its methods or its conclusions. Peer review means little these days--particularly in this subject matter). Furthermore, I simply take it for granted that climate, vegetation, and wildlife patterns will change. I assume species will become extinct--as the have for billions of years. Most studies and articles regarding climate change do not particularly alarm me or cause me to become concerned. I pretty much go ""so what" when someone reports that weather, climate, vegetation and wildlife are changing (they have been been changing for billions of years--what's new?)

You and I disagree--AND THAT's O.K.

(That being said, I think that your intense interest in this subject--and the fact that you find the article "good" and "interesting" DID definitely impact your moderating of this thread--and not for the better. You let your personal feelings and your personal beliefs impact the moderating process. And, based upon some of the posts that were not deleted-I get the feeling that other people agree with me on this matter).

Let's just agree, to disagree--agreeably.

[Alligator]

Gator--We will just have to agree-to disagree--agreeably.
Well settle down then;).


You find this topic (and this particular research) to be interesting and important. You also find the article and this "journal" to be good. You belive the article provided you with some good and interestng information that might be of value to other people.About half right. I was not interested in reading the article. I would most likely have not read it ever. There were some interesting points that I mentioned because I did end up reading it. I secretly hoped no one would read it so I wouldn't have to read it in depth as I didn't want to and there would be no arguing. It had relevancy to the AT so that made it important enough to not close the thread. I didn't post the link or start the thread.

I didn't give my personal rating of the journal. The journal was rated on its impact factor and placed 10 out 84, a top ten finish. Those are facts independent of my personal assessment. I was fact checking your rating. It's possible I may have read articles from it but it's not on my list of regular journals. I am lucky to remember author and year, journal name much rarer.


Conversely, I find the research to be (relatively) inconsequential. I believe the research premise and the research methods are sloppy and slanted toward a pre-selected conclusion. (That pre-selected conclusion is one that many of the "peers" in the "peer review" process support. Thus, I don't really see the "peers" significantly challenging the study, its methods or its conclusions. Peer review means little these days--particularly in this subject matter). Furthermore, I simply take it for granted that climate, vegetation, and wildlife patterns will change. I assume species will become extinct--as the have for billions of years. Most studies and articles regarding climate change do not particularly alarm me or cause me to become concerned. I pretty much go ""so what" when someone reports that weather, climate, vegetation and wildlife are changing (they have been been changing for billions of years--what's new?)

You and I disagree--AND THAT's O.K.
Hey, no problem as long as one read's the article and gives a fair assessment but you did have a pre-selected conclusion yourself.

I disagree with your assessment of peer review, particularly if it is done anonymously as it is at most journals. I personally have given some critical negative reviews and received a few of the same (and that's not even considering WB:cool:).


(That being said, I think that your intense interest in this subject--and the fact that you find the article "good" and "interesting" DID definitely impact your moderating of this thread--and not for the better. You let your personal feelings and your personal beliefs impact the moderating process. And, based upon some of the posts that were not deleted-I get the feeling that other people agree with me on this matter).

Let's just agree, to disagree--agreeably.I never said it was good. There are points that are interesting. You really have it wrong and it gets kind of old where people seem to know what I'm thinking (it would be a little freaky if they did but not). I opened this thread and thought oh great another global warming thread. Like I said, they don't usually go well, and unfortunately we have to read them because members misbehave in them. So they have been getting closed. Then it got worse, after looking at the link I saw that it was an area affecting the AT. So it had be left open. Then the first three posts were off topic mostly about lithium and mining and priuses and not a word about northern hardwood forests. That's poster case hijacking of a thread when it happens on posts 2-4, not post 20 or 40 or 60. They were removed. So I realized I needed some clear ground rules and I had the idea that at least if people read the article then they have at least done the minimum common courtesy for a review. I felt this would at least put off some nonsense and help to elevate the debate. Prior history with these types of threads has shown them to be very problematic. I thought I adequately expressed my view on these types of threads--PITA.

Back to the paper. To properly peer review, one has to know the journal the publication is going into and I don't have any familiarity with Bioscience or its editorial guidelines, so this isn't exactly what I might write to the authors. This paper seems more like a research note. It is not a standard experimental research study with an underlying hypothesis stated, introduction, methods, results, discussion, conclusion. It's more observational, there aren't explicit controls, the authors report findings and measurements which are related back to other studies. The statistics included while needing attention to correlation aren't particularly involved. They simply require knowing how to handle longitudinal data (Masters level stats upper level Bachelors for stats majors). They should have perhaps used the word purpose instead of objective. The paper is cohesive in that changing ecological conditions (streamflow, snowpack, etc.) are related to changing climatic conditions. The strength of the paper is the long term data but it has weaknesses in replication and randomization. The data presented lay the groundwork for future studies in that there are multiple concepts mentioned that might serve as research topics in their own right if properly laid out.

[Pedaling Fool]

This is not the North Appalachian forests, but it's interesting look at how quickly climate can change. I just find it incredible that an area would change back and forth from savanah to forest 5 - 6 times in just 200,000 years.

Fluctuating environment may have driven human evolution


UNIVERSITY PARK, Pa. -- A series of rapid environmental changes in East Africa roughly 2 million years ago may be responsible for driving human evolution, according to researchers at Penn State and Rutgers University.

"The landscape early humans were inhabiting transitioned rapidly back and forth between a closed woodland and an open grassland about five to six times during a period of 200,000 years," said Clayton Magill, graduate student in geosciences at Penn State. "These changes happened very abruptly, with each transition occurring over hundreds to just a few thousand years."

According to Katherine Freeman, professor of geosciences, Penn State, the current leading hypothesis suggests that evolutionary changes among humans during the period the team investigated were related to a long, steady environmental change or even one big change in climate.

"There is a view this time in Africa was the 'Great Drying,' when the environment slowly dried out over 3 million years," she said. "But our data show that it was not a grand progression towards dry; the environment was highly variable."

According to Magill, many anthropologists believe that variability of experience can trigger cognitive development.

"Early humans went from having trees available to having only grasses available in just 10 to 100 generations, and their diets would have had to change in response," he said. "Changes in food availability, food type, or the way you get food can trigger evolutionary mechanisms to deal with those changes. The result can be increased brain size and cognition, changes in locomotion and even social changes -- how you interact with others in a group. Our data are consistent with these hypotheses. We show that the environment changed dramatically over a short time, and this variability coincides with an important period in our human evolution when the genus Homo was first established and when there was first evidence of tool use."

The researchers -- including Gail Ashley, professor of earth and planetary sciences, Rutgers University -- examined lake sediments from Olduvai Gorge in northern Tanzania. They removed the organic matter that had either washed or was blown into the lake from the surrounding vegetation, microbes and other organisms 2 million years ago from the sediments. In particular, they looked at biomarkers -- fossil molecules from ancient organisms -- from the waxy coating on plant leaves.

"We looked at leaf waxes because they're tough, they survive well in the sediment," said Freeman.

The team used gas chromatography and mass spectrometry to determine the relative abundances of different leaf waxes and the abundance of carbon isotopes for different leaf waxes. The data enabled them to reconstruct the types of vegetation present in the Olduvai Gorge area at very specific time intervals.

The results showed that the environment transitioned rapidly back and forth between a closed woodland and an open grassland.
To find out what caused this rapid transitioning, the researchers used statistical and mathematical models to correlate the changes they saw in the environment with other things that may have been happening at the time, including changes in the Earth's movement and changes in sea-surface temperatures.

"The orbit of the Earth around the sun slowly changes with time," said Freeman. "These changes were tied to the local climate at Olduvai Gorge through changes in the monsoon system in Africa. Slight changes in the amount of sunshine changed the intensity of atmospheric circulation and the supply of water. The rain patterns that drive the plant patterns follow this monsoon circulation. We found a correlation between changes in the environment and planetary movement."

The team also found a correlation between changes in the environment and sea-surface temperature in the tropics.

"We find complementary forcing mechanisms: one is the way Earth orbits, and the other is variation in ocean temperatures surrounding Africa," Freeman said.

The researchers recently published their results in the Proceedings of the National Academy of Sciences along with another paper in the same issue that builds on these findings. The second paper shows that rainfall was greater when there were trees around and less when there was a grassland.

"The research points to the importance of water in an arid landscape like Africa," said Magill. "The plants are so intimately tied to the water that if you have water shortages, they usually lead to food insecurity.

"Together, these two papers shine light on human evolution because we now have an adaptive perspective. We understand, at least to a first approximation, what kinds of conditions were prevalent in that area and we show that changes in food and water were linked to major evolutionary changes."

The National Science Foundation funded this research. http://live.psu.edu/story/63354

[JAK]

Cool article on Climate Change in our region over past 20,000 years or so...

http://www.gov.ns.ca/nse/ea/whitespointquarry/09.Reference.Documents/17.Fader.GLACIAL.Sea.Level.Change.pdf

[fcoulter]

This is not the North Appalachian forests, but it's interesting look at how quickly climate can change. I just find it incredible that an area would change back and forth from savanah to forest 5 - 6 times in just 200,000 years.


I wonder how many times we've had an ice age (defined as an expansion of the ice caps to the US / Canadian border) in the last 200,000 years?

I was just going to ask about an ice age, but it turns out that an ice age is not defined the way I would define it. From what I can tell on Wikipedia, an Ice Age is anytime there's ice. Apparently, for most of Earth's history, we haven't had ice.

Or I'm just reading Wikipedia incorrectly.