PDS APES 5th Period 2009-10

Last Friday, we discussed the origins of global warming. However, climate change is a more accurate term since some regions are cooling, not warming.

First off, it must be established that not all greenhouse gases, like water vapor, CO2, CH4 and N2O are “bad.” In fact, without the natural greenhouse effect earth would be very cold, thus uninhabitable, but the natural greenhouse effect makes the Earth warm enough to sustain life. Essentially, when solar radiation reaches Earth’s surface, some is absorbed by land and water, but a good portion is reflect as infrared radiation. Greenhouse gases trap IR, causing warming in the troposphere. Take a look at this diagram:

http://www.ncrlc.com/01-GCC_imgs/figure03.jpg

However, there are several anthropogenic, or human-caused increases in greenhouse gases, such as fossil fuel use, deforestation, and agriculture. This “unnatural greenhouse effect” contributes to global warming, whose effects include but aren’t limited to an increase in average temp, glacier retreats, and severe weather events like hurricanes due to higher ocean temps. However, global warming gets political when people feel forced to relinquish their Hummers on the bases of hypothetical “what if” situations surrounding global warming, such as rising sea levels and their resulting population shifts. So when did all the hype about anthropogenic causes of climate change begin?

Origins of Climate Change:

It’s important to note that Al Gore didn’t invent “Global Warming.” In reality, research on the relationship between increased CO2 levels from the Industrial Revolution and higher temperatures began in 1896 by chemist Svante A. Arrhenius. For more on the history of climate change research, see http://www.npr.org/templates/story/story.php?storyId=10307560.

One important chemist, Charles Keeling, is known for his study of temperature and CO2. His results yielded the Keeling Curve, which “launched the current debate over what to do about rising greenhouse gas levels.”

http://sio.ucsd.edu/keeling/images/Keeling_Curve.jpg

Today, research illustrates with near certainty that average temperatures in the troposphere are increasing. But as for the debate over whether climate change exceeds the natural cycle of warming and cooling, or if human activity is causing climate change, many argue that more research is needed before any decisive conclusions are formed. As with all scientific questions,  the question of why the Earth is warming falls somewhere on the spectrum of certainty. In order of least to greatest certainty are: hypothesis, theory, and finally law. With increased data and observation, a hypothesis can either be supported or refuted.

Hey guys,

Looking over my study guide, I’m confused about the difference between net energy and efficiency. Is there a difference? As I understand it:

Net energy is the amount of energy available minus energy needed to extract/process/etc.

Efficiency is input= output/percent efficient.

Aren’t these definitions basically two different ways of saying the same thing–that the second law of thermodynamics ensures that heat will be lost in all reactions, thus input will never equal output, yet the degree to which energy is lost in the reaction varies?

Thanks!

Hey APES class!

Question 43 on the study guide asks for alternatives to synthetic pesticides. The book lists “natural enemies/biological controls” and explains that introducing a natural predator could help reduce the numbers of the pests. Granted, later in the paragraph the text qualifies this statement by acknowledging that sometimes introducing foreign species is disruptive to ecosystems. Nevertheless, I’m having a hard time reconciling this statement after watching Cane Toads.  Is this actually a legitimate solution, or is it sort of hit or miss? Are there any examples of this strategy working without the predator totally invading the habitat like in Cane Toads?

Thanks! -Coco

So for those of  us not in class Thursday, (Meaghan…) we finished King Corn–> kingcorn.net and discussed the environmental and economic advantages and disadvantages associated with industrialized agriculture.

Summary (sorry if there’s overlap, I can’t remember where we stopped Wed.):

When we last left Ian and Curt, the pair was in Brooklyn investigating high fructose corn syrup and soda consumption in NYC. 70% percent of all high fructose corn syrup produced goes into beverages, so it’s no surprise that one in eight New Yorkers have diabetes.

Carl and Ian spend some more time looking into the sunset and playing baseball, but eventually harvest time rolls around. Now they must decide what to do with their harvest. After calculating the market rate for each bushel of corn, and subtracting the costs of renting the land, buying seeds and herbicides, Carl and Ian lost money.

So how do farmers grow money growing corn, anyway? The pair talk with that older farmer that’s usually hanging around to find out the answer: government subsidies. Without these subsidies, Mr. Experienced Farmer explains, no one would make a profit. Corn is being produced at such high rates (the county had a record harvest, remember the overflowing grain elevator?) that the market is flooded and prices dive down. The farmers are making a profit off of the government.

Carl and Ian then go and talk to Earl Butz, (the Nixon-era Secretary of Agriculture and brainchild of the subsidy system) and he explains that the prior policy subsidized farmers not to grow, but he didn’t think this was right. Butz’s program of providing government subsidies encouraged production, not discouraged it.

It turns out that Carl and Ian do make money off of their acre, but it’s only because of  government subsidies. In the end, they buy the land. The closing shot of the film shows the pair playing baseball (what else) in a meadow-like patch of land (their acre) that’s surrounded by a million other corn fields. It’s their comment on the impersonalization of agriculture. The family farm doesn’t exist anymore; it’s all industrialized agriculture. Most of the corn that’s grown isn’t even edible, it is processed into cow feed or syrupy sweeteners.

Then we got out the dry erase boards to evaluate the environmental and economical pros and cons of industrialized agriculture.  Take a look:

_____________________________________________________________

_____________________________________________________________

_____________________________________________________________

_____________________________________________________________

_____________________________________________________________

There was of course,  debate regarding the statements on the boards. For example, the ecological board lists a con noting that industrialized agriculture decreases biodiversity by supporting monoculture, yet the pro board claims a protection of biodiversity since the land is used more efficiently, thus reducing the need to cultivate new fields. It’s a matter of opinion, really. As we’ve learned throughout the course of the class, there is rarely a clean cut right or wrong answers concerning the relationship between humans and the natural world.

Hope this helps! Have a lovely long weekend.

Okay, so I understand there is a difference between water-soluble toxins and lipid soluble toxins. But which one is more concerning? I know lipid soluble toxins stick around longer and accumulate in tissue, and water-soluble are transported more easily, but which type is easier to treat? Or are they each dangerous in their own right? Also, what are some examples of each?

Thanks!

There’s a sentence in the texts that’s confusing me about the types of grasses found in rangelands and pastures.

It reads: ” Blades of rangeland grass grow from the base, not the tip. Thus, as long as only its upper half is eaten and its lower half remains, rangeland grass is a renewable resource that can be grazed again and again.”

But what about pastures? I know they are managed and planted with domesticated grasses, but is it only the rangeland grass which is renewable? Or does pasture grass also grow from the base?

Thanks!

On the last test I was confused as to whether pre-industrial or post-industrial had lower growth rates. I understand that pre-industrial countries have Zero Population Growth because their birth and death rates are practically the same. But where does that leave post-industrial countries, whose death rates exceed their birth rates?  Does that mean that now post-industrial countries have negative growth rates? I understand the social/economic/scientific reasoning behind the patterns within each individual stage, I just get confused when it comes down to contrasting the Stage 1 and Stage 4 in terms of overall growth, moreover which one experiences less of it.

I was reviewing the test for chapters 4 & 6, and I got this question 31 wrong. I know the midterm doesn’t take much from the previous tests, but I still do not understand the concept/reasoning behind this question’s answer:

“In a rain forest, two species of fruit eating pigeons live among the same species of trees. The larger species of pigeon uses the stronger branches to perch and eats larger fruits; the smaller species of pigeon eats small fruit from the weak, slender branches. This is an example of ____”

The correct answer was competitive exclusion, but I don’t understand why. It seems to me as if the birds are different sizes in the first place, and it makes sense that the larger bird gravitates towards the larger branches which can support him.  Wouldn’t they be occupying different niches in the first place? I just don’t understand how competition entered the equation. Thanks!

On the last page or so of the chapter there is a yellow box which includes ways to promote smart growth.  Under the heading of ‘Taxes’ the book explains to “tax land, not buildings” and “tax land on value of actual use (such as forest and agriculture) instead of on highest value as developed land.” I don’t understand how taxing land, not buildings would limit sprawl. Is it that land owners are more likely to maximize the land’s potential when it’s more expensive pay taxes on land, not buildings?  If so, why? As for the second question, does it mean that a plot of land with the potential to support agriculture/forests, but is instead developed, should be taxed more than developed land that’s unsuitable to agriculture/forests? Thanks.

A few weekends ago I was reading the Sunday Times and came across an Op-ed that I thought related to our study of human population dynamics. The subject of the article is naming these past ten years, and one Stanford professor suggested we call it the decade of overshoot. He explains that because in the ’90s we ignored the warning signals of problems to come (terrorism, environment, economy), these problems escalated and surpassed the preexisting institutions’ capability to solve them, thus the past decade has been spent dealing with the consequences of this overshoot.

Anyway, here’s the link:

http://www.nytimes.com/2009/11/15/weekinreview/15segal.html?_r=2&pagewanted=1&sq=decade%20&st=cse&scp=3