pretty much done

food_energy.tex

@@ -184,7 +184,7 @@ The questions described thus far have largely been centered within a physics con
 
 Estimates of Tenochtitlan's population in 1500CE vary widely, from 40,000 \cite{40k} to more than 400,000 \cite{400k} inhabitants, comparable in size to Paris at that time. These estimates come from oral and written records and estimates of archaeological building density and land area.   While cannibalism was part of Aztec religious ritual and practice \cite{Aztec_Cannibalism}, the staple Calorie sources for the Aztecs were corn and beans.
 
-Few if any Native American cultures made use of draft animals for food or power before the columbian exchange.  This means that the food that fed Tenochtitlan must have been brought to the city center by foot or canoe.  How much land must have been devoted to chinampas to feed the population, or conversely, how many people could be supported by the land within walking or paddling distance from the city center?
+Few if any Native American cultures made use of draft animals for food or power before the Columbian Exchange.  This means that the food that fed Tenochtitlan must have been brought to the city center by foot or canoe.  How much land must have been devoted to chinampas to feed the population, or conversely, how many people could be supported by the land within walking or paddling distance from the city center?
 
 A 1964 paper in Scientific American \cite{Chinampas_1964} gives a general outline of the chinampas in the area of Tenochtitlan in 1500CE.  This map seems to be the basis for the similar figure in Wikipedia \cite{chinampas_wikipedia}.  Descriptions of chinampas agriculture indicate that as many as 7 successive crops could be grown and harvested from the same plot of soil each year, two of which could be maize (corn).  This is truly amazing productivity, given that in the midwestern United States corn is normally grown, at most, every other year because of it's extreme nutrient demands on the soil.
 
@@ -204,38 +204,38 @@ This crop productivity is in remarkable agreement with the 1917 USDA yields, $35
 
 
 \section{Example: Was the Irish Potato Famine a Natural Disaster?}
-In contrast to cultures of the Americas, Ireland's population boomed with the introduction of the potato. \cite{potato,little_ice_age}.  Figure \ref{ireland_population} shows that from about 1700 onward there was a dramatic growth in the island's population.  There's never just one reason for historical events, but potatoes, kale, and milk formed a nutritionally complete diet that greatly reduced hunger-related mortality among the poor working-class in Ireland.  If you look closely at the data in figure \ref{ireland_population} you might believe that there were \textit{two} weather and potato related famines, the most obvious 1845-49 and the second, with much smaller effect on population in 1740-1.  Both famines were precipitated by poor weather, but an important difference is that in 1740, Ireland was a sovereign state but by 1845 the island was effectively an economic colony of the British Empire \cite{little_ice_age}.  
+In contrast to native cultures of the Americas, Ireland's population boomed with the Columbian Exchange and the introduction of the potato. \cite{potato,little_ice_age}.  Figure \ref{ireland_population} shows that from about 1700 onward there was a dramatic growth in the island's population.  There's never just one reason for historical events, but unlike grains, potatoes thrived in Ireland's cool damp climate and potatoes, kale, and milk form a nutritionally complete diet that greatly reduced hunger-related mortality among the poor working-class in Ireland.  If you look closely at the data in figure \ref{ireland_population} you might believe that there were \textit{two} weather and potato related famines, the most obvious 1845-49 and the second, with much smaller effect on population in 1740-1.  Both famines were precipitated by poor weather, but an important difference is that in 1740, Ireland was a sovereign state but by 1845 the island was effectively an economic colony of the British Empire \cite{little_ice_age}.  
 
-As the story goes, the two main commodity crops in Ireland were potatoes (for humans), and oats, which as horse feed, were something like gasoline in today's economy.  A sovereign government can halt the export of food to feed English horses, which is what happened in 1741 (and 1782), and the grain was diverted back to starving people in Ireland, reducing the mortality of the famine. However, by 1845, most of Irish farmland was economically controlled by foreign (English) landlords and grain traders who refused to divert oats (horse feed) for the sake of income from their investments.  
+As the story goes, the two main commodity crops in Ireland were potatoes (for humans), and oats, which as horse feed, were something like gasoline in today's economy.  A sovereign government can halt the export of food to feed English horses, which is what happened in 1741 (and 1782). The grain was diverted back as relief to starving people in Ireland, reducing the famine's mortality. However, by 1845 most of Irish farmland was economically controlled by foreign (English) markets, and grain traders typically refused to divert oats (horse feed) as famine relief for the sake of their investment income.
 
-This inflammatory claim, which is certainly a simplified version of history, serves as a useful evaluation example for students. Specifically, in years that the potato crop failed because of weather or late blight, could the amount of oats produced (and exported) have fed the Irish population?  More broadly, was the Great Famine due to natural causes ``we can't do anything about'' (weather and disease) or was the depth of the tragedy a result of political choices?
+This inflammatory claim, which is certainly a simplified version of history, serves as a useful evaluation example for students. Specifically, in years that the potato crop failed because of weather or late blight, could the amount of oats produced (and exported) have fed the Irish population?  More broadly, was the Great Famine due to weather and disease, natural causes ``we can't do anything about,''  or was the depth of the tragedy a result of political choices?
 
 Some estimates follow:  Ireland's population in 1845 was about 8.5 million people.  The island has an area of about $70,000km^2$ and you might estimate that $64\%$ of the land ($44,800km^2$) is arable for agriculture \cite{arable_percentage}.  
 It seems reasonable to use the 1917 productivity,  figure \ref{1917_yields},  to make calculations for Ireland in 1845.  Reminder, in 1917, potatoes produced $1.908\times10^6 kcal/acre$ and oats $1.254\times10^6kcal/acre$.
-With students, the question could be approached as a series of questions:
+With students, evaluation of the claim could be approached as a series of questions:
 
 How much food does the island need?
 \bea
 food~needed~per~year &=& 8.5\times10^6~people
 	\cdot \frac{3000}{person\cdot day }
-	\cdot \frac{365days}{year}\\
+	\cdot \frac{365days}{year} \nonumber \\
-&\approx& 9.3\times 10^{12} kcals 
+&\approx& 9.3\times 10^{12} kcals \nonumber
 \eea       
 
 How much land area, sown in potatoes, would produce this food?
 \bea
-9.3\times10^{12}kcals /\left(1.908\times 10^6\frac{kcal}{acre}\right) &=& 4.87\times10^6 acres \\
+9.3\times10^{12}kcals /\left(1.908\times 10^6\frac{kcal}{acre}\right) &=& 4.87\times10^6 acres \nonumber\\
- &\approx& 19,700 km^2
+ &\approx& 19,700 km^2 \nonumber
 \eea
 
 How much land area, sown in oats, would produce this food?
 \bea
-9.3\times10^{12}kcals /\left(1.254\times10^6\frac{kcal}{acre}\right) &=& 7.41 \times10^6 acres \\
+9.3\times10^{12}kcals /\left(1.254\times10^6\frac{kcal}{acre}\right) &=& 7.41 \times10^6 acres \nonumber \\
- &\approx& 30,000 km^2
+ &\approx& 30,000 km^2 \nonumber
 \eea
 
-Added, $49,700km^2$, these two land areas devoted to oats and potatoes are close to the amount of arable land estimated above for Ireland in 2022 ($44,800km^2$).  What do the numbers mean?  Did there have to be a famine?  If all of the potato crop failed because of late blight, there would likely have been enough oats to feed a $2000kcal$ ratio of oats with leftover to spare.  
+Added, $49,700km^2$, these two farmland areas devoted to oats and potatoes only slightly exceed the amount of arable land estimated above for Ireland, $44,800km^2$ \cite{arable_percentage}.  What do the numbers mean?  Did there have to be a famine?  If all of the potato crop failed because of late blight, there would likely have been enough oats to feed the population a $2000kcal$ ration of oats with leftover to spare.  
-Like the Holodomor or the Great Leap Forward, the numbers suggest that large-scale suffering wasn't  natural disaster, but rather a human disaster resulting from poor government policy insensitive to the value of human life.    
+Like the Holodomor or the Great Leap Forward, the numbers suggest that large-scale suffering wasn't  a natural disaster, but rather a human disaster resulting from poor government policy insensitive to the value of human life.    
 
 
 
@@ -250,7 +250,7 @@ The population of Ireland over time, file from Wikipedia \cite{pop_image}, data
 
 
 \section{Conclusion}
-
+A class about Energy and Social policy and the author hasn't mentioned climate change, coal, or solar panels even once!  What is he thinking?  How many tons of carbon does your car release in a year? How many shiploads of iron oxide will we have to dump into the ocean for algae to eat up the equivalent about of carbon?  Every question in a class like this is, to at least some extent, informed by numerical calculation and it's pretty arrogant to assume that ``those students'' don't need to (or can't) do the math.  If you're going to have success talking about numerical calculations, you might as well start with examples that everyone can relate to, and everyone eats!  Along the way you might find fascinating historical questions to investigate.