Climate Change and Agriculture

by Chand Prasad, Ph.D.

Agriculture accounts for close to 25% of global greenhouse gas emissions and 70 percent of all freshwater use. Agricultural related greenhouse gas emissions stem from the production of crops and animal products, as well as the conversion of forests, savannas, and peatlands to crop and pasture lands. The amount of land used for total agricultural production has grown at a rate of more than 10 million hectares per year since the 1960s. Agriculture employs roughly 2 billion of the planet’s people and uses about one-half of vegetated land i.e., land that is not covered by ice, water, or desert [1]. Pastureland alone occupies 25% of the planet’s land mass, excluding Antarctica [2]. Croplands and pasture lands have expanded at the expense of tropical forests.  The environmental impacts of agriculture will intensify—in the coming decades, billions of people will join the global middle class and adopt meat-centered diets, exacerbating land degradation, water shortages, and adverse effects from climate change [1].

The impacts of global warming are already apparent.  Greenland lost about 2 billion tons of ice in one day (June 13th, 2019).  Ice losses of this magnitude are part of a recent pattern. This extreme melting did not occur prior to the late 1990s.  Since then, however, Greenland experienced a a sequence of large melt seasons—2007, 2010, and 2012—that would have been unprecedented earlier in the record. Barring any offsetting factors, if these periodic extreme melts become a regular occurrence, then this new normal would significantly contribute to rising global sea levels [3].


A record-setting melt year occurred in 2012, when almost the entire ice sheet experienced melting for the first time in recorded history. The recent sudden spike in melting this early in the summer of 2019 could foreshadow another record amount of Greenland ice loss.  When snow and ice melt early in the season, it makes it easier for for additional melt to occur later in the summer. “White snow and ice, which is bright and reflects the sun’s rays back into space, reduces the amount of heat that is absorbed and helps to keep the ice sheet cold (a process known as ‘albedo’). These melt events result in a changed surface albedo, which will allow more of the mid-summer sun’s heat to be absorbed into the ice and melt it.” [3]

 
The year 2019 witnessed unusually early season melt days in April—the melt season commenced about three weeks earlier than average (and earlier than the record-setting melt year of 2012), with snow cover that was already lower than average in Western Greenland.  These factors indicate that the snow and ice melt of 2019 is likely to at least rival or even potentially exceed the record melt year of 2012 [3].

 
A preliminary step towards cutting greenhouse gas emissions is reduced consumption of animal products.  Dietary changes would improve the well-being of humanity, as most of the world’s people consume more milk and meat than necessary, and many consume more than is healthy [1].  In the United States, the average male consumes approximately 100 grams of protein per day, almost twice as much as the amount needed (56 grams). Although wealthy regions of the world are the highest consumers of protein, global average per person protein consumption (68 grams in 2009) substantially exceeded dietary requirements in all regions [2].

 
The most reliable estimates indicate that even poultry, the most resource-efficient source of meat, converts only around 11 percent of gross feed energy into human food [1] while using three times more land and generating three times more greenhouse gas emissions than beans. Compared to plant-based protein sources, beef production is a particularly inefficient way of producing edible calories and protein, requiring 20 times more land and creating 20 times more greenhouse gas emissions per unit of edible protein than beans, peas and lentils [2].  Based on the most credible global average estimates, beef converts only 1 percent of gross animal feed energy into food for people. Beef production is projected to sharply increase in the coming decades and, with its large land requirements to produce feed, would be a significant contributor to global warming [1].

A more comprehensive strategy for reversing climate change is the principle of cow protection, which will automatically control the growth of the cattle population.  The key to this principle is to engage and employ bulls to work the land, implying that cows are bred only to the point where the bovine population meets the demand for draft power, rather than the demand for the byproducts, e.g., milk.  In sharp contrast, raising cows for the purpose of producing milk is an egregious error—the cow will not produce milk unless it has calves, and since half will be male, the result is an excess bovine population that is costly to support.  Farming practices that do not engage the bulls will essentially condemn them to the slaughterhouse, since they will have no economic value other than their meat.  If cows are bred only to the point where the bovine population meets the demand for draft power rather the demand for meat, the result will be a substantially smaller cattle population and net reductions in greenhouse gas.  An in-depth explanation of these issues can be found in Global Warming and Geo-Engineering.

[1] World Resources Institute (2013). Creating a Sustainable Food Future, World Resources Report 2013-14: Interim Findings, Washington D.C.

[2] Ranganathan, Janet and Richard Waite (2016). Sustainable Diets: What You Need to Know in 12     Charts, World Resources Institute, Washington D.C. April 20.

[3] Miller, Brandon (CNN Meteorologist). “Greenland lost 2 billion tons of ice yesterday, which is very     unusual”, CNN. Updated 3:41 AM ET, Sat June 15, 2019.

 

 

 

 

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