Merv, I don’t think there is such a thing as BAU when it comes to agriculture and energy. Agriculture started with grazing and plowing and land expansion, and now it expands with labor reduction and energy use and improved genetics, and improved agronomy. BAU is always temporary.
Diesel and gasoline have contributed huge labor reductions and improved efficiencies. They have kept down the price of food, and reduced the literal human footprint on the land, replacing it with efficient soil management, and more timely seeding and harvesting. Oil has contributed pesticides which permit double or triple yields, thus reducing the need for land expansion to meet the same food production requirements. Fertilizer on the other hand, especially nitrogen, is primarily produced by natural gas, not oil. Natural gas is methane, a ghg about 21 times as potent as CO2, so converting it to fertilizer or to CO2 (thru combustion), reduces its potential to warm the climate. The crops that utilize the fertilizer to produce organic plant material also absorb more CO2 in the process, benefiting the ghg balance. These fertilized crops absorb considerably more CO2 than most native grasslands. And vast buffalo herds produce considerably more methane than wheat or canola crops do.
Erosion that is happening because of farming is mostly happening where fertilizer and pesticides are not being used, or where equipment for sustainable farming techniques is too expensive. In north america, erosion has been dramatically reduced over the last twenty years, and much land is improving in quality, rather than being depleted as it was in the 1920s -1980s. This improvement of land is also ocurring in Western Europe, Australia, Israel, and in certain parts of Brazil and Eastern Europe. The ancient erosion problems of Egypt, Asia, and other locations are now slowly but surely being not repeated.
I wonder if the more we change and reduce our lifestyle, the less need there will be for alternative energy sources. Necessity and economics will drive the search for alternative energy. When oil and gas become too expensive, then solar panels and wind power thru mass production become cheaper and more affordable. Then various hydroelectric options become more viable.
I agree to some degree that using less is a good option; We use less than half the average household water use at our home. But from a policy perspective, we need to understand the drivers for energy change, as well as being more holistic about ideological pronouncements, and being fully cognizant about the potential for unintended consequences.
In addition, so often it is those who use the most energy who are quite happy to tell others to use less (Al Gore being a prime example). Utilization of energy may be the best way to reduce soil erosion, as well as reduce unnecessary expansion of farmland by improving yields on existing lands.