Agriculture has many unintended consequences. It has impacted the global carbon footprint for thousands of years; scientists at Lamont-Doherty (which is in my immediate neighborhood) discovered some ten years ago that evidence suggests this effect began as much as 5,000 years ago, as soon as mankind began clear-cutting large tracts of land for cultivation in Asia Minor. Interestingly, studies of arctic ice cores suggest that the carbon emissions produced by agriculture underwent significant dips during successive episodes of bubonic plague in Europe and the Middle East—plagues which substantially reduced populations and took large areas of agricultural land out of production, returning it (however temporarily) to forest.
One of the most dangerous and pernicious effects of agriculture, however, has relatively little to do with its very serious impact on atmospheric carbon levels; and that is the application of fertilizers.
Fertilizers, which dramatically increase the available amount of nitrogen and phosphorus in soil, work hand-in-hand with fossil fuel (mechanized) agricultural production methods to magically boost soil productivity. As we have explained in earlier posts, this boost in soil productivity comes directly at the long-term expense of microbial populations; and the detrimental effects of that soil quality depreciation have only recently begun to be understood, because most of the negative effects are both long-term, and invisible.
Today, when we see vast desert areas that used to be rich, fertile agricultural land (much of Asia Minor, for example, falls into that category) we assume it's because of climate change; but the first and foremost cause of the decline of the land into unusable desert began with the destruction of its microbial communities, a long-term degradation that was unseen and beyond the ability of the cultures causing it to understand or measure. We are now at a point where some few scientists do understand this problem; yet it is receiving little or no attention in the press, because it lacks glamor, and is difficult to solve. Nonetheless, it represents one of the greatest long term threats to human populations. Continued destruction of the microsphere (my own newly coined term for the microbial communities we rely on for survival) will eventually do society as we now know it in if it isn't halted.
This recent article about the effects of fertilizer runoff on coral reefs underscores the unseen effect of agriculture on ecosystems. Although the scientists involved had their attention drawn to the situation because of the damage being done to coral reefs—which are glamorous, touristy, and thus deemed worthy of consideration by the public—what the article does not make clear is that the damage extends to a wide range of other creatures which cannot be so easily seen. The damage cited here is, after all, damage specifically inflicted on very tiny creatures—coral polyps. The only reason we notice it is because these nearly microscopic creatures secrete exotic skeletal structures—corals—which we find aesthetically appealing. There are a host of other microscopic creatures around them, both in their immediate vicinity and all the way down to the reefs through the waterways that carry the pollutants—which are also affected.
The damage to the coral reefs, which is grave, is thus only the last damaging effect we can see; the end result, so to speak, of a pollution event that has damaged ecological infrastructure all the way down the line from the place where it was originally applied to the soil. The soils have been negatively affected; the streams that carry the runoff from the agricultural areas are affected; the rivers the streams feed into are affected; and the estuaries the rivers run into are affected.
After running this damaging course which leads all the way to the sea, the runoff finally wipes out corals, and suddenly we are alarmed and take notice. It's kind of like having a cancer that has spread through the entire body but only gets noticed once it has erupted on the skin. There is widespread, systemic damage; but our assessment of that damage is crudely limited to the areas where it's most visible.
The coral reefs are indeed telling us we're in trouble; but what they are telling us is that the trouble is everywhere. Not just on the coral reefs.
Intelligent, long-term solutions to the problem of agricultural runoff are thus vital to the future of both agriculture and the ecosystems that support it. Mankind's future well being depends on understanding this properly.