Farming must be intensified to save half the earth for nature

Link: https://allianceforscience.cornell.edu/blog/2018/08/sparing-half-earth-nature-still-feeding-humanity/

Sparing half the Earth for nature while still feeding humanity

Setting aside half the planet’s most biodiverse land area for nature conservation will not be possible unless major efforts are made to intensify agriculture, a new scientific study suggests.

The study makes clear that unless crop yields grow very rapidly in order to offset food supply losses resulting from allowing farmland to revert back to nature, it will likely not be possible to meet the “Half-Earth” target advocated by many leading conservationists while still feeding the current human population of more than 7 billion people.

The paper, published in the peer-reviewed journal Nature Sustainability, is titled “The challenge of feeding the world while conserving half the planet.” The study assesses different scenarios for meeting the half Earth target. At the global scale, setting aside half the planet’s land surface for nature appears relatively easy, as agriculture and human settlements currently cover 37 percent of ice-free land. Much of the remainder is relatively barren, however, being tundra, mountains or deserts.

Protecting the most valuable ecoregions, on the other hand, which most conservationists advocate in order to slow the loss of global biodiversity, requires some heavy trade-offs because it means giving up useful or productive land in more densely-populated areas.

If the nature-sparing approach aims to create contiguous reserves — important for the survival of many megafauna, and for biological connectivity — across 50 percent of each ecoregion, this implies the global loss of ~31 percent of cropland, ~45 percent of pasture, ~25 percent of non-food calories and ~29 percent of food calories, the researchers calculate.

In other words, all other things remaining equal, sparing half the planet for nature would mean wiping out a third of humanity’s food supply.

The amount of food calories lost depends to a large extent on assumptions made in the model. If a “nature sharing” approach is adopted, with efforts to adopt more wildlife-friendly farming practices instead of excluding agriculture altogether from nature reserves, more food can be produced.

The lead author is post-doctoral researcher Zia Mehrabi at the University of British Columbia (UBC) in Canada, while co-authors are geographer Erle Ellis at the University of Maryland and Mehrabi’s UBC colleague, Navin Ramankutty.

They write: “Simply put, the trade-offs between agriculture and Half-Earth will be much lower if landscapes are allowed to remain as mosaics of shared land uses, and will be much higher if large contiguous areas are given back, as may be required for the conservation of some species, such as megafauna.”

So how can this conundrum be solved, and nature spared without condemning a third of the planet’s human population to starvation?

The authors point out that “potentially massive calorie losses would need to be offset by massive increases in the intensity of food production” — in the order of 45-70 percent above today’s productivity levels — in order for the Half-Earth strategy to work without disastrous impacts on food security, which would disproportionately affect the world’s poor.

The paper also supports the efforts of vegans and those adopting animal-free diets by pointing out that 36 percent of crop calories are currently fed to animals. If diverted to direct human consumption, far more land could be spared for nature without adversely harming food security.

A 2013 study by Cassidy et al in the journal Environmental Research Letters found that “growing food exclusively for direct human consumption could, in principle, increase available food calories by as much as 70 percent.” In other words, an entirely vegan planet should also be able to spare half its most biodiverse ecoregions for nature and reverse biodiversity losses.

The current challenge is even greater, Mehrabi et al point out, because future increases in human population and consumption are not factored into the analysis, which looks only at today’s population level. Therefore “our findings should be seen as conservative with respect to Half-Earth’s potential negative impacts on agriculture,” they write.

Intense Farming Better Than Organic

A new study reviews hundreds of articles on several farming systems (dairy, beef, wheat, and rice) to compare different approaches to farming and their net effect on the environment. They conclude that intensive farming systems are the “least bad” option for providing the food we need. This is in line with previous studies showing that organic farming uses significantly more land than conventional farming.

Farming has a huge negative impact on the environment. There is no way around that basic fact – farmland displaces natural ecosystems and has significant externalities, such as water use, release of CO2 from the soil, and runoff of chemicals into the environment. Right now we are using 11% of all land on Earth for farming, which is most of the land that is reasonably suitable for farming. To meet the needs of a growing population, we may need to expand farmland, into less and less productive land, which would significantly increase the negative impact of farming on the environment.

Some previous studies compared different farming systems by measuring the impact they have on the land. But this type of analysis is misleading – the authors of the current study instead looked at the environmental impact for a given production of food. That is what really matters. They also looked at studies that measured externalities, as listed above. They found:

Their results from four major agricultural sectors suggest that, contrary to many people’s perceptions, more intensive agriculture that uses less land may also produce fewer pollutants, cause less soil loss and consume less water.

They found that organic dairy farming uses twice as much land as conventional farming, for example.

The study is a blow to the propaganda of the organic lobby, who base their methods on the appeal to nature fallacy, rather than the best scientific evidence. Their response to this study was a typical non sequitur:

Organic group though are not impressed with the study’s conclusions. They argue that the world produces enough food already and that the issues with feeding populations are economic and political, not agricultural.

First, no we don’t. We do not produce enough food to give every person on Earth the minimum nutrition as indicated by the USDA. These recommendations, by the way, are not for an overfed Western diet. Developed countries would generally decrease their land use if they adopted USDA recommendations. But the rest of the world would dramatically increase their land use, in an unsustainable way.

Organic apologists often argue that we produce more calories than we need to feed the world. This is one of those “true but misleading” statements. You cannot just consider calories. Most calories produced and consumed are staples, mostly grains like rice, wheat, and corn. These are great sources of calories, but not balanced nutrition. Keeping everyone well fed requires more than calories – it requires a diversity of food with lots of vegetables and sufficient protein.

Further, the assumption that we produce enough food is based on zero waste, which is ridiculously unrealistic. Sure, we can reduce waste in the food system, and we should strive to make the system as efficient as possible. But food spoils and is vulnerable to pests. You cannot eliminate waste entirely.

So – even if we reasonably reduced food waste and optimized economic and political distribution of food – we would not produce enough food to adequately feed the world.

Further, even if true, this point is irrelevant. It misses the fact that we already are using a massive amount of land for farming, with massive impacts on the environment. We should be striving to minimize our agricultural footprint, and that means getting the most food out of every acre we farm.

And finally, the human population is growing. We will likely hit 9 billion people by 2050. It is not clear where the population will top out, but it will be more than the current population. We don’t have more viable land to expand farming into, and we don’t want to. We want to reduce our land use, not increase it.

Whenever I bring up this point someone whines incoherently that I am wrong to talk about producing more food than reducing the human population. Of course, I advocate addressing poverty and women’s rights, which correlate with reduced population growth. This is a win-win, increase quality of life and stabilize the population. But nothing we do is going to prevent the population from rising over the next 50 years, unless it is your intent to deliberately cause mass starvation as a way of limiting our environmental impact.

And again – at any human population, we should strive to minimize the environmental impact of farming. That means looking at the evidence objectively (not through ideological filters). We need to produce the most amount of food on the land we are using, minimize externalities, minimize waste, and optimize distribution. There is no false choice among these options – we should do it all.

We should also use every technology at our disposal to accomplish these ends. That includes biotechnology, such as various types of genetically modified organisms. The anti-GMO movement is based entirely on propaganda and pseudoscience, and is harmful to the environment.

We also need to do more research into these very questions, as the authors acknowledge. But the evidence we have is very clear – organic and other ideologically based farming practices are harmful to the environment. We should use whatever techniques the evidence says are best, and not artificially limit our choices in an unsustainable way.