Climate change ‘skeptics’ who have been pushed off of all their denialist positions by ugly empirical facts often resort to arguments that climate change will actually be positive. One argument they make is that output from agriculture will increase globally, with especially far northern areas benefiting from increased arability. Are they right? No, of course not at any systemic level. Arguing that “more CO2 is good for plants” or “warmer is better for Arctic agriculture” is both vastly simplistic and mostly wrong.
Arability depends on several factors, many of which won’t be made better by climate change. In general, some limitations on arability will be removed, but most others will remain, so while very northern areas would eventually become arable, the timescale is in the hundreds to thousands of years depending on how much money and effort humans want to invest.
For convenience, this is a simplified view of the factors, assuming a projection into the future of a few degrees of warming and a stabilization of the climate at that new normal. It includes current and future Arctic bogs, tundra, and deltas against current and future grain prairies in North America and Europe, as well as major river delta agricultural areas in temperate and tropical climates.
In general, on this scale a score of between 15 and 20 is indicative of minimum viability for arable land in any economic sense. Below that, you are looking at hard scrabble subsistence farming on semi-arable land or highly nomadic grazing.
What’s much more relevant than the increase in potential for very northern farming is the decrease in arability of current agricultural areas. Prairies will face increased threats of drought and flooding. River deltas will see salting of the soil due to sea level rise, and some tropical deltas will become too hot for summer labor. Both of these factors threaten our current food supply, and there is little chance that northern ‘improvements’ in arability will replace it.
Stable base for infrastructure
Much of the north is frozen marsh and small lakes. When frozen, as it has been for millennia, it can be built on. As it melts, it becomes a difficult and expensive engineering challenge to create stable foundations for houses, never mind lengthy roads capable of hauling heavy loads. There are no roads to speak of in northern regions that are stable and run on robust foundations. Ice highways are the most common mechanism, and they are recreated annually. With climate change, these ice highways are in trouble too.
Predictable water supplies
Different agricultural crops require different amounts of water, but they all require it in relatively predictable annual amounts. Too much water or too little at the wrong time severely diminishes or eradicates yield. A changing climate almost by definition makes the availability of water much more variable year-to-year. In drier regions in more southern latitudes this has been dealt with by thousands of years of investment in dams and canals which provide irrigation to crops, with the first historical example in 6000 BC in Mesopotamia. In wetter areas, flood control systems of various types prevent massive damage and capture water for drier seasons. That entire infrastructure doesn’t exist in the north and would have to be recreated.
So first the climate would have to stabilize into a relatively new normal, and then the infrastructure we take for granted would have to be recreated in large areas. And as the first point makes clear, there isn’t a stable base for that infrastructure in many places, and its vastly expensive to build it in others.
High quality soil
Good soil for agriculture is a thriving ecosystem of its own, extending from a couple of feet to tens of meters deep. It’s got a huge amount of embodied carbon, nitrogen, and other nutrients laid down by millennia of vegetation before humans ever decided to plant crops on it. It has earthworms and bacteria in uncountable numbers. That’s the base for our efforts.
Soil in the north has been frozen for millennia in most cases. It has almost no bacteria, insect or worm cultures. In most places it’s bog, a very thin surface of barely adequate soil or merely sand or clay. It’s possible to make good soil from poor quality soil, but it requires a lot of work.
The most arable land is in river deltas which have over millennia (there’s that word again) benefited from nutrients and silt flowing down the river, and ocean migrations bringing salmon protein and the like into the delta. That’s why agriculture started in those types of regions.
Making sections in Saskatchewan into productive soil for grain, for example, was back-breaking and expensive work for a relatively low margin crop. Poor Europeans were induced with the offer of free land and immigrated to take advantage of the very sparsely populated spaces, and invested enormous amounts of sweat and deaths to eke livings out of the relatively poor soil. It’s important to note that while settler fatality rates were high, indigenous populations suffered much greater rates of death.
What’s more relevant than the poor quality of northern soil is the threat to river delta soil due to sea level rise. Flooding due to storm surges will put unprotected soil at risk due to salt, significantly decreasing arability. This threatens our food supply.
Level of CO2 and oxygen in the air
Plants breathe. They have a cycle. When the sun is shining, they breathe CO2, break it up, bind the carbon into their structure and release oxygen. When it’s dark, they breathe oxygen to oxidize glucose and release CO2. Different plants are differently sensitive to varying levels of CO2 and oxygen in the air. Some find more CO2 problematic. Some grow better with more CO2 up to a point. With the significant increase of CO2 in the atmosphere, the plants that benefit from more CO2 have one limiting factor removed.
Global warming is being felt most strongly at the poles, with the Arctic seeing two to three times the warming of the equatorial regions. With warmer temperatures come earlier springs and later winters, so the growing season is longer. This removes one limitation on a range of plants, so agriculture is more viable. What’s most concerning about this factor is that some tropical agricultural areas are likely to become too hot for effective summer agricultural use, effectively diminishing their arability.
Climate change doesn’t affect this major factor for agriculture. Plants need sunlight to grow, and in the Arctic the sun is missing entirely for extended periods and is weaker due to traveling further through the atmosphere when it is present. Plants also need some darkness for their respiration cycle as stated above, and the midnight sun in the far north places further limitations on plant species. Growing seasons are going to continue to be much shorter, and the number of plants which will be able to thrive is much smaller. Some crops will be able to take advantage of the extra sunlight, but mostly ones with either very short growing seasons or extensive labor assistance starting in artificially lit greenhouses.
This is a generalized assessment. There would definitely be specific northern areas which would be arable in an economic way and able to ship produce to southern markets. But there would also be more currently productive southern land which would see a degradation of overall arability. Overall, our agricultural system and food supply are much more at threat due to climate change than any northern arability bonus could overcome. As stated early in this discussion, any arability bonus would depend on stabilization of the climate at a new normal.