Earth’s farmland is running low on water. Maybe we should do something?

I’m periodically reminded that the internet is full of people who either think climate change isn’t happening, or who think that it is, but that it’s nothing to do with humanity. That latter group always puzzles me – they insist that they don’t deny that the temperature’s rising, and all the rest, they just don’t seem to think we should do anything about it. That’s not just about stuff like ending fossil fuel use, but also stuff like changing how we do agriculture, or how coastal communities are built.

It’s almost like they don’t actually believe anything is happening.

Anyway, all of this is to say that it seems like I’ll be posting stuff like this in perpetuity – a sort of collective Sisyphean task shared by everyone who wants climate action. To the great shock of nobody who’s been paying attention, “agricultural water scarcity is expected to increase in more than 80% of the world’s croplands by 2050“:

The new study examines current and future water requirements for global agriculture and predicts whether the water levels available, either from rainwater or irrigation, will be sufficient to meet those needs under climate change. To do so, the researchers developed a new index to measure and predict water scarcity in agriculture’s two major sources: soil water that comes from rain, called green water, and irrigation from rivers, lakes and groundwater, called blue water. It’s the first study to apply this comprehensive index worldwide and predict global blue and green water scarcity as a result of climate change.

“As the largest user of both blue and green water resources, agricultural production is faced with unprecedented challenges,” said Xingcai Liu, an associate professor at the Institute of Geographic Sciences and Natural Resources Research of the Chinese Academy of Sciences and lead author of the new study. “This index enables an assessment of agricultural water scarcity in both rainfed and irrigated croplands in a consistent manner.”

In the last 100 years, the demand for water worldwide has grown twice as fast as the human population. Water scarcity is already an issue on every continent with agriculture, presenting a major threat to food security. Despite this, most water scarcity models have failed to take a comprehensive look at both blue and green water.

Green water is the portion of rainwater that is available to plants in the soil. A majority of precipitation ends up as green water, but it is often overlooked because it is invisible in the soil and can’t be extracted for other uses. The amount of green water available for crops depends on the how much rainfall an area receives and how much water is lost due to runoff and evaporation. Farming practices, vegetation covering the area, the type of soil and the slope of the terrain can also have an effect. As temperatures and rainfall patterns shift under climate change, and farming practices intensify to meet the needs of the growing population, the green water available to crops will also likely change.

Mesfin Mekonnen, an assistant professor of Civil, Construction and Environmental Engineering at the University of Alabama who was not involved in the study, said the work is “very timely in underlining the impact of climate on water availability on crop areas.”

“What makes the paper interesting is developing a water scarcity indicator taking into account both blue water and green water,” he said. “Most studies focus on blue water resources alone, giving little consideration to the green water.”

The researchers find that under climate change, global agricultural water scarcity will worsen in up to 84% of croplands, with a loss of water supplies driving scarcity in about 60% of those croplands.

The press release goes on to recommend agricultural practices like mulching and no-till farming to reduce water loss, as well as changing planting times to coincide better with seasonal rainfall. All of that is great, and I have no problem with it, but I think we need to do more. There’s a limit to how much we can get out of better water conservation, especially with heat waves getting hotter and longer. I do not believe this is a crisis we can escape by making minor adjustments to how we do things. We need to develop new ways to produce food.


  1. Katydid says

    Friends of mine have a farm that’s been in the family since the 1800s. Over the past decade, they’ve been complaining that the spring is always extremely wet and dreary and the summers are blazing hot and drought-y. They do not make the connection of climate change. I’ve tried the argument that one bad year is weather, a decade of bad years is climate.

    I don’t know what they’ll end up doing.

  2. says

    @Katydid – Maybe their need to keep producing food will lead them to change practices, whether or not they can bring themselves to accept what’s happening. It’s always discouraging to see that kind of denial from people who’re in a position to see the change happening for themselves.

  3. says

    Meanwhile, Republicans are calling the current inflation “Biden inflation”. I’m betting a large part of the inflation now, at least in food, is due to the extended drought out west. And I don’t see this “climate change inflation” getting better, either.

    Link to nationwide drought map:

  4. says

    It goes way beyond the western US. The invasion of Ukraine and resulting trade embargo, plus the heat wave in India, plus crop problems in China – It’s a global problem.

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