What do Scientists Really Think About Climate Change?

Back in the States, global warming combatants regularly appeal to scientists to support their positions. Flip on a conservative news channel, and someone will probably be citing a scientist who refutes the warnings of mainstream climate science. Open the New York Times, and you’ll read that 97% of climate scientists say that our greenhouse gases are disrupting the global climate. It’s not surprising that people are a little confused. With presumed experts on both sides, whom do we believe?

Well, this last week has been a real eye-opener for me. I’m on beautiful Prince Edward Island in the Canadian Maritimes, where I’ve spent much of the week with about one hundred agroforestry scientists. I’ll admit, it’s been a little intimidating: one hundred PhD’s, plus me – a finance guy-turned-farmer.

And what, you ask, do agroforesters know about climate science?

Alley-cropping in France: wheat grown with walnut trees

Alley-cropping in France: wheat grown with walnut trees

That’s part of the beauty of this experience. In truth, if it were one hundred climate scientists, the debate would be a mismatch. Indeed, there would be no serious debate on the core matter of human-caused climate change. It really is beyond dispute in their ranks: they’re convinced that we’re fundamentally disrupting the planetary systems that have nurtured civilization. But what about other scientists whose specialties only tangentially touch on climate? I listened carefully to the agroforesters this week for the answer to my question.

To make sense of this, I’ve got to answer the question you’re already wondering about: What, for heaven’s sake, is agroforestry? In North America, most of us know about farms, and about forests; but not the two combined. My prediction: you’ll be hearing more about this science in the coming years – much more.

So, with apologies to my new scientist-friends, here’s a layman’s take on their calling: Agroforestry is the science of trees grown on farms, not incidentally, but as an intentional part of the farm ecosystem, to enhance farm profits and sustainability. And these agroforesters are very practical people. They can tell you what kind of willow or poplar is best to plant along your stream bank; or whether hazelnut orchards are worth trying in your microclimate; or whether planting a spruce windbreak across your field will improve your blueberry harvest; or what kinds of mushrooms are worth growing in your woodlot. Not much use for theoretical arguments here. In the natural systems that feed us all, what works, and how?

And what does this group of scientists think about climate change? To begin with, let me admit that I’ve heard no one taking a poll of agroforesters on the topic. But they are immersed in climate systems, and are working daily do deal with the effects of climate. Fish don’t believe in water; they just swim in it. These scientists don’t debate climate change; they devise means to deal with the climate chaos all around them. Let me give you a few examples from this week’s meetings:

  • Windbreaks to reduce soil moisture evaporation: North American farms are subject to hotter weather today than ever, and the increased heat dries out soils and harms crops. Dry soils are also subject to wind-driven erosion, depriving farms of their most fertile soils. Agroforesters are helping farmers to design windbreaks to shelter dried out fields and protect soil moisture in today’s hotter climate conditions.
  • Riverside buffers to deal with runoff from severe rains: Today’s hotter air holds more moisture, resulting in more intense rainstorms, which erode precious topsoils on farms. In addition to damaging farms, runoff also pollutes waterways with leaching from chemical fertilizers and animal wastes. The harmful consequences are legion, including contaminated downstream drinking water, damaged river habitats, and the massive Gulf dead zone beyond the Mississippi Delta. Agroforesters are designing “riparian” (river-related) buffer zones of willow and other plants whose roots absorb harmful nutrients and block surface runoff.
  • “Silvopasture” to deal with heat’s toll on livestock: On today’s hotter pastures, dairy cows produce 20-30% less milk when temperatures break 90 degrees Fahrenheit; and forage dries up in the extreme heat.  But agroforesters are designing “silvopasture” systems that are partially shaded beneath a canopy of trees, resulting in significant livestock yield improvements.
  • Alley cropping to deal with hotter, stormier weather: Today’s extreme drought and flooding often destroy grain crops entirely. By contrast, trees are much more resilient in the face of extreme weather. Furthermore, tree root systems can bind soils together to resist flood-driven erosion; and their shade can help retain soil moisture in drought conditions. Agroforesters are designing “alley cropping” systems that feature alleys of grain and vegetable crops between rows of timber or tree crops, making farms more resilient in today’s harsher climate.
  • Tree-crop production to reduce drought exposure to extreme weather: Extreme weather increases the risk of farming, often causing complete failure of fragile grain crops. Agroforesters are helping farmers take a portfolio approach to their farms with resilient woody crops that can tolerate extreme events in a changing climate.
  • New introduction of warm-climate crops and trees:  American plant hardiness zones are moving northward every year. When the USDA revised its zone maps last year, 18 of the 34 listed cities changed zones. As a result of this warming, agroforesters are helping farmers identify which new species of plants and trees will thrive on their warmer farms, and which old ones no longer will.
  • Changes in crop mixes suitable to warmer conditions: Potatoes are perfectly suited to cold conditions, and they once dominated Prince Edward Island farming. But in the 2000-2010 decade, potato acreage declined by 22.5%, while warm-weather crop acreage increased sharply: corn acreage almost quadrupled and soybeans increased tenfold. Agroforesters are engaged in designing farm systems to accommodate this wholesale shift in food production.
  • Protection of unfrozen winter soils: Northern farm fields used to be covered all winter with a thick blanket of snow. In today’s hotter world, even Canadian farms have to make it through the winter with their soils exposed to the elements, with resulting erosion and degraded tillage. Agroforestry systems are being designed to shelter soils from winter exposure, including cover crops, windbreaks, and erosion buffers.
  • Designing farm systems to sequester more carbon: About one-third of all human greenhouse gas emissions come from change in land use, mostly related to conventional farming. Agroforestry systems are being designed for farms to absorb more carbon than they emit, and tree-based systems are at the heart of these changes.

From my time among these practical scientists, it was clear that virtually all of them have concluded that the endless biological deserts that dominate today’s heartland farm belt cannot be sustained in the changing climate of the coming decades. The U.S. and Canada will have to incorporate diverse natural systems, including trees and habitats for all kinds of creatures, to protect and sustain our capability to produce food in a hotter, stormier, and less predictable climate.

I wouldn’t bother to ask agroforesters if they believe in human-caused climate change. But you may want to ask them why they are restoring trees and natural habitats to our trampled and abused farm landscapes. They see a fundamentally changing climate, and are helping us reimagine farm systems that can continue to feed us in a harsh new world of disrupted climate systems.

Thanks for reading, and may God bless you.

J. Elwood


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