With 95 per cent of this year’s crop seeded as of this week, Manitoba farmers are again watching the skies for rain, along with thousands of firefighters and the tens of thousands of people displaced by wildfires across Western Canada.

Most of Manitoba received a good shot of moisture two weeks ago, but this weekend’s forecasted rain could prove pivotal to whether this year’s crops will be sparse or plentiful and whether entire communities will be razed or spared. Environment Canada is forecasting continued hot and dry weather into summer.

If it seems the rain we do receive these days doesn’t go as far as it did in the past, it’s more than a hunch.

We’ve all had the experience of drinking more on a hot day. As it turns out, the atmosphere reacts similarly under global warming.

In the study “Warming accelerates global drought severity” published in the journal Nature, University of California’s Santa Barbara Climate Hazards Center director Chris Funk says global warming is causing the atmosphere to behave “like a sponge, soaking up moisture faster than it can be replaced.”

In other words, the air is getting thirstier, a phenomenon that researchers say has increased the intensity of global droughts by 40 per cent over the past four decades.

Scientists tracking global warming have only recently begun calculating “atmospheric evaporative demand,” a measure of how much more moisture is absorbed from the air, land and plants as the planet heats up.

“Drought is based on the difference between water supply (from precipitation) and atmospheric water demand.Including the latter reveals substantial increases in drought as the atmosphere warms,” Funk says in a release.

The research shows that typically dry regions are becoming drier and wet areas are experiencing drying trends. Globally, the areas in drought expanded by 74 per cent between 2018 and 2022 and the atmospheric evaporative demand was responsible for 58 per cent of that increase.

“The year 2022 was record-breaking, with 30 per cent of the global land area affected by moderate and extreme droughts, 42 per cent of which was attributed to increased AED,” the study says. “Our findings indicate that AED has an increasingly important role in driving severe droughts and that this tendency will likely continue under future warming scenarios.”

Most now accept that the climate is heating up, although debate continues as to the cause. Less well understood is the connection between global warming and the “desiccating influence of the atmosphere,” Funk said.

This drying out process sets the stage for the devastating wildfires now sweeping through wide swaths of Western Canada’s boreal forests every spring and summer, creating the prolonged and hazardous smoke conditions cloaking the region.

There are lots of questions swirling around the effects of smoke on crops. Plants appear to tolerate the haze relatively well, but these conditions can wreak havoc with how well insect pollinators can do their jobs.

Some crop-protection products don’t perform as well on weeds when the sun isn’t shining.

The same conditions that cause the smoke to descend and linger are conducive to atmospheric “inversions,” which can lead to problems with herbicides drifting onto unintended targets.

However, one of the unanticipated outcomes from all that smoke is its counterbalancing effect cooling things down.

A University of Washington paper also released this month says wildfires in Canada and Siberia may reduce the earth’s warming by up to 12 per cent globally and 38 per cent in the Arctic over the next 35 years.

“Because the aerosols in smoke brighten clouds and reflect sunlight, summer temperatures during fire season drop in northern regions, leading to reduced sea ice loss and cooler winter temperatures,” lead author Edward Blanchard-Wrigglesworth says in a release.

No one can say this is good news.

“These increasing fires still have a lot of negative impacts for human health and for forest biodiversity,” he said.

But as our understanding of our changing climate continues to evolve, I’m reminded of an expression I’ve heard from some of the more seasoned farmers now and again.

Nature always bats last.

Laura Rance is executive editor, production content lead for Glacier FarmMedia. She can be reached at lrance@farmmedia.com