April 22 (UPI) -- As carbon dioxide levels in the atmosphere continue to increase, scientists expect humans to struggle with strategic thinking and complex decision making.
New models suggest CO2 levels in indoor environs, whether at work or at home, will reach 1,400 parts per million -- three times the current amounts of carbon dioxide found indoors. As a result, the human brain will struggle to get the amount of oxygen necessary for high-level thinking.
Researchers shared their analysis in a paper published this week in the journal GeoHealth.
"It's amazing how high CO2 levels get in enclosed spaces," Kris Karnauskas, an associate professor of atmospheric sciences at the University of Colorado, Boulder, said in a news release. "It affects everybody -- from little kids packed into classrooms to scientists, business people and decision-makers to regular folks in their houses and apartments."
At baseline, indoor enclosures feature the same amount of CO2 as outdoor environs, but when indoor spaces are poorly ventilated and host large numbers of people, human exhalation causes CO2 levels to rise. As CO2 levels outside rise, indoor spaces will be more likely to feature especially high concentrations of carbon dioxide.
The phenomenon helps explain why students often become drowsy and easily distracted toward the end of lengthy lessons inside poorly ventilated lecture halls.
When scientists modeled the current trajectory of CO2 emissions, and the effects on indoor environs, they found that if atmospheric CO2 levels reach 930 parts per million, CO2 levels inside some building could reach 1,400 parts per million.
"At this level, some studies have demonstrated compelling evidence for significant cognitive impairment," said study co-author Anna Schapiro, assistant professor of psychology at the University of Pennsylvania. "Though the literature contains some conflicting findings and much more research is needed, it appears that high level cognitive domains like decision-making and planning are especially susceptible to increasing CO2 concentrations."
Scientists looked at previous research on the cognitive effects of oxygen deprivation to better estimate how rising CO2 levels will affect human decision making. When blood is forced to carry more CO2, less oxygen gets delivered to vital organs like the brain. Without sufficient oxygen saturation, brain performance can suffer.
The latest research suggests indoor CO2 levels of 1,400 parts per million would likely reduce decision-making performance by 25 percent and complex strategic thinking by as much as 50 percent.
Rising CO2 levels are certain to trigger a variety of dangerous climate effects, including more frequent heat waves, prolonged droughts, bigger storms and rising seas. The likely reduction in critical thinking revealed by the latest research is just one more reason for leaders and policymakers to spearhead aggressive CO2 emissions reduction efforts.
"This is a complex problem, and our study is at the beginning. It's not just a matter of predicting global (outdoor) CO2 levels," said Karnauskas. "It's going from the global background emissions, to concentrations in the urban environment, to the indoor concentrations, and finally the resulting human impact. We need even broader, interdisciplinary teams of researchers to explore this: investigating each step in our own silos will not be enough."