There has been much discussion of the effect of greenhouse gases on global climate change (especially carbon dioxide, which is the primary greenhouse gas). And this should be enough to cause humans to take action to control the rising CO2 levels (which is currently at 400 parts per million, and rising). But now there is evidence that climate change is not the only problem associated with elevated levels of CO2. Studies now show that elevated CO2 levels also affect the cognitive and decision-making abilities of humans. This is some pretty scary stuff, and I urge you to read the entire article at Think Progress.
Here is part of that thought-provoking article:
In a landmark public health finding, a new study from the Harvard School of Public Health finds that carbon dioxide (CO2) has a direct and negative impact on human cognition and decision-making. These impacts have been observed at CO2 levels that most Americans — and their children — are routinely exposed to today inside classrooms, offices, homes, planes, and cars. Carbon dioxide levels are inevitably higher indoors than the baseline set by the outdoor air used for ventilation, a baseline that is rising at an accelerating rate thanks to human activity, especially the burning of fossil fuels. So this seminal research has equally great importance for climate policy, providing an entirely new public health impetus for keeping global CO2 levels as low as possible. . . Significantly, the Harvard study confirms the findings of a little-publicized 2012 Lawrence Berkeley National Laboratory (LBNL) study, “Is CO2 an Indoor Pollutant? Direct Effects of Low-to-Moderate CO2 Concentrations on Human Decision-Making Performance.” That study found “statistically significant and meaningful reductions in decision-making performance” in test subjects as CO2 levels rose from a baseline of 600 parts per million (ppm) to 1000 ppm and 2500 ppm. Both the Harvard and LBNL studies made use of a sophisticated multi-variable assessment of human cognition used by a State University of New York (SUNY) Upstate Medical University team, led by Dr. Usha Satish. Both teams raised indoor CO2 levels while leaving all other factors constant. The findings of each team were published in the peer-reviewed open-access journal Environmental Health Perspectives put out by the National Institute of Environmental Health Sciences, a part of NIH. The new study, led by Dr. Joe Allen, Director of Harvard’s Healthy Buildings program, and Dr. John Spengler, Professor of Environmental Health and Human Habitation at Harvard, used a lower CO2 baseline than the earlier study. They found that, on average, a typical participant’s cognitive scores dropped 21 percent with a 400 ppm increase in CO2. . . The researchers explain, “The largest effects were seen for Crisis Response, Information Usage, and Strategy, all of which are indicators of higher level cognitive function and decision-making.” The entire article is a must-read as is the LBNL-SUNY study. . . All of this new research is consistent with — and actually helps explain — literally dozens of studies in the past two decades that find low to moderate levels of CO2 have a negative impact on productivity, learning, and test scores. See here for a research note and bibliography of some 20 studies and review articles. For most of human evolution and modern history, CO2 levels in the air were in a fairly narrow and low range of 180 to 280 parts per million. Also, during the vast majority of that time, humans spent most of their time outdoors or in enclosures that were open (like a cave). Even once humans built dwellings, those were not tightly sealed as modern buildings are. So even though we generate and breathe out CO2, homo sapiens were not generally exposed to high, sustained CO2 levels. But in recent decades, outdoor CO2 levels have risen sharply, to a global average of 400 ppm. Moreover, measured outdoor CO2 levels in major cities from Phoenix to Rome can be many tens of ppm higher — up to 100 ppm or more — than the global average. That’s because CO2 “domes” form over many cities primarily due to CO2 emissions from traffic and local weather conditions. The outdoor CO2 level is the baseline for indoor levels. In buildings — the places where most people work and live — CO2 concentrations are considerably higher than outdoors. CO2 levels indoors that are 200 ppm to 400 ppm higher than outdoors are commonplace — not surprising since the design standard for CO2 levels in most buildings is 1000 ppm. In addition, that differential increases when more people are crammed into a space and when the ventilation is not adequate. As the Harvard researchers point out, in recent decades, buildings have become more tightly sealed, and there has been less exchange of inside air with fresh outside air. . . But the implications for climate policy are stark. We are at 400 parts per million (ppm) of CO2 today outdoors globally — and tens of ppm higher in many major cities. We are rising at a rate of 2+ ppm a year, a rate that is accelerating. Significantly, we do not know the threshold at which CO2 levels begin to measurably impact human cognition. The LBNL study found a measurable negative impact on human cognition at 1000 ppm. The Harvard researchers had a more comprehensive study that found significant negative impact at 930 ppm. Moreover, many measurements made by the Harvard team point to a much lower threshold, as the top figure shows. Equally important, the researchers found “The exposure-response between CO2 and cognitive function is approximately linear across the concentrations used in this study.” So the impact threshold may be quite below 930 ppm. Clearly more research needs to be done to solve this detective story. The latest IEQ research does offer strong suggestions that the threshold could be near (or possibly even below) levels the entire world could experience outdoors over the next hundred years — levels that are essentially irreversible for centuries. As one clue to where that threshold may be, we can turn to recent research from Carnegie Mellon University (CMU) for the U.S. General Services Administration, which found a threshold of about 600 ppm. At 1,282 workstations in 64 diverse buildings across the country, CMU measured CO2 levels and surveyed occupancy perception of air quality. . . We have to do everything we can to keep outdoor CO2 levels below 600 ppm because something serious starts happening then.
Note in the chart below that we are currently heading toward levels of outdoor global CO2 that will affect humans. If we do nothing (which is what we are currently doing), the level by 2100 will be about 910 ppm. If the countries actually do what they say they want to do, the level will be about 675 ppm by 2100 -- a level that is still far too high (and will both cause serious global climate change, and significantly affect human cognitive and decision-making abilities). We must take radical action to protect both the environment and humanity. Not doing so is simply unthinkable.
