Could CO2 Bring on the Zombie Apocalypse? More Evidence.

October 26, 2015

inhofebrainzIt may have already.
Let’s recap.

We already know that a warming world increases the general level of violent behavior.
We know that a warmer world enlarges the range for brain-eating amoebas.

I’ve posted before that might be a deadly combination.
Now this.


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.

In a series of articles, I will examine the implications for public health both today (indoors) as well as in the future (indoors and out) due to rising CO2 levels. This series is the result of a year-long investigation for Climate Progress and my new Oxford University Press book coming out next week, “Climate Change: What Everyone Needs to Know.” This investigative report is built on dozens of studies and literature reviews as well as exclusive interviews with many of the world’s leading experts in public health and indoor air quality, including authors of both studies.

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. Here are their astonishing findings for four of the nine cognitive functions scored in a double-blind test of the impact of elevated CO2 levels:

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.

NASA has also observed CO2-related health impacts on International Space Station (ISS) astronauts at much lower CO2 levels than expected and has identified a mechanism by which CO2 levels could affect the brain, as I will discuss in Part 2. As a result, NASA has already lowered the maximum allowable CO2 levels on the space station. The ISS crew surgeon who is the lead for studying the impact on astronauts of CO2 (and other gases) told Climate Progress he considers the original LBNL-SUNY study “very credible.” Indeed, NASA itself is now starting terrestrial studies to look at the impact of CO2 on judgment and decision-making for the astronaut cohort — and it is partnering with the same SUNY team of behavioral psychologists.

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.

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.

How high can CO2 levels get indoors? As but one salient example, the 2012 LBNL-SUNY article notes, “In surveys of elementary school classrooms in California and Texas, average CO2 concentrations were above 1,000 ppm, a substantial proportion exceeded 2,000 ppm, and in 21% of Texas classrooms peak CO2 concentration exceeded 3,000 ppm.” In Part 3, I’ll look at the extensive literature on the relationship between high classroom CO2 levels and poor student performance — and the simple strategies Indoor Environmental Quality experts say that parents, teachers, and school administrators should be doing now to address this serious problem.

Yet, the vast majority of studies linking CO2 levels to poorer performance at work and school merely used CO2 as a measure of ventilation rates and indoor air quality (since monitoring CO2 levels is relatively cheap and easy). As the LBNL-SUNY study notes, “It has been widely believed that these associations exist only because the higher indoor CO2 concentrations occur at lower outdoor air ventilation rates and are, therefore, correlated with higher levels of other indoor-generated pollutants that directly cause the adverse effects,” such as volatile organic compounds and particulates.

As a result, “CO2 in the range of concentrations found in buildings (i.e., up to 5,000 ppm, but more typically in the range of 1000 ppm) has been assumed to have no direct effect on occupants’ perceptions, health, or work performance.” In short, CO2 had not been a suspect in the negative impacts measured in all these studies. Indeed one of the authors of the LBNL-SUNY study, Dr. William Fisk, leader of LBNL’s Indoor Environment Group, told me that he was surprised when the testing showed significant impacts from just raising CO2 indoor CO2 levels 400 ppm.

13 Responses to “Could CO2 Bring on the Zombie Apocalypse? More Evidence.”

  1. jimbills Says:

    Peter – thanks for the Inhofe image. Laugh of the day.

    • dumboldguy Says:

      Ditto. Strom Inhofe has definitely suffered from “brain-eatin’ ‘meebers” (in Suthrun-speak) and is now one of the Walking Dead. Oklahoma is one of the places the ‘meebers are found, and having a brain that looks like swiss cheese may be a prerequisite to getting elected to the Senate there.

  2. rabiddoomsayer Says:

    This study brings down the level that CO2 is known to affect us, previously I thought 1000 to 1200 ppm the start of adverse effects.

    I suspect as outside CO2 levels increase, so too will recovery time. Come out of a high CO2 situation and you start to feel better within minutes, how much will that change?

    Are there any figures for how the duration of mid level exposure affects results?

  3. earlosatrun Says:

    Just out of curiosity, has the concentration of O2 also changed?

    Or is that a dumb question? 🙂

    • greenman3610 Says:

      I believe that’s correct, but it’s only detectable because we have insanely accurate instruments.

      “While no danger exists that our O2 reserve will be depleted, nevertheless the O2 content of our atmosphere is slowly declining–so slowly that a sufficiently accurate technique to measure this change wasn’t developed until the late 1980s. Ralph Keeling, its developer, showed that between 1989 and 1994 the O2 content of the atmosphere decreased at an average annual rate of 2 parts per million. Considering that the atmosphere contains 210,000 parts per million, one can see why this measurement proved so difficult.

      This drop was not unexpected, for the combustion of fossil fuels destroys O2. For each 100 atoms of fossil-fuel carbon burned, about 140 molecules of O2 are consumed. The surprise came when Keeling’s measurements showed that the rate of decline of O2 was only about two-thirds of that attributable to fossil-fuel combustion during this period. Only one explanation can be given for this observation: Losses of biomass through deforestation must have been outweighed by a fattening of biomass elsewhere, termed global “greening” by geochemists. Although the details as to just how and where remain obscure, the buildup of extra CO2 in our atmosphere and of extra fixed nitrogen in our soils probably allows plants to grow a bit faster than before, leading to a greater storage of carbon in tree wood and soil humus. For each atom of extra carbon stored in this way, roughly one molecule of extra oxygen accumulates in the atmosphere.”

    • sheilach2 Says:

      The O2 saturation level in our atmosphere has declined but I haven’t been able to find by how much.
      In the past, O2 levels were about 30%, now their around 21%

      High C02 levels are far more dangerous as a greenhouse gas.
      The levels have risen so much, that it has destabilized methane, an even more potent greenhouse gas, speeding up global warming/climate change.

      What I expect to see in the near future is the collapse of our agricultural system, record droughts, flooding & more severe storms will cut food production. I then expect to see mass migration of people who are trying to escape starvation caused by the collapse of their food system.
      If Europe is having problems now with illegal migrants, wait until there are hundreds of millions of desperate people fighting to get in, fighting to escape starvation & thirst. Europe will be overrun.
      There will be no more “Europe” as we know it now.

    • neilrieck Says:

      Not a dumb question at all. Atmospheric oxygen levels have been dropping ever since official measurements began in 1990 by the Scripps institute:



      When the processes which consume oxygen (combustion in oxygen-breathing lungs, combustion in our machines, natural fires) exceed the ability of living things to regenerate atmospheric oxygen (primarily photosynthesis) you will see oxygen drop. The carbon fuel we burn was laid down over the course of many tens of millions of years but we have released much of it in only 200 years so have upset the balance.

  4. Kiwiiano Says:

    The zombie apocalypse HAS already started, quite apart from the scenario envisaged in this posting. Ask the Europeans, who are facing hordes of Middle Eastern & African refugees with nothing left to lose.
    Imagine what it’s going to be like when coastal cities are drowning, inland cities are suffering serious food supply shortages, river cities hit by regular floods, southern cities by unliveable temperatures….. wave after wave of more & more desperate folk with no west to go, no jobs, no homes, nothing left…..

    • dumboldguy Says:

      You make this comment and yet you support Jeffy4Z’s foolishness? Conflicted much?

      • Kiwiiano Says:

        Both J & I are hoping we can avoid bloodbaths, something the gun-crazy ‘Mercans seem to delight in. Unless it happens at their school, church or cinema when they are mystified as to where did that come from???

        • dumboldguy Says:

          A comment worthy of Omnologos. Are you trying to usurp his position as Crock’s resident village idiot? He is a master at using the straw man and the non sequitur, but you’re showing promise.

  5. the idea that human contribution to CO2 is the primary driver of global temperature has not stood the test of time, and I suspect the notion that human activity effects the oxygen level on the planet will also die a slow death when real science and objective evaluation of this work done with the CO2 blinders installed is published and makes it out into the public domain.
    If Hansen 1988 failed, as it has by more than 1.5ºC, why are we the people still financing this work?

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