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As carbon dioxide levels pass a new milestone, misconceptions about climate change persist

September 10, 2013

Guest post by Jeremy Cohen

Something happened on Earth this past month that hadn’t occurred in over three million years. Average carbon dioxide (CO2) levels in our atmosphere surpassed 400 parts per million (ppm), after hovering around 200-275 ppm between the dawn of human history and 1900. Since then, the sharp increase in CO2 concentrations is a consequence of the burning of carbon-based fossil fuels, such as coal, gas, and oil. Why is this important? CO2 does one thing very efficiently: it traps heat that arrives from the sun, keeping it on Earth and turning up the temperature of the planet (Figure 1).


(Fig.1) Global temperature and CO2 levels have a close causal relationship, since CO2 traps heat. The spike in CO2 in the last 100 years suggests an increase in temperature to follow.

Unfortunately, warming is only one aspect of climate change. The planet is heating unevenly, causing widespread shifts in wind and weather patterns. Dry regions are becoming drier and wet areas are wetter, resulting in more droughts and floods and affecting the food supply. As the climate becomes more variable, extreme weather such as heat waves and storms are increasing in intensity. Rising sea levels threaten to displace billions and submerge coastal cities such as Miami and New Orleans. Ecosystems are shifting north and changing the timing of their seasons, threatening species that have adapted to specific environments. A recent USF study showed that parasites can adapt quicker than their hosts and benefit from rapid climatic shifts, suggesting that climate change can also bring an increase in disease.

Despite this, the same, tired misconceptions about climate change continue to float around the media. Although climbing CO2 levels and temperatures are finally starting to become well-accepted, the “controversy” has shifted to whether the ramifications of these increases are meaningful. A 2013 Gallup poll found that 40% of respondents thought the effects of climate change are “greatly exaggerated” in the media. Recently, an op-ed in the Wall Street Journal questioned whether CO2 is truly harmful, suggesting that it promotes plant growth. While technically correct, this point ignores a much greater problem: CO2-driven changes in global weather patterns that disrupt conditions to which plants have adapted. Similarly, the argument that CO2 levels have been higher in the distant past, also posed in the WSJ, ignores the fact that the Earth has never experienced such drastic rate of change in atmospheric content. Rates matter because species need time to adapt to changes in the environment, and sudden shifts can cause massive extinctions and a breakdown of ecosystem services we depend on. Although skepticism is healthy, in this case it is often used as a political tool by special interests that do not want CO2 emissions limited by policy. Among climate scientists, there is virtually no doubt that climate change is both human-caused and a severe threat to the well-being of humanity. A review of nearly 14,000 peer-reviewed articles published between 1991-2012 found that only 0.2% rejected climate change.

Sadly, I have little hope that policies to curb CO2 emissions will improve anytime soon, especially since the issue has become so politicized. For example, a recent study in PNAS suggested that people who identified as conservatives actively avoided products that are labeled as environmentally-friendly, even if they are efficient and cut personal energy costs. This is everyone’s planet and we must all act soon to slow the acceleration of this global catastrophe, regardless of ideology.

One Comment leave one →
  1. Lisa Crummett permalink
    September 10, 2013 4:11 pm

    Nicely done Jeremy. I plan on having my students read your post in my Liberal Arts Biology course.

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