Something happened on Earth last week that had not occurred in more than 3 million years: A reading of carbon dioxide (CO2) levels in the atmosphere nearly surpassed 400 parts per million (ppm).

The number is telling: as recently as the 19th century, CO2 levels were at 275 ppm — a number that had been maintained since the dawn of human history.

Since then, the sharp increase in CO2 concentrations can be largely attributed to the burning of carbon-based fossil fuels, such as coal, gas and oil. On May 9, the National Oceanic and Atmospheric Administration reported a reading higher than 400 ppm, which has since been revised to 399.89 ppm.

Why is this important? CO2 does one thing very efficiently: it traps heat from the sun, keeping it on Earth and turning up the temperature of the planet.

Unfortunately, warming is just 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 becoming wetter, resulting in more droughts and floods and affecting food production. As the climate becomes more variable, anomalies such as heat waves and storms are increasing in intensity. Sea level rise threatens to displace billions and submerge coastal cities such as Miami and New Orleans. Ecosystems are shifting in latitude and in their seasonal timing, threatening species that have adapted to specific environments.

A recent USF study published in Nature Climate Change, led by Thomas Raffel in the Department of Integrative Biology, suggests that even parasites, which are small and can adapt faster than hosts, benefit from rapid climatic shifts.

Despite this, commonly encountered misconceptions continue to run rampant in American society.

Though climbing atmospheric carbon levels and temperatures are finally starting to gain universal acceptance as facts, the “controversy” has shifted to whether the ramifications of these increases are meaningful. A 2013 Gallup poll found that 41 percent of respondents believe the effects of climate change are exaggerated.

A May op-ed piece in the Wall Street Journal questioned whether CO2 is truly harmful, suggesting that it promotes plant growth. While this is certainly true, it ignores CO2-driven changes in global weather patterns that disrupt the climatic conditions plants have adapted to. Similarly, the argument that CO2 levels have been higher in the distant past, also posed in the piece, ignores the fact that the Earth has never experienced such drastic rate of change in atmospheric content.

While 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 anthropogenic and a severe threat to the well-being of humanity.

There seems to be little indication that policies to curb CO2 emissions will improve any time soon, especially since the issue has become so politicized. A recent study published in the Proceedings of the National Academy of Sciences of the United States suggests that people who are self-identified conservatives actively avoid products that are labeled as environmentally-friendly, even if they are otherwise efficient and cut personal energy costs.

This is everyone’s planet and we must act soon to slow the acceleration of this global catastrophe, regardless of ideology.