Monday marks a major milestone for life on Earth, and it isn’t one to be proud of. Carbon dioxide levels in the atmosphere are the highest they have been in at least 800,000 years, reaching beyond 402 parts per million. Scientists warn us that we must act immediately if we want to slow the effects of carbon dioxide in the atmosphere, even as those levels continue to climb into uncharted territory.

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Scientists use air bubbles trapped inside ice in Greenland, Antarctica and some glaciers to determine the historic CO2 level in the atmosphere. Prior to today, the only time carbon dioxide levels reached this high was somewhere between 800,000 and 15 million years ago – most likely before human civilization even existed. Modern CO2 monitoring started on the top of Hawaii’s two mile high Mauna Loa volcano in 1958, which showed a reading of 402.2 ppm on April 7, 2014. NOAA showed a reading of 402.11 ppm on the same date.

Related: Scientists Report Greenhouse Gas Emissions Have Reached a “Troubling Milestone”

Even more concerning is the fact that we may not have even reached our highest level for the year. Historically, CO2 peaks in May so the level may continue to climb this year. Last year in May levels reached 400 ppm for the first time. And while the planet may have reached 400 ppm in the past, it is important to note that those fluctuations in the atmosphere happened naturally. This time the change is caused by mankind and the consequences are proving to be disastrous.

Via Mashable

Lead image via eutrophication&hypoxia