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The New 400ppm World: CO2 Measurements at Mauna Loa Continue to Climb

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The level of carbon dioxide in the atmosphere reached 400 parts per million for the first time in human history at Mauna Loa Observatory in Hawaii in May last year. That same level has been reached again in the last few days. This year we’ve hit the target in March, two months earlier, and it will stay above 400ppm for longer. At that rate, it will only be a handful of years until we are living in an atmosphere permanently above 400 ppm. While 400 ppm is a somewhat arbitrary marker, humans did not exist the last time atmospheric CO2 was at that level.

Each year, the amount of CO2 in the atmosphere rises during the northern hemisphere autumn and winter, then decreases through the spring and summer as plant growth removes the CO2 from the air during the growing season. The annual peak usually occurs in May, so this season we potentially have a couple of months to experience this new milestone of 400ppm CO2 before the annual decline occurs. Source: Scripps Institute of Oceanography.

Each year, the amount of CO2 in the atmosphere rises during the northern hemisphere autumn and winter, then decreases through the spring and summer as plant growth removes the CO2 from the air during the growing season. The annual peak usually occurs in May, but this season we will experience this new milestone of 400ppm CO2 for a couple of months before the annual decline occurs. Source: Scripps Institute of Oceanography.

The excess carbon that you and I have been dumping into the atmosphere for the last half century — from deforestation and from burning coal, oil, and natural gas — has pushed CO2 levels more than 25% higher than when measurements of air began at Mauna Loa in the late 1950s. These critical measurements by the Scripps Institution of Oceanography represent the longest continuous monitoring of CO2 in air. However, facing a funding crisis, Scripps has astoundingly had to resort to crowdsourcing to make up the shortfall in federal funding. They are one of only two agencies that carries out measurements at Mauna Loa (the other one being NOAA, that began monitoring about a decade later than Scripps).

Carbon dioxide (CO2) concentration in air at the Mauna Loa observatory in Hawaii have increased by 27% increase since measurements began in 1958 when levels were at 317ppm. Today they have topped 400ppm. Source: Scripps Institute of Oceanography.

Carbon dioxide (CO2) concentration in air at the Mauna Loa observatory in Hawaii has increased by more than 25% since measurements began in 1958 — when levels were at 317ppm. Today they have topped 400ppm. Source: Scripps Institute of Oceanography.

As I’ve described in an earlier blog, my scientific career began in a 350ppm world. And, now in our 400ppm world, we need a world-changing view to tackle the challenge that we face. We must reduce global emissions of carbon, by transforming both how we produce energy and how we choose to live going forward. What is required of us is enormous but I believe we are up to the task — after all, the 450ppm world is fast approaching.

Featured image courtesy of Flickr user Sharloch.

Posted in: Global Warming Tags:

About the author: Melanie Fitzpatrick, a climate scientist with the UCS Climate and Energy Program, is an expert on local and global impacts of climate change. She holds a Ph.D. in Geophysics from the University of Washington, specializing in the role of sea ice and clouds in Antarctica. See Melanie's full bio.

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  • rabbit

    If 90% of the heat from global warming is being taken up or absorbed by the oceans, where is all that heat going? How much of this total oceanic warming occurs at the poles, and how much is being transported to the poles by ocean currents? Or is the heat transported by ocean currents into deep ocean layers without affecting the poles? The poles are warming faster than mid latitudes–to what extent is ocean warming contributing to heating at the poles?

  • rabbit

    RE the site for CO2 measurements: if CO2 is a well mixed gas, would it be possible to obtain reliable and representative measurements of CO2 more cost effectively at a low cost site, eg, at an existing lab at sea level somewhere much less expensive to operate? Perhaps this is being done at many sites and if so, why is Mauna Loa helpful or necessary?

    Re CO2 measurements, as noted the CO2 in the atmosphere is 400 ppm, but the global warming average has not kept pace or more likely has been offset in the last decade by oceans absorption of the added warming; is this global warming oceanic absorption expected to continue as the surface waters rich in CO2 sink and join deep cold water currents near the North Atlantic? I have more questions but thats all for now! Thanks in advance.

  • http://www.campbellpetro.com Donald Campbell

    One solution to this is to wean ourselves from carbon-based fuels. A reasonable means of doing this is via the Carbon Fee-and-Dividend proposal of the Citizens Climate Lobby. CF&D is a gradually increasing fee on the potential CO2 produced at oil/gas wells, coal mines, and at ports of entry. This will stimulate development of renewable energy sources which will help to satisfy our energy demand and reduce atmospheric CO2 and slow the rate of acceleration of climate change. It will take an international effort on the scale of World War II. And probably require centuries. Therefore, we urgently need to start this process now. Check it out at: http://citizensclimatelobby.org/about-us/faq/

  • Richard

    I hope we are ‘up to the task’ of facing the challenge of a 400ppm+ world.

    I must add, though, that we need more than hope. It will take concerted efforts by those of us concerned (excuse the pun) in order to overcome the inertia that is operating in most of the world about this issue.

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