Carbon dioxide measured at Mauna Loa reaches worrying new levels
April 2014 has become a depressing new 'milestone' for carbon dioxide levels in our atmosphere, as it was the very first time the monthly average reached over 400 parts per million - a new high in human history.
Just shy of one year ago, when carbon dioxide values at the top of Hawaii's Mauna Loa volcano reached a May peak, scientists at both the U.S. National Oceanic and Atmospheric Administration (NOAA) and the Scripps Institution for Oceanography revealed that the daily average for CO2 levels had climbed above 400 parts per million. While this milestone didn't represent some apocalyptic tipping point, it did show us further evidence of the dangerous path that we're on, pumping billions of tons of carbon dioxide into the atmosphere every year and putting an ever-increasing burden on our already-stressed environment.
Now, less than a year later, and a month shy of actually reaching the yearly peak carbon dioxide values at Mauna Loa, measurements there have showed that the entire month of April averaged out to over 400 parts per million.
Measuring from the top of a volcano
It may seem strange to measure carbon dioxide levels at the summit of a volcano, since volcanoes emit carbon dioxide (among other gases). However, Mauna Loa is an excellent location to read the 'background' levels of carbon dioxide in the atmosphere. The volcano, being in the middle of the northern Pacific Ocean, is situated far from any direct sources, and the summit is far above local sources and any 'sinks' like the forests and plants of the island. As for any carbon dioxide the volcano itself emits, the scientists can easily tell the difference just by watching the hour-to-hour readings they collect. The values collected that represent the background amount rise and fall very slowly. Changes from the volcano itself show up as spikes in the data. All the scientists do is filter out these spikes and they're left with the global average concentration. NOAA's Dr. Steve Ryan goes into this more on the NASA Earth Observatory blog.
Although some who try to cast doubt on the science of climate change and try to turn the issue into a debate have put forward the idea that the amount of CO2 being put into the atmosphere by human activity is tiny compared to what's produced by volcanoes, the exact opposite is true. The amount we produce through our activities dwarfs what's produced by volcanoes, as we emit over 100 times as much every year.
Is carbon dioxide the only strong greenhouse gas? No, water vapour and methane are powerful ones too. However, water vapour is fairly well balanced in the atmosphere, as the water cycle acts very quickly. For methane, which is a very powerful greenhouse gas, values are on the rise - partly from things like defrosting Arctic tundra and from the bottom of the Arctic Ocean, and partly from activities like natural gas extraction (fracking) - the Earth still has the ability to 'take up' these excess amounts (at least for now). Carbon dioxide is the worry because we've putting so much of it into the atmosphere, when we've already overtaxed the environment's ability to deal with the amounts being introduced into the system. As a result, our oceans are becoming more acidic as the water absorbs more and more CO2, the oceans are warming up as surface layers absorb some of the heat from the atmosphere and mix it down to deeper layers, and the ability of the atmosphere to trap heat from the sun is increasing, leading to rising global temperatures.
The Dangerous Path
These levels - 400 parts per million, meaning that on average, for every million molecules in the air, 400 of them are carbon dioxide molecules - may seem very small, but the problem comes from how much there is now, compared to what the Earth's climate is used to. Levels before the Industrial Revolution (towards the left side of the above graph) averaged out at around 270 ppm, so levels now represent a nearly 45 per cent increase over what Earth's ecosystem is currently adapted to deal with. Earth's climate and ecosystem were in careful balance before we started adding more CO2 to the atmosphere, and the changes we've made have happened very quickly (again, see the above graph) - much quicker than they've happened in the past. It is true that carbon dioxide levels have been higher than 270 ppm in the past. Scientists have seen this by examining gases trapped in ice cores. Levels have even gotten up slightly above 300 ppm for very brief periods. However, look back 800,000 years and they haven't gotten up this high - not even once.
It's really time to get off this path and on to one that will actually take us towards a sustainable future. As it is now, we're headed, step by step, for disaster.