During February 2014, the Scripps Institution of Oceanography measured an average of 398.03 ppm CO2 concentration at their Mauna Loa, Hawai’i Observatory.
This value is important because 398.03 ppm is the largest CO2 concentration value for any February in recorded history. This year’s February value is approximately 1.23 ppm higher than February 2014′s. Month-to-month differences typically range between 1 and 2 ppm. This particular year-to-year jump is within that range, albeit smaller than some other recent months. For example, February 2012’s year-over-year change was +3.37 ppm and May 2012’s change was +3.02 ppm. Of course, the unending long-term trend toward higher concentrations with time, no matter the month or specific year-over-year value, as seen in the graphs below, is more significant.
The yearly maximum monthly value normally occurs during May. 2013 was no different: the 399.89ppm mean concentration in May 2013 was the highest recorded value (neglecting proxy data). May 2013′s record will hold until the end of this month when the annual cycle pushes a monthly value above this record. Just like in years past however, May 2014 is likely to set another new all-time monthly record (until February or March 2015 … you get the idea.)
Figure 1 – Time series of CO2 concentrations measured at Scripp’s Mauna Loa Observatory in February from 1959 through 2014.
How do concentration measurements change in calendar years? Let’s take a look at two charts that set that context up for us:
Figure 2 – Monthly CO2 concentration values (red) from 2010 through 2014 (NOAA). Monthly CO2 concentration values with seasonal cycle removed (black). Note the yearly minimum observation occurred five months ago (red curve) and the yearly maximum value occurred nine months ago. CO2 concentrations will increase through May 2014, as they do every year, before falling again towards this year’s minimum value.
The data in this graph doesn’t look that threatening. What’s the big deal about CO2 concentrations rising a couple of parts per million per year anyway? The problem is the long-term rise in those concentrations and the increased heating they impart on our climate system. Let’s take a longer view – say 50 years:
Figure 3 – 50 year time series of CO2 concentrations at Mauna Loa Observatory (NOAA). The red curve represents the seasonal cycle based on monthly average values. The black curve represents the data with the seasonal cycle removed to show the long-term trend (as in Figure 2). This graph shows the relatively recent and ongoing increase in CO2 concentrations.
The big deal is, as a greenhouse gas, CO2 increases the radiative forcing toward the Earth, which over time increases the amount of energy in our climate system as heat. This excess and increasing heat has to go somewhere or do something within the climate system because the Earth can only emit so much long wave radiation every year. The extra heat added to the climate system within the past 15 years has almost exclusively gone into the deep ocean. This is the result of low-frequency climate oscillations’ recent states. That process cannot and will not last forever. Within the next 5-15 years, those oscillations will switch phase and the excess energy will be more apparent near the Earth’s surface. Meanwhile, the extra oceanic heat will continue to expand the ocean’s volume, which will further increase global mean sea level.
CO2 concentrations are increasing at an increasing rate – not a good trend with respect to minimizing future warming. Natural systems are not equipped to remove CO2 emissions quickly from the atmosphere. Indeed, natural systems will take tens of thousands of years to remove the CO2 we emitted in the course of a couple short centuries. Moreover, human technologies do not yet exist that remove CO2 from any medium (air or water). They are not likely to exist at a large-scale for some time. Therefore, the general CO2 concentration rise in the figures above will continue for many years, with effects lasting tens of thousands of years.
The rise in CO2 concentrations will slow down, stop, and reverse when we decide it will. Doing so depends primarily on the rate at which we emit CO2 into the atmosphere and secondarily how effective CO2 removal in the future is. We can choose 400 ppm or 450 ppm or almost any other target (realistically, 350 ppm seems out of reach within the next couple hundred years). Our concentration target value choice is dependent on the type of policies we decide to implement. It is our current policy to burn fossil fuels because we think doing so is cheap, although current practices are massively inefficient and done without proper market signals. We will widely deploy clean sources of energy when they are cheap; we control that timing. We will remove CO2 from the atmosphere if we have cheap and effective technologies and mechanisms to do so, which we also control to some degree. These future trends depend on today’s innovation and investment in research, development, and deployment. Today’s carbon markets are not the correct mechanism, as they are aptly demonstrating. But the bottom line remains: We will limit future warming and climate effects when we choose to do so.