During April 2014, the Scripps Institution of Oceanography measured an average of 401.33 ppm CO2 concentration at their Mauna Loa, Hawai’i Observatory.
This value is important because 401.33 ppm is the largest CO2 concentration value for any April in recorded history. This year’s April value is approximately 2.97 ppm higher than April 2013′s. Month-to-month differences typically range between 1 and 2 ppm. This particular year-to-year jump is outside of that range, but not extreme. 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.
April 2014’s mean value of 401.33 ppm also represents the first time in contemporary history that a monthly mean exceed 400 ppm. The last time CO2 concentrations were this high was at least 800,000 years ago, and likely even longer – on the order of millions of years ago. The implications of this measurement are in some ways subtle and in some ways overt, as I discuss below.
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) in 2013. May 2013′s record held until April of this year when the annual cycle pushed a monthly value above this record. Just like in years past, May 2014 is likely to set another new all-time monthly record (until February or March 2015 … you get the idea.) April 2014 is the first calendar month with mean CO2 concentrations above 400 ppm, but it won’t be the last. May 2014 will be the second. September 2015 will likely be one of the last months with mean concentrations below 400 ppm. After that, we probably won’t witness <400 ppm again.
Figure 1 – Time series of CO2 concentrations measured at Scripp’s Mauna Loa Observatory in February from 1958 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 seven months ago (red curve) and the yearly maximum value occurred eleven 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 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 during the past 150 years has almost exclusively gone into the ocean; during the past 15 years into the deep ocean (>700m). The latter is the result of low-frequency climate oscillations’ recent states (e.g., negative IPO phase). That process cannot and will not last forever. Within the next 5-15 years, those oscillations will switch phase and the excess energy will once again be more apparent near the Earth’s surface (where measurements are numerous and accurate). Meanwhile, the extra oceanic heat will continue to expand the ocean’s volume, which will further increase global mean sea level. That heat will also one day transfer to the atmosphere, causing further changes for land-based systems.
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.
Climate change as a result of increasing GHGs is affected cumulatively – that is, climate change effects we witness today are mostly a result of previous decades’ GHG concentrations, not today’s. Today’s concentrations will exert climate influence in future decades, not tomorrow. This lagged effect is one significant problem with climate action. Theoretically, if we could reduce CO2 emissions to zero today, today’s concentrations would cause further climate change for decades. All that said, the most obvious way to reduce additional future climate change is to reduce emissions. That requires either economic contraction or decarbonization (reducing the amount of carbon emitted per unit of economic output).
Since we don’t want the former to happen, we have to focus on the latter. What does that entail? That entails directing public money to widespread science and technology research, development, and deployment. That entails innovators trying thousands of ideas so that we implement a few successes that are really efficient. Not every attempt will succeed – indeed, most will fail. We have to find out what doesn’t work as part of the process to find out what does work. That entails a sustained commitment to such efforts. This won’t happen with three years’ funding. It will happen with thirty and three hundred years funding. The California-related reports I mentioned yesterday (and will write about) demonstrate just how challenging the task is. Those challenges relate to opportunities, which is exactly how we have to frame them in order to get people to support them. As I often write, CO2 emissions and later concentrations will decline when we as a society want them to.