SquareState - CO2 concentration

December 2011 (Scripps) CO2 Concentrations: 391.80ppm

WeatherDem — Mon, 16 Jan 2012 18:49:35 GMT

The Scripps Institution of Oceanography measured an average of 391.80ppm CO2 concentration at their Mauna Loa, Hawai'i's Observatory during December 2011. These readings are from the Scripps' dataset, not NOAA's, which was my original data source when this series began.

391.80 is the highest value for December concentrations in recorded history. Last year's 389.68 was the previous highest value ever recorded. This December's reading is 2.12ppm higher than last year's. As I've written before, this increase is significant. Of course, more significant is the unending trend toward higher concentrations with time, no matter the month or specific year-over-year value.
The yearly maximum monthly value normally occurs during May. Last year was no different: the 394.34 concentration is the highest value reported both last year and all time. If we extrapolate last year's value out in time, it will only be 3 years until Scripp's reports 400ppm average concentration for a singular month (likely May 2015).

Judging by the year-over-year increases seen per month in the past 10 years, I predict 2012 will not see a monthly concentration below 390ppm. I had earlier predicted that 2011′s minimum would be ~388ppm. I overestimated the minimum somewhat since both September's and October's measured concentrations were just under 389ppm.

CO2Now has the following graph on their front page:

It shows concentrations in the Scripps dataset going back to 1958. As I wrote above, concentrations are persistently moving upward.

Given our historical emissions to date and the likelihood that they will continue to grow at an increasing rate in the next 25 years, we will pass a number of "safe" thresholds - for all intents and purposes permanently as far as concerns our species. It is time to start seriously investigating and discussing what kind of world will exist after CO2 concentrations peak at 850 and 1100ppm. I don't believe the IPCC has done this to date. To remain relevant, I think it will have to do so moving forward.

Cross-posted at WeatherDem - the blog.

October, November 2011 (Scripps) CO2 Concentrations: 388.92ppm, 390.31ppm

WeatherDem — Thu, 29 Dec 2011 18:23:25 GMT

The Scripps Institution of Oceanography measured an average of 388.92ppm CO2 concentration at their Mauna Loa, Hawai'i's Observatory during October 2011 and 390.31ppm CO2 concentration during November 2011. These readings are from the Scripps' dataset, not NOAA's, which was my original data source when this series began.

That value is the highest value for October and November in recorded history. Last year's 387.15 and 388.62 were the previous highest respective values ever recorded. This year's readings are 1.77ppm and 1.69ppm higher than last year's. While under 2ppm per year, these two increases are significant. Of course, more significant is the unending trend toward higher concentrations with time, no matter the month.

The yearly maximum monthly value normally occurs during May. This year was no different: the 394.34 concentration (value updated since my last post) is the highest value reported both this year and all time.
I am more convinced than earlier this year that we will not witness CO2 concentrations below 390ppm during any calendar month. September and October were the only months this year which recorded concentrations below 390ppm. Judging by the year-over-year increases seen per month in the past 10 years, I predict 2012 will not see a concentration below 390ppm. I had earlier predicted that 2011's minimum would be ~388ppm. I overestimated the minimum somewhat since both September's and October's measured concentrations were just under 389ppm.

CO2Now has the following graph on their front page:

It shows concentrations in the Scripps dataset going back to 1958. As I wrote above, concentrations are persistently moving upward. For additional reference, here are two graphs showing historical CO2 emissions and historical CO2 concentrations dating back 10,000 years:

Courtesy of Skeptical Science

Courtesy of Skeptical Science

And while previous increases in CO2 concentrations occurred naturally (i.e., PETM), this event is decidedly unnatural. Moreover, it is occurring over an incredibly short time-frame. It is the speed at which concentrations are rising (see last figure above) that is likely to pressure ecosystems in the coming centuries.

400ppm will be a much-discussed threshold due to its psychological significance. We will likely pass that threshold on an annual basis in 2015. 450ppm is another threshold thrown about in the global warming discussion. We will likely pass that threshold in the late 2030s - or about 25 years from now. Given our historical emissions to date and the likelihood that they will continue to grow at an increasing rate in the next 25 years, we will pass a number of "safe" thresholds - for all intents and purposes permanently as far as concerns our species. It is time to start seriously investigating and discussing what kind of world will exist after CO2 concentrations peak at 850 and 1100ppm. I don't believe the IPCC has done this to date. To remain relevant, I think it will have to do so moving forward.

Cross-posted at WeatherDem - the blog.

Climate Change Basics - Gases, Forcing & Surface Temperature

WeatherDem — Thu, 07 Jul 2011 22:43:08 GMT

After running across some resources again recently, I thought it would be a good idea to put some posts together that showed the background of many of the common facts I discuss. In this first post, I wanted to show the relationship between greenhouse gases, radiative forcing and temperatures. In doing, I will use graphics from the IPCC's 4th Assessment Report Technical Summary.

First, here is a graphic of changes in greenhouse gases from ice core and modern observational data, spanning the time period of 20,000 years ago through current:

The portion of this graph I'd like to focus on is the upper left quadrant displaying the time series of atmospheric carbon dioxide concentration. First, note is the transition from ~180ppm 20,000 years ago to between 260 and 280ppm. This transition helped bring the last interglacial period to an end. Of greater import is the more recent transition from 280ppm to 380ppm (as of ~2005; current concentrations are ~390ppm).
The graph's vertical axis is of the same scale, which shows the incredible magnitude of the recent increase in true historical context. More recent research suggests that the 20th century change in atmospheric CO2 concentration is faster than anything in the past 120 million years. Ecosystems can respond to slow climate change, as happened during the Cretaceous Hothouse, when volcanic eruptions put enough greenhouse gases in the climate system to increase temperatures by 5C over millions of years. No massive life form die-offs occurred largely because the oceans were able to absorb the extra CO2 over time. In contrast, life suffered during the Paleocene-Eocene Thermal Maximum. Global temperatures again increased by 5C, but they did so over only ~20,000 years. That rate of change made all the difference in how life was unable to respond in time before going extinct.

All of which leads to the question: how fast will temperatures increase during this event? Many times faster than the most extreme climate shift ever known. 40 to 160 times faster, in fact. And that is based on 1 to 4C warming over just the next 100 years. Overall, warming of 2 to 10C over the next 200 to 300 years could occur. As previous climate events have proven in the past, that level of warming over such an incredibly short time period will likely prove disastrous for many species.

Which leads me to the next graph - one that explains the physics more clearly: how do natural and human-caused sources affect radiative forcing? Do they add to solar radiation or do they act in opposition to it?

As the top portion of the graph shows, CO2 is clearly the largest magnitude positive radiative forcing constituent. CO2 contributes over 1.5W/m^2 by itself. If methane and N2O are included, another 1W/m^2 is added to the mix. The current best estimate of cloud albedo effects is negative .75W/m^2. The bottom portion shows the relative probability of radiative forcing of total aerosol effects (blue dashed line) and greenhouse gas forcing (red dashed line). As you can see, the greenhouse forcing has stronger forcing and much higher relative probability. The result when all the effects are combined is shown by the solid red curve. The highest probability indicates between 1.5 and 2W/m^2 of total anthropogenic radiative forcing - on top of the positive natural radiative forcing.

The third and last graphic shows what the radically higher CO2 concentrations shown in the first figure have already done to global surface and tropospheric temperatures by way of the additional forcing shown in the second figure.

The globe's surface warmed at 0.045C per decade over the past 150 years (ending in ~2005). In the past 100 years, that warming is 0.074C per decade. Most recently, over the past 25 years, the surface has warmed at 0.177C per decade. As the graph clearly shows, the rate of warming is increasing. Moreover, the warming is unequivocal. The chemistry and physics involved in these processes have had measurable effects in the past. They are having the same measurable effects in the present. We know with increasing confidence what the first-order effects of the future will be. This warming won't stop until the emission of greenhouse gas pollution stops.