Tweet
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.
17 Comments
So a question related to this post:
Do humans or volcanos emit more Carbon Dioxide gas? Since we know that CO2 is a green house gas emitted by humans and volcanos, the question demands some attention.
The answer to the question can be found in the Cover article of American Geophysical Union’s EOS Newsmagazine, June 14, 2011.
To get to the point. According to the article human activity release ~35 gigatons of CO2 in 2010, a level that has increased significantly from ~20 gigatons in 1900. Naturally there is uncertainty in the measurements. The uncertainty range is 80 (low) to 195 (hi) gigatons per year in 2010 and 10 (low) to 28 (hi) gigatons in 1900.
Volcanic eruptions in the historic past on average emit 0.26 gigatons per year. Look at the numbers and consider the implications. Even taking into account uncertainties, humans account for at least 2 orders of magnitude more CO2 than volcanic emissions. It would be interesting to compare the anthropogenic numbers with the total natural emission from all sources. Regardless, the numbers clearly show human activity swamps volcanic emissions.
But what about in the past and super eruptions you say? Interestingly, the author considered super eruptions effects. To quote the author:
“Supereruptions are extremely rare, with recurrence intervals of 100,000–200,000 years; none have occurred historically, the most recent examples being Indonesia’s Toba volcano, which erupted 74,000 years ago, and the United States’ Yellowstone caldera, which erupted 2 million years ago. Interestingly, these calculations strongly suggest that present-day annual anthropogenic CO2 emissions may exceed the CO2 output of one or more supereruptions every year.”
Get that? Anthropogenic emissions exceed one or more super eruptions EVERY year – which is a hypothetical number since they are so rare. The author provides more information that conclusively shows that volcanos, compared to human activity, are not a major source of CO2.
Bottom line for you disbelievers in human caused climate change: Wake up and smell the coffee!
For more information see “Human Activities Emit Way More Carbon Dioxide Than Do Volcanoes” on the AGU website:
http://www.agu.org/news/press/pr_archives/2011/2011-22.shtml
for a summary of the article by Terry Gerlach, Cascades Volcano Observatory, US Geological Survey published in EOS.
I think the problem is plants they can’t move animals can move. But if plants die animals starve. A massive plan to move plants north might save some species.
Volcano’s put ash in the air that has a cooling effect for about a year the CO2 counters this.
Human caused CO2 has no cooling effect CO2 caused by men would have no counter balance even for a year.
This makes things worse.
Agreed. But the real point is that a volcano’s level of CO2 production is nothing to worry about anyway.
I think that sums up the above nicely. Volcano produced CO2 in the scheme of things? Eh, no worry there.
You might find this piece at washingtonsblog interesting, Weatherdem:
http://www.washingtonsblog.com/2011/07/world-temperatures-did-not-rise-from.html
Seen it before. If you pick your years right, you can get something that looks flat from the jitter. But the graphs on this page are a little bit irrefutable over climate-lengthed timescales. It’s like what they say on Mount Washington about the weather: Don’t like the weather? Wait a minute. But climate is measured adiabatically.
@ WeatherDem … great piece. The Climate Change case is made manifest by your straightforward construction … the charts portray a stark picture indeed.
It boggles the mind that RUSHBO and his army of ‘Mini-Me’s’ ‘inform’ half the nation.
Global Warming and Limbaugh’s Idiocy
Consider that conservatives choose to believe a puny pack of tinfoil-hat conspiracy theorists instead of a veritable army of reputable scientists who claim that global climate change is a serious and emerging crisis …
Article:
http://beeryblog.wordpress.com/2011/06/10/more-on-global-warming-and-limbaughs-idiocy/
It takes a lot of voices to break through Right Wing lies.
The subject is beleaguered while not the serious facts, themselves. Graphs and spreadsheets have been around awhile without producing the desired results.
What’s missing is a broad acceptance by the public. New credible spokespersons are needed most urgently, and they all must be cleaner than a hound’s tooth to fend off public cynicism here. Where do we go with this part?
It does take a lot of voices to break through right wing lies. Yet let’s remember that there is a small handful of scientists whose primary specialty has been dedicated to climate science for a long, long time. New, young, prospective scientists in that endeavor would rightly be discouraged by the toxic aura which prevails. That doesn’t offer reasons for optimism.
There is a large army of support, but it’s somewhat peripheral, and I’m wondering what they do differently going forward to get the public on board. Need a critical mass there for action, and to prevent still more bad things from happening.
Excoriating the public will be ineffective, I think. Am I unreasonable in that view?
Your problem is that the climate people have cried “Wolf!” too many times. Couple that with trying to demonize a gas required for life, comprising .000380 part of the atmosphere. I’m just not worried about it. It’s a hoax, ersatz religion, and/or tax scam.
Oh. You again.
They are clearly reptiloids, trying to prepare the Earth’s atmosphere for an invasion. Carbon dioxizi — diaxi — CO2 is harmful to the way their gills work and their own beta cernturian atmosphere has far less CO2.
thanks, WeatherDem, for taking a factually based stand in this Reality/Information War.
when it came out in 2007, the IPCC (AR4) assessment was conclusive regarding anthropogenic forcing due to GHG emissions, i.e., CO2 and CH4 (as the graphs you pulled clearly indicate).
one of the aspects that is particularly difficult to encapsulate in regards to the profound consequences of the ~150 year buildup of greenhouse gases (and the ocean’s increasing acidity due to the uptake of CO2) is the widespread and diverse regional effects that are taking place at almost every conceivable level in the Earth System, i.e., in the biosphere, the hydrosphere, the atmosphere, and the cryosphere; e.g., distinct changes in: a) the metabolic functioning of micro-organisms in the soil, b) precipitation rates, c) ocean and atmospheric circulation, d) extinction rates and, most notably, e) the extremely rapid and unprecedented melting of the Arctic sea-ice (the pole soon to be exploited by oil prospecting, drilling, and transportation).
side note: since humans have co-evolved with the Earth System and all that that entails, then our (and all the other) species is (are) witnessing evolutionary processes that otherwise would most likely have been hidden from view from individual organisms, perhaps, since the PETM (Paleocene-Eocene Thermal Maximum) 56 million years ago.
however, the present rate of global warming (~350C/20,000yrs) far surpasses the 6C/20,000 year rate 55.6 million years ago.
hold on to your hats, folks!
To varying degrees, both plants and animals have trouble moving either poleward or higher in altitude in short time frames. If this warming were occurring over thousands of years, species’ movement could be successful. Inside of 100 years? Too many species won’t have a chance. Moving plants, or alternatively collecting seed samples for a large number of species, unfortunately would cost large sums of money.
Interesting.
The choice of 1998 is quite purposeful. The warmest El Nino in recorded history occurred during 1997-1998, resulting, quite predictably, in very warm global temperatures for the calendar year 1998: +0.56C (compared to 1951-1980 baseline) occurring after a +0.39 and a +0.32C anomaly in 1997 and 1999 (NASA GISS observations).
More important, however, are decadal average temperatures, since yearly values reflect short-term effects that add to or subtract from the longer time scale signal. The 2000s were warmer (in a statistically significant way) than the 1990s, which were warmer than the 1980s, etc. Barring a major volcanic eruption, the 2010s will be warmer than the 2000s.
One implication of the paper, and I haven’t read it so can’t comment on it fully, could be that the 2000s would have otherwise been even warmer if the sulfur emissions hadn’t been so high. Or put another way, the 2010s could be considerably warmer than the 2000s were as the sulfur emissions’ effects subside.
Actually, I think the public broadly accepts that climate change is predominantly being caused by human factors now. They may not be clamoring for action like the crisis demands, but only because they are largely unaware of the specifics.
Climate scientists are becoming more aware of the need for them to be publicly visible on the subject. They are starting to take bolder actions in support of action. That development might be late in coming, but it’s good to see it finally occurring.
In addition, youth around the world are becoming more and more active about demanding action for their sake. That effort will continue to grow to the point where it cannot be ignored politically, despite the ridiculous sums of money being spent to maintain the status quo.
The public doesn’t need to be excoriated. More nudging in the correct direction will be sufficient.
Thank you for the very well constructed comment, x174.
The encapsulation problem you mention was one of the reasons why I never wrote about many of the IPCC materials. The more I sought out information, the more overwhelming the problem appeared to me. It has to be taken in by bits and pieces. But the basics should be easily accessible and understood by more of the public. Thus, this diary and others that will follow in the future.