And the Future?.......

 

gapyear.com (2012). The future of travel [online]. Available from: <https://www.gapyear.com/news/163953/the-future-of-travel>. [Accessed 09th January 2016].

Just to look at future situations a little more, as after all, the past is behind us, the present is now, but the future, well that’s a whole blank page.  Trying to predict what will be written on that page is of great importance to all life on the planet and the actions and choices we make today will play out in the future for generations to come. 

You many by now of noted somewhat of a bias to my view. You would not be wrong and although I remain optimistic, I am a self-confessed climate change worrier, I try to remain impartial but as I see it, it is far better to assume worst case scenario and act to limit the effects then to sit back and wait to see what happens. 

I continued looking at paper relating to future situations and came to note a paper by  Schimela et al, (2015) discussing increasing CO₂ in relation to the terrestrial carbon cycle, “feedbacks from the terrestrial carbon cycle significantly affect future climate change” (Schimela et al, 2015), well that got my attention, I read on and according to Schimela et al, (2015) this is among one of the largest and most uncertain feedbacks, but the paper looks at this in relation to the CO₂ effect, which is described as an increase in photosynthesis rates in relation to  increasing CO₂ on terrestrial carbon storage (Schimela et al, 2015).  It would seem that out little green friends (the plants, I have not gone mad and started hoping that E.T is coming to save the world!) are working hard to try to clean up after us.  This effect increases with increased CO₂ and temperature, meaning that in warmer climates we really do need to limit deforestation and look after our green friends. 

Unfortunately, there is a limit to this effect and when this is exceeded the CO₂ effect is no longer able to keep pace as it were, at this point growth rates of CO₂ will increase. 

What I am left considering is the fact that so far all of the paper I have looked at point to ever increasing levels of CO₂ leading to increasing global temperature, so I am left pondering, if the plants are already working hard, how fast will rates increase when they’re no longer able to keep pace?  Again it would seem that in order for nature to help us we must also help it by limiting CO₂ emissions.  But would we see continued warming following a halt to emissions?  This was a question addressed by Frölicheret al, (2014), they comment that many studies have shown that even following an emissions halt there is a high likelihood that for many centuries to follow the global mean surface temperature would not decrease and could in fact increase.

What does this mean for us? Well Salinger(2005) has considered this question too, working on the idea that temperature increase will fall somewhere between 2°C to 4.5°C, Salinger (2005) suggest that we are likely to see extremes of climate and alterations to precipitation such a heavy rains and droughts and predicts unprecedented changes to climate that human settlement has never had to endure.  That all sounds a bit scary, but it does bring me back to my first blog post when I was discussing the book I was reading by Mark Lynas, Six Degrees, Our Future on a Hotter Planet.  It seems to me that all signs point to one thing, reduce CO₂ emissions or be prepared to adapt to the consequences.  But that is just my view and although I am aware that it is a view shared by many, it may not be yours. 

References;

Frölicher, T.L.  Winton, M.  Sarmiento, J.L.  (2014). Continued global warming after CO₂ emissions stoppage. Nature Climate Change. 4, pp.40 – 44

Salinger, M.J. (2005). Climate Variability and Change: Past Present and Future – An Overview.  Climatic Change. 70, pp.9 - 29.

Schimela, D.  Stephens, B.B.  Fishera, J.B.  (2015). Effect of increasing CO₂ on the terrestrial carbon cycle. PNAS. 112, pp.436–441.

‘Blue sky thinking’!

BeckyBendyLegs (2015). Why is the sky blue? [online]. Available from: <http://beckybendylegs.com/why-is-the-sky-blue/>. [Accessed 09th January 2016].

Previously we saw that in order to meet the 2°C target that action should be taken now, reading a little more in to future issues I came across a number of papers discussing such issues.  Booth et al, (2012) use “full coupled climate–carbon cycle model and a systematic method to explore uncertainties in the land carbon cycle feedback” what they found was that the feedbacks were lager that even those estimated by the IPCC, stating that the most important uncertainty was that of photosynthetic metabolism in response to temperature, their study showed these responses to play a key role in future changes (Booth et al, 2012).  So we need to limit temperature increases to minimise the effect to plant metabolism to limit their effect on temperature, but to do this we need to reduce CO₂ emissions. 

Friedlingstein et al, (2014) discuss the growth of such emissions and their implications, they state that these emissions have increased by “2.5% per year on average over the past decade” (Friedlingstein et al, 2014). We are already two thirds of a way through our quota of CO₂ if we are to meet the 2°C target, continuing at the current rate we have less than 30 years left of our quota.  Not very long at all.  The business as usual approach that I touched upon at the start of my blog is just no longer viable.

The business as usual approach would see continued use of fossil fuels but McGlade et al, (2015) suggest that continued unabated use would push us over our target temperature.   They state that if were are to even have a 50% chance of keeping with in our target temperature range, then between 2011 and 2050 the cumulative carbon emissions must not exceed 1,100 giga-tonnes.  Using all of the fossil fuel reserves would push us three times over that limit.  It may be a hard pill to swallow for some, for example to meet the targets over 80% of coal reserves should not be used between 2010 and 2050 (McGlade et al, 2015). 

Maybe ‘business as usual’ needs some ‘blue sky thinking’!

References;

Booth, B.B.  Jones, C.D.  Collins, M.  Totterdell, I.J.  Cox, P.M.  Sitch, S.  Huntingford, C.  Betts, R.A.  Harris, G.R. Lloyd, J.   (2012). High sensitivity of future global warming to land carbon cycle processes. ENVIRONMENTAL RESEARCH LETTERS. 7, pp.24002 (8pp).

Friedlingstein, P.  Andrew, R.M.  Rogelj, J. Peters, P.G.  Canadell, J.G.  Knutti, R.   Luderer, G.   Raupach, M.R.  Schaeffer, M.  Vuuren, P.D.  Le Quéré, C.  (2014). Persistent growth of CO2 emissions and implications for reaching climate targets. NATURE GEOSCIENCE. 7, pp.709 - 715.

McGlade, C.  Ekins, P.  (2015). The geographical distribution of fossil fuels unused when limiting global warming to 26C. NATURE. 517, pp.187 - 202.

Time to Act.

Having looked at accelerating atmospheric CO₂ in the previous post I decided to move things along a little and consider the challenge that humanity faces to keep warming to a minimal and the impacts of delaying actions.  Thankfully as we saw in an earlier post COP21 is trying to address these issues.  But I found two interesting papers in Nature that looked at just such issues, Peters et al, 2013 and Allen and Stocker, 2014 both discuss such issues in their papers.

Peters et al, 2013 postulate that as emissions track towards the high end of scenarios it is uncertain if warming will stay below the 2°C target and that delay in mitigation will create significant problems in attaining the 2°C target as well as raising the issue of a delay in response to any mitigating actions allow emissions to continue to rise even after implication of mitigating actions.  Put quite simply this means that even if we act now we may still pass our 2°C target.

Allen and Stocker, 2014 look in to the impacts in delaying mitigation actions and discuss the rate of peak warming during mitigation delay.  They find that “peak-committed warming is increasing at the same rate as cumulative CO₂ emissions, about 2% per year, much faster than observed warming, independent of the climate response”, they show in their paper that delays now will require an increased rate of reduction in the future.  Allen and Stocker, 2014, provide an illustrated figure of the emission scenarios (see below, figure 1). They echo the ethos of Peters et al, 2013, that in order to meet the agreed target emissions must be reduced and go on to say that temperature targets alone are insufficient, stating that stronger mitigations should be implemented incorporating other additional climate targets. 



Figure 1 Illustrating emission scenarios. 

Allen, M.R.  Stocker, T.F.  (2014). Impact of delay in reducing carbon dioxide emissions. NATURE CLIMATE CHANGE. 4, pp.23 - 26.

 

What I take from this is that action is required now so do mind admitting that I am glad that COP21 took place.  In my personal opinion it is a step in the right direction, however I do feel that we still have quite a way to go if we are to even meet the suggested target.  What about you dear reader?  Do you feel the same?

 

 

Figure 1 references as cited by Allen and Stocker, 2014. 

9. Stocker, T. The closing door of climate targets. Science 339, 280–282 (2012).

22. Andres, R. J. et al. A synthesis of carbon dioxide emissions from fossil-fuel combustion. Biogeosciences 9, 1845 (2012).

Reference;

Peters, G.P.  Andrew, R.M. Boden, T. Canadell, J.C.  Ciais, P.  Le Quéré, C. Marland, G. Raupach, M.R. Wilson, C.  (2013). The challenge to keep global warming below 2 °C. NATURE CLIMATE CHANGE. 3, pp.4 - 6.

Allen, M.R.  Stocker, T.F.  (2014). Impact of delay in reducing carbon dioxide emissions. NATURE CLIMATE CHANGE. 4, pp.23 - 26.

 

 

 

 

 

 

Accelerating atmospheric CO2

 

Although the paper I am about to discuss is a little dated (it was published in 2007) it still offers some very insightful information in regard to CO₂ and natural sinks.   The paper by Canadell et al (2007) was published by Proceeding of the National Academy of Science of the United States of America or PANS and was titled “Contributions to accelerating atmospheric CO2 growth from economic activity, carbon intensity, and efficiency of natural sinks”  It sets out to summarise the current (at the time) situation in regard to CO₂ increases in relation to three increases, two resulting from emissions and the third in relation to “increase in the airborne fraction (AF) of CO₂ emissions” (Canadell et al, 2007), which they say is evidence that natural carbon since, such as the ocean are becoming less efficient at sequestering anthropogenically produced emissions.  They find that AF observations are larger than initial model projection.     

Their findings, despite being now dated do make for an uncomfortable truth.  They found that from the start of the Industrial Revolution to 2006 CO₂ rose from 280 ppm to 381 ppm.  This they say is the highest it has been during the last 650,000 years (Canadell et al, 2007).  They also showed that emissions from 1850 to 2006 accounted for ≈ 330 PgC and that land use change added a further 158 PgC over this period.

Canadell et al (2007) also considered Gross World Product (GWP) in terms of carbon intensity, which is defined as  F_Foss/GWP, this is a ratio which “refers to  CO₂ emissions required to produce a unit of economic activity at a global scale” (Canadell et al, 2007) this value has been increasing by ≈ 3 % per year since 2000. 

They also looked at natural sinks and atmospheric growth rates of CO_2.  They state that anthropogenic emissions are exceeding sequester rates of natural skins (the worlds clean-up crew can’t keep pace with us).  AF (as discussed earlier) can vary greatly and since 1959 it was 0.0 to 0.8, but these rates have increased and from 2000 to 2006 AF was 0.45 (Canadell et al, 2007).  Canadell et al (2007) go on to say that since 1959, which saw the start of CO₂ monitoring, 2000 to 2007 have seen the most rapid increases in CO_2.

Table 1. Canadell et all (2007) produced this table to summaries the findings of their study in relations the global carbon budget.  Even just by glancing quickly at the ‘Sources’ column it is clear to see an increase from a total mean of 6.7 PgC y^-1  from 1959 to 2006 to a total of 9.1 PgC y^-1  from 2000 to 2006. 

 

Reference;

Canadell, J.G. Le Quéré, C. Raupach, M.R. Field, C.B. Buitenhuis, E.T. Ciais, P. Conway, T. J. Gillett, N.P. Houghton, R.A. Marland, G. (2007). Contributions to accelerating atmospheric CO2 growth from economic activity, carbon intensity, and efficiency of natural sinks. Proceeding of the National Academy of Science of the United States of America. 104, pp.18866–18870.

 

 

 

 

 

A Year of Carbon Dioxide Animated

 

 

Below is a short video produced by Nasa Goddard Flight Centre which was posted on You Tube illustrating a years of CO₂ for the Earth.  It is interesting to see how it moves around the globe and where levels are highest. 

 

 

 

 

 

Reference;

Nasa Goddard (2014). NASA | A Year in the Life of Earth's CO2. [online]. Available from: <https://www.youtube.com/watch?v=x1SgmFa0r04>. [Accessed 08th January 2016].

Atmospheric CO₂

Time to look more to the present.  CO₂ is a relatively regular feature in the news and something we all often hear discussed in various situations.  With this in mind I found a rather interesting paper by Lacis et al (2010) in Science titled “Atmospheric CO₂: Principal Control Knob Governing Earth’s Temperature” (Lacis et al, 2010).  The paper opens with a nice little introduction explaining to the reader that CO₂ “does not condense and precipitate from the atmosphere at current climate temperatures” (Lacis et al, 2010).  CO₂ along with other noncondensing greenhouse gases such as ozone, N2O, CH4, and chlorofluorocarbons prevent a collapse of the greenhouse effect due to their radiative forcing effects and account for 25% of the greenhouse effect (Lacis et al, 2010).  Its true’ to say that they are a necessity of life, without the greenhouse effect the planet would become icebound.  But as with most things in life, it’s about just the right balance, too much of a good thing is never good in the long term.  The paper goes on to say the remaining 75% of the greenhouse effect is provided by water vapour and cloud due to feedback processes. 

“It often is stated that water vapour is the chief greenhouse gas (GHG) in the atmosphere. For example, it has been asserted that about 98% of the natural greenhouse effect is due to water vapour and stratiform clouds with CO₂ contributing less than 2%.  If true, this would imply that changes in atmospheric CO₂ are not important influences on the natural greenhouse capacity of Earth, and that the continuing increase in CO₂ due to human activity is therefore not relevant to climate change.”  (Lacis et al, 2010). 

 

However Lacis et al (2010) go on to explain that whilst the strongest climate feedbacks are resulted from water vapour in radiative forcing experiments global climate change forcing is not as a result of this.  Their study found CO₂ to be the principle controlling atmospheric gas with respects to controlling the greenhouse effect.  (Are you shocked by this?  I doubt it somehow.)  In relation to our current climate they note that solar irradiance has only negligible impacts.  At the time of publishing in 2010 the current CO₂ level stood at 390 ppm, but an interglacial maximum’s typical levels would be approximately 280 ppm.  CO₂ has a very long residence time of thousands of years, Lacis et al (2010) express their concern at ever increasing levels due to anthropogenic activity by stating “the atmospheric CO₂ control knob is now being turned faster than at any time in the geological record.” (Lacis et al, 2010)

 

NASA (2010). How Carbon Dioxide Controls Earth's Temperature [online]. Available from: <http://www.giss.nasa.gov/research/news/20101014/>. [Accessed 08th January 2016].

Reference;

Lacis, A.A. Schmidt, G.A. Rind, D. Ruedy, R.A. (2010). Atmospheric CO₂: Principal Control Knob Governing Earth’s Temperature. Science. 330, pp.356-359.

Decoupling of atmospheric CO₂ and global temperatures.

In a previous post you may recall that I looked a paper by Retallack (2002) titled “Carbon Dioxide and Climate over the Past 300 Myr”, in it the idea of decoupling of atmospheric CO₂ and global temperatures was touched upon.  As I plan to move on to look at present situations shortly, I felt it may be useful to have a look at the evidence for decoupling.  As a result I came across a paper by Veizer et al (2000) published in Nature titled “Evidence fordecoupling of atmospheric CO2 and global climate during the Phanerozoic eon”. 

The paper focuses on the Phanerozoic eon and Veizer et al (2000) present a reconstruction of tropical sea surface temperatures.  I highly recommend following the link on the paper title and reading it in detail for yourself as I will only be covering the basic details.  It was found that “large oscillations of tropical sea surface temperatures in phase with the cold ± warm cycles, thus favouring the idea of climate variability as a global phenomenon”  (Veizer et al, 2000), however when this data was compared with a mass balance model reconstructing temperature which was produced using atmospheric CO₂ there was a conflict in findings.  In order for the results to be reconciled it would be necessary to assume that CO₂ was “not the principal driver of climate variability on geological timescales for at least one-third of the Phanerozoic eon, or if the reconstructed carbon dioxide concentrations are not reliable” (Veizer et al, 2000). 

As we have seen previously, it is generally accepted that increases in CO₂ result in increased global temperatures.  So surely it should also follow that lower CO₂ levels in the atmosphere would see lower global temperatures.  The Permo/Carboniferour and Cenozoic icehouse episode follow this idea and show low partial pressures of CO₂ in the atmosphere.  However biochemical models for the late Ordovician/earliest Silurian and late Jurassic/early Cretaceous show high values of CO₂ despite them being classed as icehouse episodes.  Veizer et al (2000) explain that theoretical models resolve this by “advocating the development of permanent high-latitude ice sheets at more than 10 times present-day CO₂ levels have been proposed” (Veizer et al, 2000) and then go on to offer their own alternative interpretation by mean of experimental evidence to “suggest large variations in tropical sea surface temperatures (SSTs; up to 9°C) between the peaks of greenhouse/icehouse modes” (Veizer et al, 2000). 

There are three possible finding suggested as a result of Veizer et al (2000) study, the first is that past CO₂ reconstructions are at least in part incorrect, the second is that for a least two of the icehouse episodes of the Phanerozoic pCO₂ was not the driving force of climatic changes and finally, that climate models are not able to correctly represent past climates as they are calibrated to the present interstadial . 



The Phanerozoic eon. 

Roy Shepherd (2002). Phanerozoic eon [online]. Available from: <http://fossilsandfossils.weebly.com/fossil-periods.html>. [Accessed 08th January 2016].

 

Reference;          

Veizer, J. Godderis, Y. and François, L.M. (2002). Evidence for decoupling of atmospheric CO2 and global climate during the Phanerozoic eon. Nature. 408, pp.698-701.