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Can Humanity Coexist With Rising CO2 Levels?

According to the Working Group III contribution to the IPCC’s Fifth Assessment Report (AR5), without additional efforts to reduce GHG emissions beyond those in place today, emissions growth is expected to persist driven by growth in global population and economic activities with the result, without additional mitigation, global mean surface temperature by 2100 will have increased from 3.7°C to 4.8°C over pre-industrial levels. These are the median values within a range of 2.5°C to 7.8°C and assume CO2 concentrations of 720 to 1000 ppm compared to 400 ppm today.


The World Bank report “Turn Down the Heat: Why a 4°C Warmer World Must be Avoided,” warns, as the title suggest, such a world must be precluded because it would be marked by extreme heat-waves, declining global food stocks, loss of ecosystems and biodiversity, and life-threatening sea level rise and further that these effects would be “tilted against many of the world’s poorest regions”.

The initial response to the proposition posed by this piece would therefore appear to be no, we cannot coexists with rising CO2 levels, at lease not the most vulnerable of us and not without mitigation.

Even Royal Dutch Shell’s CEO acknowledged in a recent speech the need for lowering carbon emissions, which he suggests should be accomplished through a carbon-pricing system and a shift from coal to natural gas.

Mr van Beurden claims his industry must make the case that the world’s energy needs will underpin the use of fossil fuels for decades but this is at odds with the recent study published in Nature that 52% of the world’s natural gas reserves, 35% of its oil and 88% of its coal cannot be burned if we are to have a 50:50 chance of remaining below the widely accepted 2oC safe temperature increase from the pre-industrial base.   

The following visual produced by Rosamund Pearce of the Carbon Brief based on the Nature article, shows the regional breakdown of resources that will have to be left in the ground.


It also highlights how politically difficult it would be to implement such cutbacks. For example oil represents a slightly higher percentage of the Canadian than the U.S. economy, about 5.8% compared to 4.3%, yet Canada would be expected to forego 75% of the economic benefit of its oil reserves as opposed to a U.S. cutback of only 9%.

And then there are the sectoral rivalries. As a producer of natural gas Shell naturally favours its resource over coal but a number of coal producers, such as Peabody Energy in the US,  have pointedly rejected Mr van Beurden’s message that “You cannot talk credibly about lowering emissions globally if, for example, you are slow to acknowledge climate change; if you undermine calls for an effective carbon price; and if you always descend into the ‘jobs versus environment’ argument in the public debate” by labelling efforts on the part of those trying to combat global warming as “alarmism”.

Mr. van Beurden, says that “ineffective, inefficient or even counterproductive measures are taken in some countries and regions” to address climate change, yet the National Research Council and National Academy of Sciences report released just a few days ago suggests  his company’s favoured response to the problem, CCS, falls into the same category. It points out “most carbon dioxide removal strategies have limited technical capacity, and absent some unforeseen technological innovation, large-scale deployment would cost as much or more than replacing fossil fuels with low carbon-emission energy sources.”

The NRC/NAS report also says that albedo-modifying technologies, which aim to increase the ability of Earth or clouds to reflect incoming sunlight, which is the other most widely considered geoengineering strategy, poses considerable risks and should not be deployed at this time either.

Marcia McNutt, editor-in-chief of Science said in a release titled, Climate Intervention Is Not a Replacement for Reducing Carbon Emissions; Proposed Intervention Techniques Not Ready for Wide-Scale Deployment, “That scientists are even considering technological interventions should be a wake-up call that we need to do more now to reduce emissions, which is the most effective, least risky way to combat climate change.”

Fortunately for the Shells, Peabodys and those of us at greatest risk to climate change another recent study in Nature, led by Dean Roemmich of the California-based Scripps Institution of Oceanography suggest another alternative. That study points to the fact the world’s oceans are heating at the rate of two trillion 100-watt light bulbs burning with the result there has been “no significant trend” in mean sea-surface temperatures since 1998, confirming a “hiatus” that deniers of climate science often point to when claiming global warming isn’t happening.

Is it possible Shell, Peabody and others can continue to market their carbon emitting resources provided the oceans continue or increases their heat uptake and what would the result of such an endeavor be?

The Roemmich report relying on an array of about 3500 Argo buoys from 2006-13 shows temperatures warmed at about 0.005 degrees a year down to a depth of 500 metres and 0.002 degrees between 500-2000 metres.

By comparison the NOAA National Climatic Data Centre says the 2006  global annual land temperature was 0.78°C above average and the 2013 land temperature was 0.99°C above average for an increase of about .02625 degrees per year or about 13 times the increase in deep water temperatures. Extrapolating .02625/year out to the end of the century, comes to an atmospheric increase of about 2.25°C, which is 1.45 degrees lower than the 3.7°C minimum the IPCC shows for a business as usual fossil fuel burning scenario.

My take on this is the forcible movement of heat into the deep ocean, whereas the events of 2006-13 have been induced by natural phenomena that are assumed to be temporary, would keep the atmospheric temperature close to the 2°C acceptable limit even if we continued to burn fossil fuels. The consequence to the deep ocean – the 500-2000 meter region – on the other hand would be a negligible increase of .17°C.

John Church, one of the authors the Scripts study says the temperatures in the atmosphere – which accounts for just 1 per cent of the planet’s heat uptake – would rise sharply if oceans absorbed less of the heat.

Conversely atmospheric temperatures would be more gradual if the oceans absorbed more heat as is suggested here can be accomplished economically and to the benefit of the environment.

Heat movement into the ocean deep can produce real, zero-emissions, energy that can run real light bulbs, provide real energy for transportation and heat and air-condition our homes and work places and consequently this is a mitigation strategy that would be self-sustaining.

Rather than investing current profits in future reserves that very well might not be burnable, it is probably in the better interest of the shareholders of fossil fuel companies to invest in technology that best preserves the value of existing reserves and insures the continuation of those companies in the energy business long after the fossil fuel era has ended. This is an approach that would keep atmospheric warming within safe limits as this transition comes about and will relieve fossil fuel companies of their greatest public relations problem in the interim.

This is climate intervention that reduces carbon emission as well as the risk of taking the necessary action, leaving but one hurdle, the politics of trying to figure out the best way to tax planetary salvation.

Jim Baird's picture

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Spec Lawyer's picture
Spec Lawyer on February 17, 2015

Of course we CAN.  We’ll just lose many major cities due to sea level rise.  We’ll lose many valuable fertile farmland areas based around river deltas due to sea level rise.   We many have mass starvation due to crop failures from drought, floods, fires, storms, heat waves, etc.


Kinda seems like something we would rather avoid.  But many people don’t seem to care about their progeny so party on!

Hops Gegangen's picture
Hops Gegangen on February 17, 2015


I find it difficult to assess the impact of ocean acidification. Maybe it is just a big unknown right now. But if mankind pushes CO2 up to 560+ ppm, nature may add further increases. We are already seeing some signs of stress in oysters at 400 ppm, and I’m sure the oceans haven’t caught up with the atmosphere yet.

So, I don’t know if just mitigating the heat is enough. 

Hops Gegangen's picture
Hops Gegangen on February 17, 2015


Interesting. Here’s question. Given a desire to overturn ocean water and perform electrolysis, do we use OTEC or put nuclear reactors on ships that just cruise the ocean doing that?

Or some combination thereof?


Hops Gegangen's picture
Hops Gegangen on February 17, 2015


But making all the equipment for OETC will require vast amounts of steel made with fossil fuels, no? I just wonder whether nuclear would make better use of the resources. I would think the heat of the nuclear would be small relative to the power output and the amount of water overturned.

Perhaps the nuclear could turbo-charge the OTEC…

I mean, I look at a map of the Earth, and the hot areas in the Pacific are just enormous. How do we put a dent in the problem?


Engineer- Poet's picture
Engineer- Poet on February 17, 2015

I hate to nitpick, but “terawatts annually” is a rate of acceleration.  I believe you meant just plain “TW”.

Engineer- Poet's picture
Engineer- Poet on February 17, 2015

In your zeal to promote OTEC, I think you’ve forgotten that the problem of heat accumulation in the environment isn’t eliminated by burying the heat.  That heat is still there even if it’s not manifesting as strongly, and it’s still piling up.  Any delay in dealing with the problem of excess greenhouse effect means the problem keeps growing.

OTEC is an interesting idea but I’ve been seeing variations on it since about the late 1960’s without any of them proving commercially viable.  An OTEC system at the far end of a set of chemical transformations and a shipping route has to be even cheaper than a grid-connected system to be viable.  I don’t see how this can be done, though I am willing to be convinced (by someone using their own money, of course).

A direct attack on the GHG problem seems more viable to me.  Widespread distribution of crushed ultramafic minerals like olivine on warm-climate soils and in shallow, wave-worked seas would convert dissolved CO2 to carbonate, reducing both atmospheric CO2 and ocean acidity.  Remediating the atmosphere and oceans this way, combined with elimination of most fossil fuel consumption, would return conditions to what we had before.

Mark Heslep's picture
Mark Heslep on February 24, 2015

The transfer of the identified deep ocean energy from ocean to atmosphere won’t happen all at once, and it won’t happen entirely so as to cause a 36C surface rise, ever. The atmosphere is not a dewar flask into which one can pump energy and temperature reacts accordingly. Rather, as the surface temperature changes relative to its surrroundings, heat is transported into surrounding bodies such as the ocean or back to space at a rate allowed by GHGs and other factors. There was not a die roll, deep ocean or surface, that saved the surface from a delta T of 36C. 

Andy Maybury's picture
Andy Maybury on February 27, 2015

Putting a price on carbon seems a much more market-friendly approach than setting a limit, which begs all sorts of questions like who gets how much of the budget. Set the price, distribute a rebate so that anyone who uses an average amount is no worse off and then let people decide how much they want to spend.

Mark Heslep's picture
Mark Heslep on November 13, 2015

Jim – Very late comment.  If you are still inclined, I’m attempting to clarify the SPM statement.

As you indicate, the SPM states:

“without additional mitigation, global mean surface temperature by 2100 will have increased from 3.7°C to 4.8°C over pre-industrial levels. These are the median values within a range of 2.5°C to 7.8°C and assume CO2concentrations of 720 to 1000 ppm compared to 400 ppm today.”

Your IPCC AR5 sourced graphic and, for instance, Table SPM.2 from AR5 breakdown the projected surface temperature change by various emissions scenarios (RCPs).  Currently the scenarios we appear to be on are RCP 4.5 or RCP 6.0.  Scenario RCP 8.5 has become impossible, which for example requires the currently declining rate of global population increase to quickly reverse and begin increasing again, and coal consumption to rise six or eight fold.  RCP 6.0 in table SPM.2 has a mean temp rise by 2081-2100 of 2.2C, range 1.4C to 3.1C, with a mean 19 inches of sea level rise. RCP 4.5 mean temp change of 1.8C and so on. 

What is your understanding of how the original SPM statement checks against the per RCP data given elsewhere? 

Table spm.2, page 21 here




Jim Baird's picture
Jim Baird on November 13, 2015

In all honesty Mark I took the SPM statement at face value. My interest is in the production of energy that can zero out atmospheric temperature rise an mitigate the two greatest risks of climate change – sea level rise and storm surge. To my mind speculation as to the what might be does little to solve the problem.


Mark Heslep's picture
Mark Heslep on November 13, 2015

Jim –  What speculation?  The figures I reference were also from IPCC AR5, which I could not completely justify against the statement you referenced.   

Jim Baird's picture
Jim Baird on November 14, 2015

Without additional efforts to reduce GHG emissions beyond those in place today, emissions growth is expected to persist driven by growth in global population and economic activities. Baseline scenarios, those without additional mitigation, result in global mean surface temperature increases in 2100 from 3.7 °C to 4.8 °C compared to pre-industrial levels (median values; the range is 2.5 °C to 7.8 °C when including climate uncertainty, see Table SPM.1)11 (high confidence). The emission scenarios collected for this assessment represent full radiative forcing including GHGs, tropospheric ozone, aerosols and albedo change. Baseline scenarios (scenarios without explicit additional efforts to constrain emissions) exceed 450 parts per million (ppm) CO2eq by 2030 and reach CO2eq concentration levels between 750 and more than 1300 ppm CO2eq by 2100. This is similar to the range in atmospheric concentration levels between the RCP 6.0 and RCP 8.5 pathways in 2100.12 For comparison, the CO2eq concentration in 2011 is estimated to be 430 ppm (uncertainty range 340 – 520 ppm)13. [6.3, Box TS.6; WGI Figure SPM.5, WGI 8.5, WGI 12.3]

Page 9 

Mark Heslep's picture
Mark Heslep on November 14, 2015

Ah, I see part of the difference.  You’re referencing the the SPM WG3, and I’m referencing the Physical Science Basis WG1 SPM.  In WG1’s table spm.2 , they reference temperature anomally, i.e. zero, to 1986-2005, not “pre-industrial levels”.  The difference in starting time is 0.6C.  

The different reference doesn’t explain all though.  I see no way to obtain a high side of 7.8C from even the worst emissions scenario (RCP 8.5) from WG1 table spm.2.  That should be 4.8+0.6 = 5.4C.   And as I said above, the supposed worst case, no mitigation scenario RCP 8.5 is no longer a “baseline”, as some  “mitigation”, as the scenario literature defines it, has already begun (some replacement of coal, declining western energy consumption, declining rate of population increase).

Page 21


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