Macro-Mitigation: Opportunities within IPCC SR1.5

Macro-Mitigation: A Creative Reflection on the Implications of the IPCC Special Report on 1.5o C of Warming


October 17th, 2018


Imagine that humans were shrunken to a size in which all 7.2 Billion of us were able to inhabit a single tree in the rainforest. Within the trunk and along each branch, our societies would grow and thrive. Not so long ago, we would discover that striking the trunk of our magnificent tree would release an abundance of sap, a prized commodity with utility in nearly every sector. Each day, we would take turns descending to the forest floor and walloping the tree trunk while others would stand by ready to collect the impending flow of sap. Over the years, our technologies would flourish and we would enhance our methods to meet the growing sap-demands of industry and everyday life. However, we would gradually come to realize that our continuous trunk walloping had begun to impact life in other regions of the tree. For instance, windstorms would cause much more damage than before because the compromised tree trunk would sway further and further with each powerful gust, causing hundreds of thousands to lose their leafy homes to the inhospitable forest floor.

In the year 2018, when scientists would finally be able to quantify and describe the damages we had inflicted upon our tree, they would find that humans had already thwacked nearly 75% of the way through the resilient, yet teetering trunk. Faced with this daunting discovery, we humans would band together and commit to doing our very best to alleviating the stress we had placed on our tree and on each other. But traditional practice, day-to-day reliance and tree-wide development trends would force people to continue harvesting sap, at least for the time being. Will humans transition to a world of non-sap-based consumption? Will we undo the damage we’ve already caused? Will we be able to do it in time? What happens if we don’t? These are amongst the biggest questions answered by the IPCC in its recently released Special Report on the Impact of Global Warming of 1.5o C above Pre-Industrial Levels.


The latest IPCC Special Report provides a blunt wake up call to citizens and policy makers worldwide. Laid atop the robust structural foundation of 6,000+ peer-reviewed scientific papers and organized by 91 authors from 44 nations, this 2018 Special Report represents a non-biased, non-partisan and all-encompassing assessment of where we are and where we are headed with respect to the 1.5o warming limit encouraged by the Paris Agreement.


If human-caused greenhouse gas emissions continue at the current rate, this report claims with high confidence that we will reach the 1.5o C (2.7o F) warming mark between 2030 and 2052. In fact, the report utilizes current trends to estimate a warming increase of 0.2o C per decade. Given that we’re already witnessing warming of 1o C (1.8o F) worldwide in the year 2018, we are likely scheduled to breach the 2 degree C warming ceiling laid out by the Paris Agreement by the year 2068.


While nations continue to put forth effort to ratchet down, or mitigate, national emissions, IPCC Working Group III Co-Chair Jim Skea reminds us that, without drastic and thus-far unprecedented change, we will both hit and exceed the 1.5o mark in the coming years.


In the years leading up to the historic signing of the Paris Agreement back in 2015, the Alliance of Small Island States, better known as AOSIS, exerted tremendous effort to catalyze the global call for a 1.5o C limit to human-caused warming. In Paris, burdened by the looming and existential threat of sea level rise, these brave nations demanded a 1.5o C limit be adopted by the Paris Agreement and galvanized global support behind the frank slogan, “1.5 TO STAY ALIVE”. Judging from this Special Report, it would seem, the impacts of a 1.5-degree warming future will extend much further than the borders of these Small Island Nations.


To put the difference between 1.5 and 2 degrees of warming into perspective, the report suggests that a future with 1.5o C of warming could expect to see 1 ice-free Arctic summer per century, while a 2o C warming future could expect to see 1 ice-free Arctic summer per decade. Imagine the impact all of that excess ice-melt would have on elevating sea levels. Additionally, a 2o C warming future would basically guarantee the global loss of coral reefs.


On page 16 of the Special Report’s Summary for Policy Makers, the IPCC states with medium confidence that it would take the emission of nearly 3,000 Billion Metric Tonnes (Gigatonnes) of carbon dioxide to elevate global mean surface temperatures (GMST) to 1.5o C above pre-industrial levels. At the end of 2017, total anthropogenic emissions since the beginning of the Industrial Revolution were reported at 2,200 Gigatonnes. That means we’re already almost 75% of the way there. However, the IPCC makes it clear that breaching a 1.5-degree warming threshold does not entirely exclude us from removing Greenhouse Gases and decreasing global average temperatures in subsequent decades. In other words, there’s still hope.


As stated in the IPCC’s Press Release delivered on Monday, October 8th, from Incheon, Republic of Korea, “Allowing the global temperature to temporarily exceed or ‘overshoot’ 1.5o C would mean a greater reliance on techniques that remove CO2 from the air to return global temperature to below 1.5o C by 2100.” Yet many of these ‘techniques’, such as Solar Radiation Modification, which involves altering the albedo of the Earth’s atmosphere to restrict solar energy input, present immense uncertainties and beg deep questions of ethics and responsible governance. Hopefully, if we do indeed exceed the 1.5o C limit, we will not have to rely solely on harmful and unnatural anthropogenic techniques to remove carbon dioxide from the atmosphere.


Natural Climate Solutions, which involve the restoration and enhanced management of key global ecosystems, present an immense opportunity to responsibly respond to the drastic findings of the IPCC. For example, recent decades have witnessed the rise and success of sustainable forest management in efforts to mitigate carbon emissions and build long-term community resilience. There is also much promise in the field of agriculture thanks to recent innovations in Regenerative Soil Techniques, a point urged by Rick Ridgeway, Patagonia’s Vice President of Environmental Affairs, and others at the 23rd UN Conference of the Parties in Germany last November. However, the role of other Natural Climate Solutions, such as the carbon uptake and secure long-term storage potential of oceanic Macroalgae and other Blue Carbon ecosystems, has yet to be widely adopted in the global mitigation framework. Macroalgae, a polyphyletic category of organisms comprised of brown, red, green and blue-green algae, has the potential to contribute radically to reducing annual increases in atmospheric carbon. Conservative estimates place the global export of Macroalgal Carbon at 173 Million Metric Tonnes per year (Krause-Jensen et al. 2018). Unaffected by ocean acidity, Macroalgal habitats will continue to offer robust mitigation, adaptation and associated co-benefits well into the era of environmental conditions that may prevent other carbon-rich ecosystems from doing the same. Due to the great diversity of Macroalgal species, their rapid growth and export of carbon-rich biomass and the vast range of near-shore and open-ocean Macroalgal coverage (estimated 3.4 Million Km squared), the protection, enhancement (including enhancement of long-term storage capacity) and utilization (PEU) of Macroalgae represents an extremely viable option for removing CO2 from the air and returning global temperature to below 1.5o C by 2100. Additionally, global investment in Macroalgal PEU would spur progress in 11 of the 17 United Nations Sustainable Development Goals (SDGs), as demonstrated in the table below:


Potential Benefits of Macroalgal Protection, Enhancement and Utilization with regard to the UN SDGs


Sustainable Development Goal What role will Macroalgal PEU play?
SDG 1: No Poverty Macroalgal PEU creates diverse jobs, products and outcomes that help free people from destructive cycles of poverty
SDG 2: Zero Hunger Sustainable growth and export of seaweed can feed millions of people worldwide. Also, the excess grain from substituting macroalgae in livestock diets can go to feeding humans worldwide
SDG 3: Good Health and Well-Being Seaweed has fantastic nutritional value (protein, carbohydrates, vitamins) which can serve as an enabler of healthier lifestyles
SDG 8: Decent Work and Economic Growth Working Waterfronts would yield increased employment and economic diversification. For instance, Macroalgal ecosystems help to ensure sustainable fishery regeneration and are resilient to ocean acidity
SDG 9: Industry, Innovation and Infrastructure Macroalgal biomass can be used to help coal mines to offset residual leakage, can spark the development of working waterfronts and help unite global markets
SDG 10: Reduced Inequalities Macroalgal PEU offers opportunity for local communities to empower themselves and aid in the empowerment of others
SDG 12: Responsible Production/Consumption Macroalgal PEU methods involve ecological sustainability, limited resource consumption and extensive social/environmental/financial co-benefits
SDG 13: Climate Action Community-outreach and training programs will educate and empower citizens to support and share the climate benefits of Macroalgal PEU.
SDG 14: Life Below Water Macroalgae protects marine calcifiers vulnerable to ocean acidification and fosters immense biodiversity, conferring radiating ecosystem services worldwide
SDG 15: Life on Land Macroalgae protects coastlines from sea level rise and increased storm surge
SDG 17: Partnership for the Goals Macroalgae represents an undeniable opportunity to unite as a global community and enhance marine and coastal management in order to create lasting change


Finally, this IPCC Special Report finds that in order to limit warming to 1.5o C, global net anthropogenic carbon dioxide emissions would need to fall by 45 percent from 2010 levels by 2030 and reach ‘net zero’ by 2050. Not only does Macroalgal PEU represent a strong candidate for long-term mitigation and storage of atmospheric carbon, but it also presents a clear opportunity for public and private entities to quickly offset outstanding emissions sources by investing in the growing capacity of Macroalgae to help regulate the global climate in future decades. When combined with the extensive co-benefits detailed above (in table), it becomes clear that supporting Macroalgal PEU both generates immediate and long-term benefits across a multitude of global stakeholders.


In conclusion, the data provided in this IPCC report calls for immediate and sustained action in order to avoid surpassing the 1.5o C mark. As a global community, we must step up to this pressing challenge and work creatively and adaptively to implement driving solutions. To find out more about the growing role of Macroalgal PEU in addressing the concerns of the IPCC, please sign up for our newsletter.


Article written by Andrew Orozco, Carbon Institute Fellow




  1. Krause-Jensen, Dorte, Lavery, Paul, Serrano, Oscar, Marbá, Núria, Masque, Pere, and Carlos M. Duarte. 2018. Sequestration of macroalgal carbon: the elephant in the Blue Carbon room. Biology Letters. Volume 14, Issue 6.
  2. Further official IPCC Documents referenced include:
    1. Official IPCC Press Release, October 8th, 2018.
    2. IPCC SR1.5 Summary for Policy Makers (SPM)



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