Agriculture under a changing Climate

The agriculture sector in PICs is critically important for food security and livelihoods at the household, community, national, and regional levels. Climate change is already impacting and will continue to impact agriculture in both the short and long term. PICs need to transform the agriculture sector for it to remain prominent and relevant in Pacific communities. There is a need for the agriculture sector in PICs to become resilient to the negative impacts of climate change while simultaneously increasing production to feed a growing population. In addition, there is a need to reduce the negative environmental impacts of unsustainable agriculture on soil, waterways, and the atmosphere (through the release of greenhouse gas emissions). Agricultural transformation can be achieved in PICs through focusing on a systems-oriented perspective that recognizes the foundational importance of healthy soils. Opportunities exist to strengthen existing partnerships and forge new ones to address information and resourcing constraints

Testing the climate intervention potential of ocean afforestation using the Great Atlantic Sargassum Belt

Ensuring that global warming remains 2 emissions reduction. Additionally, 100–900 gigatons CO2 must be removed from the atmosphere by 2100 using a portfolio of CO2 removal (CDR) methods. Ocean afforestation, CDR through basin-scale seaweed farming in the open ocean, is seen as a key component of the marine portfolio. Here, we analyse the CDR potential of recent re-occurring trans-basin belts of the floating seaweed Sargassum in the (sub)tropical North Atlantic as a natural analogue for ocean afforestation. We show that two biogeochemical feedbacks, nutrient reallocation and calcification by encrusting marine life, reduce the CDR efficacy of Sargassum by 20–100%. Atmospheric CO2 influx into the surface seawater, after CO2-fixation by Sargassum, takes 2.5–18 times longer than the CO2-deficient seawater remains in contact with the atmosphere, potentially hindering CDR verification. Furthermore, we estimate that increased ocean albedo, due to floating Sargassum, could influence climate radiative forcing more than Sargassum-CDR. Our analysis shows that multifaceted Earth-system feedbacks determine the efficacy of ocean afforestation