By Eamonn Ryan, from the webcast
The CSIR study, led by Dr Tommy Ryan-Keogh, reveals that climate models have underestimated the decline, threatening global ecosystems and food security. This is Part 3 of a five-part series on the urgent need for better climate models to secure global ecosystems and food security.
The CSIR study’s new model ranking system highlights the need for more accurate climate models to predict ocean productivity, which directly impacts the global cold chain. As ocean productivity declines, seafood availability may decrease, straining cold chain logistics, which rely on timely transportation and refrigeration. The mismatch between projected and observed productivity in climate models signals the potential for unexpected disruptions in seafood supply. This could lead to longer supply chains, increased costs, and greater challenges in maintaining the cold chain infrastructure, particularly in regions dependent on seafood for food security. Strengthening climate models and cold chain systems is crucial to safeguard global food systems from these emerging threats.
To address the limitations of current climate models, Dr Ryan-Keogh and his team developed an innovative model ranking system to assess how well different models replicated the observed changes in ocean primary production. By using a variety of satellite data products, the team assessed the models’ ability to simulate the impact of environmental drivers like sea surface temperature and nutrient availability on ocean productivity.
The study found that five out of six satellite algorithms agreed that ocean productivity is declining, with the best-performing models consistently predicting a future decrease. However, these models still underestimated the scale of the decline. While some models projected minimal changes or even an increase in ocean productivity, these models ranked poorly in the new system, confirming that many models are not adequately capturing the magnitude of the issue.
Dr Ryan-Keogh explained that even the best models, which aligned most closely with satellite observations, only predicted a small decline in ocean productivity of around 1%. This mismatch with observed data calls into question the accuracy of future projections and highlights the need for climate models to better replicate the complex relationships driving ocean productivity.
As the models suggest, the future of ocean productivity is heavily influenced by global CO2 emissions. Dr Ryan-Keogh highlighted two potential scenarios: one where CO2 emissions remain high and global temperatures rise by 3.6 to 4.4°C, leading to significant decreases in ocean productivity, and another where emissions are reduced, leading to smaller temperature increases and less severe declines in ocean primary production.
The urgency of mitigation and the impact on global food security
The study’s findings underscore the urgency of mitigation efforts. Dr Ryan-Keogh emphasised that “the best time to begin mitigating and reducing our CO2 emissions was yesterday, and the next best time is today.” The sooner action is taken to curb emissions, the less impact ocean productivity will experience, thus preserving ocean ecosystems and food security for future generations.
The study’s conclusions have significant implications for global fisheries, which depend on healthy ocean ecosystems. As Dr Ryan-Keogh pointed out, over three billion people rely on seafood as their primary protein source, with some countries depending on it for up to 50% of their protein intake. Declining ocean productivity could disrupt these vital food sources, with dire consequences for food security and the livelihoods of millions of people.
What this means for fishing economies
In response to questions about the potential impact on economies reliant on fishing, Dr Ryan-Keogh explained that the effects would not be uniformly felt around the world. Some regions may experience an increase in ocean productivity, while others could see significant declines. The overall global trend, however, suggests that fishing industries could face considerable challenges as ocean ecosystems degrade. In particular, countries with already fragile marine resources may suffer the most.
The study emphasises the importance of taking action to protect the foundational elements of marine food webs, like phytoplankton. By doing so, we can help ensure that the global fishing industry remains sustainable and that food security is preserved for future generations. However, without significant efforts to mitigate climate change, the disappearance of marine ecosystems could become a reality for many fishing communities.