WWW.WAS.ORG • WORLD AQUACULTURE • JUNE 2014 3 Editor’s Note Regular readers of my editor’s note will know that climate change has been a recurring theme of these columns. I had not intended that this would be the case but the increasingly pressing need for urgent action has compelled me to give the issue regular attention. In the last few months, a number of reports have been released and events with global implications have occurred. In late March, Working Group II of the Intergovernmental Panel on Climate Change released a report called Climate Change: Impacts, Adaptation and Vulnerability that was seven years in the making. Then, in early May, the US Global Change Research Program issued its third National Climate Assessment, focusing on effects in the US. Both reports emphasize the message that climate change is happening now and that a considerable amount of future change is essentially locked in because of inherent lags in response to current greenhouse gas concentrations. Many changes are irreversible, even if action is taken now. Furthermore, the IPCC reports are inherently conservative in their predictions because every country must sign off on the findings. Recent experience suggests that IPCC projections underestimate the magnitude of climate change. Also in early May came reports from two independent studies indicating that the West Antarctic Ice Sheet is collapsing, with the ice sheet thinning from below caused by interaction with relatively warmer water. This will cause accumulated glacial ice to move faster into the sea, causing an anticipated rise in global sea levels by 60 cm within 200 years. The ice held behind this glacier will then move unimpeded to the sea, causing an additional sea level rise of 3 to 4 m. Greenland’s glaciers also appear to be more vulnerable to melting than previously anticipated. Taken together, a sea level rise of 3 m by the end of the century seems increasingly likely. Paleoclimatologists say that, in the history of the planet, the last time the atmosphere had the current levels of carbon dioxide, sea level was 20-30 m higher than it is now! One can’t help but think about the global infrastructure of coastal aquaculture ponds and other culture systems that are vulnerable to such substantial rises in sea level. A sea level rise of 3 m will result in the loss of 3 million hectares of land in China and more than 1 million hectares each in Vietnam, India, Bangladesh, and Myanmar, all major aquaculture producing nations. Sea level rise in places such as the deltas of the Yellow River and Pearl River in China and the Mekong River in Vietnam is exacerbated by groundwater extraction for aquaculture that leads to land subsidence, increasing apparent rates of sea level rise by a factor of 100. Aquaculture has been growing at a tremendous rate since the 1980s and needs to continue this growth to supply the increased demand for seafood associated with global population increases and the expansion of large middle classes in China and India. It now seems clear that continued global growth in aquaculture is jeopardized by sea level rise, just at the point where growth must continue to keep pace with demand. What will be the fate of coastal aquaculture infrastructure? Protection of coastal ponds from uncontrolled inundation will become increasingly urgent. There is now open discussion about building sea defenses to protect major coastal cities in the world but what about protecting the hundreds of thousands of hectares of coastal and river delta ponds used in aquaculture around continental margins worldwide? Although more unlikely, countries can abandon the most coastward ponds and start an orderly retreat from vulnerable coastal areas and move inland. Ultimate abandonment seems likely because sea level is rising inexorably and at some point there will be no other option. Given that protection or reestablishment of this infrastructure will require many decades and will be extremely costly, it seems prudent to begin this process now. At minimum, countries with coastal aquaculture need to begin not just planning but implementation of infrastructure protection measures. Of course, climate change will be disproportionately impact the most vulnerable segments of humanity, many of whom live in coastal areas. About 40 percent of the world’s population lives within 100 km of a coastline, many of which are rural or urban poor or otherwise marginalized. Aquaculture and smallscale fisheries provides important employment options for these populations of vulnerable poor. One can easily imagine scenarios of large-scale displacement from coastal areas and migrations to already-strained urban areas in developing countries. The prospects for social unrest, caused by the same underlying drivers of a lack of opportunity and a perception of hopelessness that initiated the Arab Spring, seem increasingly likely. The challenge before us seems immense, maybe impossible. All the same, action must be taken to adapt and mitigate the worst effects of climate change on aquaculture. One later chapter of the National Climate Assessment is called Decision Support: Connecting Science, Risk Perception and Decisions. It is perhaps here that aquaculture scientists may be able to make the greatest contribution. Technical information provided by aquaculture scientists can be integrated to inform actions and policy decisions to adapt and mitigate the effects of climate change. The broad aquaculture community can participate in identifying response options, assessing uncertainty, and clarify tradeoffs associated with various alternatives. Actions can be taken at many levels, such as a shrimp farm deciding to invest in higher pond levees, a provincial or national government developing resiliency or mitigation plans, or commitments of national governments to reduce greenhouse gas emissions. Decision support tools are now available to build a consensus for action. Although curbing emissions remains a longterm necessity, it is prudent to begin adapting and mitigating the effects of climate change on coastal aquaculture now. — John A. Hargreaves, Editor-in-Chief Climate Change is Here Now
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