I have often thought that every editorial I write for World Aquaculture could be about the effects of climate change on aquaculture, given its importance as an existential threat to our future on this planet. I have restrained myself so as not to be either boring or a purveyor of doom. However, current events and news releases of ongoing studies have raised my level of alarm once again.

The Stockholm Resilience Center has reported that the world is at risk of passing five dangerous climate tipping points if global temperatures rise above 1.5 C. These include collapse of the Greenland and West Antarctic ice sheets, widespread abrupt permafrost thaw, collapse of the Labrador Sea subpolar gyre and massive die-off of tropical coral reefs. The number of tipping points has increased from 9 to 16. The study concluded that we may have already left the safe operating space for humanity. Surpassing more tipping points escalates the risk of further climate destabilization. A recent study in Nature Climate Change concluded that a minimum sea-level rise of 27 cm in the next 100-150 years from melting of the Greenland ice sheets is now inevitable given the emissions that have already occurred and regardless of any actions taken now to avert further climate change. Many climate scientists believe that multi-meter sea level rise in the next 100-200 years is likely.

This would be absolutely devastating for the 600 million people who live in coastal zones from sea level to an elevation of 10 m above, let alone the enormous economic effects associated with damage to coastal infrastructure. Take some time to look at Google Earth imagery for the coastal zones of important aquaculture producing nations around the world. It is not too difficult to imagine the inundation of coastal fish and shrimp ponds and associated shore-based support facilities over time. The existing system of embankments appears flimsy and fragile. As a point of reference, I recall the inundation of coastal aquaculture ponds in Aceh, Indonesia as a result of the devastating tsunami following the late-December 2004 Indian Ocean earthquake. Of course, a huge tsunami wave is categorically different from the gradual increase in sea level associated with climate change. Despite the limitations of this comparison, the destruction of the means of livelihoods and displacement of coastal inhabitants seems inevitable without massive investments.

There has also been climate change news around record-setting heat and drought in China, Europe and the US West, where conditions are being described in terms of a 1200-year “megadrought.” The Yangtze River has fallen so low that hydropower production has been slashed to the point where some fish farmers in Sichuan Province have been unable to pump water or aerate ponds. Drought is obviously not favorable for pond aquaculture that is dependent on surface water flows. Equally of concern is the effect of extended heatwaves and drought on agriculture more broadly, with clear implications for food security, especially in resource-poor nations. Last year, according to the American Meteorological Society, 32 percent of global land area experienced drought of moderate or worse severity. In addition to potential shortfalls associated with human food production, the availability of plant-based ingredients used in aquafeeds could also be put under pressure.

Excessive heat also affects crop production. The frequency, duration and intensity of heatwaves is trending upward, in part due to “stuck” jet stream patterns. Perhaps it is not surprising that the temperatures that are favorable for the growth of warmwater species in aquaculture (25-30 C), are also favorable for the growth of soybeans, corn and other grains. As with warmwater aquaculture species, growth performance declines steeply above those temperatures. In brief, the combination of drought and heatwaves have slowed the growth of global agricultural productivity, with declines measured even in relatively wealthy breadbasket countries like the US, Brazil, Argentina, Australia, China and India. Despite these challenges, global grain production has continued on an upward trend since the advent of The Green Revolution in 1960, mainly due to advances in technology.

The Global Commission on Adaptation has estimated that global agriculture yields may decline by 5-30 percent by 2050, affecting small farms, including fish farms, most profoundly. The prevalence of undernourishment has been increasing in recent years after reaching historically low levels in the 2010s. The inflation adjusted FAO Food Price Index is now at the highest level since 1961. It seems that progress derived from the Green Revolution has now stalled, in part caused by climate shocks associated with extreme weather events and certainly exacerbated by the covid pandemic. It’s not hard to imagine food system shock scenarios involving extreme weather events leading to severe social disruption — food riots, famine, civil war and mass migration.

Nearly half the planet is now living in areas that leave people vulnerable to the effects of extreme weather. How to adapt to climate change and develop resilience capacity remains a key challenge going forward in the short to medium term. The response are necessarily complex and must occur at multiple levels and time scales. Of course, farmers are most concerned with the next crop cycle and so access to insurance and credit programs will be key.

What should we in the professional aquaculture community be doing? It seems like an overwhelming problem with no straightforward solution and where piecemeal approaches seem insufficient. I’m sure many of us would just prefer to “stick to the science” and leave the policymaking to others. Scientists have a critically important role to play in society. In his 2007 book “The Honest Broker,” Roger Pielke Jr. describes four categories of scientist with reference to their interaction with policymakers: the pure scientist, the science arbiter, the issue advocate, the stealth advocate and the honest broker of policy alternatives. Which one are you? I encourage every professional aquaculturist to have some form of constructive policy engagement on this issue.

— John A. Hargreaves, Editor-in-Chief