Human-caused climate change causing 'ocean amnesia'

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As it turns out, the ocean has a memory and is capable of losing it.

According to research published in Science Advances, ocean memory is described as the persistence of circumstances across time, and it is declining as a result of the climate catastrophe.

“We discovered this phenomenon by examining the similarity in ocean surface temperature from one year to the next as a simple metric for ocean memory,” stated Hui Shi, the lead author at the Farallon Insitute in Petaluma California.

Shi stated that “it’s almost as if the ocean is developing amnesia.”

The weather in the atmosphere fluctuates greatly from day to day, but not in the ocean. Temperatures under the waves tend to remain relatively stable, allowing scientists to forecast future ocean conditions.

The top layer of the water, known as the "mixed layer", enables this memory. The thicker the mixed layer, the more memory the ocean has, but global warming is "shoaling", or making it shallower, according to the study's authors.

Li Cohen told CBS that “similar to how a thicker mattress provides better cushioning, a thicker sea surface layer allows for a better memory because of the thermal inertia at play,” adding that as global warming increases and the ocean temperature rises, that top layer thins out. "And like a thinning mattress, the support, or in this case the year-to-year ‘memory', weakens.”

The researchers used a range of models to predict how ocean memory will change over time and discovered that it would drop for most sections of the ocean by 2100. In certain locations, the drop might be as high as 100%.

According to the study's authors, this oceanic memory loss might have a number of serious repercussions. For starters, it may make future ocean conditions more difficult to anticipate. This is due to both the memory deterioration and the weakening of the mixed layer, which will result in more random changes in sea surface temperatures.

Study co-author and atmospheric sciences professor at the University of Hawai‘i Mānoa Fei-Fei Jin told the university of Hawai'i news that “reduced ocean memory together with increased random fluctuations suggest intrinsic changes in the system and new challenges in prediction under warming."

According to the study authors, “The previously unknown challenges in forecasting brought by ocean memory loss are crucial to address as we prepare for potentially more frequent and intense temperature and hydrological extremes in a warming world."

Furthermore, the alterations may have an effect on fisheries and other marine life. Stock numbers and sustainable harvesting limits are currently determined based on environmental factors such as ocean temperature, therefore management tactics may need to adapt when memory fades.

But it's not just fisheries that might be affected by ocean memory loss.

“The biological implications of changes in ocean memory are more uncertain, but consequential impacts on populations are likely,” they wrote but noted that some species are most likely to adapt more optimally than others.