Marine heatwaves will get more frequent and intense. There’s a great risk of the loss of important coral and seaweed and of the migration of invasive species, reports Channel Asia.
The ocean sustains all life on our planet. It provides food to eat and oxygen to breathe, while playing a key role in moderating our climate. But marine life is increasingly threatened by climate change.
The ocean is becoming considerably warmer, affecting its ability to sustain life. The searing temperatures seen around the Mediterranean this year are indicative of rising global temperatures.
Frequent and intense heat waves
A marine heatwave is defined as an extended period of abnormally high sea temperatures, relative to the seasonal average. They have doubled in frequency since the 1980s.
Because of the delay between undertaking and publishing ecological work, the most comprehensive study we have on Mediterranean marine heatwaves covers the period from 2015 to 2019.
The study found that the sea temperatures recorded in the Mediterranean over the period were the highest since recording began in 1982. Of almost a thousand field surveys conducted, researchers found that 58 per cent of them contained evidence of the widespread mortality of marine life, tightly linked to periods of extreme heat.
The research provides an insight into the future ecological impacts of marine heatwaves elsewhere. This is significant as substantial temperature increases are forecast for tropical and polar regions in particular.
While the ocean acts as a large carbon sink, we still face increases in the surface temperature of the sea ranging from 1 degrees Celsius to 3 degrees Celsius before the end of the century. Linked to this overall warming are marine heatwaves of increasing frequency and intensity.
Much of the research on marine heatwaves finds that they affect certain habitats particularly strongly, including coral reefs, seagrasses and seaweeds. Marine heatwaves were found to be responsible for the loss of up to 80 per cent of the population of some Mediterranean species between 2015 and 2019.
A mass mortality event is a single, catastrophic incident that rapidly wipes out vast numbers of a species. Around 88 per cent of these events in the Mediterranean were associated with hard sea floor inhabitants, such as corals. However, seagrasses and the more diverse community of the soft sea floor were also severely affected, accounting for 10 per cent and 2 per cent of these events respectively.
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Source: Channel Asia