In recent years, the world has witnessed a concerning increase in ocean temperatures, reaching unprecedented levels. In April, the surface temperature of the ocean soared to 21.1 degrees Celsius, shattering the previous record set in 2016. This surge in ocean temperatures has given rise to a worrisome phenomenon known as marine heat waves (MHWs). As a result of global warming and other climatic factors, these MHWs are becoming more frequent, longer-lasting, and intense, posing significant threats to marine ecosystems and coastal communities.
What are Marine Heat Waves (MHWs)?
A marine heat wave is an extreme weather event characterized by a significant rise in the surface temperature of a particular region of the sea. It is officially considered an MHW when the temperature exceeds the average by 3 or 4 degrees Celsius for at least five consecutive days. These events can last for weeks, months, or even years, wreaking havoc on marine habitats and species.
Current Status of Marine Heat Waves
According to the latest forecast by Mercator Ocean International, several regions of the world are currently grappling with the impact of MHWs. These regions include the north-east Pacific, the southern hemisphere in the southern Indian Ocean and the Pacific, the north-east Atlantic, tropical North Atlantic, and the Mediterranean. The widespread occurrence of MHWs is a clear indication of the escalating severity of this phenomenon.
Global Warming’s Role in Intensifying MHWs and Ocean Warming
Numerous studies have pointed to global warming as the primary driver behind the intensification of MHWs and the warming of the world’s oceans. Research from 2018 demonstrated that rising global temperatures have led to MHWs becoming more frequent, lasting longer, and growing in intensity over the past few decades.
One of the significant contributors to ocean warming is the absorption of excess heat by the oceans. Around 90 per cent of the additional heat resulting from the release of greenhouse gases into the atmosphere, primarily from burning fossil fuels and deforestation, has been absorbed by the oceans. This has led to an increase of nearly 0.9 degrees Celsius in the global mean sea surface temperature since 1850.
The Alarming Influence of El Nino
Adding to the concerns of intensifying MHWs, the El Nino weather pattern has re-emerged after a seven-year absence. El Nino refers to an abnormal warming of surface waters in the equatorial Pacific Ocean, and its presence amplifies the risk of extreme heat events. Scientists and experts predict that the current El Nino conditions will contribute to more frequent and intense MHWs, potentially breaking temperature records in different regions worldwide.
Impacts on Marine Ecosystems and Coastal Communities
Marine heat waves have far-reaching consequences for marine ecosystems and coastal communities. Prolonged exposure to elevated temperatures can lead to coral bleaching, disrupting delicate marine habitats and posing a severe threat to marine biodiversity. Fisheries may suffer from declining fish populations and shifts in species distribution, impacting livelihoods and food security for coastal communities.
Furthermore, MHWs can trigger more frequent and severe storms, threatening coastal infrastructure and exacerbating coastal erosion. Additionally, the warming of ocean waters can influence weather patterns, leading to altered precipitation and drought conditions, further impacting agriculture and freshwater resources.
Mitigating the Impact of Marine Heat Waves
Addressing the challenges posed by MHWs and ocean warming requires a collective effort on a global scale. Reducing greenhouse gas emissions is essential to slow down the rate of global warming and alleviate the stress on marine ecosystems. Transitioning to renewable energy sources, enhancing energy efficiency, and implementing sustainable land-use practices are crucial steps toward mitigating the impact of MHWs.
Additionally, investing in marine conservation and restoration projects can help protect vulnerable marine species and habitats. Building climate-resilient infrastructure and promoting adaptive strategies for coastal communities can enhance their ability to cope with extreme events.