What’s happening? The rising ocean temperatures due to climate change are causing a concerning northward expansion of Vibrio bacteria, particularly Vibrio vulnificus. The microbe, known for causing flesh-eating infections, has traditionally been a problem in the Gulf of Mexico but is now emerging in the upper East Coast.

The bacterium can enter the body through minor injuries, posing a severe health risk. Climate-induced ocean warming is changing the geography of infectious diseases, causing concern among healthcare professionals and beachgoers. As Vibrio moves north, it may threaten public safety on beaches, with cases expected to increase along the eastern US coast. (Scientific American)

Why does this matter? The Vibrio species are usually limited to warmer seas in the Gulf of Mexico, where locals are accustomed to the dangers of the microbe. Living with Vibrio means limiting shellfish consumption to winter months and taking antibiotics after sustaining an injury in the sea. Approximately 80% of infections in the US take place between May and October and almost 60% are caused by contaminated food. For those living in the north of the US, the microbe is unfamiliar and preventative measures are not common.

Deadly bacteria – According to the Centre for Disease Control and Prevention, Vibrio causes over 80,000 illnesses a year in the US, most of whom recover within three days without lasting effects. However, those who contract Vibrio vulnificus face more serious consequences. The species enters through a break in the skin and quickly begins eating limbs. The health consequences are serious – more than one in five patients infected with Vibrio vulnificus die, with amputation the only option to prevent the disease from spreading. Out of the 43 recorded infections in Florida this year, 10 have died.

Future projections – Worryingly, this is likely only the beginning. In a study published in Nature, researchers from the UK studied Vibrio’s spread along the east coast of the US between 1988 and 2018. Over this period, cases increased eightfold as the microbe migrated northward 30 miles each year due to warming waters. Cases have been reported in Long Island and New York this year after an unprecedented surge. According to the researchers, the warming caused under a medium-to-high emissions scenario will allow Vibrio to spread to every eastern US coastal state as early as 2081.

Snow crab decline – Humans aren’t the only ones at risk from warmer waters. Over the past few years, the population of snow crabs in the sea off Alaska has seen a drastic decline, with over 10 billion snow crabs perishing. This drop in population is linked to a 2018 heatwave in the Bering Sea, causing mass starvation among the crabs. Warmer waters led the crabs to expend more energy regulating their body temperature, coupled with insufficient food to support their increased energy requirements. Additionally, the higher temperatures made them more susceptible to disease. Though there has been a slight increase in snow crabs in 2022 and 2023, it will take many years of cooler conditions for the population to recover fully.

Earth system effects – Warming oceans are troubling climate scientists, with a range of expected impacts – for example, warm water increases the likelihood of coral bleaching and speeds up the melting of ice caps. Further, as water temperatures rise, evaporation and energy transfer between the ocean and atmosphere increase. This means hurricanes passing over warm seas result in stronger winds and heavier rainfall, increasing the risk of damage.

Warm future – Looking forward, the threats of intensified storms, coral bleaching and flesh-eating bacteria are likely to increase. Since the pre-industrial era, global sea temperatures have increased by 0.72C. This trend has recently accelerated – the last decade saw the warmest seas since at least the 1800s, while 2022 was the warmest year for oceans on record. According to a UK government report, ocean temperatures are expected to increase by a 1.5C by 2050 and 3.2C by 2100 under a business-as-usual scenario. Limiting global warming is fundamental for a sustainable future and will be central to discussions at COP28 which will convene next month in the UAE.