Sea surface temperatures have displayed significant anomalies over the past few days, breaking previous records and causing concern amongst scientists that this could mean increased marine heatwaves.
Data from the National Oceanic and Atmospheric Administration (NOAA) shown below, indicated the sharp upturn of sea surface temperatures over the past weeks, with data over the weekend breaking new records over the North Atlantic.
This data continues the record breaking, with highs being recorded in April this year as well. The Guardian reported then that the ocean surface temperatures were “Headed off the charts” and that “More than 90% of the extra heat caused by adding greenhouse gases to the atmosphere from burning fossil fuels and deforestation has been taken up by the ocean”.
What has caused these high temperatures?
There are competing arguments for what has been the main cause of these rising temperatures, all of which still need to be explored in more depth before conclusions can fully be drawn.
Professor Stefan Rahmstorf, professor of physics of the oceans at Potsdam University, suggested today that a weakened subtropical gyre may be a factor: “Is the current North Atlantic sea surface temperature anomaly also due to a weak subtropical gyre? On the eastern side this normally brings down cold water from the north, in the west warm water. If weak, the west side gets cold, the east side warm.”
Professor Michael Mann, distinguished professor of atmospheric science at Penn State, and creator of the famous ‘hockey stick’ graph, supports the view that the absence of the cooling impact of the low windblown Saharan dust has also played a part in these sea temperatures. Yesterday on social media he posted:
In response, Michael Lowry, hurricane specialist and storm surge expert, posted in agreement: “The dearth of Saharan dust over the tropical North Atlantic is helping drive the ongoing ocean heatwave. Dust concentration running low much of 2023, but at record lows (since 2003) for early June.”
Eric Holthaus, meteorologist and author of The Future Earth, also argues that a partial explanation may be linked with sulfate aerosol emissions: “In 2020, new shipping regulations sharply limited sulfur pollution from ocean ships in the North Atlantic, and sulfate aerosol emissions — which have a planetary cooling effect — have fallen sharply since. If you run the numbers, as Hansen has, such a sharp reduction might partially explain the surge in Atlantic Ocean temps.”
He continued, “For more than three months, the oceans have been warmer than ever before in the history of human recordkeeping. Right now, North Atlantic temperatures are about 35% higher than the previous record — a shockingly large amount that is further above the previous record than any other recordbreaking year in history”.
What is the effect of a warming ocean?
Professor Eliot Jacobson, who created the graph from the NOAA data, told Yorkshire Bylines:
“Ocean temperatures have been setting unprecedented daily records, spiking to highs that are shocking climate scientists, as they look for possible reasons.
“The planet’s oceans absorb nearly 90% of the excess heat generated by global warming. Over the last three La Nina years, this heating has been equivalent to about 9.8 Hiroshima bombs per second, or about 930 million Hiroshimas in total. The ocean is hot, but until now we haven’t directly seen that heat.
“There is an obvious reason to explain some of the ocean heating that is happening right now: the unexpectedly rapid onset of El Nino, which typically drives massive surface heating of the Eastern tropical pacific.
“The consequences are clear. As we enter Northern hemisphere summer, large regions of the planet will experience record heatwaves, fires, storms and flooding. These events will set records in intensity, duration and frequency. The planet’s overall temperature will spike to new highs for the modern era, with 1.5C in sight for 2024. Polar sea ice will continue its retreat, exposing more open ocean to incoming solar radiation and heating. Crops will fail. Infrastructure will break beyond repair. Climate mitigation will spike.
“That’s where we are headed, not at some future dystopian moment, but now. And this is all happening in the midst of the current political and social chaos. These next two years are a preamble to what it will mean for the world to pass the Paris 1.5°C barrier.”
The Emergence of El Niño
However, Professor Mann cautioned against easy readings of complex systems when he told Yorkshire Bylines:
“Basically, what we’re seeing at the annual timescale is the emergence of a large El Nino event. El Nino often combines with human-caused warming to yield new global temperature records like we’re seeing currently.
“We can expect the emergence of Saharan windblown dust at some point soon. At that time, we can expect to see a pretty rapid return of North Atlantic Sea Surface Temperatures to more typical levels.
“One region that’s gotten a lot of attention is the North Atlantic, where we see warmth particularly in the eastern tropical/subtropical region of the basin. That appears to be tied to an anomalous dearth of windblown Saharan dust that normally has a cooling impact on the region.
“One would be very hard pressed to attribute that feature to human-caused warming. Instead, it underscores the interplay between human-caused warming and natural variability, the latter being particularly important at these sorts of regional scales.”
Dr Thomas E L Smith, associate professor in environmental geography at the London School of Economics and Political Science, also confirmed the emergence of a strong El Niño impact when he told Yorkshire Bylines:
“It has been over three years since the last El Nino, and some forecasts suggest this will be a strong El Nino. Usually, this leads to dryer conditions in southeast Asia and northwestern Australia, often leading to drought and wildfires, while the west coast of South America experiences flooding.
“However, the global situation with the unusually warm Atlantic and Indian Oceans means that this El Nino may not be like others. What we do know is that warmer oceans lead to a more energetic atmosphere. More water evaporates into the atmosphere and when this condenses to form clouds, it releases energy driving storm systems. It’s a complex situation. Usually, El Nino dampens hurricane activity in the Atlantic, but the current spike in Atlantic temperatures throws these ‘teleconnections’ into uncertainty.”
‘More storms for us’
The response to this climate information has certainly been muted over the past few days, with only a few outlets covering this record-breaking event. It is possible that many members of the public will have been unaware of the rising sea temperatures, which have been ongoing for weeks now.
Meteorologist Laura Tobin told Good Morning Britain: “More heat in the ocean means more heat in the atmosphere, which means more storms for us.”
More effective climate communication such as this is needed, particularly as emissions continue to rise and governments appear slow to act. The importance of putting information into context cannot be underestimated. Nor can applying cautious scientific rigour to an element of the climate. Unfortunately, the cries of ‘tipping points’ often shout louder than a methodical process.
As Professor Mann said, “In my view, hyping and cherry-picking individual anomalies does a disservice to the social media discourse on climate change. It’s what climate deniers often do to cast doubt on the science. Climate advocates need to be better than them”.
