Standing at the Atlantic’s edge on a typical afternoon, there is a moment when the vast, gray-green ocean appears unchanged. The waves always break in the same manner. Overhead, gulls wheel. It seems to last forever. It isn’t. The Atlantic just recorded its hottest year ever recorded, according to scientists. What’s more difficult to accept is the almost casual certainty with which scientists deliver the news: this is not the worst of it.
Climate tracking organizations report that ocean heat content has broken records worldwide for nine years running, but the Atlantic’s numbers are quite different. Surface temperatures in large areas of the ocean were 5°C higher than seasonal averages, which should be startling but is hardly surprising in light of recent history. Researchers have described the margin of the record as abnormally, almost unsettlingly wide. Last summer, conditions in parts of the North Atlantic exceeded anything seen in the satellite era. One NOAA researcher stated, “What we used to consider extreme is no longer an extreme today,” and it’s difficult to read that statement without sensing a change.
This is caused by layered mechanisms that defy easy explanation. The main factor is climate change; decades of emissions from fossil fuels have filled the atmosphere with gases that trap heat, and the ocean has absorbed about 90% of this extra warmth, acting as a kind of global thermal sponge. Beneath all of that, however, is a compounding set of factors: a Super El Niño event that the World Meteorological Organization now estimates has an 80 percent chance of occurring by this summer; anomalously warm subsurface waters in the tropical Pacific feeding surface temperatures; and weaker Saharan dust winds reducing the natural solar shield over the Atlantic. In certain monitoring zones, subsurface Pacific temperatures are 6°C higher than average, which truly caught some researchers off guard.
Even though they don’t always make the front pages, the biological effects are already apparent. Since the 1980s, the frequency of marine heatwaves has doubled. Once occurring once every generation, coral bleaching events now occur almost seasonally. In just four years, the number of snow crabs in Alaska fell from about 11 billion to less than 2 billion, a decline so drastic that the state closed its crab season for the first time. These represent structural failures in food systems, economies, and ecosystems that took millions of years to form; they are not abstract data points. Between 25 and 50 percent of the world’s coral reefs have already been destroyed, according to UNEP estimates.
Warm Atlantic surface water, a hurricane that intensified more quickly than forecast models predicted, and flooding in a coastal city that wasn’t expected to flood until 2050 can all be traced. The sea does not remain in its designated path. Stronger storms, sea level rise, and disruptions to the atmospheric circulation patterns that control rainfall across entire continents are all caused by warmer seas. These changes have resulted in what researchers have called the worst Caribbean drought in 500 years.
Observing all of this build up gives me the impression that, for years, the discussion surrounding ocean temperature has been caught between alarm and numbness. Headlines emerge, records drop, and the news cycle continues. For their part, scientists are becoming more straightforward. According to research released prior to this year’s assessments, a significant portion of the world’s ocean may experience a permanent heatwave by the end of the century compared to any historical baseline. This is not a worst-case scenario, but rather a reasonable middle path if emissions trajectories don’t change.
The Atlantic of fifty years ago is not the same as the one we are measuring today. It used to be dependable enough to absorb climate disruptions in silence, but it is now warmer, more acidic, and less able to do so. Perhaps how long someone is willing to wait before using the word will determine whether or not that qualifies as a crisis.
