Recently the New York Times reported the following:
An Annual Blast of Pacific Cold Water Did Not Occur,
Alarming Scientists
The cold water upwell, which is vital to marine life, did
not materialize for the first time on record. Researchers are trying to figure
out why.
NYT - By Sachi Kitajima Mulkey
Sept. 12, 2025
Each year between January and April, a blob
of cold water rises from the depths of the Gulf of Panama to the surface,
playing an essential role in supporting marine life in the region. But this
year, it never arrived.
“It came as a
surprise,” said Ralf Schiebel, a paleoceanographer at the Max Planck Institute
for Chemistry who studies the region. “We’ve never seen something like this
before.”
The blob is as much as 10 degrees Celsius colder than the
surface water. In Fahrenheit terms, the
water would be 18 degrees colder than the surface water. That cold water is
also rich in nutrients from decomposing matter that falls to the ocean floor,
providing food for local fisheries and wildlife.
Dr. Schiebel was one of the scientists who recently
documented the lack of this yearly upwelling in a paper in Proceedings of the
National Academy of Sciences and identified a likely culprit: The lack of
strong trade winds, which typically blow across Panama and kick off the dry
season in January. When the trade winds reach the Gulf of Panama they push hot
surface water away from the coast, which makes room for cold water to rise from
the deep.
Steven Paton, one of the paper’s co-authors, runs a large
environmental monitoring program at the Smithsonian Tropical Research
Institute. The record he helps maintain shows the upwelling has taken place
annually for at least 40 years. With that data and other long term records, “we
can very clearly say something very unusual happened that we need to pay
attention to,” he said.
It’s unclear whether a warming planet played a role in the
disappearance of the cold blob this year. But the researchers have a few
theories about what affected the trade winds.
Trade winds, like the ones that drive the cold upwelling in
the Gulf of Panama, typically form when air moves from high pressure to low
pressure systems. But this year Panama saw only a quarter of the usual dry
season trade winds and when they did emerge, it was only for a short period of
time.
The Bermuda-Azores High is a high pressure system that moves
around the Atlantic Ocean, affecting seasonal weather patterns across Europe,
Africa and the Americas. A separate, low pressure system, known as the
Intertropical Convergence Zone, wraps around the Equator and moves south of
Panama in winter. This southward movement, in combination with the difference
in pressure from these two systems, causes the force that drives Panama’s dry
season trade winds.
La Niña, the cool phase of an oscillating cycle of water
temperatures in the Pacific Ocean, may have shifted the position of the low
pressure system. Hot ocean surface temperatures may have also affected the
strength of the two atmospheric systems. But the impact of these factors is
unclear until more research is done, the researchers said.
Andrew Sellers, a marine ecologist at the Smithsonian
Tropical Research Institute who coauthored the paper, said the disappearance of
the cold water upwelling could cause “major repercussions throughout the food
web.”
Nutrient rich waters are important for Panama’s fishing
industry, which is concentrated on the Pacific side of the isthmus, rather than
in the Caribbean, he said. The upwelling also supports large marine life, like
dolphins, rays and migrating whales that pass through the region.
The lower temperatures also provide
respite for coral reefs, which are made up of living organisms that can bleach
white and die when they get too hot.
Richard Aronson, a
professor of marine sciences at the Florida Institute of Technology, has
studied this particular patch of ocean off the coast of Panama for decades. The
cold blob gives those corals a better chance of surviving marine heat waves
than other areas, he said.
Heat stress has plunged the world’s coral reefs into ongoing
mass bleaching that began in January 2023. About 85 percent of the world’s
coral reef areas have been affected, according to the National Oceanic and
Atmospheric Administration.
“The climate is warming, that’s putting coral reefs at
risk,” said Dr. Aronson, who was not involved with the paper. While corals can
adapt to changes in temperature, the climate is changing too quickly for them
to keep up in the long run, he said. Sea surface temperatures have risen by
more than 1 degree Celsius since humans began burning fossil fuels during the
Industrial Revolution, breaking records in 2024 and 2023.
It’s too soon to tell if the blob will return in future
years. But if it disappears repeatedly, then “it’s cause for grave concern,”
Dr. Aronson said.
There are other cold water blobs across the world, including
in the Galápagos and off the coast of Costa Rica, each driven by different air
and ocean patterns. As the planet warms, Dr. Schiebel said, other atmospheric
pressure systems that drive trade winds may diminish, too.
“Our fear is now that it would also happen to other
upwelling systems,” he said.
(Sachi Kitajima Mulkey covers climate and the environment
for The Times.)
Translation
太平洋年度冷水爆發並未出現，科學家憂心忡忡
對海洋生物至關重要的冷水上湧，在有記錄以來首次未能出現。研究人員正在努力找出原因。
每年1月至4月，一團冷水從巴拿馬灣深處湧向海面，這對該地區海洋生物的生存至關重要。但今年，它卻遲遲未見。
研究該地區的 Max Planck 化學研究所古海洋學家 Ralf Schiebel 說: 「這是令人意外的」;「我們從未見過這樣的現象」。
這團冷水比地表水低攝氏10度。以華氏度計算，水溫比地表水低攝氏18度。這些冷水還含有大量來自沉降到海底的腐爛物質的營養物質，為當地漁業和野生動物提供食物。
Schiebel 博士是最近在《美國國家科學院院刊》上發表論文，記錄了這種年度上升流未出現的科學家之一，並指出了一個可能的罪魁禍首：缺乏強勁的信風。信風通常會在一月吹過巴拿馬，開啟旱季。當信風到達巴拿馬灣時，它們會將地表熱水推離海岸，從而為深海冷水的上升騰出空間。
論文的合著者之一 Steven Paton 在 Smithsonian熱帶研究所負責一個大型環境監測計劃。他有參與保全的記錄顯示，這種上升流至少在
40 年內每年都會發生。有了這些數據和其他長期記錄，他說: 「我們可以非常清楚地說，一些十分不尋常的事情發生了，我們需要留意」。
目前尚不清楚是否全球暖化是今年的冷水團消失的原因。但研究人員對什麽影響信風提出了一些理論。
信風，例如驅動巴拿馬灣冷上升流的信風，通常是在空氣從高壓系統移向低壓系統時形成的。但今年巴拿馬只出現了往年旱季信風的四分之一，而且即使出現，也只持續了很短的時間。
百慕達-亞速爾高壓是一個環繞大西洋的高壓系統，影響歐洲、非洲和美洲的季節性天氣模式。另一個獨立的低壓系統，稱為熱帶輻合帶，環繞赤道，在冬季移至巴拿馬南部。這種向南的移動，加上這兩個系統之間的氣壓差，形成了驅動巴拿馬旱季信風的力量。
拉尼娜現像 (La Niña) 是太平洋水溫振盪週期中的冷階段，它可能改變了低壓系統的位置。高溫度海面也可能影響了這兩個大氣系統的強度。但研究人員表示，這些因素的影響尚不清楚，需要進行更多研究。
Smithsonian熱帶研究所的海洋生態學家Andrew Sellers是該論文的共同作者，他表示，冷水上湧的消失可能會「對整個食物網造成重大影響」。
他表示，營養豐富的水域對巴拿馬的漁業至關重要，因為巴拿馬的漁業集中在巴拿馬地峽的太平洋一側，而不是加勒比海。水上湧也支撑着大型海洋生物的生存，例如海豚、鰩魚和途經該地區的遷徙鯨魚。
較低的溫度也為珊瑚礁提供了喘息的機會，珊瑚礁是由一些生物組成的，這些生物在過熱時會白化並死亡。
Florida理工學院海洋科學教授Richard Aronson 幾十年來一直在研究巴拿馬海岸附近的這片特殊海域。他表示，這團冷水使這些珊瑚比其他地區更有機會在海洋熱浪中存活。
高溫導致全球珊瑚礁陷入大規模白化，這場白化始於2023年1月。美國國家海洋暨大氣總署(NOAA)的數據顯示，全球約85%的珊瑚礁區域已受到影響。
並未參與這篇論文的Aronson博士說: 「氣候正在變暖，這正危及珊瑚礁」。他表示，雖然珊瑚能夠適應溫度變化，但氣候變化太快，它們無法長期跟上。自工業革命期間人類開始燃燒化石燃料以來，海面溫度已上升超過攝氏1度，並在2024年和2023年打破紀錄。
現在判斷冷水團未來幾年是否會再次出現還為時過早。但如果它反覆消失，Aronson博士說: “就值得嚴重擔憂” 。
世界各地還有其他冷水團，包括加拉帕戈斯群島和哥斯達黎加沿海，每個冷水團都受到不同的空氣和海洋模式驅動。Schiebel博士說，隨著地球變暖，其他驅動信風的氣壓系統也可能減弱。
他說: 「我們現在擔心的是，其他上升流系統也會發生同樣的情況」。
So, each year
between January and April, a blob of cold water rises from the depths of the
Gulf of Panama to the surface, playing an essential role in supporting marine
life in the region. But this year, it has not arrived. It’s too soon
to tell if the blob will return in future years, but if it disappears
repeatedly, it would be a cause for grave concern. There are other cold-water
blobs across the world, as the planet warms, other atmospheric pressure systems
that drive trade winds may diminish, too. Apparently, global warming is changing
our environment.
Note:
1. Trade wind (信風)is the wind that
blows steadily towards the equator from the northeast in the northern
hemisphere or the southeast in the southern hemisphere, especially at sea. Two
belts of trade winds encircle the earth, blowing from the tropical
high-pressure belts to the low-pressure zone at the equator. (Wikipedia)
2. The
Intertropical Convergence Zone (ITCZ)(熱帶輻合帶) known by sailors as the doldrums or the calms
because of its monotonous windless weather is the area where the northeast and
the southeast trade winds converge. It encircles Earth near the thermal
equator, though its specific position varies seasonally. When it lies near the
geographic equator, it is called the near-equatorial trough. (Wikipedia)
