As a professor and scientist, I often find teachable moments in almost any situation. This time it comes from my daughter and some of her cohort who recently studied abroad in the United Kingdom. While exploring the attractions of Ireland, my daughter texted that it was warmer compared to previous days in England. The temperature variance certainly may have been related to the weather pattern at the time, but it prompted me to share a scientific nugget. Ireland is known for its beauty, the awesome band U2, Ed Sheeran, and dark beer. Palm trees likely do not come to mind, but you can find them there too. Here’s why.
Geography, oceanography, and meteorology conspire to shape the weather of the United Kingdom. Ireland and the other countries of the United Kingdom are some of the cloudiest locations on the plant. Why so? A NASA website notes, “Air masses from the Arctic, southern and northern Europe, the Maritimes, and the Gulf Stream all come crashing together in this region.” The image above, which was taken on June 27, 2018, shows a rare clear day over the United Kingdom as captured by NASA’s Aqua and Suomi NPP Earth observation satellites.
The satellite imagery below shows the cloud fraction for Earth during the month of April 2024. The United Kingdom is covered with clouds. The NASA website adds, “According to a 2012 study based on MODIS data, the probability of cloud-free skies on any given day over Great Britain is 21.3 percent, with a maximum probability of 33.3 percent in November and 12.9 probability in March.” I warned my daughter of this as she packed for her United Kingdom adventure.
Ok, let’s get back to the palm trees. According to a 2011 review article published in the Annals of Botany, palm “trees” are a type of flowering plant and among the oldest according to fossil records. They are typically found in sub-tropical and tropical locations. There is some debate about whether they are even trees at all. On the University of Florida website, Larry Figart says not really. He is “Team No They Are Not Trees.” The urban forestry extension agent writes, “The basis of the debate is in biology. Palms are part of a group of plants called monocots. Other monocots include corn, grasses, lilies, and onions. Typical trees belong to a group of plants called dicots. Most shrubs, vines and other woody plants are dicots.” He also lays out arguments on why “Team Yes They Are Trees” has valid points.
Whatever you call them, Ireland is certainly not tropical or sub-tropical so how do palm trees exist there? To answer that question, I must introduce you to the Gulf Stream. NOAA’s SciJinks website defines it as, “A strong ocean current that brings warm water from the Gulf of Mexico into the Atlantic Ocean. It extends all the way up the eastern coast of the United States and Canada.” It is one of the poleward flowing currents in the ocean that helps the Earth redistribute heat from the tropics to the poles.
The Gulf Stream reaches Ireland so the warm current can moderate the climate of the western part of the British Isles. In 2010, Abigail Tucker wrote an instructive piece in Smithsonian Magazine. She clarified that the cabbage palm or Cordyline australis made its way from New Zealand in the 1800s and was popular in Irish gardens. As non-native species often do, they spread aggressively in Ireland over time. Tucker goes on to say, “The cabbage palms are able to thrive in Ireland because of warm ocean currents. Ireland is at about the same latitude as Newfoundland, but its winters are much milder.” In the graphic below, notice how much warmer the waters are near Ireland during December 2024 than they were at the same latitude near Newfoundland.
The Gulf Stream is an interesting phenomenon that affects weather patterns, marine life, the fishing industry and many other things. It is also the reason you might see a palm tree in Ireland.
