This week Hurricane Ida dumped inches of rain, in some cases over a foot, along its path. While rain is part and parcel of a hurricane, it is not expected to fall at the summit of an ice sheet where below-freezing temperatures are the norm. Therefore, scientists were astounded when rain fell for several hours on August 14th at the highest elevation of the Greenland Ice Sheet– the first time such precipitation was ever recorded there. Although not as much in quantity as Hurricane Ida produced, the summit rainfall was just as disturbing.
Raindrops fell on scientists heads off and on for thirteen hours some 10,551 feet above the Greenland Ice Sheet mid-month. No one knows exactly how much precipitation came down because there are no rain gauges at the National Science Foundation’s Summit Station. Such a weather event was unprecedented since scientists have been making observations there, so who would think to install a rain gauge?
Although rain has occasionally fallen on the Greenland ice sheet itself, rainfall has never occurred on its summit–until now that is. Guess there’s a first time for everything. With below freezing temperatures, snow is the precipitation scientists anticipate. And temperatures have risen above freezing at the summit only three times previously in the last 32 years.
Timing, as they say, is everything. Scientists are unsettled not only by the rain falling on the summit but by the fact it is falling at this time of the year. Mid to late August marks a change from summer to autumn in the far north. This progression of seasons should result in lower temperatures and snow for precipitation if any is to come down.
This anomalous weather, scientists believe, is the result of global climate change. While the actual rain event did not itself have a huge impact, it illustrates the increasing extent, duration, and intensity of melting on Greenland. You don’t have to hold an advanced science degree to understand global warming means higher temperatures which lead to ice melting, be it ice cubes in your glass or ice sitting on top of the largest island in the world.
And the Greenland Ice Sheet is a gargantuan piece of ice. It covers 660,000 square miles, around 79-81% of the surface of Greenland. Talk about ice, ice baby…Its surface area is almost as big as Alaska and over three times that of France. This ice sheet is the second largest ice body in the world with only the Antarctic Ice Sheet being bigger. From north to south the Greenland Ice Sheet extends 1,800 miles, the equivalent of stretching from Key West to a hundred miles beyond Portland, Maine. The ice is thick as well as long with the average thickness generally over 1.2 miles and around 2 miles at its thickest point. That’s one big ice cube!
With this much ice, what’s the big deal with a little bit of rain? The deal is that ice melts snow. When rain falls on the summit of an ice sheet, generally the water percolates down into the packed snow to colder temperatures where it refreezes and doesn’t drain away. On the other (hopefully mittened) hand, rain falling on the periphery of an ice sheet can generate a significant of melt water that runs off the ice sheet and into the ocean raising sea levels.
When it rained at the Greenland Ice Sheet’s summit some two miles above sea level, the precipitation coincided with a “melt event” where the temperature gets high enough that the thick ice on the ice sheet begins to melt. Northern Greenland has experienced record-setting temperatures this summer. Some areas experienced temperatures more than 18 degrees Celsius warmer than average temperatures. In fact, 2021 even saw the latest date in the year when above-freezing temperatures were recorded at the Summit Station. So, the location is high up and experiencing record high temps.
The August melt event affected 337,000 square miles and followed two major melt events in July. The later July melt event affected 340,000 square miles. Previously, there were melt events in 2019, 2012, and 1995; before those occurrences, no melt events had taken place since the late 1800’s per the U.S. National Snow and Ice Data Center. (They have a center for everything, don’t they?)
When the ice melts, it has to go somewhere. As an ice sheet melts, global sea levels rise. Rising sea levels are a concern because nearly one-third of the world’s population lives in or near a coastal zone. Everyone likes waterfront property or being near the water, but they may get more than they bargained for if too much ice melts. The Greenland Ice Sheet contains 8% of the Earth’s fresh water. If all that ice sheet’s ice melted, global sea levels would rise 24 feet. That’s over the head of anyone reading this post.
Thankfully, the situation isn’t that dire yet, but it is still concerning. The melt event which occurred at the end of July was of such a scale that the amount of ice which melted on one day of that event alone would cover the entire state of Florida with two inches of water according to the World Meteorological Organization. Woo hoo! All Sunshine State residents could then say they lived on the water; unfortunately, there would be no dry land for sunbathing.
While too much rain, as in the case of Hurricane Ida, is a bad thing, rain where and when none is expected is also a bad thing. The Greenland Ice Sheet may not be located anywhere near us and we may never set foot on it, but what happens to that part of the Earth can and will affect all of the world’s inhabitants. Let’s hope the story of rain falling at the summit of this ice sheet will not fall on deaf ears; instead, let the weather story be a wake up call to what’s happening to the planet we call home.
Are you surprised to learn that rain fell at the summit of a massive ice sheet? What weather events have convinced you or would convince you that global warming is occurring? Have you considered the ramifications of rising sea levels on coastal communities?