By Alissa MacMillan
Q: We hear so much about the ice caps melting away. How serious is this and what does it really mean for the environment and for Ireland?
A: At two ends of the earth, the polar ice caps and glaciers, which cover about 10% of the globe, help keep the planet habitable for us. In recent years, “in both poles really, there has been drastic change,” says Dr. Michelle McCrystall, a climate scientist and assistant professor at Maynooth University. The Arctic region, the main focus of McCrystall’s research, is “changing three to four times faster than anywhere else on the planet.”
This is a big deal, for several, interrelated reasons, one being the role of ice caps in the regulation of the earth’s temperature.
“Having this white surface is so important for the radiation balance of the planet,” explains McCrystall. “Sunlight warms the planet, and it needs a certain level. White surfaces have a high albedo, so it reflects a lot of sunlight away and works as a cooling mechanism.” When the ice warms, it thaws into water and stops doing its job of reflecting.
“As the planet warms, melting sea ice and snow, it’s a loss of those absorption services,” the planet losing its ability to cool itself. The oceans will rise not only from the water from melted glaciers, but the additional heat in the planet causes “thermal expansion” – the kind of process you see when you boil water to make tea, the cup filled slightly higher. This happens writ large as the ocean warms.
The science behind these changes is subtle, McCrystall adds, and predictions are hard to make.
“The climate system is so nuanced and interwoven and interconnected, if you change something somewhere it might affect what you hadn’t thought about.” This makes it an exciting area of research, she adds, but “there is so much change, it would be better if the focus of study was not our actual planet, which also impacts people,” as well as the species that live in the Arctic region and beyond, like polar bears, whose environment and habitat have been impacted.
CLOUDS & WATER VAPOUR
Scientists do know that as CO2 in the atmosphere increases temperature increases, and then they see changes in the ice sheets. In terms of the Arctic Sea ice, there are “large systems of internal variability,” she explains, the temperature increasing over the last twenty years, 2024-2025 being the warmest on record in over a century.
Another factor for changing temperatures, although nuanced and difficult to model in studies, is the clouds, which themselves hold a lot of heat and have an impact on radiation and reflection. “If you have really high cirrus clouds, nice white and bright, you have a lot of reflection. The thick clouds here in Ireland still have good reflection but not as much.”
Along with this, water vapor from evaporation, the process that converts water to a gas, is actually the most potent greenhouse gas. “The more CO2 we pump into the atmosphere, the warmer it becomes; the warmer it becomes, the more it can hold in the atmosphere,” so a warmer atmosphere with much more water vapor in it will have more energy in the system, warming the planet more in “a positive feedback loop.”
Ice is also crucial for maintaining ecosystems, sea ice in Antarctica declining from 2015.
“When the sea ice is up against the land, it acts as a buttress to the glaciers,” she says. “As it moves, those glaciers can flow, and it causes that land ice to move into the ocean which can contribute to further sea rise.”
The Pacific Islands are experiencing problems because of sea level rise – as more saltwater gets on land, if they have depleted water resources and it mixes with ground water, it makes the water difficult to treat for consumption, McCrystall explains.
Another possible impact for mid-latitude weather, so for places like Ireland, is the weakening of the jet stream, which is dependent on the temperature gradient in the upper atmosphere. “There is still uncertainty, but some studies suggest that with declining sea ice and a warmer Arctic we will get a more meandering jet stream.” As a barrier between the cold in the Arctic and the warm in the tropics, the uncertainty may make Ireland more susceptible to extreme weather events.
There is also concern about AMOC (Atlantic Meridional Overturning Circulation) being affected by the melting of the Greenland ice sheet, impacting the gulf stream.
While “there is always variability” it is also true that “changes are happening,” no matter what it portends. The center of Greenland experienced rainfall for the first time in 2021, which “could be an anomaly,” but is surprising.
Instead of getting depressed about the facts, McCrystall dives into the science, focusing on coding and looking to the changes and projections, “trying to see what more should be done” in the face of coming variability. Policy is especially important, but there is no one easy fix, she says, requiring effort from all government departments and communities.
Although McCrystall is hesitant to say we’ve reached a tipping point, “we are definitely not going in the right direction.” We won’t lose sea ice in the Arctic completely – this is miscommunication about what happens in September and October, when sea ice is at its minimum and “very thin and removed around the archipelago regions, the Beaufort Sea region, North Canada, and Upper Greenland.”
Rainfall is one of McCrystall’s biggest concern: “Whatever’s coming off the Atlantic, we are the first to be hit, and places like Galway will be difficult to live in,” she says. “We are still an agricultural society and people’s livelihoods are being destroyed. These beautiful environments we live in are just being completely washed away.”
SMALL CHANGES MAKE A DIFFERENCE
We can’t shy away from the difficult challenges, she says. “The time is now to step up and make change.”
“It’s so interesting how it all works,” she notes, hoping others might see the interconnectedness of it all, question why we do things, and be more accountable in our day-to-day lives, doing things like lessening consumerism and walking instead of driving. “If we all tried in some small way, the change that can be made is quite large,” a good example being how we closed the hole in the ozone. “We were able to solve it,” she says, galvanizing enough countries and giving her hope that it’s still possible to make change happen.
“Small things will make a difference,” she adds. “Nothing is ever an inevitability. We can’t think that way.”
