Researcher Examines Impact Of Melting Polar Ice On Hurricanes

Apr 30, 2019

Scientists have long been tracking the melting of polar ice caps. Many have attributed their melting across the globe to rising CO2 emissions warming the planet's waters. Dr. Jennifer Francis is a senior researcher with the Woods Hole Research Center in Massachusetts. She told WLRN's Sundial, "Over the last three or four decades, the amount of arctic sea ice [in the world] has been cut in half." 

Francis' research is focused specifically on the impact melting glaciers have on extreme weather events like hurricanes. She's found a correlation between more intense hurricanes and strange tracking patterns for storms as a result of the melting ice. We spoke with Francis about the ways in which Hurricanes Michael and Harvey were impacted by climate change and where her research is headed in this field. 

WLRN: Can we say there's a correlation between climate change and the melting of polar ice caps and hurricanes?   

FRANCIS: First of all, everybody needs to recognize that the fuel that drives hurricanes is really the heat in the atmosphere, the heat in the ocean and the water vapor in the atmosphere. And as we're warming the Earth because we're increasing the amount of so-called greenhouse gases in the atmosphere, particularly carbon dioxide, we are warming the oceans and we're warming the air. 

Because of that we're seeing more evaporation from the oceans and that's putting more water vapor into the atmosphere. Water vapor is incredibly important because when it condenses into clouds, it releases heat into the atmosphere and hurricanes especially feed off that heat. By warming the globe, we're increasing the fuel available for hurricanes to become stronger. It's connected to the Arctic in that as we lose all that sea ice and snow up in the Arctic area, you can think of it as though we're losing the Earth's mirror. The Arctic ice and the snow cover reflect a lot of the sun's energy right back to outer space, so it never enters the climate system at all. But by losing all that snow and ice, we're now absorbing a lot more of that energy into the Earth's climate system.

It's been estimated in some recent studies that global warming is between 25 and 40 percent higher because of the loss of sea ice and snow in the Arctic. So by losing this mirror in the Arctic, we are increasing global warming and we're providing more fuel for hurricanes. So what we think that's going to translate to and what we've already seen in some of the past several decades is a tendency for more of the strongest hurricanes. So Category 4 and 5 and also a tendency for these storms to intensify more rapidly.

You look at Hurricane Michael. You talked about increasing intensity so quickly. Michael was just recently upgraded from a Category 4 to a 5. And within 24 hours it was in the Gulf of Mexico and it just became this massive powerful storm. 

Yes, and that's exactly what I'm talking about. The intensification of hurricanes has been documented as happening much more rapidly. And that's expected to increase even further in the future. The intensity of tropical storms is still a very difficult thing for hurricane forecasters to predict. Because it is not just related to the temperature of the ocean, but it's how deep that layer of ocean is warm. And so if you have a shallow layer of  warm water sitting on top of, say, a colder layer, then there's not that much energy available for the storm. But if that layer is very deep, then it can provide a lot of energy for that storm. And we just don't have the data to tell us how deep those layers are in many cases. So a huge area of research that's happening right now is to try to do a better job of understanding where deep heat layers are, because that affects the intensification of the storm so dramatically.

There's research coming out of Rutgers University where they have basically developed some sort of autonomous vehicle that they're putting in the ocean to measure water temperatures. Is this research part of trying to understand and getting that data [on ocean water temperatures]? 

Yes, it is absolutely, and they're at one of the forefront universities working on this particular project. So they've developed an underwater autonomous vehicle or a glider that they can set off on its own with a pre-programmed course to follow. Or they can guide it from land and steer it right into the paths of tropical storms as they're coming up the coast. They can get a much better understanding of exactly how much heat there is available in that upper layer of the ocean and how deep that heat extends. It will make a big difference in determining accurately the intensification of these storms.