The Arctic is warming almost four times faster than the rest of the planet. Fresh off scientific fieldwork in the Arctic, marine geophysicist Dr Kelly Hogan and marine biogeochemist Professor Kate Hendry explain what the consequences of a melting Arctic could be, and how the Arctic influences the climate we enjoy today.
In this edition of Beyond the Ice, they reflect on what they saw and studied in this spectacular and important environment this summer. Kelly digs into the significance of Greenland’s glaciers to the warm ocean currents that heat Europe, and Kate explains how glaciers function as major nutrient factories that support life and carbon cycling in the global oceans.
Dr Kelly Hogan joined this edition from The Arctic Circle Assembly in Reykjavik in October, a major meeting of Arctic interests in science, business and politics, where she shared immediate science reflections from the fieldwork campaign in Greenland.
Listen to the full discussion on the Beyond the Ice podcast:
The discussion, in brief:
Dr Kelly Hogan and Professor Kate Hendry both led science investigations in the Arctic this summer. Did they notice any visible changes while they were there?
Kelly talked about the experience of seeing huge volumes of meltwater in the Greenland summer, and contextualised this within the wider trend of ice loss:
“To some extent, that’s normal for Greenland and for the summer – that you have a melt season, and then everything freezes up again in the winter. You could see it moving past the ship that we were on, because it’s moving so fast. But as we know, melting is increasing and the summer melt seasons are getting longer. We’re losing ice on the ice sheets, and the glaciers are retreating.””For one of the fjords that we went into, we looked up some of the historical maps about where the ice used to be and some old of aerial photographs from the 1980s, and where we were working had been covered by ice. We were on fresh seafloor, fresh territory. Within my lifetime that ice has moved back several kilometres. So that is pretty stark.”
Kate reflected on the conversations she’d had with Norwegian scientists working at Ny-Ålesund in Svalbard during her summer work there:
“You can talk to the Norwegians who’ve been there year after year, they’ve been working there for decades. And they’re not worried about the changes that they’ve seen over the last 30 or 40 years. They’re worried about what they’ve seen over the last 3 or 4 years. And really that is possibly the starkest reminder I’ve had. That’s just how quickly it’s accelerating.”
The Arctic is warming up to four times faster than the rest of the planet. How can it be that a particular area of the planet is warming faster than the rest?
Kate explained that this phenomenon is called ‘Polar Amplification’, and is partly due to how the atmosphere and the oceans move around the planet, and the balance between warmer and cooler regions. But she also described how warming can produce reinforcing feedbacks in the polar regions:
“In the Arctic, if you start warming the air and the oceans, it’s likely you’re going to start melting sea ice. And that then reduces how much of the energy (and therefore heat) coming in from the sun can be reflected back into space. That’s just the albedo effect – the white ice reflects better than the darkness of the ocean.”
Why have we not seen the same phenomenon in Antarctica?
Kelly said that while Antarctica is still warming, we’re not currently seeing it warm faster than the rest of the planet because of the positioning of land and currents:
“One of the reasons that we haven’t seen so much warming in the Antarctic yet is because of the way that the ocean currents move on the planet. Antarctica is surrounded by a big ocean current that goes all the way around it as a landmass – called the Antarctic Circumpolar Current. You get the same phenomenon in the atmosphere, and that acts to isolate it thermally from heat from the equator.”
“In the we all benefit from the Gulf Stream bringing warm water from the equator up to Western Europe. And that’s why we’re so much warmer here than equivalent latitude in Canada. But in the Antarctic, that transport of heat from the equator to the pole is sort of stopped, or at least, you know, inhibited by this big current that moves around it. And so it protects Antarctica from the same thermal effects.”
What role has the Arctic been playing so far in the balance of the global climate?
Through atmospheric and ocean connections, what goes on the Arctic doesn’t really stay in the Arctic, explained Kate:
“A major proportion of the weather systems that we get in the UK come straight from the Arctic or from the sub-polar regions. So we’re heavily influenced by what’s going on in terms of atmospheric processes in the Arctic.”
“The Arctic also sets the the balance of the amount of freshwater that gets into the Atlantic and the Pacific, and that really controls the really large scale ocean circulation processes that move heat, carbon and nutrients around the planet. So if the Arctic changes, that will change the entire sort of conveyor belt, if you like, of what’s moving around the oceans. This also causes changes to biology and what can live in different areas of the global oceans.”
Kelly also pointed out the link of the Arctic with global sea levels:
“The other thing is that the Arctic stores large reservoirs of fresh water as ice. Really we’re talking about the Greenland ice sheet here, but also the glaciers in Svalbard and the Canadian Arctic. So far, a lot of the sea level rise that we have seen from melting ice sheets of glaciers has come from Greenland, because the Arctic has warmed more rapidly than the Antarctic, and it was warmer to begin with.”
Investigating the link between Greenland’s glaciers and major ocean currents
This summer, Kelly co-led a major investigation, KANG-GLAC, into how the accelerating decay of the Greenland Ice Sheet will progress with climate change, and to better understand the knock-on effects this will have on ocean circulation and marine productivity. The project was co-lead with Durham University, and was based on the UK’s Royal Research Ship Sir David Attenborough. Kelly explained:
“We are studying those glaciers that drain right into the ocean, and we’re trying to understand how they will melt, and what happens in the fjords and to the ocean currents beyond.”
“The way that we’re doing it is to look at the last time temperatures in the Arctic were higher than they are today – about 9,000 years ago, when temperatures were 2-4°C warmer than today. How much did it melt? How quickly did it lose ice? That will help us to understand what will happen in the future as our temperatures get warmer.”
“The other side was looking at freshwater and nutrients you get if you start to melt the glaciers into the fjords. What happens to the marine ecosystems that live in those areas at the time? And what happens to the carbon they help to cycle and sequester?”
Kelly spoke about some of the specific work done on the KANG-GLAC mission. This included sampling of sediments in the fjords, and using different species of microscopic creatures as indicators for temperature and nutrients at different points in time. Geologists also sampled rocks on land to understand when and how quickly ice had previously melted.
She then explained the wider impact of glacier melt on currents and circulation:
“One of the big climate tipping points for the Greenland ice sheet is if you start to increase melt rapidly, you get a very cold, fresh ocean layer and it stops the some of the big ocean circulation from happening, or makes it less powerful.”
“The big ocean currents that bring heat to Western Europe would slow down. There are some models that predict that whole system might shut down by 2040, which is not very far away. If you imagine being as cold as equivalent latitudes in Canada – our whole way of life in Europe would change.”
“We’re looking for the exact mechanisms of how it all happens. We don’t have a great handle on that in the computer models that we use to look at the whole Earth system, and that’s a problem. It makes us less certain about predictions for the future.”
Understanding glaciers as nutrient factories for the global oceans
This summer, Kate led the initial phase of the SiCLING (Silicon CycLing In Glaciated environments) project at Ny-Ålesund in Northern Svalbard. The project aims to understand the role that processes in Earth’s cold places have in cycling silicon through the global oceans – and what the impact of climate change will be on these polar processes.
One organism in particular illustrates the importance of silicon nutrient cycling to global ocean processes and food chains, explains Kate:
“Silicon is needed by everything on Earth, and most organisms need silicon in fairly small amounts. But some things need it in much higher amounts – including one of the important forms of algae that grow in water, called diatoms, which make their cell walls out of silica. They’re responsible for a huge amount of carbon export from the atmosphere to the ocean via photosynthesis.”
“They form the basis of the food chain – everything feeds on them. But also they’re really important for carbon cycling, because they take up carbon from the atmosphere and they lock it up in organic matter through photosynthesis. They’re quite dense because they’ve got these big silica shells and they sink really easily and quickly. So they, they’re really good at transferring that carbon, that organic matter from the surface of the ocean down into deep into the sediments where some of it will get locked away.”
Glaciers are major factories for nutrients like silicon, explained Kate, because of the huge scale at which they grind rock into very fine powder, which is then transported to the ocean:
“We call it glacial flour, because it’s so fine. For decades people thought glaciers were these sort of inert environments – but now we know they’re chemically really strange underneath, like nutrient factories or big nutrient factories. And they produce a lot of this flour, which dissolves in seawater and the nutrients are available for the algae.”
“So a lot of what we’re trying to do in SiCLING is to get to grips with how these nutrients interact together in this environment and what this might mean globally if we loose these nutrient factories – in a way that brings together chemistry, physics and biology.”
Collaboration in the Arctic
Shortly, Kelly travelled to Iceland to attend The Arctic Circle Assembly to talk about the key science and the work that took place in Greenland. It was also an opportunity to show that the UK is well positioned to keep working with international partners to keep doing science research in the Arctic.
Speaking to the Beyond the Ice podcast from the meeting in Reykjavík, Kelly reflected on the opportunity of meeting the international community at The Arctic Circle Assembly:
“What’s brilliant about it is that you get a chance to talk to governments, or politicians and policymakers, who I might not necessarily reach normally as a scientist at a science conference. So that is really fantastic.”
“Everyone is very open to talking about the challenges that there are in the Arctic – be that national security, or the security of the Arctic region in regards to climate change – and actively working with indigenous or local populations. And everyone has been very frank and open, and that is very refreshing. It leads to very productive conversations.”
The Beyond the Ice podcast from British Antarctic Survey is available on all podcast platforms, and is embedded at the top of this article.
Professor Kate Hendry is a chemical oceanographer and marine biogeochemist at British Antarctic Survey, and an honorary professor at the University of Bristol. Her research explores the impact of climate change in the polar regions on marine nutrient cycling.
Dr Kelly Hogan is a marine geophysicist at British Antarctic Survey specialising in Arctic and Antarctic ice sheet history, glacial geomorphology and glacial-marine processes. She uses use seafloor measurements and sediment cores to reconstruct past ice sheet behaviour and changing environmental conditions during the last ice age and during Holocene natural variability.