In our changing climate, the Arctic is undergoing an incredible transformation that will have profound ripple effects far beyond the Arctic circle and in all of our lives. In this first part of our series called the Arctic Episodes, we discuss the state of disappearing Arctic sea ice and its implications.
The Arctic, located above the line of latitude about 66.5° North of the Equator, marks the northernmost region of our planet. With long frozen winters and short chilly summers, its climate can historically be categorized as variations of extreme cold. A large portion of it is covered by ocean water, most of which remains frozen almost all year round, better known as sea ice.
The sea ice is surrounded by snow and ice-clad landmasses including northern parts of Scandinavia, Russia, Canada, Greenland, and the U.S. state of Alaska. During winters, temperatures can drop below -45°C in some places and nights can last for weeks or even months. With average temperatures being less than 0°C even in summer months, this is one of the harshest environments to live on Earth.
All of that is changing, fast!
The Arctic is currently undergoing an incredible transformation, a fact which is oblivious to most people. A transformation that will have profound ripple effects far beyond the Arctic Circle and in all our lives. This, perhaps, is the most important story of our times.
It is now a well-established scientific fact that our climate is changing. Ever since the industrial revolution, human emissions of greenhouse gases like carbon dioxide and methane are causing global temperatures to rise at an unprecedented rate. Nowhere is this more apparent than at the Arctic.
The 2018 Arctic Report Card, issued by the U.S. National Oceanic and Atmospheric Association (NOAA) last month, unequivocally states that the Arctic is warming at least twice as fast as the rest of the world.
There are multiple reasons for this dramatic rise in Arctic temperatures, known in the scientific community as “Arctic Amplification”. In this article, which is part one of our series called the Arctic Episodes, we discuss the first main cause for Arctic Amplification and its implications.
THE ALBEDO EFFECT
The Albedo Effect is just a fancy scientific term to describe the ability of a surface to reflect sunlight, also called solar reflectivity. White surfaces like ice and snow reflect around 80% of Sun's radiation back into space. On the other hand, dark surfaces like ocean water, land vegetation and dark building rooftops reflect less than 10% of solar radiation.
Of course, all of us have observed this phenomenon firsthand when we wear a black shirt versus white on a summer day. It gets unbearably hot in black after a couple of hours in the Sun. This is because dark surfaces have a low albedo (or reflectivity) and white surfaces have a high albedo (or reflectivity). In other words, low albedo surfaces absorb more solar radiation than it reflects.
As the Arctic is warming along with the entire planet, the sea ice is melting. When the sea ice melts away, the white surface is replaced by dark ocean water which greatly reduces the albedo of the surface. The darker ocean water absorbs a lot more heat from the Sun which causes further warming. This additional warming leads to further melting of sea ice and the whole system enters a self-reinforcing loop (a.k.a “positive feedback loop”) wherein the effects of initial warming lead to more warming and cause even larger effects and the cycle goes on.
So, as it turns out, the loss of Arctic sea ice is not only an effect of global warming it is in fact also a driver of global warming!
A study published in the Proceedings of National Academy of Sciences journal in 2014 estimated that the albedo reduction feedback due to retreating sea ice is contributing around 25% extra warming to the greenhouse effect from man-made CO2 emission. In other words, the albedo feedback is accelerating global warming as if we were adding 25% more greenhouse gases by burning fossil fuels than we are right now.
What is most worrisome about such self-reinforcing loops is that once initiated they can get out of control quickly as the effects are compounded. After that no additional force is required because the system drives itself. Experts believe this is exactly what is happening in the Arctic.
THE DISAPPEARING SEA ICE
The sea ice is in, what scientists are calling, the Arctic Death Spiral.
Since the 1970s the Arctic sea ice cover has retreated significantly. The summer minimum sea ice extent (which occurs in the month of September) has decreased by more than 40%. In 2018, the sea ice minimum was the sixth lowest extent since satellite measurements began in 1979. The 12 lowest extents in the satellite record have all been in the last 12 years!
While sea ice extent (or surface area) is a useful metric to assess the albedo effect, it does not capture the entire picture. Sea ice volume, which takes into account the thickness of the ice, is a better descriptor of the ice condition.
Typically, older multi-year ice which has been frozen for four or more years can be 4-5 meters thick and hence has more volume. Whereas one or two-year ice is much thinner and has less volume.
In the early 1980s, more than 25% of the ice was thick multi-year ice. Today, such ice is barely measurable. Almost all of the ice pack is now thin one or two-year ice.
Thinner ice is easier to break and more susceptible to storms and extreme heat events in the Arctic. This makes it harder for field scientists to set up their camps on the ice and make measurements. Ironically, it opens up the coastal Arctic seas for oil exploration because thin ice is easier to navigate with icebreaker ships.
THE BLUE OCEAN EVENT
At this point, the sea ice decline seems almost unstoppable unless we take dramatic action to stop all greenhouse gas emissions or use some type of solar geoengineering technique to counteract the albedo feedback. Soon enough, there will come a time when there will be nearly no sea ice left in the Arctic in the Summer or what the scientists are calling a Blue Ocean Event (BOE).
It is hard to predict when it will happen. Current estimates for a BOE range from as early as 2020, based on extrapolation of observational trends, to as late as the mid-century or second half of this century, based on global climate model projections. All approaches have their pros and cons which makes it hard to pick one estimate. Moreover, an extreme weather event like a powerful storm or a heatwave in the Arctic could cause severe damage to the thinning ice in a short period of time. Surprise elements like these are even harder to predict.
Nevertheless, there is no doubt that it will happen. A BOE will mean that for the first time huge amounts of sunlight will not be reflected back into space and instead be absorbed by the Arctic ocean. Scientists believe that this would be a critical “tipping point” for climate change and could lead to a sudden increase in the global average temperature.
This change would essentially be irreversible. At first, it will be a few weeks of no sea ice in the Summer but gradually that time duration will increase to a month and then a couple of months. Eventually, there will be no sea ice in the Arctic all year long.
Clearly, Arctic sea ice is in terrible shape and the stakes are extremely high!
The albedo reduction feedback loop in the Arctic has already been triggered by the amount of global warming we have had so far. It will likely not be enough to just reduce our future carbon emissions if we want to stop it. We must give serious thought to more creative solutions like solar radiation management or carbon capture and sequestration (removing CO2 directly from the atmosphere and putting it deep underground) if we want to have a real chance of stopping Arctic Amplification.
The albedo reduction effect is not the only feedback loop that is responsible for accelerating warming at the Arctic and around the world. In the next two episodes, we will talk about how the melting of the Greenland ice sheet and Arctic permafrost are also a part of this vicious cycle of exacerbating climate change and its impacts.
Apart from accelerating global warming, the sea ice retreat has also been linked to extreme weather events all around the world. Latest research suggests that the recent bitter cold spells in North America, the multi-billion-dollar hurricanes in the US, the global heatwaves and wildfires were all made worse by climate change and particularly by the changes that are happening in the Arctic. In the fourth and final instalment of this series, we will take a deep dive into the connections between the Arctic and extreme weather events.
References and useful links:
We have a vision of a planet where everyone, everywhere is actively engaging in the conversation on climate change. This blog is a place where we will share the latest news, views and breakthroughs on the defining issue of our time in our effort to realize the vision.