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Why you should care about the Arctic
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| Arctic Sunset. Wikimedia Photo: P J Hansen |
The Arctic is Warming
Rising temperatures in the Arctic are contributing to melting sea ice, thawing permafrost, and destabilization of a system also known as “Earth’s Air Conditioner”. The Arctic regulates ocean and atmospheric circulation and keeps the the planet cool. Climate change is impacting weather patterns, natural systems, and human life around the world. The Arctic, however, is central to these impacts as it is warming more rapidly relative to lower latitudes, about twice as fast as the rest of the globe, making it “the canary in the coal mine”. What happens in the Arctic is of utmost importance to us humans if we want to know how climate change will impact our only home, planet Earth.
Reinforcing feedbacks and potential tipping points
The Arctic is very sensitive to global heat forcing, and any small warming there could rapidly trigger a number of feedbacks that generate more warming for the Arctic and the globe. These feedbacks include but are not limited to: A) snow and ice melting; B) changes in ocean and atmospheric circulation; C) thawing permafrost and methane release. The concept of a “tipping point” - a threshold beyond which a system shifts to an alternate state - has become familiar to most people concerned with the climate debate. If tipping point means crossing a critical threshold in which a system enters substantial, potentially irreversible, change that causes it to move into an entirely new state, there may be precursors or early warning signals of such change. Such warnings are exactly what climate researchers and ecologists are looking for and trying to map out. The graphic below shows potential tipping elements in the Arctic region.
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Map show potential tipping points in the Arctic region: ice melting (white); ocean and atmospheric circulation (aqua green); and biome changes (dark green).
Source: Lenton (2012) |
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| Source: meltfactor.org |
Changes in ocean and atmospheric circulation
In recent years radical shifts in atmospheric circulation patterns have occurred in the Arctic, strengthening poleward heat transport and bringing warm air and warm ocean currents from the Atlantic right into the centre of the Arctic (Lenton, 2012). This behavior in wind and water circulation limits winter sea-ice growth and thus contributes to further summer sea-ice decline. The additional warming in the Arctic affects weather patterns in the Arctic and beyond by altering the temperature gradient in the atmosphere and atmospheric circulation patterns (WWF, 2011). The polar jet stream is a high-altitude, blisteringly fast wind that blows around Earth at mid- and polar latitudes. It dips into and out of the Arctic, shifting high and low pressure air masses. Rising temperatures in the Arctic slows and increases the waviness of the Jet Stream which generates more south to north transfer of temperate and tropical warmth into the Arctic together with a greater export of Arctic cold to lower latitudes. Experts view a tipping point for ocean circulation to be somewhere around 4C warming (Lenton, 2012) while atmospheric circulation is more difficult to assess and needs to be further investigated.
Thawing permafrost & Methane
Permafrost—the ground that stays frozen for two or more consecutive years—is a ticking time bomb of climate change. Some 24 percent of Northern Hemisphere land is permafrost. That's 23 million square kilometers found mostly in Siberia, the Tibetan Plateau, Alaska, the Canadian Arctic, and other higher mountain regions. When the Arctic warms, permafrost can start thawing and releasing carbon and methane into the atmosphere (figure 2). In a controversial paper in Nature, Comment, Whiteman et a. (2013) posited a scenario whereby a 50 Gigatonne (Gt) methane pulse would occur over a decade time period and calculated its potential economic costs. To put this in context, the total amount of methane in the world’s air now is about 5 Gt, and the annual input is about 0.5 Gt, so this would double the methane in the air within the first year. Newspapers such as the Guardian and popular blogs were quick to pick up the story and claimed that there was a possibility of an Arctic “methane bomb”. Following articles have, however, shown little evidence pointing to the likelihood of such a scenario. A group of international scientists wrote in Nature Geoscience in 2014 that “significant quantities of methane are escaping the East Siberian Shelf as a result of the degradation of submarine permafrost over thousands of years” (Shakova et al. 2014). The authors claim that a sudden release of methane, in a “pulse”, seems unlikely and that methane will probably continue to bubble up slowly, contributing to greenhouse gases in the atmosphere. But they do caution that its possible that global warming could cause more storms in the Arctic Ocean, releasing methane on a bigger scale. There is no established tipping point for methane release, but some studies suggest that a tipping point for continuous Siberian permafrost thaw could be as low as 1.5°C warmer than the pre-industrial period (Oxford University). Consequences
Sea level rise |
| Sea level rise at +1-4C warming scenarios. Source: PIK |
Sea levels are rising due to thermal expansion from warmer oceans and melting of land-based ice. Satellite measures since 1993 show global sea level rise of around 3.2 mm/year (CSIRO). The potential for increases in sea level rise is enormous because the ice caps of Greenland and Antarctic contain over 99% of all the freshwater on Earth (NSIDC). Estimates suggest that if Greenland ice sheets would melt completely it could raise sea level 6 meters. In other words, a one per cent loss of the Greenland ice cap would result in a sea level rise of 6cm (NSIDC). In a process that is accelerating, ice caps are losing mass. In past periods of Earth’s history, levels of atmospheric greenhouse gasses and sea levels have followed one another closely, allowing an inference about where sea level is headed. Sea levels may rise by more than 2 meters for each degree Celsius of warming the planet experiences over the next 2000 years (see figure), according to one study (Levermann et al. 2013). But even a one meter sea level rise could cause major problems for low-lying countries such as the Maldives and Bangladesh, forcing inhabitants to migrate. Around 150 million people live within 1 metre of high tide level (CSIRO). Coastal cities, ports and airports could be flooded, as could cities sited near tidal estuaries, like London. And many nuclear installations are built by the sea which is of great concern knowing what happened in Fukushima.
Extreme weather events  |
| Jet stream and hurricane Sandy. Source: mprnews |
Shifts in atmospheric circulation could influence weather patterns. Rising temperatures seems to slow down and increase the waviness of the jet stream, increasing long duration extreme weather patterns such as droughts, floods, and heatwaves (YaleEnvironment, 2012). This has significant impacts on temperature and precipitation patterns in Europe and North America. That weather patterns can "get stuck" might explain why the intensity of extreme weather events has increased. We have seen many examples of “stuck” weather patterns during the past few years. Deep southward dips in the jet stream hung over the U.S. east coast and Western Europe during the winters of 2009/2010, 2010/2011, and 2012/2013 bringing a seemingly endless string of snow storms and cold. In the early winter of 2011/2012, in contrast, these same areas were under northern peaks in the jet stream which brought unusually warm and snowless conditions (Francis, 2013). And in summer times persistent weather have been responsible for droughts and heat. The record heat waves in Europe and Russia have been linked to early snowmelt in Siberia (Jaeger and Seneviratne, 2011). These changes affects agriculture, forestry and water supplies. For example, farming becomes more precarious as weather patterns and prognosis are no longer reliable. Changes in weather patterns also impact storm surges and hurricanes. Some scientists suggest that changes to the jet stream drove hurricane Sandy west, towards the coast of northeastern United States (LiveScience, 2013). Ranking as the second costliest hurricane in United States history (Huffington Post, 2013) one can see how changes to storm patterns can have enormous costs to society and the economy.
Warming & Acidic Oceans |
| Coral reef at +1-3C warming. Source: FurmanWiki |
The complete loss of Arctic summer sea ice has major knock-on effects, such as boosting phytoplankton and absorbing more heat in the oceans. Ocean warming effects marine life in temperate latitudes making species such as cod, haddock and flounder shift their geographic ranges, leaving fewer cold water species (NASA, 2013). Disease also spread faster in warmer water so parasites are having larger effects on species, especially sensitive coral reefs. Because the planet’s oceans currently absorb about a quarter of the carbon dioxide, which lowers the pH level of the water, the oceans are becoming acidic. Acidification makes shell-formation among marine organisms such as plankton and mollusks more difficult, which could have major cascading effects on marine life as these organisms make up the base of the ocean’s food chain. Coral reefs, which are marine biodiversity hotspots, are particularly sensitive to changes in temperatures and pH. Coral reef ecosystems are in global decline and this means loss of storm buffers and loss of estuaries for fish species that generate 200 million jobs and food for a billion people (NOAA).
Summary - Tipping points
Greenhouse gasses
According to most scientists, a CO2 amount of order 450 ppm or larger, if long maintained, would probably push Earth toward an ice-free state (Hansen et al. 2008, 2013). 450 ppm is considered a climate tipping point, beyond which we would have no control. We are at 400 ppm today, which constitutes high risk of transgressing the tipping point. According to science we need to get back down to 350 ppm to be considered in the safe zone.
Arctic ice free summers
Some studies suggest that we may have passed a tipping point in relation to having sea-ice free summers in the Arctic already in 2007 (Livina and Lenton, 2013). The loss of reflective surfaces in the summer reinforces further warming, as dark water absorbs more heat from the sun, causing further melting. The loss of summer sea-ice cover is reversible, given that warming slows down (i.e. drastic reduction in greenhouse gas emissions).
Greenland ice sheet
By looking at sediment records a team of scientists found that 1°C warmer than today's temperatures in Greenland contributed to a 4-6 meter sea level rise from the collapse of the southern part of the ice sheet (Reyes et al., 2014).
Permafrost methane release
At 1.5°C warming, from pre-industrial levels, Siberian permafrost starts thawing on a large scale (Vaks et al., 2013). Crossing this tipping point could potentially lead to runaway climate change because of the scale of carbon stores and because methane is 20 times more effective in increasing global temperatures than equal amount carbon dioxide.
Conclusion
What is happening in the Arctic impacts us all. Rapid climate changes are now taking place in the Arctic with impacts on a planetary scale. We do not know how to fix it except from lowering our emissions. Many experts say we need a rapid reduction in greenhouse gas emission, starting now. Global leaders have to come to an agreement that substantially reduces emissions, the rich world taking the lead. Our only home, the Earth, is changing rapidly and we are now running into dangerous risks of substantial warming and triggering climate tipping points that reinforces further warming beyond our control. The last call is coming up in November of 2015 Paris Climate Meeting. “The Arctic acts as an early warning system for the entire planet” (Dr. Chip Miller, NASA Jet Propulsion Laboratory). We should all follow what happens there closely and warn the world of the potential dangers of going on with "business as usual".
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