The Impact of Melting Glaciers

There is much effort in the media today bent on showing the amount of ice melting, but its effects are often only lightly discussed

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Rising Water

When glaciers melt one way or another the vast majority of the water makes its way to the ocean. As this happens the oceans will swell. Since glaciers all around the world are melting, this is bad news for our coasts. As sea levels rise many parts of our coasts will go under water. Over the last century the sea level has risen about 10-20 centimeters, the rate has doubled during the last twenty years and is predicted to go up by an entire meter by the end of the century. Other events, like a complete melt of the greenland ice sheet are possible, as the melting water is lubricating the ice sheets. When the ice sheets become lubricated the entire sheet is more likely to start sliding towards the ocean. A full collapse of these ice sheets could increase the sea level by as much as 7 meters. Glaciers will account for an estimated 35% of this. [1][2][6]

Scientists go to great efforts to measure information about the world’s glaciers. Right now the majority of data is collected by satellites. The problem with this data is that it's hard to measure the specifics of what’s going on within the ice sheets and glaciers, just general trends. That does not mean satellites are not helpful, it's just the opposite. Overall trends are important to research of all kinds. Satellites are invaluable when measuring the amount of ice that forms and melts, and the change in sea level, but not much else. The problem is that overall trends are not enough to predict what will happen in the future, because we in in uncharted territory. Planes are often used to measure detailed change over a relatively small area. To study more specific things like the humidity and temperature over long periods of time, probes will eventually be used. (I could not find any mention of any in the mass production phase, but I am not expert). [3][4]

Rising sea levels will plunge hundreds, or even thousands, of towns and cities underwater. Studies have found that in America alone 414 towns/cities will go underwater, no matter how much we reduce emissions. At just a meter 4.9 million people will be displaced in the US, by the end of the century a possible two meter rise could displace 13.1 million. The economic impact will be massive as entire cities go under water and groundwater is polluted with seawater. [5][6][7]

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Keeping it Cool

(I regretted thinking of that header immediately)

The ocean can be thought of as a massive reservoir of heat energy. This is because water is the darkest natural chemical on the surface of Earth, and more importantly has a very high heat capacity. Water is not just a dark material, it is also covers most of the surface. This means most of the world's heat energy is absorbed by the ocean, but its high heat capacity means it actually lags behind the rest of the Earth in temperature.[8][9]

To determine how fast the temperature of the ocean is increasing scientists employ a variety of tools. To measure the surface of the ocean satellites are used. These satellites either measure the energy in the microwaves or infrared rays coming from the surface layers of the ocean, which are measured from 1mm or 10 µm respectively. Each of these have their own uses, for example, infrared has a better resolution but is affected more by clouds. The deeper ocean is more complicated to measure because instruments actually have to go there. One program, called Argo, sends out small floats that can drop down to 2000 meters below sea level and come back up. Since there are 3000 of these this gives us enough data to get basic measurements of large areas on the ocean. The data that has been taken has shown us that the whole ocean has increased by about 0.055C over the last 30-50 years, while in the same time period the surface layers gave increased by about 0.17C and the atmospheric temperature has increased by 1C. [10][8][9][15]

Frozen water is the most reflective natural chemical on the surface of the Earth. As the glaciers melt the effect is twofold, they increase the surface area of water and expose darker materials beneath them. The temperature of the ocean around the arctic is increasing at six times the global average, and the arctic holds 91% of the world's ice. As this ice melts the planet absorbs significantly more heat energy. Since the melting of ice is already accelerating once it all runs out we will be due for a massive upsurge in temperature increase. We are already in an era of the fastest change we have ever seen. It is predicted that the increase in temperature will have massive negative impacts on life in the deep ocean. By 2100 food will drop by 55% down there. We know very little about the deep sea ecosystems and the impact could spread far beyond just the deep sea. [11][12][13][14]

Around 1.7% of the world's water is ice and about 97% of it is in the ocean. Calculating the specific cooling effects of the ice requires its temperature, which varies with the depth of the ice in the glaciers. I will be basing estimates off the antarctic ice sheet as it is the vast majority. As the ice gets deeper it actually gets warmer, up to -9C at about 2800 meters below the surface. Eyeballing the graphs from this study gives me an estimate of about -40C on average. The specific heat capacity of ice is 2093 J K^−1 kg^−1 (just about half that of water). That alone is enough to cool the entire ocean by around 0.35C. Then the actual melting of the ice takes a massive amount of energy, around 334 joules per gram. Heating water takes around 4.184 joules per gram per degree Celsius/Kelvin. This is the reason why the ice in your drinks lasts so long, snow takes so long to melt, and icebergs can last years. This is enough to cool the entire ocean by an additional 1.4C. This will help offset the cooling for a time, which only delays the effects. Even when we do start fixing the climate today it will continue getting worse for decades. [15]

(A lot of assumptions and estimates were made, including that the atmosphere does little to none of the warming of the ice, however the effect is still many times smaller than that of the ocean.)

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Weather, Shipping Routes and Everything Else

Melting glaciers alter a lot about the ocean. Ocean currents are one example, and are far more important than many people think. They are products of all the forces that the water of Earth feels. They last long times and help bring large amounts of water from one area to another, the gulf stream is one example. It brings large amounts of warm water to Europe, keeping it quite a bit warmer than the area around it. These currents keep contained because of differences in temperature created by differences in temperature or water content. Hot water has a tendency to rise to the top and flow over to the cooler poles. As the water cools down it sinks and makes its way back to the warmer waters closer to the equator. Freshwater is less dense than saltwater, and as freshwater enters from the glaciers it disrupts the cycle. This has actually happened before, the Younger Dryas Event around 12,700 years ago was likely caused by glaciers and caused a major disruption to the gulf stream. Since the gulf stream warms Europe it dropped by around 5C. Climate change could actually cause a larger drop, the crop damage alone would be massive.[15][16][17]

The size and thickness of ice around the poles makes it nearly impossible to navigate through areas like the North of Russia. Since the ice is melting at an alarming rate it's getting easier and easier to get through those areas. In future decades it will likely be faster to go through the arctic than around the more common southern routes. We could see icebreaking cargo ships going through the arctic by 2030. [18]

The melting glaciers also harm wildlife in many ways. Animals near the poles depend on them for survival. Polar bears for example need sea ice to both hunt for food and store it. They can’t do that if there isn’t any sea ice. [19]

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Sorry for all of those US-centric statistics, google wasn’t helping out when I wanted worldwide (or land loss, even though I’ve found stuff on it before). Melting glaciers are a major problem for everyone. At this point it will be impossible to stop, we can only mitigate the effects. Although, we aren’t even doing that effectively.

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[1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [11] [11] [13] [14] [15] [16] [17] [18] [19]