Quick evaluation the Earth’s health

The Fall has come! That beautiful period of the year when nature starts to slowly retreat is finally among us. Summer holidays are gone, and humans, as well as animals, are preparing for the long nights of winter.

Beginning of the ice cap in southern Iceland: picture by Gianluca Di Marco

In this period of the year, it is always good to check out satellite images of the Arctic to evaluate the Earth’s health. The ice cover of our Planet is very important during a period of increasing greenhouse gases and climate change, but to understand this we need to take a step back and think about a different concept: the albedo.

The albedo of an element is the capacity of a certain object to reflect sunlight. It can be expressed through numerical figures and, to keep things simple, we will assume that the colour white has an albedo of 1 (meaning is the frequency of radiation that reflects the most of sunlight) while the colour black has an albedo of 10. We can already notice something here: when you complain about your black car being heated because “attracts the sunlight” you are wrong: the colour of your car or clothes does not attract the sunlight but it is simply unable to reflect it back, and so the car gets hot.

But what has this to do with the planet?

If you make a couple of mental notes, climate change is simple to grasp. We need a high volume of surfaces with high values of albedo, in order to reflect more sunlight back into the outer space. And what is the white thing we have on the surface of our planet? Ice and snow. If we reduce the amount of ice and snow (by releasing more greenhouse gases into our atmosphere that will increase the Earth’s temperature, resulting in the melting of the ice caps) we will keep fueling the positive feedback loop of more GHG, higher temperature, less ice, less sunlight reflected back, and so on.

Obviously, ice is more abundant in Northern Latitudes. The beginning of Autumn declares also the end of the polar summer, the hottest period of the year at the poles, during which the ice naturally melts, despite of climate change. However, it is important to check the ice cover and compare it to previous years: this will give us an estimate of the melting of the ice rate, an important data we can use to evaluate the state of climate change (it can also be used to show proofs to your dumb friends who denies it at all).

Following are ice cover in the Arctic for the following year: 2020, 2019, 2018, 2000 (all the pictures shows the same day, 15th September) (Source: Nasa Earth Observation)


I can barely notice any difference when sliding the images. Does that mean that the Planet is not warming, or that the ice caps are not melting? Absolutely not.

That is a sign that the process is happening at a slower rate of what we might believe, but careful: I do not intend to pass the message that climate change is happening at a slower rate than we think. Simply, as we can see from this satellite images from NASA, the ice caps are melting at a slower rate than we think.

However, to quantify the gravity of the situation for those of you who are now feeling more comfortable with the climate crisis, we should compare the ice caps at the end of the Arctic summer with images from pre-industrial period to have a visual glance of how we are impacting the planet.

The purpose of this annual exercise is to embrace you with knowledge: just so you know, the next time you see a breaking news of an ice cap melting in the North Pole in July, you could simply notify the source that it is absolutely normal, and that it has been happening at a more or less steady rate for the past 20 years or so.

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