Stop climate change.
Climate is changing. Rapidly. We are seeing it with our own eyes in every part of the world.
We are the first generation to feel the effects of climate change, to know we are destroying our planet, and the last generation who can do something about that. This was said by WWF in Manifesto 2019. (https://www.wwf.org.uk/sites/default/files/2019-10/election_Manifesto2019.pdf).
The terrible truth of our times here, on the Earth. Climate is changing. Rapidly. We are seeing it with our own eyes in every part of the world. Only this year (2022) brought devastating droughts to Europe, floods to Asia, and heatwaves – to everywhere. Ice in Greenland and Antarctica is melting faster and faster every year. Oceans are rising. Some coastal areas have already suffered from being flooded, and more of them will experience floods in the future. Temperatures will continue rising as well. Even if we keep them under an average of +1,5 Celsius, according to the Paris agreement 2015, that would mean that globally on average it can be not more than that, but in regions that are usually or already hotter – temperatures can grow up to 3-5 degree Celsius. According to the worst-case model scenario from IPCC, if people don’t manage emissions, temperatures would rise to 4,4oC on average, and up to 6-8oC in some regions. Deadly high. And we are the ones who must solve the issues our ancestors created, starting from the Industrial revolution. But before it all starts being a heavy stone on your chest, let’s learn about climate change more, what the reasons for that are, and whether people are the only ones to blame. Spoiler: no. But people do make it worse.
There are natural and anthropogenic reasons for climate change. In this article, we will discuss natural ones.
First, what is climate? It’s nothing else than the average weather. When I am writing this text with my morning cup of organic black tea, it’s the 17th of October, and the weather is unusually warm – it’s already +15oC at 10 AM, and in the afternoon it is going to be 22oC. It’s sunny, the wind is western, 2 m/s, pressure is 770 mm Hg, humidity equals 90% and there will be no precipitation today. This is all about the weather. To conclude what the climate is for Prague, where I live, we must know the average values of all these parameters for daily/monthly/yearly periods, to understand what the weather patterns are. It is also needed to have information about the frequency of severe weather events, like floods/droughts/hurricanes (yes, it happens even in Central Europe sometimes). For example, on the 17th of October 2021 maximum temperature was 11oC! 11 degrees less than today.
What controls the climate? There is a list of things. You might know that the climate on our planet has changed several times during its 4,54 billion years of history. The Earth receives energy from the Sun – this process is called insolation. This energy comes into directly on the equator, and at angles on the poles. The amount of solar radiation may decrease or increase a bit, during the solar cycle, nevertheless, on average it is growing higher by 10% every billion years. It’s a way too long period for us to notice any changes due to that fact. The Earth is also rotating, so, depending on that, the planet is closer or farther from the Sun. The closer, the more concentrated sunlight is. But energy doesn’t just enter. It also gets away, back to Space. As in any system (and the Earth is a system), the conditions are controlled by the balance between how much energy comes and leaves. How does energy getaway back to Space? Thanks to Albedo and Greenhouse gases effects.
When it’s hot, we usually wear white clothes. For a reason. White reflects the sunlight, and consequently, we’re not getting as hot as we would, wearing black. This effect is called albedo – how reflective the surface is. The albedo of a dark field equals 0%. The whiter the surface, the more reflective it is. A perfectly white surface, like, for instance, an ice shield, reflects 100% of sunlight, lowering the temperatures of the surroundings. Today, the average albedo of the Earth is only 30%. But if it is higher, it creates a loop which is called positive feedback. The more snow and ice are on the surface, the higher albedo, and the more energy is reflected in space. If it’s enduring in that way, the Earth is all covered with snow and ice, and the temperatures are low. We call such conditions ice age. The last one was 650 million years ago. And the other way around, what we have now. Albedo is not high enough to cool the climate. And it’s becoming warmer.
(Darkfield. Albedo is almost 0. Source: Wikifarmer)
(Perito Moreno glacier in Argentinian Patagonia. Albedo is around 100%. Source: Escales Ponant magazine)
(Surface of the Earth with clouds removed. Poles covered with snow and deserts are bright, reflecting the sunlight. While oceans and continents are darker. Source: NASA Goddard Space Flight Center Image by Reto Stöckli. Courtesy of NASA’s Earth Observatory)
Sounds like we have found the main reason for climate change, but Albedo does not explain everything. The Earth has a thick atmosphere, consisting of 5 layers, which work as reflective surfaces and as a trap for gases. Imagine the sunlight striking the Earth’s atmosphere. Half of that energy is reflected, and the other half is absorbed. It comes through all 5 layers to the surface. If the surface is white, it reflects the sunlight in the atmosphere. But since it’s quite thick, it reflects energy toward the surface of the planet again. Then, it reflects from the surface once more, and some of that energy finally return to space. It’s like a game, if you drop a ball, it will jump up once it touches the floor, until the energy you put into the system is balanced, and finally the ball stays on the ground. Before some of the sunlight is finally released from the atmosphere, it warms the surface up. The longer energy is trapped, the warmer the planet’s surface becomes. That effect is called Greenhouse gases.
Something else controls the climate on Earth. It has already been discussed that our planet rotates around itself and the Sun. But the rotation is not the same. The Earth changes its orbit’s shape and angle during the cycle. There are 3 ways how the Earth rotates: eccentricity, axial tilt, and axial precession. These cycles are called Milankovitch cycles.
Eccentrical rotation means that the planet’s orbit goes from ellipse to circular over 400,000 years. The way back from circular to ellipse orbit takes less, “just” 100,000. Now the Earth is on its longest journey. It is closer to the Sun in January, and further from it in July.
Axial tilt explains why we have different seasons. Each hemisphere is located either toward the Sun or away from it. The angle can vary between 22.1 and 24.5 degrees. The less this angle, the fewer temperature differences between seasons. And if the angle would be 0, there would not be seasons at all! Currently, the angle is 23.5 degrees, and it will decrease over the next 20,000 years.
Axial precession is the term that determines the direction of the Erath’s rotation. There are two stars – Vega and Polaris – towards which our planet is pointing. When it’s towards Vega, the summer peak in the Northern Hemisphere is in January. When the leading star is Polaris, like it is now, we have summer peak, as we’re used to, in July.
(Milankovitch Cycles Illustration of the three variables in Earth’s orbit, with periods of variation marked. Source: COMET® at the University Corporation for Atmospheric Research (UCAR) pursuant to a Cooperative Agreement with the National Oceanic and Atmospheric Administration, U.S. Department of Commerce. ©1997-2009 University Corporation for Atmospheric Research. All Rights Reserved).
To sum it up, today the planet’s orbit is almost circular (we have warmer winters), and axial tilt is equal to 23,5, which is midway to the minimum of 22.1 degrees – again, milder winters. Considering all these parameters, it is the Interglacial period. For instance, at the beginning of each of the recent ice age periods, the orbit was more elliptical, and the axial tilt was minimal – 22.1 degrees (lower temperature in summer). Now the angle is 23.5 – winters are milder, and summers are hot as well. Moreover, the excessive amount of CO2 in the atmosphere (the highest record in the Quaternary period) impacts the climate. That can explain why the climate gets warmer. The ice is melting due to two main reasons: levels of CO2 and the location of the Earth. The less area of the ice sheet, the less albedo. It creates positive feedback, warming up the temperatures more.
It must be also mentioned that the composition of the Earth’s atmosphere wasn’t stable all the time. Due to volcanic activity, carbon dioxide, sulfur, and ash levels were much higher than we have today. High CO2 levels warmed the planet throughout its history. That’s why archeologists find dinosaur fossils in Alaska. These giant creatures wouldn’t survive there with modern average temperatures. Sulfur and ash create the opposite effect – the latest immense volcanic eruption in 1991 (Mt. Pinatubo in the Philippines) lowered global temperatures in the following year 1992 by half a degree Celsius. Because of ash and sulfur, sunlight couldn’t reach the planet’s surface.
Today, due to human activity, the most abundant gas after nitrogen (78%), oxygen (21%), argon (1%), and water vapor (0-5%) is carbon dioxide. The amount of CO2 is rising every year. For instance, in August 2019 atmospheric CO2 was 409,95 ppm (parts per million).
August 2020 – 412,55 ppm.
August 2021 – 414,47 ppm.
August 2022 – 417,19 ppm.
You can say what the trend is. Check it by yourself. (Source: https://www.co2.earth).
That confirms that composition is changing all the time. And gases can be removed naturally – it just takes time. CO2 dissolved in the atmosphere is used by plants for photosynthesis. It also gets dissolved in the oceans and, subsequently, becomes carbonate sediments. The CO2 produced by humans is also removed naturally. However, the rates of pollution are too large and fast for the Earth to take care of and balance the atmospheric composition. The estimated time to remove all the carbon emissions we ejected into the air by now (if we stop all emissions this exact second) is around 1000 years.
It is not said to make you feel terrified or neglected. The reason is the other way around. You, yes, you, can do what is in your arms. And there are many things.
In the next post I will tell you more about anthropogenic reasons for climate change, and sources of pollution that worsen the situation.
Victoria Zueva
