The Science

What is climate change, and how do we know?

greenhouse cycle

The Greenhouse Effect

In order to truly understand how something is changing, it’s helpful to take a step back and examine how it works.

Imagine, for a moment, a brick wall sitting in the sun. The sun produces a wide spectrum of radiation, which runs into the bricks. Some of the sun’s energy is reflected from the bricks – they appear red to us because the bricks are absorbing most of the radiation, and only reflecting the wavelengths that correspond to what we can see as “red”.

Much of the sun’s energy is absorbed, however, and then released again as heat radiation – hold your hand close to the wall on a hot day, and you just might burn yourself!

The earth works on similar, if more complicated, logic. Our atmosphere acts as an insulator – protecting us from much of the incoming energy from our sun, and retaining much of the heat emitted from the earth. Our landmasses reflect some light and heat, and release more heat that had been absorbed throughout the day. Our oceans reflect some energy, but tend to absorb most radiation and heat, slowly causing the oceans to slowly warm.

carbon dioxide

CO2 Molecule

So, now we understand (in a very basic way) how a few systems are working together. How do CO2 and other greenhouse gasses actually lead to climate change?

Carbon Dioxide (and other greenhouse gases) just so happen to have their molecules arranged in just such a way that as the heat and radiation being reflected and emitted from the earth ‘excite’ the O2 atoms in the carbon dioxide molecule, by increasing the activity of the oxygen’s electrons.

Unfortunately for all of us, those ‘excited’ electrons result in the entire CO2 atom to vibrate. Heat is the measure of kinetic energy in an area, so as the CO2 vibrates, it causes an increase in heat. Going back to our brick wall analogy – just like the bricks get warm when exposed to energy, so too does carbon dioxide and other greenhouse gasses.

To use another analogy, our atmosphere acts somewhat like a blanket – it keeps out the cold of space, and it keeps in warmth. As we change the composition of that blanket, it’s getting better at holding in heat, which is causing the current, substantial, warming trends.

So, why do we care?

Climate Change is already having devastating impacts, and is in danger of becoming an exponentially increasing danger to humanity, and every other species alive today.

Looking locally, you can already see impacts on Colorado’s ski and snowboarding industry. In March (historically the highest snowfall month in CO), Denver didn’t get any snow. Effects of climate change will continue to worsen, ultimately driving away the thriving ski and snowboarding industries that so many Coloradans work in and love.

Many low income and minority populations are disproportionally affected by climate change. They can’t afford to take mitigating steps, and so must suffer through the worst of it. It isn’t the rich who pay the costs for decades of unsustainable business practices, because they can afford to prevent issues in their own back yards. It’s those of us who have the least who must pay the most. We actively work to increase awareness and action related to these ‘frontline’ communities.

When you zoom out, consequences are equally dire. Around 30% of humanity lives in the ‘coastal impact zone’, which will be underwater thanks to melting ice reserves and warming waters. To make matters worse, much of the most productive farmland in the world resides in these coastal impact zones. Changing weather patterns are already resulting in national and international conflict – war-torn Syria has been suffering from an extreme, protracted drought, which has contributed substantially to regional instability.

Another reason to be aware is Amplifying Feedback Systems. These are systems in which planetary systems end up feeding back into themselves, resulting in dramatically increasing devastation.

An example that is near and dear to our hearts is forest fires. Trees are great at capturing carbon – they pull it out of the air, and store it in their wood. Climate change is resulting in higher fire dangers, so when fires do start, they tend to get worse. The fire itself releases a ton of stored carbon, which in turn increases greenhouse gas concentrations in the atmosphere, exacerbating climate change.

melting snow

Another example of an Amplifying Feedback System is the melting polar ice caps. Ice and snow, as white solids, actually reflect a tremendous amount of energy. However, liquid water absorbs energy instead of reflecting it. The more the sun warms the water, the more ice melts. The more ice melts, the more water there is to absorb heat.

As though these were not already terrifying enough, most Amplifying Feedback Systems end up growing exponentially. When people say that we need to check temperature change at 2C, it’s because the consequences of waiting longer become increasingly impractical to address.

The time to fight for our climate and for our peoples has come. Join us in marching for Climate, Jobs, and Justice at Civic Center Park on April 29th, at 10AM.

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