J-School blog #3

Prepare for a slew of posts, as I upload the blogs I made for class and rant about them:

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Have you heard about this thing called ‘global warming’?

Climate change is complicated. People argue endlessly in the media and online about its many dimensions, and it’s easy to get caught up in debates about climate models, sunspots and warming trends. But whenever I get into a sticky internet climate change debate and am about to get lost in the quagmire of intricacies, I take a step back and remind myself of the basics.

Global warming is a matter of physics.

The simple model I learned on Children’s BBC news programs in the 1990s is the version most people know: carbon dioxide, CO2, forms a layer in the atmosphere that traps heat. It acts like a blanket. This is an over-simplification, and the reality makes it easier to understand why CO2 is so deeply linked to temperature.

Incoming light and heat from the Sun is in the form of ultraviolet radiation which is of a certain wavelength – it has a characteristic intensity. This radiation penetrates most of the atmosphere and is absorbed by the Earth. A certain amount of this radiation is then emitted back out by the Earth, but at a different wavelength to the radiation that came in from the Sun; this time as infrared radiation. CO2 is a molecule with a set of properties that make it especially good at absorbing infrared radiation, and then emitting it back out again, down towards the Earth’s surface.

CO2 is a bendy molecule. From Angel C. de Dios, Georgetown University 

As a molecule made of three particles, two oxygens and a central carbon, CO2 has many opportunities to bend and stretch. When infrared radiation comes into contact with a CO2 molecule, it causes the atoms in the molecule to vibrate more vigorously; it excites the bonds between the C and the Os. The movements cause electrons to shift about in the molecule, and allow the particles of radiation, photons, to enter, cause havoc, and leave again.

And the large majority of those photons leave again in the direction of Earth, to enter the cycle of absorbing, emitting and absorbing all over again.

These are undeniable facts of physics: they are well-documented properties of CO2 and infrared radiation.

It is an undeniable fact that atmospheric CO2 has risen from approximately 280 ppm before the industrial revolution to just over 390 ppm as of the end of 2011. Even if the units are meaningless to you, it must seem obvious that a nearly 40% rise in the total will have some effect on the thermostat of our cozy home.

If you believe humans have nothing to do with this unprecedented rise in Co2, and that it has no effect, I will not beat around the bush: you are incredibly naive.

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