This is a huge topic with many nuances, but below I’ve kept it pretty simple and focused on just the basics.

Composition of Earth’s Air

The air we breathe consists of various gasses and a bit of water vapor. The gasses in air are: 78% Nitrogen, 21% Oxygen, 0.9% Argon and 0.2% other gasses like Carbon Dioxide, Neon, Methane and Helium.

Note that Carbon Dioxide, the main greenhouse gas, only makes up 0.03% of air. Two other primary greenhouse gases, Methane and Ozone, make up only 0.0002% and 0.000007% respectively. These greenhouse gasses are very effective – just a little goes a long way!

The Greenhouse Gas Effect

The Earth is a special place. It’s neither too hot nor too cold for life to exist.

Our Goldilocks existence is due to just the right amount of greenhouse gasses that trap heat, but not too much. Here’s a great explanation of how the greenhouse gas effect works from physicist Michio Kaku:

Carbon dioxide acts as a one-way street for sunlight. Light can readily enter through the carbon dioxide in [the] atmosphere because the gas is transparent. But once the light bounces off the ground, it turns into heat or infrared radiation, which cannot easily escape the atmosphere. The radiation becomes trapped, in a process similar to the way a greenhouse captures sunlight during winter or the way cars heat up in the summer sun. 

Source: The Future of Humanity by Michio Kaku

So – a tiny fraction of the gasses in our air is sufficient to trap enough heat to keep us from freezing (realize that space is very cold). It’s pretty amazing.

Humanity’s Production of Greenhouse Gasses

Burning of fossil fuels generates carbon dioxide, the most common greenhouse gas. Why Burning Fossil Fuels Generates CO2.

Since the industrial revolution, we’ve been on an increasing pace of burning fossil fuels and thus have emitted billions of tons of CO2 and other greenhouse gasses into the atmosphere. The below chart shows the annual emission broken out by fuel type:

Additionally, as world’s population has increased and global standards of living has improved, we’ve consumed a lot more meat. Meat production, particularly beef, is associated with production of Methane – a very potent greenhouse gas.

Not surprisingly, all this CO2 emitted since the industrial revolution has increased the concentration of CO2 in the atmosphere dramatically. Concentrations of other greenhouse gases have increased as well.

The basic scientific model suggests that as the concentration of greenhouse gases in the atmosphere increase, global average temperatures increase as well. Makes sense. And that’s what has happened – temperatures have risen:

Of course, the Earth’s climate has varied in the past – it’s cycled between ice ages and warm periods. Could the recent warming be just a normal cycle? Possible but highly unlikely. Climate scientists have concluded that the recent rise in Earth’s temperature is not consistent with a normal cycle and that the current warming is driven by human greenhouse gas emissions.

Why Is Global Warming a Political Issue?

What has confounded me is that global warming is a political issue in the U.S. (it isn’t nearly as political in other countries). As the chart below shows, belief in man-made climate change varies dramatically by political/ideological identification.

Whether humans are causing global warming should be just a scientific issue – not a political one. The political issue is what, if anything, we do about it. Concerns that tackling global warming will harm economic growth are valid concerns. It is natural for political viewpoints to shape possible solutions. For example, a liberal might prefer a regulatory solution while a conservative would likely favor one that is more market driven.

More polls/stats on views of global warming by political affiliation here.

Possible Solutions to Global Warming

There are a number of potential solutions to global warming. Solutions fall within two categories: (a) stabilize/reduce greenhouse gas emissions or (b) the geoengineering of the atmosphere.

(a) Reduce Greenhouse Gas Emissions

• Institute a carbon tax (by making carbon emissions more expensive, new investments should flow into alternative energy technology and/or carbon capture)
• Another version of a carbon tax is a “cap and trade” program. Cap and trade was created by the Reagan administration in the 1980s in response to the acid rain problem and the program was passed while Geoge H.W. Bush was president. It worked by allowing industry (rather than the government) to figure out how to reduce sulfur dioxide emissions. It’s been very effective.
• Provide subsidies/incentives for investment in new energy technology
• Increase regulations and restrictions on emissions of greenhouse gasses

They key to reducing greenhouse gas emissions is technology advancements. Everyone merely pumping up their tires, driving hybrids and adjusting their thermostats, while helpful, does not move the needle enough to be the solution. The increases in global population and the growth of the global middle class ensure that greenhouse gas emissions will rise even if everyone attempts to take personal steps to reduce their carbon footprint. Conservation is important, but not sufficient. What is needed is plentiful low to no carbon emission energy. Capitalist inspired technology is likely the best hope. The key is to make investing in new energy attractive. Check out this IFOD on Nuclear Fusion.

More on the economics of carbon based energy in this related IFOD: Carbon Emissions, Externalities and the Tragedy of the Commons

Here’s a great quiz on climate change solutions: Climate Change Quiz

(b) Geoengineering

There are a number of potential ways to geoengineer the Earth’s atmosphere to counteract the greenhouse effect. A prior IFOD hit this topic: Geoengineering – A Possible Antidote to Climate Change?

Related IFOD on Eco–anxiety