Sunday, November 16, 2014

A Global Climate Change Primer

A friend out here in California says she believes global warming is real, but struggles to remember and convey the evidence coherently when it it comes up in conversation. I wrote this short essay to help her.

What is Global Climate Change?
"Global Climate Change" is the changing of climates and secondary effects worldwide due to increases in carbon dioxide (CO2), methane, and other heat-trapping gases in the atmosphere.

What's the science behind Climate Change? How does it happen?
The sun continuously shines  on the earth. Some energy is radiated back into space, and some is absorbed by the ground and the atmosphere. Gases like CO2, methane, and others are called 'greenhouse gases' because they trap heat energy in the atmosphere, warming the earth's surface and the air (think of greenhouse glass that lets in the sun's energy and holds it in).

The climate is changing because humans are adding gargantuan amounts of CO2 and methane to the atmosphere - about 30 billion tons annually. Fossil fuels are mostly carbon based, so when we burn them in engines and power plants, the 'waste products' from the combustion are CO2. So long as humans have been burning significant amount of carbon-based energy (the beginning of the industrial revolution, around 1750), we've been altering the atmosphere.

What are some effects of climate change?
This depends heavily on the location: some places get more flooding and others more drought, some are cooler but most are much hotter, etc. In general, expect the intensity of weather events to increase - more violent storms, more severe flooding or hurricanes, etc. This makes sense; more heat energy is trapped on the earth by greenhouse gases, and that energy leads weather to be more energetic.

What effects are we seeing?
There are hundreds of major effects all over the globe.  Here are just a few examples of evidence you can cite to non-believers:
  • Oceans are 30% more acidic than 200 years ago: this makes the ocean inhospitable to many species who can't live in more acidic environments. More CO2 reacts with salt water to make the ocean more acidic. [0]
  • Insurance companies plan on increasing sea levels and more intense storms[1]
  • Wildlife has moved to find areas with the right temperatures: on sea and land, animals are migrating away from their original habitats towards the poles to stay in areas with temperatures they're used to. [2]
  • Shipping Companies have new shipping routes due to ice loss: the northwest passage, along the northern coast of North America, has been permanently frozen since before recorded history. As of a few years ago, it melts enough every summer to allow shipping traffic. [3]
What happens if we can't reverse climate change?
There are many ways this could go bad. Huge heat waves or droughts could cause large crop failures, leading to famines lasting a very long time. For example, heat waves linked to climate change lead to crop failures in 2010, dramatically raising food prices and setting off revolutions all over the middle east[4]. This is one of many possible outcomes, none of them good. The worst case is that climate change destroys enough human habitat that there simply isn't room for us on this planet anymore - not enough other plants and animals to survive on, or farmland that will grow food.

What can I do about it? How can I think about this problem in a reasonable way?
I'll share my thoughts in an upcoming essay.

[0] Oceans more acidic:
[1] Insurance industry issues:
[2] Wildlife shifting:
[3] Ice melting is leading to shipping through northwest passage (northern North America):
[4] climate change leads to droughts and heat waves, and thus to crop failures and revolutions: