U.S. Clean Energy Fund is committed to help fight global climate change. Part of this mission is to help people better understand the problem we are facing.

I’ve written this article (and its companion article, Clean Energy 101) to get everybody up to speed on modern understanding of global climate change.

Global Warming and Climate Change

Global warming is the phenomenon of our planet getting warmer. Scientists have observed average global temperatures increasing by an average of 0.3°F per decade since the 1970s.

Global Average Temperatures, relative to 20th-century Average

Climate change refers to the effects of global warming on overall weather patterns. Most recent discussions about the issue use this term, because many of the effects are not obviously related to temperature. (Also - for those of us living in northern climates, “global warming” sounds like a good thing!)

We are beginning to see the effects of climate change, and they are projected to grow worse over time:

  • Increased occurrences of severe weather
  • Disruptions to ecosystems, especially in the Arctic
  • Decreased crop production
  • Rising sea levels
  • And much more…

The world has maintained approximately the same temperature for most of human history. Disrupting this equilibrium will cause a multitude of problems.

Greenhouse Gases

Our planet gets nearly all of its heat by absorbing the sun’s radiation. Earth then radiates some of this heat back towards outer space, cooling the planet. A portion of this outgoing radiation is absorbed by our own atmosphere before it can escape, locking in the heat. This is called the greenhouse effect.

The greenhouse effect depends on some specific gases in our atmosphere called greenhouse gases (GHGs). The primary GHGs causing global warming are carbon dioxide (CO2) and (to a lesser extent) methane. These gases make up less than 0.05% of our atmosphere, but they are the primary regulators of the overall temperature on Earth.

Atmospheric CO2 Concentration, in ppm (source)

Over the past 200 years, the levels of these gases in the atmosphere have been going up:

  • CO2 has increased 43% from 280 to 400 ppm (parts per million).
  • Methane has increased 142% from 715 to to 1,732 ppb (parts per billion).

Scientists agree that these higher concentrations of greenhouse gases are responsible for the global increase in temperature.

Water Vapor

Technically, the most impactful greenhouse gas is water vapor. However, water behaves quite differently from the other greenhouse gases. Its concentration is determined mainly by local geography (e.g. deserts vs. swamps) and temperature (warmer temperatures increase humidity). Emitting more water vapor into the atmosphere will generally not increase its concentration - it will eventually just condense into liquid water and fall as rain.

Feedback Loops

One of the nasty things about global warming is that it builds upon itself. As the global temperature rises, it will cause higher levels of GHGs in the atmosphere:

  • As the air gets warmer, it holds a higher concentration of water vapor.
  • As oceans get warmer, they release dissolved CO2 into the atmosphere.
  • As frozen bogs in the Arctic thaw, they release methane.
  • As ice sheets melt, they release trapped pockets of CO2 and methane.

These are called feedback loops. They present the possibility of a theoretical “tipping point” in climate change, in which global warming would continue even if humans stop emitting greenhouse gases.

Human-Caused GHG Emissions

So what is causing the increased levels of greenhouse gases?

For carbon dioxide, the answer is simple: it is coming from burning fossil fuels (oil, coal, natural gas). For methane, things are bit more complicated: deforestation, livestock (mainly cattle), rice farming, landfills, and the natural gas industry all contribute significantly.

In the U.S., nearly 85% of total GHG emissions originate from fossil fuels.

By Petr Štefek - Own work, CC BY 2.5

The Future

If no action is taken to combat climate change, the future looks bleak. Computer models built by climate scientists project temperature increases of 3.5-9°F by the end of this century. Such a drastic change in the environment would cause major problems for civilization.

The most important thing we can do — especially here in the U.S. — is to reduce our usage of fossil fuels. There are a number of ways we can work towards this, and as a society we should pursue all of them:

  • Drive fewer miles with more fuel-efficient vehicles.
  • Upgrade equipment for energy efficiency.
  • Fly less often on airplanes.
  • Heat and air-condition our homes less dramatically.
  • Transition our electricity production from coal and gas to solar and wind.

U.S. Clean Energy Fund believes that last one is the most important, and we’re working towards it. If you’re interested in our progress, sign up for our email list below!


Further Reading

There’s a ton of great resources on the internet to learn more. Here are a few that I found useful while writing this: