We're Cooked!

The Beginner’s Guide to Climate Change
Part 3: Are Humans Causing Climate Change?

The Climate Record

The Earth has undergone many drastic climate changes over the course of its history; there have been 5 major extinction events, and all of them have been connected in some way to rapidly shifting atmospheric conditions. We have established that climate change is certainly happening, but is it possible that humans are not involved in this switch at all?

Scientists have been successful in compiling somewhat of a climate “road-map” that records the conditions of Earth’s atmosphere even before humans were around. This timeline was constructed using various geological tools such as ocean sediments, ice cores, tree rings, and many more; for the full climate record and additional information on how it was created, please see “Earth in The Future: Climate Records”.

In short, the Earth’s climate record does NOT explain the warming that has been tracked since the 1950s. Whilst the climate has been warmer before than it is now, the rate of change is the crucial variable to be aware of; the Earth has never experienced warming at such an alarming rate of change. If that is the case, what is different now that is suddenly allowing such a rapid shift in average global temperature?

Potential Natural Culprits

• Earth’s Orbit & Rotation
  • “Wobbles” in the Earth’s axis and rotation have rapidly reduced/increased the average global temperature; warmer years are known as interglacial periods, and colder years are known as glacial periods (aka Ice Ages)
  • At most, the increase of temperature resulted in only 2°F warmer than what it is today
• Variations in Solar Activity
  • The Sun doesn’t always give off the same amount of energy; these energy readings have been measured regularly since 1978
  • There is no correlation between solar energy output and modern climate change trends; see Figure 1 for the comparison of these readings
    
• Volcanic Activity
  • Volcano eruptions release colossal quantities of the greenhouse gas carbon dioxide into the atmosphere; they were responsible for the great Permian Extinction
  • The quantity of volcano eruptions is currently normal, and humans release more than 100 times as much carbon dioxide as volcanoes each year

Whilst these are the most notable examples of natural causes, you can find more at (EPA) Climate Change Causes.

Greenhouse Gases

Humans have been continually releasing more greenhouse gases into the atmosphere since the Industrial Revolution. As a result, the greenhouse effect has steadily intensified. Although there are other greenhouse gases to be concerned with, this blog will focus on the most abundant one: carbon dioxide. The quantity of carbon dioxide in the atmosphere at any moment is directly proportional to the warmth of the globe in that coinciding time period. Figure 2 says it all; take careful note that the peaks and valleys exist at the exact same time for both measurements.

Human activities, according to the Environmental Protection Agency (EPA), currently emit over 30 billion tons of carbon dioxide every year into the atmosphere. Greenhouse gas concentrations are greater than they have been at any point in the last 800,000 years. The puzzle pieces fit so perfectly that there is little room for error when drawing conclusions. Whilst human activity may not be the only contributor, it is highly likely (>95% chance) that humans are the primary cause of climate change. Next time, we will take a look at what impacts we can expect climate change to have.