What is Climate Change? What Causes Climate Change?

What is Climate Change? What Causes Climate Change?

We are in the middle of an unprecedented global pandemic. Because of this, most of us have seen drastic changes to our day-to-day lives, such as working or studying remotely and decreased in-person social interaction and travel. Our political and economic system struggled to react and adjust, and we will likely feel the effects of the pandemic for years, maybe decades.

We were warned by experts that it was not a matter of if, but when a pandemic like this would strike in our increasingly interconnected and globalizing world. We knew the disease would most likely be zoonotic, or jumping from animals to humans, and would likely be a respiratory coronavirus, similar to the common cold or the seasonal flu. Public health experts knew we were not prepared, and they have been overall proven correct in their predictions.

While the human species wrestles on a personal and public level with COVID-19, more and more symptoms are showing of another crisis. We have known about this crisis for decades now, and we have mostly ignored taking action on what will be a civilization-altering process. Like the reactions to COVID-19 in many countries around the world, this crisis has also become politicized or outright denied.

Climate change and its resulting feedback loops have started. The record-breaking wildfires in California, Oregon, and other areas of the West Coast. The wildfires earlier this year that raged across Australia. Deadly floods in Sudan. Permafrost in the polar regions and glaciers in the planet’s mountains are melting. And yet not nearly enough is being done, not even close.

My aim in this article is to explain how the natural process of the greenhouse effect, altered by human activity, is causing climate change. This will be the first post in a series diving into the global climate crisis, its causes and consequences, possible mitigation and adaptation techniques, and the people and organizations acting on (or impeding action on) this crisis.

To begin, let me explain the Greenhouse Effect.

What is the Greenhouse Effect?

The sun emits solar energy into space. Some of these rays pass through our planet’s atmosphere, while others “bounce off” our atmosphere and reflect back into space. The energy that does make it to Earth is absorbed and emitted as infrared radiation, or heat. The trapping of this infrared energy or heat by gases in our atmosphere is called the greenhouse effect. Think of a greenhouse, whose glass roof and walls allows solar energy in, but stops the resulting heat from escaping.

Life would not be able to survive on this planet without this phenomenon, as Earth would be around 30C (86F) colder. The greenhouse effect, in itself, is not a problem, and is a necessary component of life on Earth.

What are Greenhouse Gases?

The greenhouse effect is only possible because of the composition of our atmosphere. According to the US National Aeronautics and Space Administration (NASA), the Earth’s atmosphere is made up of –

  • 78% nitrogen (N)
  • 21% oxygen (O)
  • .93% argon (Ar)
  • .04% carbon dioxide (CO2)
  • Trace amounts of methane, water vapor, and other gases

Greenhouse gases are those that allow light through, but trap heat in our planet’s atmosphere, just like the glass roof and walls of a greenhouse. The primary greenhouse gases in Earth’s atmosphere are water vapor, carbon dioxide, methane, nitrous oxide, and ozone. These gases’ impacts on warming and global temperature are determined by three factors –

  • Concentration, or abundance: How much of this gas is in the atmosphere?
  • Length of time a gas remains in the atmosphere: How long does this gas remain in the atmosphere?
  • Heat trapping capacity: How effective is this particular gas at trapping heat?

Water vapor is the most effective at trapping heat, but this gas only lasts in the atmosphere for a few days. On the other hand, carbon dioxide remains in the atmosphere for a much longer length of time – 300-1,000 years. This is important to keep in mind, because it means that we will be seeing the impacts of the greenhouse gases we emit today for centuries to come.

What is Causing Climate Change?

The climate is changing because humans are altering the composition of the atmosphere by emitting a large amount of heat-trapping greenhouse gases. Historical ice core studies and recent air monitoring sites show that greenhouse gas levels are higher now than at any time in the last 800,000 years (US Environmental Protection Agency). Human activity has released large amounts of carbon dioxide, along with other gases like methane and nitrous oxide, into the atmosphere. Most of these gases come from burning fossil fuels such as coal, oil, and natural gas. At the same time, we are also cutting down the forests that act as a carbon sink, which means that their capacity to absorb carbon dioxide is decreasing alongside our increased emissions.

This means that too much infrared energy is being trapped by our atmosphere’s greenhouse gases instead of escaping back into space. Because of this, the Earth’s average surface temperature is increasing. This increase in our planet’s average surface temperature is called global warming.

What is Climate Change?

More greenhouse gas emissions → more heat trapped by our atmosphere → hotter planet → complex set of climate changes

Global warming is causing our planet’s climate, or long-term average weather patterns, to change. While you may think of global warming and climate change as synonyms, think of climate change both as a result of global warming and as a term that includes global warming, along with other changes to long-term weather patterns. The term “climate change” also recognizes and encompasses the fact that some regions of the world will experience short-term cooling as a result of a shifting climate.

The Earth’s climate has changed many times, sometimes drastically, throughout its 4.5 billion year lifespan. But these changes normally happened over hundreds of thousands, if not millions, of years. The amount of change and the rate of change in the planet’s temperature since the mid-20th century is unprecedented. The twenty hottest years on record all occurred in the past 22 years (World Meteorological Organization).

What are Some of the Effects of Climate Change?

The list of observed and possible consequences of climate change is too long for this article to be comprehensive, but here are just a few of the changes an increase in global temperatures is bringing –

  • More frequent and stronger extreme weather events – hurricanes, cyclones, storms, tornadoes, heat waves, and droughts
  • Melting land-based polar ice – increased sea levels
  • Melting alpine glaciers – flooding in the short-term, and in the long-term, droughts due to the disappearance of glacial water sources
  • Ocean thermal expansion – increased sea levels (water expands in volume as it warms)

Climate change has set off a range of feedback loops that will be difficult, if not impossible, to stop. The changes that are happening around the world because of the increase in greenhouse gases are occurring at a faster rate than many living things can adapt to. We need to take comprehensive action to 1) slow the rate of climate change and mitigate its impacts and 2) help vulnerable communities and ecosystems adapt to its inescapable consequences.

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