What’s the difference between climate change and global warming?

Rating: High school and post-secondary

Summary: Markham interviews David Herring, director of communication and education for the National Oceanic and Atmospheric Administration of the US government. He is a science writer and editor with extensive experience communicating about climate and Earth science. David leads the Climate Literacy Objective for NOAA’s Climate Mission Goal.

Related links:

NOAA climate change basics video

NOAA: Climate Change: Global Temperature

NOAA: What’s the difference between global warming and climate change?

Markham: Thank you very much for joining me today for this interview. This is the inaugural video for our new Climate 101 series and I’m very excited to be interviewing you for it. Let’s start with a basic description of global warming and climate change because we use them interchangeably, at least I do, and many others do, but they’re not the same thing, are they?

David: No, they’re related, but they’re slightly different. Climate change is a bigger umbrella term. It can refer to any of a number of variables and in either direction, there could be increased cloudiness or decreased cloudiness. There could be increased or decreased raininess. Whereas global warming specifically refers to temperature and it’s specifically referring to temperature moving in a warming direction.

Markham: What’s the basic mechanism by which global warming takes place?

Albedo Effect.

David: There are several mechanisms that can cause global warming. For example, the sun is the primary source of energy that powers the climate system. So if there were a sustained increase in the sun’s output of solar energy, that would cause our world to warm. Also, a reduction in Earth’s Albedo, or the amount of sunlight reflected to outer space, if that should reduce more energy being absorbed in the system that would cause our world to warm. Or if there was a buildup of heat-trapping gases in the atmosphere that would cause our world to warm. So these are scientific facts that have been understood since the 1800s.

Markham: What’s the primary mechanism behind the global warming that we’re concerned about today?

David: Our world is warming today and it’s mainly due to the rapid buildup of heat-trapping gases in the atmosphere from human activities.

Markham: What gases are we referring to?

David: Humans emit a variety of heat-trapping gases, including carbon dioxide, methane, nitrous oxide, chlorofluorocarbons and others, but carbon dioxide is a particular concern to climate scientists because humans produce so much of it, about 35 billion metric tons per year.

Because our rate of emission is still going up, heat-trapping gases like carbon dioxide have complex molecules, and so they’re able to absorb heat energy given off by earth’s surface. Whereas, other gases that are simpler, like nitrogen or oxygen, those gases are fairly transparent to heat energy.

Source: NOAA Climate Literacy.

It’s kind of like how a sleeping bag works when you sleep outside and it’s cold outside. Your sleeping bag keeps your body warm by catching and containing and re-radiating your body’s heat energy back towards your body. So the thicker the sleeping bag, the warmer you will feel. By analogy, if we thicken the blanket of heat-trapping gases in our atmosphere, the more efficient the atmosphere is at trapping heat energy near the surface.

Markham: How much has the earth warmed? And why is that significant?

David: Since 1901 earth has warmed by about 1.8 degrees Fahrenheit. That’s according to the United States climate science special report, which is the most authoritative and up-to-date report on the state of the science in the United States. That amount of warming, that 1.8 degrees Fahrenheit, is significant for really three important reasons.

One, in the context of earth’s geologic history, that rate of rising is unusually rapid.

Point number two, human emission of heat-trapping gases is the main cause of warming. So in other words, humans are the reason it’s happening.

Point number three, scientists have observed an overall increase in the frequency and the severity of weather and climate-related extreme events, disasters that have caused loss of life, damages to property and infrastructure and have adversely impacted human economies. Some recent studies have shown that most of these events have been made worse by global warming and that some would not even have been possible in a pre-industrial world.

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