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How Does Climate Change Work?


Blog graphic with a dusty orange picture of nature that looks like pollution, with the text Science Explained, Climate Change, Media By Michelle

Still not quite sure how climate change works? You're not alone. A survey from November 2018 showed only 71% of Americans believe climate change is real, and according to the Associated Press, almost half of those surveyed said the rise in extreme weather has them more convinced than just five years ago. A majority of both republicans and democrats believe climate change is happening.

This pie chart of American Beliefs About Climate Change in November 2018 shows 71 percent believe climate change is real, 9 percent believe it is fake, and 19 percent are unsure.

Of Americans who believe climate change is real, only 60% believe it's is caused primarily by human activity - a significantly lower amount than the consensus of more than 97% of actively publishing climate scientist who agree climate change is real and primarily caused by human activity.

This pie chart shows 28.8 percent of Americans believe climate change is real but not caused primarily by humans, and 43.1 percent believe climate change is real and primarily caused by humans.

You may say, "well 3% of scientists aren't sure, so I'm not either." But, ask yourself this question: do you believe gravity is real? You may be surprised to learn that there's a small percentage of scientists who don't believe in gravity, despite the compelling evidence and consensus of more than 99% of scientists. That's what's great about science, there's always room for skepticism. However, when a majority of experts, who have spent their lives studying and understanding these topics, agree that something is real, there's no reason to cling to misplaced skepticism.

So why the discrepancy between scientific evidence of human-led climate change, and belief among the American public? Climate change is a complex working of multiple systems, from the carbon cycle and greenhouse gasses, to global temperature shifts and planetary evolution. Experts spend decades working to understand each piece of the puzzle, learning about geology, geophysics, chemistry, and climatology, so how can non-scientists be expected to understand?

In the following infographics, we'll walk you through the most important components of climate change, starting with how our planet's climate has worked for a recorded 800,000 years, then looking at what's happening now and what it means for our future.

Two-part infographic explaining climate change using the carbon cycle and the greenhouse effect. Climate change: how it works and why. Our climate is regulated thanks to the Natural carbon cycle. A flowchart illustrating the cycle in six steps over an image. Step 1: Carbon dioxide in the atmosphere combines with water to form acidic rain. Step 2: Acid rain washes minerals including dissolved carbon into the ocean. Step 3: Sea creatures use the calcium and carbon to create their shells. Step 4: Shells become sediment and store carbon in the ocean. Step 5: Seafloor spreading pushes the ocean crust under the continental crust, melting it into magma. Step 6: Carbon dioxide is released back into the atmosphere through volcanoes. Then the cycle repeats with more acid rain. Part 2 of the infographic is titled and the greenhouse effect. Sunlight enters the atmosphere and warms Earth's surface. That heat radiates back towards space. While some heat escapes, most radiated heat is absorbed by greenhouse gases and re-emitted, further warming the Earth's surface and atmosphere. Greenhouse gases such as water, carbon dioxide, and methane help regulate our climate. Water is the most abundant greenhouse gas, but has a short cycle of about 10 days, so it doesn't build up like carbon dioxide. Carbon dioxide stays in Earth's atmosphere longer than any other major heat-trapping gas: it takes 10,000 years to totally leave. A certain amount of greenhouse effect is a good thing. It helps our planet keep our planet warm enough for human life. Link to source. But what happens when we add more trapping gases? Many carbon dioxide molecules: the background becomes a warmer color. Infographic by Michelle Babcock, 2019 copyright media by Michelle LLC.

For a more detailed explanation of how greenhouse gasses trap heat in our atmosphere, check out this page by the National Oceanic and Atmospheric Administration and National Weather Service.

Since the Industrial Revolution, we humans have been adding more and more carbon dioxide to the atmosphere, above and beyond what the natural carbon cycle would produce at any one time on its own.

"Half of human-related CO2 emissions occurred only in the last 40 years." -Union of Concerned Scientists

There are several greenhouse gasses that trap heat in our atmosphere, but none as problematic as carbon dioxide. Carbon dioxide poses a unique threat to earth's climate, because it stays in the atmosphere (influencing temperature) for thousands of years, and humans are adding more of it to the atmosphere than our planet has ever had before. The following graph shows annual figures for the different types of human-generated greenhouse gasses, with carbon dioxide from fossil fuels (gasoline, coal, oil, etc.) producing 65% of global greenhouse emissions.

This graph shows increasing greenhouse gasses due to human factors, with CO2 from fossil fuel and industrial processes producing 65 percent of all greenhouse gas emissions in 2010, CO2 from forestry and other land use producing 11 percent, methane accounting for 16 percent, nitrous oxide 6.2 percent, and fluorinated gasses 2 percent.

The following graph shows global average temperatures as reported by the Intergovernmental Panel on Climate Change. The blue line depicts what scientists would expect to see from only natural sources, such as volcanic activity and solar radiation. The black line shows actual observations, which match closely with the red line, depicting what scientists would expect to see from natural sources plus greenhouse gasses caused by human activity.

This line graph shows the global average temperature compared to what scientists would expect from natural sources, compared to natural plus human generated greenhouse gasses. The line depicting worldwide observations of global average temperature far exceeds what would be expected from natural sources only. The observations match almost perfectly with those we would expect to see from natural plus greenhouse gasses caused by human activity.

Do we know what happens when the greenhouse effect gets out of hand, when there are too many heat-trapping gasses? Yes, we only need look to our sister planet Venus. Evidence suggests that Venus may once have had liquid water, with oceans much like ours on Earth. So what happened? Were there humans who released too much carbon dioxide into the atmosphere causing a catastrophic outcome? It's much more likely that environmental factors led to the planet's current situation.

As shown in the first infographic, liquid water in the form of rain is a crucial step in the carbon cycle. Water combines with carbon dioxide in the atmosphere, rains down, and makes its way to the ocean, where that carbon dioxide is ultimately sequestered in marine shells that get buried. This allows for a certain balance, taking greenhouse gasses out of the atmosphere and eventually returning some through volcanic eruptions. Without water, we wouldn't have the carbon cycle, and without the carbon cycle, there would be no way for our planet to remove atmospheric carbon. Instead of our oxygen-rich atmosphere, we might have a carbon dioxide atmosphere that couldn't support life as we know it.

On Venus, there is a thick carbon dioxide atmosphere. Because of the an abundance of greenhouse gasses, predominantly carbon dioxide, the surface of our sister planet averages 462 degrees Celsius - that's 864 degrees Fahrenheit. In comparison, Earth's average surface temperature until the mid-1900s was a comfortable 14 Celsius, or 57 Fahrenheit.

This photo shows a global view of the northern hemisphere of Venus. It's an yellow-rust colored planet.

So what happened to Venus? Venus formed out of the same ingredients as our planet. It might have once had a liquid water ocean, and may have been habitable. But Venus is closer to the sun than we are, and because of that, it was heated just hot enough for the water on the planet to evaporate away. No water - no carbon cycle. No carbon cycle - carbon dioxide builds up in the atmosphere. From there, Venus experienced what's called a runaway greenhouse effect. Carbon dioxide built up in the planet's atmosphere indefinitely, causing soaring temperatures and a hellacious atmosphere 90 times thicker than ours.

While this greenhouse effect gone wrong was due to environmental factors, the result - too much carbon dioxide and rising global temperatures - is similar to what might happen here on Earth if we continue adding greenhouse gasses to our atmosphere without regard for the impacts it will have.

Infographic titled climate change: what's happening and how we know. Every 100 thousand years, Earth experiences relative carbon dioxide highs and lows due to the Natural carbon cycle, as measured by 800 thousand years of ice core data. Smaller peaks are due to changes in Earth's orbit, impacting how much solar energy or heat falls on the Earth. Graph of carbon dioxide level in parts per million over years before today. A line varies between 180 parts per million and 300 parts per million in a variable rise and fall for 350,000 years, then in 1950 the line rises above 300 for the first time: it Rises to 400 parts per million, a rise that is double the previously recorded rises. From the Industrial Revolution in the 1700s to now, humans have added more and more carbon dioxide to the atmosphere by the use of fossil fuels. What happens when there's too much carbon dioxide? Temperature rises.  Global average temperature correlates with carbon dioxide levels. A graph titled Global temperature and carbon dioxide has year ranging from 1880 to 2010 on the x-axis and Global temperature in Fahrenheit and carbon dioxide concentration in parts per million on either side of the y-axis. A line plots the average trend of carbon dioxide concentration, which Rises slowly and steadily from 1882 to 1970, and then Rises steeply until the end of the graph at 2010. Overlaid with the line are individual year bars of global average temperature, rising from about 56.25 degrees at the beginning of the graph to about 58 degrees at the end of the graph. Why does it matter? Expert predictions. 97 percent or more of actively publishing climate scientists agree on five predictions. 1, extreme weather will be stronger and more frequent. 2, ecosystems and agriculture will be compromised. 3, sea level rise will harm infrastructure and economies. 4, residents will be displaced due to coastal flooding / erosion. 5, insect outbreaks will happen and food and water insecurity are expected. Quote 2 degrees may not seem like a lot. You likely wouldn't notice a 2 degree fluctuation during your average day. But climate change and global warming refer to long-term trends. End quote. Popular Science magazine. Quote if we warm by 2 degrees Celsius, the world will be a lot drier, which will impact economies, agriculture, infrastructure, and weather patterns. Rising temperatures will damage ecosystems and species that cannot adapt ellipses 2 degrees Celsius could determine the existence of whole Nations. End quote. A map of the US with colored dots indicating what symptoms of climate change will happen in the northwest, Midwest, Southwest, southeast, Northeast, Great Plains, and Alaska and Hawaii. What will happen here? 12 potential symptoms include heat waves or drought, more and worse hurricanes, ecological impacts, flooding, insect outbreaks, sea level rise and erosion, infrastructure damage, fresh water shortages, frequent wildfires, reduced crop yields, economic impacts, Public Health impacts. Quote the emissions we are currently releasing will help determine the climate future our children and grandchildren experience. End quote. Union of concerned scientists. Infographic by Michelle Babcock, 2019 copyright media by Michelle LLC.

"CO2 (and other gases emitted from industrial and agricultural sources) trap heat in the atmosphere, so it is no surprise that we are now witnessing an increase in global average temperature." -Union of Concerned Scientists

The Intergovernmental Panel on Climate Change (IPCC), is a body of climate scientists from around the world who produce neutral reports on topics related to climate change. The IPCC warns that if we don't reduce our greenhouse gas emissions, Earth's surface temperature is projected to rise between 3.7-4.8 degrees Celsius by the year 2100.

In 2018, the IPCC released a special report detailing the impacts of a 1.5 Celsius rise in global average temperatures. Currently, human activities have led to approximately a 1.0 Celsius rise in the global average temperature, with temperatures projected to rise 1.5 degrees between 2030-2052.

With all this gloom and doom, it's natural to ask what we can do to mitigate carbon dioxide pollution from human activity and the corresponding global temperature rise. The most important thing we can do right now is share this important information with others, and demand our elected policy makers hold the nation and industries accountable for reducing carbon dioxide emissions. This problem is bigger than one generation, bigger than business, bigger than any nation - this problem is worldwide. But, there is hope.

"Anything else you’re interested in is not going to happen if you can’t breathe the air and drink the water. Don’t sit this one out. Do something. You are by accident of fate alive at an absolutely critical moment in the history of our planet.” -Astrophysicist Dr. Carl Sagan

Part of the work of the IPCC is to predict greenhouse gas emission might change in different situations, based on human activity. These predictions are called Representative Concentration Pathways (RCPs), and are based on factors like technological advances, population growth, changes in energy generation, land use, regional and global economic factors, and other circumstances.

The following graph shows four possible pathways. The worst case scenario is RCP8.5, shown by the red line. In this future, population rises quickly, technology stagnates, and we continue to produce greenhouse gas emissions, reaching 2,000 ppm atmospheric carbon dioxide levels just after the year 2200. The second graph, showing corresponding global temperature rise, indicates "an apocalyptic temperature rise" of 9 Celsius, or about 16 Fahrenheit, according to information from the IPCC interpreted by YaleEnvironment360.

The next-worse scenario is RCP6.0, shown in orange, shows carbon dioxide peaking around the year 2100 at 700 ppm, corresponding to a 3 Celsius temperature rise. The most optimistic pathway is RCP2.6, shown in dark blue. This scenario represents carbon dioxide in the atmosphere peaking right now, between 2010-2020. Shortly after the peak, humans would need to find a way to neutralize, or suck more carbon dioxide from the atmosphere than we produce by the year 2070.

this graph shows 4 potential RCPs for atmospheric CO2. RCP8.5 is the worst case scenario and shows about 2000 ppm by the year 2200. RCP2.6 is the best case scenario, with CO2 levels peaking around 2050 just under 500 ppm, then slowly sinking over hundreds of years to below 400 ppm.
This graph shows temperatures corresponding to various RCPs.

What can we do as individuals to mitigate the effects of climate change?

  • Educate ourselves about climate change and share the information with others

  • Make an effort to reduce personal greenhouse gas emissions. You can do this by minimizing gasoline use (try biking, carpooling, or walking), and cutting out disposable plastics (which produce industrial greenhouse gas emissions when produced)

  • Support candidates who believe in climate change and are serious about reducing carbon dioxide emissions

  • If you're able to, consider going to school to study science or politics, so you can help invent solutions and create meaningful policy

FREQUENTLY ASKED QUESTIONS

If CO2 only makes up part of our atmosphere, how can it cause so much trouble?

Why does it matter that we passed a carbon dioxide threshold of 400 parts per million?

I'm still not sure if I believe in climate change, is there more evidence?

What global measurements can we assess to better understand climate change?

What happens if Earth gets 2 degrees warmer?

Why are more than 70% of American's worried about climate change?

Thanks to NASA for clips used in the video from their online Image and Video Gallery, and to the Library of Congress for the audio recording of Dr. Carl Sagan's 1990 commencement address to graduates at the University of Illinois at Urbana-Champaign, which was condensed for this article and video.