The greenhouse gases are responsible for increasing the temperature of the Earth. These greenhouse gases have the ability to absorb infrared radiation from the Earth. As a result, this energy is released by the gas molecules in all directions which in turn keeps the Earth warm. Show
The three main greenhouse gases are carbon dioxide, water vapor, and methane. Greenhouse gases are important in the atmosphere to make sure the temperature of the Earth is warm enough to support life as we know it! This is called the greenhouse effect. But the increase in greenhouse gas emissions from human activity, such as carbon dioxide from coal power plants; risk causing climate change, making the Earth warmer than it naturally would be. This is known as global warming. Global warming is just the beginning of major changes to the environment such as the rise in sea levels and melting of the polar ice caps. Greenhouse gas molecules in the atmosphere absorb light, preventing some of it from escaping the Earth. This heats up the atmosphere and raises the planet’s average temperature. February 19, 2021 What do CO2, methane, and water vapor have in common? If your first thought was “greenhouse gases,” you’d be correct! Greenhouse gases trap heat in the atmosphere, in a process called the “greenhouse effect.”1 But how do these molecules actually warm our planet? We’ll start our exploration of greenhouse gases with a single carbon dioxide (CO2) molecule. Let’s say this CO2 molecule came from the exhaust in your car. From your tailpipe, it drifts up into the atmosphere, diffusing among the other gases. There, particles of light—photons—hit our molecule. So what happens to those photons? “Greenhouse gas molecules will absorb that light, causing the bonds between atoms to vibrate,” says Jesse Kroll, Professor of Civil and Environmental Engineering and Chemical Engineering at MIT. “This traps the energy, which would otherwise go back into space, and so has the effect of heating up the atmosphere.” Basically, the bonds between the carbon and oxygen atoms in our CO2 molecule bend and stretch to absorb photons. (With other greenhouse gases, the molecular bonds are different, but in all cases, they absorb photons, stopping them from leaving the atmosphere.) Eventually, our CO2 molecule will release these photons. Sometimes, the photons continue out into space. But other times, they rebound back into the Earth’s atmosphere, where their heat remains trapped. And importantly, greenhouse gases don’t absorb all photons that cross their paths. Instead, they mostly take in photons leaving the Earth for space. “CO2 molecules absorb infrared light at a few wavelengths, but the most important absorption is light of about 15 microns,” says Kroll. Incoming light from the sun tends to have much shorter wavelengths than this, so CO2 doesn’t stop this sunlight from warming the Earth in the first place. But when the Earth re-emits this light,2 it has a longer wavelength, in the infrared spectrum. And the range of wavelengths around 15 microns is a particularly crucial window. The most common greenhouse gas, water vapor, doesn’t efficiently absorb photons in this range. So when CO2 grabs photons with wavelengths around 15 microns, it’s selecting for the same light that normally has the easiest time escaping Earth’s atmosphere. There’s another reason why CO2 is such an important greenhouse gas: it has a long atmospheric lifetime. This has to do with the way CO2 reacts (or rather, doesn’t react) with the atmosphere. “The atmosphere is a very oxidative environment due to the presence of oxygen and ultraviolet radiation,” says Kroll. Oxidation occurs when oxygen steals electrons from another atom—it’s the same chemical reaction that causes iron to rust. Methane, another greenhouse gas, reacts easily with oxygen, which removes it from the atmosphere within around 12 years. That’s long enough to affect the climate, but nowhere near the lifetime of CO2, which does not react with oxygen and can last over a century. CO2’s long lifespan is the key reason that human activities are leading to climate change. As we keep taking carbon-based compounds like coal and oil out of the ground, and put that carbon in the atmosphere in the form of CO2, the added CO2 piles up much faster than it can be naturally removed. Thank you to Brittney Andrews of Clearlake, California, for the question. You can submit your own question to Ask MIT Climate here. Read more Ask MIT Climate Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International license (CC BY-NC-SA 4.0). Takeaways
The Greenhouse Effect Increasing Greenhouses Gases Are Warming the PlanetScientists attribute the global warming trend observed since the mid-20th century to the human expansion of the "greenhouse effect" — warming that results when the atmosphere traps heat radiating from Earth toward space. Life on Earth depends on energy coming from the Sun. About half the light energy reaching Earth's atmosphere passes through the air and clouds to the surface, where it is absorbed and radiated in the form of infrared heat. About 90% of this heat is then absorbed by greenhouse gases and re-radiated, slowing heat loss to space. Gases that Contribute The Role of Humans Human Activity Is the Cause of Increased Greenhouse Gas ConcentrationsOver the last century, burning of fossil fuels like coal and oil has increased the concentration of atmospheric carbon dioxide (CO2). This increase happens because the coal or oil burning process combines carbon with oxygen in the air to make CO2. To a lesser extent, clearing of land for agriculture, industry, and other human activities has increased concentrations of greenhouse gases. The industrial activities that our modern civilization depends upon have raised atmospheric carbon dioxide levels by nearly 50% since 1750. This increase is due to human activities, because scientists can see a distinctive isotopic fingerprint in the atmosphere. In its Sixth Assessment Report, the Intergovernmental Panel on Climate Change, composed of scientific experts from countries all over the world, concluded thatit is unequivocal that the increase of CO2, methane, and nitrous oxide in the atmosphere over the industrial era is the result of human activities and that human influence is the principal driver of many changes observed across the atmosphere, ocean, cryosphere and biosphere.
The panel's AR6 Working Group I (WGI) Summary for Policymakers report is online at https://www.ipcc.ch/report/ar6/wg1/. Is the Sun to Blame? Evidence Shows That Current Global Warming Cannot Be Explained by Solar IrradianceScientists use a metric called Total Solar Irradiance (TSI) to measure the changes in energy the Earth receives from the Sun. TSI incorporates the 11-year solar cycle and solar flares/storms from the Sun's surface. Studies show that solar variability has played a role in past climate changes. For example, a decrease in solar activity coupled with increased volcanic activity helped trigger the Little Ice Age. The above graph compares global surface temperature changes (red line) and the Sun's energy that Earth receives (yellow line) in watts (units of energy) per square meter since 1880. The lighter/thinner lines show the yearly levels while the heavier/thicker lines show the 11-year average trends. Eleven-year averages are used to reduce the year-to-year natural noise in the data, making the underlying trends more obvious. The amount of solar energy that Earth receives has followed the Sun’s natural 11-year cycle of small ups and downs with no net increase since the 1950s. Over the same period, global temperature has risen markedly. It is therefore extremely unlikely that the Sun has caused the observed global temperature warming trend over the past half-century. Credit: NASA/JPL-Caltech But several lines of evidence show that current global warming cannot be explained by changes in energy from the Sun:
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How does carbon dioxide contribute to global warming?Carbon dioxide (CO2) is a greenhouse gas. This means that it causes an effect like the glass in a greenhouse, trapping heat and warming up the inside. This effect is important: without the CO2 that naturally exists in the atmosphere, Earth might be too cold to support human life.
How do the carbon dioxide molecules contribute towards global warming quizlet?Greenhouse gases, particularly carbon dioxide, increase the amount of heat retained in earths atmosphere, which then leads to increased surface temperatures.
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How do the carbon dioxide molecules contribute towards global warming
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