# Carbon dioxide and global warming

• resurgance2001
In summary, the conversation discusses the role of carbon dioxide in global warming and how such a small percentage of this gas is able to have a significant effect on the Earth's climate. The participants mention the importance of comparing absolute amounts of CO2 rather than percentages, as well as the specific wavelengths of infrared radiation that CO2 is able to absorb. They also discuss the use of models and data to measure and understand the impact of greenhouse gases on the Earth's climate.
resurgance2001
Hi

I have a simple question about global warming. The percentage of carbon dioxide in the Earth atmosphere is about 0.04% . My question is how is such a small percentage of this gas able to have such a powerful affect on global warming? Thanks

I think it's wrong to focus on the percentage...

If you could somehow travel to another planet and bring back a load of nitrogen and release it into the atmosphere you could reduce the percentage of the atmosphere that is C02, however it wouldn't change the absolute amount of C02 in the atmosphere.

Just for info C02 isn't the biggest cause of the greenhouse effect..

https://en.wikipedia.org/wiki/Greenhouse_effect

By their percentage contribution to the greenhouse effect on Earth the four major gases are:[21][22]

ProfuselyQuarky
The answer is that it is simply a quantitative result. The Earth receives a lot of energy from the sun. Most of it gets radiated back. A small average difference is enougth to increase the temperature of the earth.

So I am guessing that it is 'relativity' easy to calculate the amount of heat that the Earth receives from the Sun and then also the relative amount of infrared radiation that effectively becomes trapped due to individual greenhouse gases. I will check out the wiki article. I guess I am looking for something that goes someway to introducing the mathematics that is used in modelling climate change, not something at post graduate level but something that is most likely at an intermediate graduate level. Thanks

I understand that methane can have a much greater effect than CO2 but I have also been reading somewhere in some paper recently that at according to some climate modelling, CO2 still has the greatest effect. I think the author of the paper I was reading did experiments (computer modelling) where they removed the CO2 from their model and they found that other gases such as H20 were not sufficient to sustain a greenhouse gas effect and the Earth jus got seriously colder. Thats parphrasing it roughly.

resurgance2001 said:
Hi

I have a simple question about global warming. The percentage of carbon dioxide in the Earth atmosphere is about 0.04% . My question is how is such a small percentage of this gas able to have such a powerful affect on global warming? Thanks
The density of carbon dioxide in the atmosphere is 1020/m3. Do you see how such a huge number can have a powerful effect?

It doesn't help to compare the amount of CO2 to the amount of N2 if you want to measure the effect of CO2 on the climate. The amount of CO2 we have is sufficient to absorb a significant fraction of infrared radiation going through the atmosphere, only the absolute concentration matters here.

Earth would be significantly colder without CO2, but even colder without water vapor.

I tried to find a decent website and I found that this one was explaining it rather well:
https://scienceofdoom.com/2009/11/28/co2-an-insignificant-trace-gas-part-one/

Thanks - yes it is beginning to make more sense. I would really like to see the numbers a bit, as in the basic models used to estimate the amount of Infrared absorbed and then re-emitted by those molecules. I understand the idea that the re-emitted IR is emitted in all different directions so that on average less of what was absorbed is transmitted back out into space, but I would like to see how it is calculated. Thanks

The absorption spectra of greenhouse gasses can be measured rather than just calculated.

It's not plausible to do a precise calculation of atmospheric warming since many parts of Earth are subject to local changes of cloud cover and ocean currents which are not entirely predictable.
It's more practical to measure what is actually happening over a period of time, then build models based on understood thermodynamics that explain the data.
From there it's possible to extrapolate trends within a reasonable margin of error.
You might find this NASA article interesting.
http://climate.nasa.gov/news/2264/twelve-years-of-satellite-data-help-decode-climate-change/

Thanks - I will check out that link.

## 1. What is carbon dioxide and how does it contribute to global warming?

Carbon dioxide (CO2) is a colorless gas that is naturally present in the Earth's atmosphere. It is also a byproduct of human activities such as burning fossil fuels and deforestation. CO2 acts as a greenhouse gas, trapping heat from the sun and causing the Earth's temperature to increase, leading to global warming.

## 2. How do scientists measure the levels of carbon dioxide in the atmosphere?

Scientists use a variety of methods to measure the levels of CO2 in the atmosphere. One common method is through taking direct air samples and analyzing them in a laboratory. Another method is through remote sensing using satellites, which can provide a more comprehensive view of CO2 levels globally.

## 3. What are the consequences of increased levels of carbon dioxide in the atmosphere?

The consequences of increased CO2 levels in the atmosphere are numerous and severe. These include rising global temperatures, changes in weather patterns, melting polar ice caps, sea level rise, and more frequent and intense natural disasters such as hurricanes and wildfires. These effects not only impact the environment but also have serious implications for human health and the economy.

## 4. Can we reduce the amount of carbon dioxide in the atmosphere?

Yes, it is possible to reduce the amount of CO2 in the atmosphere. This can be achieved through various methods such as reducing our dependence on fossil fuels, increasing the use of renewable energy sources, and implementing sustainable land-use practices. Additionally, technology such as carbon capture and storage can be used to capture and store CO2 emissions from power plants and industrial facilities.

## 5. Is there a link between carbon dioxide emissions and climate change?

Yes, there is a direct link between carbon dioxide emissions and climate change. Scientific research has shown that the increasing levels of CO2 in the atmosphere are the main driver of global warming and climate change. The more CO2 we emit into the atmosphere, the more the Earth's temperature will continue to rise, leading to the negative consequences mentioned above.

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