78
votes
How do 'greenhouse gases' let heat in, but not let it out?
In a nutshell:
The radiation that enters is shortwave radiation from the sun. Solar radiation is dominated by visible (as well as UV and near infrared) radiation with a wavelength mostly between 0.2 ...
- 11.6k
42
votes
Is there any experiment to prove that CO2 with the atmosphere concentration can have greenhouse effect?
Your question about water vapour is quite a common one among people learning about the greenhouse effect. Once you discover the relevant proportions of water vapour and CO2 in the atmosphere, it's ...
- 5,431
40
votes
CO₂ level is high enough that it reduces cognitive ability. Isn't that a reason to worry?
There looks like legitimate cause for further study, preferably by scientists breathing air under 950 ppm $\small\mathsf{CO_2}$ (this study showing a 15% decline in cognitive ability at this level).
...
- 1,837
26
votes
Why don't green house gases escape into space?
The reason the atmosphere (including GHGs) stays attached to the earth is gravity. This is called the Hydrostatic Equilibrium. There is one GHG that this does not fully apply to: water vapor. While ...
- 8,684
25
votes
How do 'greenhouse gases' let heat in, but not let it out?
Gerrit's got the technical answer; I'm going to answer for a layperson.
There are two ways objects lose heat.
The first, and the way people are most familiar with, is conduction. Something touches ...
- 351
23
votes
How do 'greenhouse gases' let heat in, but not let it out?
To add to Gerrit's excellent answer, I'd like to add a couple more Images. Images always help clarify things for me.
Firstly, this one shows the spectrum light coming from the sun in red. The peak is ...
- 327
23
votes
Accepted
Why is CO₂ abundance in the atmosphere still small?
The mass of the atmosphere is 5.1 × 1018 kg, which is 5.1 × 1015 t.
As stated in the edited question,
industries emits 1.5 billion metric tons of carbon dioxide each year,
That's 1.5 × 109 t.
The ...
- 24.6k
22
votes
Accepted
Why is Carbon Dioxide a Greenhouse Gas whereas Ammonia is not?
A molecular gas is a good infrared absorber if it has several atoms (not just 2, like O2 and N2) or if it is hetero-nuclear (e.g. CO and NO). These type of molecular arrangements allow more infrared ...
- 13.5k
20
votes
Why is CO₂ abundance in the atmosphere still small?
As well as the atmosphere having a lot of mass, there are many processes which remove CO2 from the atmosphere, see the wikipedia article for the carbon cycle. Plants sequester it as biomass, some of ...
- 309
14
votes
Why don't green house gases escape into space?
Trapping compounds and changing composition are two very different things.
The composition of an atmosphere is set by equilibrium chemistry. Equilibrium chemistry can be understood as mapping of a set ...
- 3,152
13
votes
How CO$_2$ warming effect stays overnight?
CO$_2$ doesn't significantly interact with solar radiation or UV, and doesn't store any significant amount of heat. What CO$_2$ effectively does is scattering infrared radiation emitted by the Earth, ...
- 17.6k
13
votes
Can anyone explain the reason why CO$_2$ increases global temperatures (not the simplistic greenhouse analogy provided for public consumption)?
Borrowing an explanation from one of my other answers, the basic mechanism of the greenhouse effect is roughly as follows (note this is also a simplified model)
The Earth is in (to all intents and ...
- 1,959
11
votes
Is there any experiment to prove that CO2 with the atmosphere concentration can have greenhouse effect?
Experiments don't necessarily prove things, per se; and in particular, a single experiment tends not to prove anything - at the very least, replication of the experiment is required. Experiments ...
- 4,090
9
votes
Are cattle really contributing to global warming?
Let's just talk about cattle here and ignore other factors related to cattle production for now.
The current cattle number (93 million) you found is probably the total number of dairy cow and beef ...
- 91
9
votes
Why can't we increase cloud coverage of the Earth to reduce mean temperature by flooding basins to increase evaporation?
Barring the technical feasibility of what you are proposing, there's a few points to consider which make your proposal problematic.
Water vapor is a greenhouse gas. If you increase evaporation, you ...
- 13.5k
9
votes
Accepted
How much does overpopulation affect the carbon dioxide concentration in the air in terms of just breathing?
Human and animal respiration has no global warming impacts. The CO2 released by respiration is in balance with the CO2 absorbed by the plants that became the foods that were the source of the CO2 ...
- 1,837
8
votes
Is there any experiment to prove that CO2 with the atmosphere concentration can have greenhouse effect?
The short answer to your question really is just this: Yes, CO2 causes global warming.
There are many resources out there on the internet that explain this in about as much detail as you can tolerate,...
- 2,028
8
votes
Is there any experiment to prove that CO2 with the atmosphere concentration can have greenhouse effect?
To see why we can't perform an experiment in lab conditions to verify the greenhouse effect, we need to start by considering how the [rather badly named] greenhouse effect operates:
The Earth is in (...
- 1,959
8
votes
CO₂ level is high enough that it reduces cognitive ability. Isn't that a reason to worry?
Two recent studies tend to contradict the 2016 study mentioned in Ken Fabian's answer.
Acute Exposure to Low-to-Moderate Carbon Dioxide Levels and Submariner Decision Making (June 2018) reports:
...
- 5,962
8
votes
Which method is used to calculate tonnes carbon from tonnes CO$_2$ equivalents of GHGs?
OK it depends a lot on what exactly you mean. There is a known problem with people talking about "carbon" / "atmospheric carbon" / "Carbon Dioxide" and using the terms imprecisely - so there is often ...
- 494
8
votes
Accepted
What exactly is "Land-Use Change and Forestry"?
You are correct that normally you see a net positive value of GHGs from land use change. However, if forests are grown or revegetated, it is considered a sink (and negative GHG value). This paper ...
- 13.5k
7
votes
The atmosphere and the dispersion of greenhouse gases
The short answer is that greenhouse gases occur at all levels in the atmosphere. However, the concentrations can vary with altitude. In the case of greenhouse gases that are always in a gaseous state ...
- 17.6k
7
votes
Accepted
How to calculate the temperature of Earth's surface
An easy calculation is to start with the solar constant, the power (energy per unit time) produced by solar radiation at a distance of one astronomical unit. This is 1.361 kilowatts per square meter. ...
- 23.1k
7
votes
About the actual radiative impact of greenhouse gas emission over time
There is no doubt that the sooner the mitigation effort happens, the greater will be its impact.
In other words, the impact on year 2100 climate of the sequestration of 20 billion tons $\ce{CO2}$-eq ...
- 17.6k
7
votes
Why is Carbon Dioxide a Greenhouse Gas whereas Ammonia is not?
The common factor among Greenhouse gases is that they absorb and scatter infra-red light.
The Greenhouse effect is caused when energy coming in from the sun is prevented from escaping again. The Sun ...
- 179
7
votes
Time for water vapor to generate more greenhouse effect than latent heat?
This is actually hinted at in the typical Trenberth energy budget diagram for the Earth:
The $86.4\mathrm{\frac{W}{\,m^2}}$ is that energy movement up into the atmosphere from vaporization. The $340....
- 8,713
6
votes
Is there any experiment to prove that CO2 with the atmosphere concentration can have greenhouse effect?
The Faint Young Sun Paradox - how greenhouse gases can keep a planet warm:
When the Earth formed 4.5 billion years ago the Sun was around 30% less luminous than it is today and it has increased ...
- 2,221
6
votes
Accepted
Is it true that methane is responsible for nearly one-third of all warming?
Yes, this is broadly true. I haven't looked into much of the report yet, but I suspect that the BBC are referring to Fig 7.7 for an estimate of the observed warming attributed to changes in methane ...
- 3,940
6
votes
Why does the mainstream greenhouse gas theory for global warming ignore the mass of the surface?
You’re possibly thinking of the steady state descriptions, as shown in something like the Trenberth diagram below. These are steady state descriptions of energy flows rather than energy stores, in ...
- 3,940
6
votes
Accepted
Why doesn't earth radiate at wavelengths where there is strong absorption?
Due to the large optical thickness, the outgoing radiation is emitted at stratospheric temperatures (the black-bodies indicated by ~210K temperatures).
Keep in mind that the black-bodies in the graph ...
- 3,152
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