The ocean temperature increases more slowly than the average atmospheric temperature. Because the temperature reflects the ocean heat content, it is an important measurement to predict the future air temperature.

The Arctic is presently increasing in temperature at least twice as fast as the rest of the world. As you can see from the graph, it will continue to increase even faster, likely reaching four or more times as fast as the rest of the world.

The correct answer is water vapour. If you guessed carbon dioxide, that is a good guess because it is the greenhouse gas responsible for causing global warming, but it is much less abundant than water vapour. If you guessed Argon, you are incorrect because Argon is not a greenhouse gas.

Visible sunlight passes right through a greenhouse gas. When the visible light hits plants, land, lakes, ocean, or even hits you, it warms them up and also warms you up, by casuing the molecules on your skin to vibrate. Warm things give off heat (also known as infrared light or IR). The infrared is invisible so we can't see it but we can feel it. As we give it off, the light heads up to ward the sky and if no greenhouse gas was in the way, it would escape, and everything would cool down. BUT - and this is a big BUT - greenhouse gas molecules have three or more atoms so they can vibrate an additional way by bending around the central atom. This allows the molecules of a greenhouse gas to catch and toss back some of the IR. Kind of like a not-so-great tennis player who has a racket and hits some but not all the tennis balls. The more greenhouse gas there is, the more IR (heat) gets trapped, warming up the planet - causing global warming. Just like two tennis players can hit more balls back than just one.

Smallest Per Capita CO₂ Emissions Ranked by Country (Top 20 Countries)

2011; (Metric Tons per Person)

Rank	Country	Per Capita Emissions
1	India	1.45
2	Indonesia	1.73
3	Brazil	2.41
4	Mexico	4.07
5	France	5.73
6	China	6.52
7	Italy	6.57
8	Spain	6.82
9	United Kingdom	7.92
10	Poland	8.01
11	Iran	8.02
12	Germany	9.19
13	Japan	9.26
14	South Africa	9.42
15	South Korea	12.53
16	Russia	12.55
17	Canada	16.24
18	United States	16.92
19	Australia	18.02
20	Saudi Arabia	19.65

Total Emissions CO₂ Emissions Ranked by Country (Top 20 Countries)

2011; (Million Metric Tons)

Rank	Country	Total Emissions
1	China	8715.31
2	United States	5490.63
3	Russia	1788.14
4	India	1725.76
5	Japan	1180.62
6	Germany	748.49
7	Iran	624.86
8	South Korea	610.95
9	Canada	552.56
10	Saudi Arabia	513.53
11	United Kingdom	496.8
12	Brazil	475.41
13	Mexico	462.29
14	South Africa	461.57
15	Indonesia	426.79
16	Italy	400.94
17	Australia	392.29
18	France	374.33
19	Spain	318.64
20	Poland	307.91

The sun is almost a constant source of energy - it varies according sunspots, but only by about 0.2% up and down. So that is a factor, but only a small factor.

The orbit of the Earth changes from circular to elliptical, the Earth tilts toward and way from the sun and it wobbles. These are called the Milankovitch cycles and they can trigger the start of a melt when everything lines up to cause the most energy striking the Earth at 65⁰N (where most of the ice collects).

The amount of greenhouse gas in the atmosphere increases and causes the temperature to rise (CO₂, CH₄, N₂O, and H₂O - water vapour).

As the ice melts, the water and land absorb more heat because they are darker.

So it is a cycle of building one factor on another in a very delicately balanced dance holding us in just a narrow band of cold and warm.

Light from the sun (an electromagnetic wave) passes right through air without warming it up. The light energy is absorbed by the surface of the planet (the ocean, the land, and the plants). This warms up the surface, which then radiates heat. The heat is radiated as infrared radiation (IR), another form of electromagnetic wave that passes right through the air. If you have ever sat in front of a campfire, you can feel the "radiant" heat even though the air around you remains cool.

So how does the air warm up? It warms up by conduction to start with - when air flows over a warm surface, it warms up. As the air heats up, the air molecules start to vibrate faster and they hit other molecules of air and make them vibrate, warming them as well. Those molecules in turn hit other molecules until the energy runs out and the temperature stabilizes. OK, so that warms the layer of air right close to the warm surface. How does the air higher up get warm?

The air that was warmed by conduction is not as heavy as the cool air, so it begins to float up into the cool air warming it up and allowing the cool air to fall and touch the warm surface of the land, plants or ocean. This is called "convection." Finally because this is happening more in some places than others, the warm air tries to equalize its distribution by flowing sideways as well as up - this is what we call "wind." Wind causes the air to mix so the temperature is more uniformly distributed.

Plants use the lightest isotope of carbon called ¹²C. Fossil fuels are made from plants or animals which have mostly ¹²C. This means the ratio of ¹³C to ¹²C will change as more carbon from fossil fuels is added to the air. That ratio is called delta ¹³C and it will go down if the carbon is from fossil fuels. In this graph it goes from -7.6 to -8.1, a drop of 0.5 parts per thousand in 30 years. So that is good evidence for a plant origin of the carbon.

What about proving it is from old carbon (all fossil fuels are millions of years old)? We know that all plants have ¹⁴C when they are alive. When they die, the ¹⁴C starts to decay with a half-life of about 6,000 years. In a million years there is none left. So -- the C14 should also decline with the increased fossil fuel added to the air. Guess what - it does. So those two combined are conclusive evidence the carbon source is fossil fuels.

If we were to add enough, and for a long continuous time, the temperature would go down. The reason is because the ocean plankton normally absorb carbon to make their bodies. This takes carbonout of the ocean and makes room for carbon from the air to enter the oceean. This reduces the carbon in the air, reducing the amount of greenhouse gas in hte air, so it cools down the surface of the planet. Complex? Yes indeed. Also just to be confusing, as the dust increases and the land and ocean cool ice forms and snow falls. Dust landing on the ice and snow causes them to warm up. So dust is tricky! Here is what happened in the past.

Cows are ruminants (like sheep, goats, camels, llamas and deer). They have four-chambered stomachs to digest the cellulose. This system uses billions of bacteria to digest the food releasing both the nutritious parts of the food and also methane.

And the answer is ....

methane is burped, not farted!

A single adult cow can burp out a huge amount of methane each day - about 280 liters (or 74 gallons). Cattle methane emission contributes about 20% of all the methane released into the atmosphere each year - about the same as from extracting natural gas. So cow burps are a major component of human-related methane emission.