The answer is:
Human actions cause climates to change abruptly
Human actions emit carbon dioxide in several ways.
Let's look into the answers one by one:
Human actions cause cooling of North Atlantic climates.
-This is false as human actions cause global warming, and the ice at North Atlantic is melting at an expotential rate due to the rising temperature.
Human actions cause climates to change abruptly.
- This is the case happened in many regions. As the atmosphere layer gets thicker due to the emission of carbon dioxide, the insolation is trapped in the layer and cannot get out. This has cause the temperature to rise in many places, changing the climate abruptly.
Human actions cause small variations within a region.
-Global warming does not apply only to a small variations, but the entire Earth, as the affected atmospheric layer would put impact on every places on Eatrth.
Human actions emit carbon dioxide in several ways.
-This is true. Many actions, especially industrial production, emits much carbon dioxide to the atmosphere during the production, when fuel is used to activate the machines. There are also other means of carbon emission, such as the use of vehicles.
Hope it helps!