The temperature at the surface at any one time is influenced by what is going on in the deep oceans, months or even years before. Quite small changes in the transport of heat or salt can have large, but hard to predict, effects on surface temperature, and thus on climate. Tiny particles in the atmosphere, from both natural sources and human activities, can have positive and negative effects. For example, soot particles absorb heat and cause warming while sulphates reflect heat, resulting in cooling. The different contributions to climate change are uncertain.
Ozone has a complex effect on climate change.
Close to the Earth's surface, increased ozone levels contribute to warming, but ozone depletion in the stratosphere has a cooling effect. But once climate change begins, many other factors we have been measuring or estimating also start to change. Some can increase the rate of change, others can produce feedbacks which slow things down, but we do not know exactly what the overall effect will be. But clouds can also prevent radiation from the earth's surface escaping, thus keeping heat in. So the effects can be positive or negative depending on the height, temperature and properties of the clouds, all of which vary in time and from place to place.