Even under global warming, surface temperatures will not necessarily rise every year. But all the evidence suggests that the oceans are continuing to absorb more heat from the Sun so that the overall trend is that the Earth as a whole is still warming.

Different sources claim that 1998, 2005 or 2007 was the warmest year since records began. Nevertheless, the Earth as a whole has warmed since 1998. In the long term, what really matters is how much heat from the Sun is gained or lost by the entire planet. For example, falling surface temperatures do not prove that the entire planet is losing heat. We can say this because the oceans are getting warmer. Water stores over 1000 times more heat per unit volume than air. Since the 1960s, over 90% of the excess heat due to higher greenhouse gas levels has gone into the oceans, and just 3% into warming the atmosphere. Globally, this means that if the oceans soak up a bit more heat energy than normal, surface air temperatures can fall even though the total heat content of the planet is rising and vice versa.

This is why surface temperatures do not necessarily rise steadily year after year, even though the planet as a whole is heating up year on year. In the long term, some of the heat being soaked up by the oceans will inevitably spill back into the atmosphere, raising surface temperatures. But unless we see a simultaneous fall in both surface temperatures and ocean-heat content, claims that the "entire planet" is cooling are nonsense.

The dust from a big volcanic eruption could potentially trigger genuine cooling for a few years but in the current situation global warming will resume again once the dust has settled.