Yes, the planet has kept warming since 1998

As part of their climate myth series, New Scientist cuts through the nonsense on what’s happened globally in the last decade:

In fact, the planet as a whole has warmed since 1998, even in the years when surface temperatures have fallen.

According to the dataset of the UK Met Office Hadley Centre (see figure), 1998 was the warmest year by far since records began, but since 2003 there has been slight cooling.

NASA's global temperature land-ocean indexBut according to the dataset of NASA’s Goddard Institute for Space Studies (see figure), 2005 was the warmest since records began, with 1998 and 2007 tied in second place.

The difference between the two datasets goes to the core of why the planet has in fact been warming since 1998:

The main reason is that there are no permanent weather stations in the Arctic Ocean, the place on Earth that has been warming fastest. The Hadley record simply excludes this area, whereas the NASA version assumes its surface temperature is the same as that of the nearest land-based stations.

It is possible that the NASA approach underestimates the rate of warming in the Arctic Ocean, but for the sake of argument let’s assume that the Hadley record is the most accurate reflection of changes in global surface temperatures. Doesn’t it show that the world has cooled since the record warmth of 1998, as many claim?

Not necessarily. The Hadley record is based only on surface temperatures, so it reflects only what’s happening to the very thin layer where air meets the land and sea.

In the long term, what matters is how much heat is gained or lost by the entire planet - what climate scientists call the “top of the atmosphere” radiation budget - and falling surface temperatures do not prove that the entire planet is losing heat.

… the planet is gaining as much heat from the sun as usual but losing less heat every year as greenhouse gas levels rise (apart from the exceptional periods after major volcanic eruptions, such as El Chichon in 1982 and Pinatubo in 1991).

How do we know? Because the oceans are getting warmer.