Every year, the World Meteorological Organization, or WMO, tracks a set of key climate indicators — including the amount of carbon dioxide in the atmosphere and the Earth’s temperature — to assess how global warming is progressing. In their latest report, released last Sunday, the authors decided to include a new measure: the Earth’s energy imbalance.  “Climate change is often discussed in terms of the change in the global mean surface temperature,” John Kennedy, lead author and scientific coordinator of the report, said in an email to Grist. But year-to-year variations in air temperatures, caused by the weather patterns El Niño and La Niña, can “hide the long-term trend” of global warming, said Kennedy. With the addition of this new key indicator, however, the WMO authors aimed to clarify the fundamental dynamics of global warming, and represent them simply.…