New Study Offers Insights on Global Warming ‘Hiatus’

A new study provides new insights about the so-called global warming "hiatus" that occurred between 1998 and 2013.

During the said period, a temporary slowdown in the global mean surface temperature (GMST) warming was observed, and a new study suggests that the phenomenon represented a redistribution of energy within the Earth system, which includes the planet's land, atmosphere and the ocean.

In a paper published in Earth's Future, a journal of the American Geophysical Union, study lead author Xiao-Hai Yan of the University of Delaware, together with scientists from NASA, the National Oceanic and Atmospheric Administration (NOAA), and other institutions discussed their new findings about the phenomenon. The paper grew out of a special U.S. Climate Variability and Predictability Program (CLIVAR) panel session at the 2015 American Geophysical Union fall meeting.

The researchers concluded that the global ocean absorbed the extra heat from the atmosphere, causing the observed decrease in GMST - a key indicator of climate change.

"The hiatus period gives scientists an opportunity to understand uncertainties in how climate systems are measured, as well as to fill in the gap in what scientists know," Yan said in a statement.

According to the researchers, natural variability plays a large role in the rate of global mean surface warming on decadal time scales. Arguably, the most appropriate single variable in the Earth's system that can be used to measure global warming is ocean heat content - from the surface to the seafloor.

"To better monitor Earth's energy budget and its consequences, the ocean is most important to consider because the amount of heat it can store is extremely large when compared to the land or atmospheric capacity," Yan said.

The researchers hope that the new study will lay the foundation for future research in the global change field, suggesting that the climate community replaces the term "global warming hiatus" with "global surface warming slowdown" to avoid confusion.

Moreover, the scientists called for continued support of current and future technologies for ocean monitoring to minimize observation errors in sea surface temperature and ocean heat content. This includes maintaining Argo, the main system for monitoring ocean heat content, the development of Deep Argo for monitoring the lower half of the ocean, and other technologies.