Earth and climate – an ongoing controversy
Researchers believe the so-called global warming hiatus ended in 2014 ‘as a new El Niño Southern Oscillation (ENSO) event was developing’. Whether there’s a struggle between natural cooling and non-natural warming is an open question. So-called internal variability can surely vary either up or down, i.e. warmer or cooler, in any time frame.
Global warming has been attributed to persistent increases in atmospheric greenhouse gases (GHGs), especially in CO2, since 1870, the beginning of the Industrial Revolution, say the researchers.
Nevertheless, the upward trend in global mean surface temperature (GMST) slowed or even paused during the first decade of the twenty-first century, even though CO2 levels continued to rise and reached nearly 400 ppm in 2013.
This episode has typically been termed the global warming hiatus or slowdown in warming. The hiatus is characterized as a near-zero trend over a period.
Detection found that the hiatus appeared during 2001-2013/2002-2012 with extremely weak interannual variability in some GMST sequences, and the slowdown in the others.
The hiatus is often attributed to internal climate variability, external forcing, or both, involving an increase in aerosols in the stratosphere during the period 2000-2010, the negative phase of the Interdecadal Pacific Oscillation (IPO) accompanying intensified trade winds, extensive heat uptake by the deep ocean or an extremely low number of sunspots during the latest solar activity cycle.
A new study published in Scientific Reports reveals that the global warming has never stopped in the past hundred years, with maximum rate of change after Second World War II and almost constant rate (0.08 deg.C/10a) during the latest three decades.
However, the key cooling against global warming comes from the interannual variability of the temperature that is coincided with the variability of the sea surface temperature in the equatorial mid-eastern Pacific.
Hence, the hiatus is merely a decadal balance between global warming and the cooling resulting from anomalous sea surface temperature in equatorial Pacific.
Continued here.
via Tallbloke’s Talkshop
November 14, 2018 at 09:27AM
Iowa Climate Science Education 