Abbreviations and Definitions

The survey from which this 97% figure arose asked whether the world was getting warmer and whether human activity contributed to that warming.  The IPCC AR6 has concluded that the world has warmed by about 1.1 C since the preindustrial period, and virtually 100% of scientists agree with that number or some number reasonably close to it.  Virtually 100% of scientists also agree that human activty (which includes urbanization and changes in land use) has caused some significant amount of that warming.  But there is significant disagreement among scientists as to whether human activity has caused a majority of that warming.

The Atlantic Multidecadal Oscillation. A cycle of warm and cold surface temperature in the Northern Hemisphere Atlantic Ocean. The cycle lasts 60-80 years. The cycle is expected to switch from its hot phase to its cold phase sometime between 2025 and 2030.  The AMO has a powerful effect on the climate of Iceland and surrounding regions.  Scientists disagree as to the extent to which the AMO can influence the climate of the world.

Assessment Reports 1-6 issued by the IPCC. AR1 in 1990 (originally called FAR for First Assessment Report. AR2 in 1996 (originally called SAR for Second Assessment Report. AR3 in 2001 (originally called TAR for Third Assessment Report). AR4 in 2006. AR5 in 2013. AR6 in 2021-2.

The long term average of the weather. “Long term” is generally considered to be at
least 30 years.

A change in the frequency or amount of a weather variable over a period of at least 30 years.

The El Nino Southern Oscillation.  The warm phase is the “El Nino” and the cold phase “La Nina.”  The phases alternate on an irregular (and unpredictable) 2-7 year cycle, and the strength of the phases vary.  Hot phases can be strong enough to clearly influence world average temperatures for the year in which they occur.  Among other things, ENSO effects hurricane activity in the Atlantic Ocean and causes cycles of rain and drought in California, Australia, and as far away as India.

The US National Oceanographic and Atmospherical Administration is the agency of the US government charged with assembling and analyzing climate data from around the world.  NOAA has an excellent reputation for both the quantity and the quality of its data, and this website and newsletter frequently reports, and relies upon, such data, which NOAA always identifies with its logo.