Factors Other Than GHG Forcing Which May Have Caused “Climate Change”

There are some significant changes which have occurred over the last decades and centuries which may well be significant to climate change.

Long Term Increase of Solar Irradiance

Changes in solar irradiance are typically excluded from consideration of climate change because short term ( solar cycle duration ) variations typically are obscured, and because after considering albedo, remaining forcing is small. But we should consider that on clear days, over high latitude oceans, TSI changes are experienced more acutely than for the global average. Also, snow melt is more a function of instantaneous irradiance than global mean. Also, days of extreme heat are associate with clear skies and so, more influenced by total direct solar.

Albedo

The CERES albedo series ( outgoing shortwave radiance as a percentage of incoming shortwave radiance ) indicates a declining trend over the brief period of record. The years of minimal global albedo, 2015,2016, and 2017, correlate with the maximal mean surface temperature. Much uncertainty will persist as to how albedo varied over past centuries.

But in comparison, model estimates of planetary albedo are much higher ( ‘around 31% ), future albedo variation due to unpredictable volcanoes is necessarily missing, and the recent decline in satellite estimated albedo is larger than modeled fluctuations:

ENSO

Accoring to the Multivariate ENSO Index, La Nina conditions have become less frequent and El Nino conditions have become more frequent.