An important process with regards to weather/climate change is the prevalence of naturally occurring multi-decadal periods of up-and-down swings in temperature, precipitation and other climate elements. The usual period of these variations is about 50 to 60 years or roughly 25 to 35 years between low to high or high to low periods.
The weather 25 to 35 years ago can often seem different from what we experience today. I have heard many adults say the weather/climate now is different than when they were kids. And this is often true. Such multi-decadal periods of up-and-down variations have been well documented backward in time for thousands of years in paleo-climate data sets of various kinds. Surface temperature measurements during the past 130 years indicate that our globe’s mean surface temperature experienced weak cooling periods between 1885 to 1910, 1945 to 1975 and the slight global cooling since 1998. Periods of global surface warming have occurred between 1910 to 1940 and 1975 to 1998.
These roughly 30-year-long up and down changes in climate are due to the natural back and forth swings of the globe’s deep ocean circulation patterns which are primarily driven by ocean salinity differences. These salinity changes are caused by precipitation and evaporation differences and have no direct association to the CO2-induced radiation changes. The Anthropogenic Global Warming, or AGW, advocates want us to believe that these natural multi-decadal changes have a human component related to greenhouse gas buildup. This plays into the hands of those not knowing the causes of such natural climate changes.