Jim D
To get back to the K-12 classroom.
If the kiddos are being taught about past warming and CO2 they should know.
Over the past 160+ years it has warmed at an average rate of a bit more than 0.04C per decade, or 0.7C over the entire period.
CO2 rose from an estimated 290 ppmv in 1850 to a measured 390 ppmv today.
The warming occurred in three similar multi-decadal warming cycles of ~30 years each, with ~30-year cycles of slight cooling in between. The last two warming cycles (early and late 20th century) have been statistically indistinguishable, while the late 19th century warming cycle was slightly less pronounced.
While both atmospheric CO2 concentration and global temperature have risen since 1850, there is no observed statistically robust correlation between the two. The temperature record is a random walk, statistically speaking.
Since January 2001 (before most of you were in school and before many of you were even born) global temperature has ceased to rise (actually cooled very slightly). Whether this is the start of another multi-decadal cycle of slight cooling or not is too early to tell and scientists have differing opinions on this today.
Scientists know that there are natural factors, which have changed our planet’s climate over its history, but the magnitude and mechanisms for these changes are largely unknown today.
Scientists also believe that greenhouse gases, such as CO2 and water vapor, influence climate through the warming caused by the greenhouse effect.
Some of this greenhouse warming has come from human emissions of greenhouse gases, principally CO2, but scientists are uncertain today just how much warming this effect has caused.
Scientists believe that this effect is logarithmic. This means that a doubling of CO2 level from 280 to 560 ppmv will have the same temperature impact as a further doubling from 560 to 1120 ppmv.
Research work is going on today to learn more about our planet’s climate and what makes it act and react the way it does. This work is done by atmospheric physicists, meteorologists and solar scientists.
This is an interesting field. Maybe some of you will pursue this when you grow up – and maybe you will help to solve some of the many mysteries that still exist about our climate.
Max