A Brief Review of Investigations into Earth’s Temperature Since the Year 1800

Abstract

For billions of years, natural processes alone, often working over millennia, drove Earth’s temperature and climate. For the last several centuries, human activities are a new driving force that is acting on a very short time scale. Knowing history helps chart necessary future actions with greater confidence. Since the end of the 17<sup>th</sup> century, investigations relating to Earth’s temperature and its climate have evolved from only scientific interest to also include practical concerns triggered by global warming. The early studies were relatively episodic with gaps of a decade or more common until the mid 20<sup>th</sup> century when they burgeoned starting with the International Geophysical Year. From the early to mid 1800s, to the early to mid 20<sup>th</sup> century, the investigations were at the initiation of the individual researchers. Starting in the mid 1950s, the investigations became more extensive, comprehensive and interrelated. Early researchers inferred that the atmosphere played a role in Earth’s temperature, and as far back as the 1850s it was concluded that higher CO<sub>2</sub> concentrations in the atmosphere could result in warming Earth. Later investigations provided information on the mechanism which established that atmospheric CO<sub>2</sub> concentration and its absorption and re-emitting of infrared radiation was a major factor in Earth’s temperature. Further, its increasing atmospheric concentration is a major driver of a warming globe at a rate far surpassing those detected in the geologic record. This paper traces the history of those researches based on the premise that knowing how we arrived at our current knowledge helps in supporting future research and actions to address the consequences of Earth’s warming.