19th Century

Early Foundations

In 1824, Joseph Fourier first described the Earth's natural "greenhouse effect," explaining how the atmosphere can increase the Earth's temperature by trapping heat. This laid the groundwork for future climate research. In 1859, John Tyndall discovered that some gases, including water vapor and carbon dioxide (CO2), could block infrared radiation, suggesting that changes in the concentration of these gases could bring about climate change.

Late 19th -Early 20th Century

Quantifying the Greenhouse Effect

In 1896, Svante Arrhenius made the first calculation of global warming from human emissions of CO2, proposing that doubling atmospheric CO2 could significantly increase global temperatures. This was a crucial step in linking human activities to potential climate change. 

Mid-20th Century

Empirical Evidence and Refined Understanding

The mid-20th century saw significant advancements in climate science: 

1. In 1938, Guy Callendar collected data from 147 weather stations worldwide, discovering that global temperatures had risen by 0.3°C over the previous 50 years. He argued that CO2 emissions from industry were responsible for this warming.

2. In 1957, Roger Revelle and Hans Suess demonstrated that seawater could not absorb all the additional CO2 entering the atmosphere, highlighting the human impact on the Earth's climate system.

3. In 1958, Charles David Kee ling began systematic measurements of atmospheric CO2 at Mauna Loa, Hawaii, providing the first definitive evidence of rising CO2 concentrations. This led to the creation of the famous "Keeling Curve," which shows the steady increase in atmospheric CO2 levels.

Late 20th Century

Advances in Climate Modeling and Consensus Builading

The latter part of the 20th century saw rapid advancements in climate science: 

1. In the 1960s and 1970s, scientists developed more sophisticated climate models. Syukuro Manabe and Richard Wetherald made a convincing calculation in 1967 that doubling CO2 would raise world temperatures by a couple of degrees.

2. The Intergovernmental Panel on Climate Change (IPCC) was formed in 1988 to assess the scientific, technical, and socio-economic information relevant to understanding climate change.

3. By the 1990s, a scientific consensus had formed. It became clear that greenhouse gases were deeply involved in most climate changes, and human-caused emissions were bringing about discernible global warming.

Present

Current Understanding

Today, our understanding of climate change and the role of greenhouse gases (GHGs) is more comprehensive: 

1. CO2 is recognized as the primary greenhouse gas contributing to global warming, accounting for about two-thirds of the warming caused by human activities.

2. Other significant greenhouse gases (GHGs) include methane, nitrous oxide, and fluorinated gases, each with varying potencies and atmospheric lifetimes.

3. The concentration of CO2 in the atmosphere has increased by 48% above pre-industrial levels (before 1750) as of 2020.

4. The global average temperature has already increased by about 1.1°C above pre-industrial levels, with the 2011-2020 decade being the warmest on record.

5. Natural causes, such as changes in solar radiation or volcanic activity, are estimated to have contributed less than ±0.1°C to total warming between 1890 and 2010.

6. The rapid increase in greenhouse gases (GHGs) is primarily attributed to human activities such as burning fossil fuels, deforestation, and intensive agriculture.

In conclusion, our current understanding of global warming and the role of GHGs is the result of nearly two centuries of scientific inquiry, observation, and modeling. This accumulated knowledge underscores the urgent need for action to mitigate the impacts of climate change.