For 800,000 years, the glacial interglacial cycles were driven by orbital cycles combined with a natural oscillation of CO2 between 170 and 300 ppm. Currently the Earth's orbital eccentricity is at a near million year low, that prohibits either glaciation or deglaciation. The Earth should be in very slow and steady cooling phase. The next ice age was due in 50,000 years. However, burning hydrocarbons and changes in land use has increased atmospheric CO2 to over 420 ppm and it's still rising. That increase in CO2 has led to:
- a significant increase in global temperature,
- a significant increases in temperatures at urban and rural stations,
- a significant increases in sea surface temperatures (as measured by both ship sensors and buoys),
- significant increases in ocean heat content,
- significant tropospheric warming (as measured by satellites and weather balloons),
- an increase in atmospheric moisture and extreme precipitation,
- an increase in the length of wildfire seasons,
- significant reduction in sea ice extent,
- worldwide glacial retreat,
- widespread permafrost thaw,
- weakening of the Atlantic Meridional Overturning Circulation,
- widespread changes in plant and animal phenology, and
- a decrease in ocean pH.
We know CO2 is the problem because the physical properties of CO2 and other atmospheric gases are known (e.g. Eunice Foote, John Tyndall). CO2 absorbs and reemits infrared radiation and therefore slows down heat from the Sun leaving the Earth. That understanding has been validated by practical outcomes (e.g. heat seeking missiles) and empirical observations (e.g. troposphere warming + stratospheric cooling; nights warming faster than days; winters warming faster than summers; faster warming in the northern high latitudes) that match predictions made by scientists in the 1980s and earlier (e.g. Svante Arrhenius, Syukuro Manabe, Jim Hansen). The current rapid warming cannot be accounted for by changes in Solar output or volcanos or any natural cycle. All possibilities have been extensively studied. Climate change deniers will show you misleading graphs that are labelled with present day where 1855 or 1950 should be. Don't fall for it. To get reliable information if science journals are too difficult for you to access try watching all the videos by Simon Clark and Potholer54. The lectures by Professors Richard Ally, Will Steffen and Stefan Ramsdorf are also easy to find.
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