Approximately 56 million years ago, our planet was in the Paleocene-Eocene Thermal Maximum as global mean temperatures were estimated as high as 73 degrees Fahrenheit, over 15 degrees above current levels. Actually, the real unprecedented warming and extreme climate change happened well before the industrial age, as the below paleo & ancient temperature proxy reconstruction charts reveal (for the most part, charts are in ' paleo -age' chronological order).

One period, which was probably the warmest, was during the Neoproterozic around 600 to 800 million years ago. The Earth eventually cooled enough for its crust to form. The late 20th and early 21st century global warming - is it really "unprecedented"? (Source: NASA/GISS). The year 2016 ranks as the warmest on record. At the bottom of this page, there is a link to download a PDF of this graph – which may be used on the condition that it is presented as is, WITHOUT MODIFICATION. Black border charts are 'C3' created charts/graphs/images. This graph illustrates the change in global surface temperature relative to 1951-1980 average temperatures. The above chart shows the relative changes in global average temperature, CO2 (carbon dioxide), and sea level over the last 420,000 years. Until 3.8 billion years ago it was a completely inhospitable environment with the surface being mainly molten lava. Very Early Earth’s History (4.5 billion – 3.8 billion years ago) The Earth was formed roughly 4.5 billion years ago. In 1950, according to NASA's Goddard Institute for Space … Nineteen of the 20 warmest years all have occurred since 2001, with the exception of 1998. The blue line traces the temperature differences (in degrees Celsius) over the last 420,000 years compared to the present time, defined as the year 1950. Mean global temperatures then stabilized at roughly 14.0°C (57.2 °F) until the 1980s. During the 1920s to 1940s, temperatures climbed about 0.1 °C (0.18 °F) each decade. The surface temperature of the Earth tends to go up rapidly and then settle down again in cycles of roughly 100,000 years as shown above in this UN Environment Programme (UNEP) chart. The average global annual temperature hovered around 13.7 °C (56.7 °F) from the 1880s through the 1910s.