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40,001 BCE
Ice age
The Pleistocene Epoch is typically defined as the time period that began about 2.6 million years ago and lasted until about 11,700 years ago. -
ocean change
Annual Climate Report the combined land and ocean temperature has increased at an average rate of 0.13 degrees Fahrenheit ( 0.08 degrees Celsius) per decade since 1880 -
Green house gases
Because of global warming due to increasing greenhouse gases, the maps from the late 1800s and the early 1900s are dominated by shades of blue, indicating temperatures were up to 3°C (5.4°F) cooler than the twentieth-century average. -
Hotter
Mean global temperatures then stabilized at roughly 14.0°C (57.2 °F) until the 1980s. The world has mainly grown hotter since 1980, at a rate of nearly 0.2 °C (0.36 °F) per decade -
Drought
The world endured a warm year as President Roosevelt wrangled with crippling drought during the first year of his second term. Scientists now say global temperatures that year, in 1937, were record-breaking for the time. The heat record fell again two years later. -
Rise in global temperature
At least three-quarters of the rise in average global temperature since the 1950s is due to human activity, -
Larger warming
By the 1970s, scientists were becoming increasingly aware that estimates of global temperatures showed cooling since 1945, as well as the possibility of large scale warming due to emissions of greenhouse gases. -
Pollution
climate change became a national issue by the 1980s. Aerosol pollution had decreased in many areas due to environmental legislation and changes in fuel use, and it became clear that the cooling effect from aerosols was not going to increase substantially while carbon dioxide levels were progressively increasing. -
Climate change increases
By the 1990s, as a result of improving fidelity of computer models and observational work confirming the Milankovitch theory of the ice ages, a consensus position formed: greenhouse gases were deeply involved in most climate changes and human-caused emissions were bringing discernible global warming. -
Warmer than usual
The decade 2000-2009 was the warmest since modern recordkeeping began, and 2009 was tied for the second warmest single year, a new analysis of global surface temperature shows -
carbon dioxide
Earth's global average surface temperature in 2020 tied with 2016 as the warmest year on record, according to an analysis by NASA. As atmospheric carbon dioxide levels increase, 86% of land ecosystems globally are becoming less efficient at absorbing increasing levels of the greenhouse gas.