Earth's Temperature Variation in the past 1,100 years

Surface Temperatures over the last 1,100 Years

Reconstructions of (Northern Hemisphere average or global average) surface temperature variations from six research teams (in different color shades) along with the instrumental record of global average surface temperature (in black). Each curve illustrates a somewhat different history of temperature changes, with a range of uncertainties that tend to increase backward in time (as indicated by the shading). Reference: NRC, 2006. (Figure reprinted with permission from Surface Temperature Reconstructions© (2006) by the National Academy of Sciences, Courtesy of the National Academies Press 22 18, Washington, D.C.).

Reproduced from EPA Climate Change Website.

The Long-Term Stability of Earth's Climate − 400,000 years

• The atmospheric concentration of CO2 measured from Antarctic ice core data implies that Earth's climate has been pretty stable over the past 400,000 years • It also shows a rapid increase of about 30% in the past few centuries… – 270 ppm (parts per million) to 370 ppm

Changes in Carbon Dioxide and Temperature in the last 400,000 years Fluctuations in temperature (blue) and in the atmospheric concentration of carbon dioxide (red) over the past 400,000 years as inferred from Antarctic ice-core records . The vertical red bar is the increase in atmospheric carbon dioxide levels over the past two centuries and before 2006. From A. V. Fedorov et al. Science 312, 14s85 (2006) 17. 18. Reproduced from EPA Climate Change Website.

How do we measure atmospheric CO₂ concentration in the past?

• Precise measurements of atmospheric CO₂ concentration is available only in the last few decades…
• Information about atmospheric CO₂ concentration and temperatures in the past can be inferred by several different methods, such as

– Tree-ring

– Deep ocean sediment

– Ice core records – Coral

– … s

Link to NOAA Paleoclimatology Website

Paleoclimatology is the study of climate prior to the widespread availability of records of temperature, precipitation and other instrumental data.