Temperature record of the past 1000 years

People measure modern temperature records using instruments. Such records were rare until the middle 19th century. The temperature record of the past 1000 years or more is found by using data from what are called "climate proxy" records. 

Proxies can be anything which relates to climate. Historical documents such as autobiographies often talk about the weather in their time, and we do have some such documents from 2000 years ago. There are also tree rings and other methods which go back about 20,000 years. Further back still, there is evidence from geology, the record of the rocks. However, this article is about the last 1000 years.Jones P.D; Briffa K.R; Barnett T.P. & Tett S.F.B. 1998, High-resolution palaeoclimatic records for the last millennium: interpretation, integration and comparison with General Circulation Model control-run temperatures, The Holocene, 8 (4): 455–471. Mann M.E; Bradley R.S. & Hughes M.K. 1999. Northern hemisphere temperatures during the past millennium: inferences, uncertainties, and limitations. Geophysical Research Letters 26 (6): 759–762.  

We are fairly sure there was a warm period about 1000 years ago, and a cold period about the 17th century. Even in the 19th century people skated on the Thames in wintertime.

Although people today talk about climate change as if it were entirely man-made, this is not the complete picture. It is quite certain that climate has always been changing on Earth. Man-made changes are on top of changes which occur naturally. The Milankovich cycle is an important factor in these changes, and there are also changes in the heat put out by the Sun.Powell, Alvin 2003. Sun's warming is global: CfA lecture links solar activity and climate change. Harvard University Gazette. 

 Related pages 
Orbital forcing
Little Ice Age
Global warming

 References 

Category:Climate change

de:Hockeyschläger-Diagramm