Read what John Houghton, the former head of the UK Meteorological Office, had to say (2003/07/29)
And (this should scare you, if nothing else does) read what the US Department of Defense thought about global warming (Observer 2004/02/22)
and this is what the simple average global surface temperature record showed back then:
Now retrievable only because of preservation by the Internet Archive (click here)
The same underlying data and a straightforward explanation of the Jan 2011 Hadley Center/UK Met Office global temperature record
Or the updated record to 2010 with explanation (Climate Research Unit at Univ. of East Anglia) similarly preserved by the IA (click here)
The CRU record updated to 2024: https://crudata.uea.ac.uk/cru/info/warming/infosheet1.pdf source of the diagram below left:
The diagram on the right, the US NOAA record to 2025, showing the same pattern, the result of the failure of our society to respond to repeated warnings of the consequences of unrestrained emission to the atmosphere of greenhouse gases, mainly carbon dioxide and methane.
The geological ("proxy") records
Because adequate global temperature records from thermometers are not available before 1850, all information on global climate before this time comes from geological ("proxy") records, including ice cores, coral and tree growth ring records, and stratified sedimentary deposits. Geological scientists have provided evidence of fundamental and primary importance both in setting the longer-term context of warming given by the thermometer temperature record, and of the potential consequences, from previous geological events of major climate change due to carbon release to the atmosphere. The ice core record The millenial proxy temperature record Paleocene-Eocene thermal maximum event