* The fifth IPCC report (2013) states that challenges persist in reconstructing temperatures before the time of the instrumental record due to limitations of spatial sampling, uncertainties in individual proxy records and challenges associated with the statistical methods used to calibrate and integrate multi-proxy information.
This report contains the following spaghetti graphs of proxy studies spliced with instrument-measured surface temperatures (the black lines): * In 2009, an unknown individual(s) released more than 1,000 emails (many dealing with proxy studies) from the University of East Anglia’s Climatic Research Unit (CRU).
The materials were authored by some of the world’s leading climate scientists and accompanied by the following note: We feel that climate science is too important to be kept under wraps.
We hereby release a random selection of correspondence, code, and documents.
Natural processes absorb the equivalent of all natural emissions plus about 57% of man-made emissions, leaving an additional 16 billion metric tons of CO2 in the atmosphere each year. † In permafrost regions, perennial snow accumulations trap air bubbles that leave records of past airborne CO2 concentrations,   and because regional CO2 concentrations vary by less than 10 parts per million over the Earth, these local records are globally representative.  * Instruments located on satellites can measure certain properties of oxygen that vary with temperature.The report states that some of the global warming since 1850 could be a recovery from the Little Ice Age rather than a direct result of human activities.So it is important to recognize that natural variations of climate are appreciable and will modulate any future changes induced by man.As of July 2015, no similar study has been conducted on a global basis. * From 1979–2014, the three temperate datasets posted above differed from one another by an annual average of 0.13ºF (0.07ºC).
The largest gap between any of the datasets in any year was 0.38ºF (0.21ºC), and the smallest gap was 0ºF/C: * To reconstruct global average temperatures in the era before instrumental measurements were made on a global scale, scientists use proxies that respond to changes in climate, such as the widths of tree rings and certain elements of the geological record, to estimate temperature variations in the past.  * The Intergovernmental Panel on Climate Change (IPCC) is a scientific body established in 1988 by the United Nations and World Meteorological Organization.
Locking onto local records, no matter how beautiful, can lead to serious errors. found that since 1979, Antarctica has been growing colder in the summer and fall seasons but warmer in the winter and spring seasons, except for 50% of East Antarctica, which has also been cooling in the winter. published a story by Andrew Revkin entitled: “Scientists Report Severe Retreat of Arctic Ice.” The last paragraph of the story reads: “Sea ice around Antarctica has seen unusual winter expansions recently, and this week is near a record high.” * In 2000, James J.