Main sources: Climate change: evidence from the geological record A statement from the Geological Society of London November 2010 An addendum to the Statement on Climate Change: Evidence from the Geological Record December 2013 The addendum is arranged such that some sections are unchanged from the original.
The lead author of the statements is Dr Colin Summerhayes who has participated as guest blogger and commenter on Energy Matters before.In some cases these changes are gradual and in others abrupt. Atmospheric CO2 is currently just below 400 parts per million (ppm) on average. How can we see warming while sunspots are in decline? First, sunspots may be in decline and still solar activity be above average and produce warming, and second, solar activity is not the only factor affecting temperature, so the final effect depends on what all the factors are doing. Solar activity is below average since 2006, and we haven’t seen much warming outside a big El Niño event. A new method of measuring ocean temperature changes based on determination of Xenon and Krypton in ice bubbles has been recently published by Bereiter et al., 2018.Evidence for climate change is preserved in a wide range of geological settings, including marine and lake sediments, ice sheets, fossil corals, stalagmites and fossil tree rings. It last reached similar levels during the Pliocene (5.3-2.6 million years ago). https://phys.org/news/2018-01Their estimate is that in the past 50 years the oceans have warmed by 0.1° C. I have newly activated a “Comment Image” plugin for the blog that will hopefully enable commenters to post images in their comments. [Unfortunately “comment images” live in the background do not seem to be working. Studies of the Last Glacial Maximum (about 20,000 years ago) suggest that the climate sensitivity, based on rapidly acting factors like snow melt, ice melt and the behaviour of clouds and water vapour, lies in the range 1.5°C to 6.4°C.If anyone is experiencing difficulty posting long comments then contact me by email.] Those who have not commented on this blog before will find the first comment goes to a moderation queue. and Bischoff, S., 2000, Carbon dioxide emissions from fossil fuel consumption and cement manufacture, 1751-1991, and an estimate of their isotopic composition and latitudinal distribution. Recent research has given rise to the concept of ‘Earth System sensitivity’, which also takes account of slow acting factors like the decay of large ice sheets and the operation of the full carbon cycle, to estimate the full sensitivity of the Earth System to a doubling of CO2.