Search results
Results from the WOW.Com Content Network
Reconstruction of the past 5 million years of climate history, based on oxygen isotope fractionation in deep sea sediment cores (serving as a proxy for the total global mass of glacial ice sheets), fitted to a model of orbital forcing (Lisiecki and Raymo 2005) [2] and to the temperature scale derived from Vostok ice cores following Petit et al. (1999).
Some temperature information is available through geologic evidence, going back millions of years. More recently, information from ice cores covers the period from 800,000 years ago until now. Tree rings and measurements from ice cores can give evidence about the global temperature from 1,000-2,000 years before the present until now. [9]
According to IPCC Sixth Assessment Report, in the last 170 years, humans have caused the global temperature to increase to the highest level in the last 2,000 years. The current multi-century period is the warmest in the past 100,000 years. [3] The temperature in the years 2011-2020 was 1.09 °C higher than in 1859–1890.
The IPCC Fifth Assessment Report (AR5 WG1) of 2013 examined temperature variations during the last two millennia, and cited the following reconstructions in support of its conclusion that for average annual Northern Hemisphere temperatures, "the period 1983–2012 was very likely the warmest 30-year period of the last 800 years (high confidence ...
500 million years of climate change Ice core data for the past 400,000 years, with the present at right. Note length of glacial cycles averages ~100,000 years. Blue curve is temperature, green curve is CO 2, and red curve is windblown glacial dust (loess). Scale: Millions of years before present, earlier dates approximate.
The blue numbers are the amount of precipitation in either millimeters (liters per square meter) or inches. The red numbers are the average daily high and low temperatures for each month, and the red bars represent the average daily temperature span for each month. The thin gray line is 0 °C or 32 °F, the point of freezing, for orientation.
The dataset should be stored at Wikimedia commons, in the Data namespace, as a tabular data (.tab) file. Currently, the file format should be JSON, representing a three column table, where the first column is the three-letter ISO country code, the second is the year and the third is the value.
A substantial achievement of the last 30 years of climate science has been the production of a large set of actual measurements of temperature history (from physical proxies), replacing much of the earlier geological induction (i.e. informed guesses). The graph shows selected proxy temperature estimates, which are detailed below.