Warm/cool epochs over past 2000 years were regional until 20th century warming

Percentages of earth’s surface experiencing abnormal warm (red shading) and cold (blue shading) temperatures. Shading intensity indicates the magnitude of warmth and cold. a, Annual data. b, 51-year averaged data.

Over the last 2000 years Europe has experienced centennial scale cool and warm epochs including the Little Ice Age (1300 and 1850 CE), the Mediaeval Warm Period (800–1200 CE), the Dark Ages Cold Period (400–800 CE) and the Roman Warm Period (250 BCE to 400 CE). A recent analysis has generated spatial temporal temperature reconstructions covering the entire globe for the past 2,000 years. The research found no evidence that preindustrial cold and warm periods recorded in Europe and elsewhere extended over the entire globe. By contrast, the warmest period of the past 2,000 years occurred during the twentieth century for more than 98 per cent of the globe.

No evidence for globally coherent warm and cold periods over the preindustrial Common Era, Raphael Neukom, Nathan Steiger, Juan José Gómez-Navarro, Jianghao Wang & Johannes P. Werner, Nature, volume 571, pages 550–554 (2019).

From Our Files

Evidence for sea level rise of 17 meters in less than 350 years

During the last deglaciation there was several episodes of rapid and substantial sea level rise. A recent study has found that during one of these, sea level rose by about 17 meters over a period that does not exceed 350 years, but could be as low as a century.

Comparison of temperature and CO2 from Vostok ice cores

Close correlation of temperature and greenhouse gas concentrations over the last four glacial-interglacial cycles

In January 1998, a collaborative ice-drilling project between Russia, the United States, and France at the Russian Vostok revealed that over the past four cycles atmospheric concentration of carbon dioxide correlates closely with Antarctic air-temperature. The analysis also suggests a sequence of events that is characteristic of every termination; warming by orbital forcing, then increasing greenhouse gases, and followed by ice sheet melting and reduced albedo.

Global warming “hiatus” not supported by new analysis

In this new study an analysis of new global ocean and land temperature data with corrections to older shipboard measurements reveals that the temperature trend over the period 2000-2014 does not differ from the temperature trend over the period 1950-1999. It is concluded that the “hiatus” reported in IPCC AR5 is most likely an artifact of older measurement techniques.

Thermokarst distribution in northern circumpolar region

Geospatial analysis reveals 20% of northern permafrost region susceptible to abrupt permafrost thawing

Northern permafrost soils represent the largest terrestrial organic carbon pool on Earth. A study the northern circumpolar permafrost zones reveals that landscapes susceptible to abrupt thawing with the release of significant quantities of carbon dioxide and methane cover 20% of the northern permafrost region and store up to half its soil organic carbon.