Post falsely claims Earth warmer than present for 83% of past 10,000 years

CLAIM

The Earth has been warmer than the modern era for 83 percent of the past 10,000 years. 

FACT

The annual global temperature at the present is the warmest in the past 10,000 years. 

WHAT THEY SAY

Climate deniers are claiming that the earth has been mostly warmer in the past 10,000 years than the present times and hence we have nothing to worry about as there is nothing called ‘global warming’ happening at the present. This claim has been often used to refute climate change. A Twitter post has recently gone viral with such a claim that we should actually ‘fear cold’ and not ‘warming’.

Here is the tweet:

The Earth has been warmer than the modern era for 83 per cent of the past 10,000 years. On a longer scale, the interglacial period (known as the Holocene) is the ONLY time of global warming in 100,000 years. These are facts from climate studies by scientists. We should fear cold. pic.twitter.com/scljb2N81C

— Peter Clack (@PeterDClack) August 25, 2022

WHAT WE FOUND

Scientists have recently concluded that the Earth at present is hotter than it’s been in at least 12,000 years based on the most recent annual global temperature data. According to a Rutgers-led study in the journal Nature, the annual global temperature at the present is the warmest in the past 10,000 years. 

“Our reconstruction shows that the first half of the Holocene was colder than in industrial times due to the cooling effects of remnant ice sheets from the previous glacial period – contrary to previous reconstructions of global temperatures,” said lead author Samantha Bova, a postdoctoral researcher associate in the lab of co-author Yair Rosenthal, a Distinguished Professor in the Department of Marine and Coastal Sciences and Department of Earth and Planetary Sciences at Rutgers University–New Brunswick. “The late Holocene warming was indeed caused by the increase in greenhouse gases, as predicted by climate models, and that eliminates any doubts about the key role of carbon dioxide in global warming.

The study says, “that previous global reconstructions of temperature in the Holocene and the last interglacial period reflect the evolution of seasonal, rather than annual, temperatures and we develop a method of transforming them to mean annual temperatures…Furthermore, our reconstructions demonstrate that the modern global temperature has exceeded annual levels over the past 12,000 years…”

Holocene temperature conundrum 

Holocene is an epoch encompassing the last 11,700 years of Earth’s history. The Holocene temperature conundrum is a debate about the changes in temperature during the Holocene. Earlier it was suggested by some researchers that the average temperature during the Holocene period peaked between 6,000 and 10,000 years ago and the planet cooled after this. Scientists have now found that global temperatures have actually risen over the past 12,000 years and factors like rising greenhouse gas emissions and climate change have contributed to it. 

Present warming is ‘unprecedented’ in the last 24,000 years

Another study by a team of scientists from the University of Arizona concluded that global temperature reconstruction over the last 24,000 years shows that the present warming is ‘unprecedented’. For the study published in Nature, the team created maps of global temperatures for each 200-year interval since the last ice age.

Global average surface temperature since the last ice age 24,000 years ago. Time is stretched for the past 1000 years to visualize recent changes. Credit: Matthew Osman, Lead Author of the Study

The study says, “In contrast with previous proxy-based reconstructions, our results show that global mean temperature has slightly but steadily warmed, by ~0.5 °C, since the early Holocene (around 9 thousand years ago). When compared with recent temperature changes, our reanalysis indicates that both the rate and magnitude of modern warming are unusual relative to the changes of the past 24 thousand years.”

“This reconstruction suggests that current temperatures are unprecedented in 24,000 years, and also suggests that the speed of human-caused global warming is faster than anything we’ve seen in that same time,” said Jessica Tierney, a UArizona geosciences associate professor and co-author of the study.

More studies confirm the same

According to a 2020 study, the warmest 200-year period of the Holocene before industrialization took place around 6500 years ago when global surface temperatures were about 0.7 degrees Celsius warmer than in the 19th century. However, later during the period from 2011 to 2019, temperatures averaged 1 degree Celsius higher than in the 19th century. This ultimately brings recent temperatures above that of the entire Holocene.

Another 2013 study reconstructed global mean surface temperatures to conclude that present temperatures are “higher than those during 90 percent of the entire Holocene.”

A 2022 technical note by Prof Kaufman concludes, “human-caused global warming is now exceeding the warmest multi-century period of the Holocene and thereby the envelope of temperatures under which agriculturally based society has flourished”.

The IPCC Report

According to an assessment report from the UN’s Intergovernmental Panel on Climate Change (IPCC), ‘Earth’s global surface temperature has increased by around 1.1 °C compared with the average from 1850–1900—a level that hasn’t been witnessed since before the last ice age, some 125,000 years ago.’

“Temperatures during the most recent decade (2011–2020) exceed those of the most recent multi-century warm period, around 6500 years ago [0.2°C to 1°C relative to 1850–1900]. Prior to that, the next most recent warm period was about 125,000 years ago, when the multi-century temperature [0.5°C to 1.5°C relative to 1850–1900] overlaps the observations of the most recent decade,” the IPCC report said.