Throughout Earth’s history climate instability has been the norm, especially since the launch of the ice age cycle 2.58 million years ago. With the exception of the past 9,500 years, the global mean temperature has jumped up and down by 10–12°C (18–22°F) on timescales of several millennia or less (see figures 1 and 2). Those jumps mean that any humans alive previous to 9,500 years ago would not have been able to sustain long-term agriculture leading to advanced civilization. Scientists continue to discover evidence for Earth’s recent climate stability and how it has allowed for human flourishing.

 

Figure 1: Global Mean Temperature Variations 80,000–10,000 Years Ago
Data taken from NGRIP (blue) and GRIP (purple) ice core records. Diagram credit: Hugh Ross

 

Figure 2: Global Mean Temperature Variations 2.00–0.01 Million Years Ago
Data is taken from C. W. Snyder, Nature 538 (2016): 226. Diagram credit: Hugh Ross

During the past 9,500 years, Earth’s global mean temperature has been remarkably stable. Scientists use what is known as proxy data to reconstruct past climate conditions. These are multiple independent preserved physical characteristics that substitute as direct measurements. Data from temperature records based on ice cores from sites in central Antarctica and central and northern Greenland has shown that the global mean temperature varied by no more than ±1.25°C.1 As I reported in Weathering Climate Change, statistician Grant Foster and petrophysicist Andy May used the 28 most reliable temperature proxies from a database of 73 temperature proxy records plus an Indonesian ocean proxy to establish that the global mean temperature, in fact, has varied by no more than ±0.65°C over the past 9,500 years.2

New Temperature Reconstruction Record
Now, a team of seven geologists, climatologists, and atmospheric physicists led by Matthew Osman used newly developed techniques for incorporating temperature proxy data into the latest global climate models to produce a high-resolution reconstruction of the global mean temperature over the past 24,000 years.3 As anyone who has backpacked for extended times at high altitude knows, temperature variations are strongly correlated with elevation above sea level. Both air pressure and atmospheric water content decline with elevation. Both act to dampen temperature variations.

To eliminate elevation-driven temperature variations, Osman’s team used only marine temperature proxies. They also amassed the largest ever database of marine temperature proxy measurements. For the first time by any research team, Osman’s team created a detailed record of the global mean surface temperature from the last glacial maximum to the present. Their temperature record is shown in figure 3.

 


Figure 3: Global Mean Surface Temperature over the Past 24,000 Years
The y-axis zero point in both diagrams is the average global mean surface temperature from 1000–1850 AD. Adapted from figure 2 of Osman et al., Nature 599 (2021): 241 and from figure 1 of Marcott and Shakun, Nature 599 (2021): 208.

Temperature Record Revelations and Implications
The temperature record derived by Osman’s team reveals that Earth’s climate over the past 7,000 years has been more stable than what any previous research team has concluded. Over that time period, the global mean surface temperature has not varied by more than ±0.15°C. Osman and his colleagues discovered that Earth’s climate is four times more stable over the past 7,000 years than what Foster and May had derived.

The extreme climate stability over the past 7,000 years is a major factor explaining the acceleration of human civilization and technology. Thanks to this extreme climate stability, beginning about 7,000 years ago humans were able to greatly expand their agricultural productivity. This expanded productivity allowed a significant fraction of the human labor force to engage in science, engineering, technology, writing, recreation, and the arts. The ongoing extreme climate stability enabled progressively larger fractions of the human labor force to focus on those pursuits. Such transfers of labor largely explain the phenomenal technological advances achieved over the past several millennia and the rapid growth in human population.

The inset diagram in figure 3 shows the global mean surface temperature over the past 1,000 years. It reveals that from 1000–1900 AD the global climate was astoundingly stable. Global mean surface temperature variations were less than 0.1°C. The inset diagram also removes any doubt about the past century’s global warming. Since 1950, the global mean surface temperature has steadily risen to a level that is now more than ten times greater than the average temperature variations observed from 1000–1900 AD.

In a published review of the Osman team’s discoveries, two paleoclimatogists, Shaun Marcott and Jeremy Shakun, suggested a research effort to deliver even more comprehensive and reliable global mean temperature records.4 Marcott and Shakun noted that nearly all of Osman’s team’s marine temperature proxies came from the Atlantic and Arctic Oceans and from offshore regions of the Pacific, Indian, and Southern Oceans. They recommended gaining temperature proxy measurements from the central Pacific, Indian, and Southern Oceans. They also proposed using terrestrial temperature proxies where the elevation effects can be calibrated out. Thus, future research may soon reveal even more evidence for Earth’s uncanny, recent climate stability.

In Revelation 7:9 the apostle John saw a vision of the redeemed host of humanity. He saw “a great multitude that no one could count from every nation, tribe, people, and language.” As I explain in some detail in Weathering Climate Change,5 God meticulously designed Earth and its climate system to make possible—within a short time period—the redemption of a great multitude, perhaps billions of human beings from their sin. Thanks to the research achievements by Osman’s team, we have yet more evidence for God’s works of creation and redemption.

Check out more from Reasons to Believe @Reasons.org

Endnotes

  1. Edward J. Brook and Christo Buizert, “Antarctic and Global Climate History Viewed from Ice Cores,” Nature 558 (June 14, 2018): 200–208, doi:10.1038/s41586-018-0172-5; J. Jouzel et al., “Orbital and Millennial Antarctic Climate Variability over the Past 800,000 Years,” Science 317, no. 5839 (August 10, 2007): 793–796, doi:10.1126/science.1141038; P. M. Grootes et al., “Comparison of Oxygen Isotope Records from the GISP2 and GRIP Greenland Ice Cores,” Nature 366 (December 9, 1993): 552–554, doi:10.1038/366552a0.
  2. Hugh Ross, Weathering Climate Change: A Fresh Approach (Covina, CA: RTB Press, 2020), 59–61.
  3. Matthew B. Osman et al., “Globally Resolved Surface Temperatures Since the Last Glacial Maximum,” Nature 599 (November 11, 2021): 239–244, doi:10;.1038/s41586-021-03984-4.
  4. Shaun A. Marcott and Jeremy D. Shakun, “Global Temperature Changes Mapped across the Past 24,000 Years,” Nature 599 (November 10, 2021): 208–209, doi:10.1038/d41586-021-03011-6.
  5. Ross, Weathering Climate Change, 57–224.

About The Author

Dr. Hugh Ross

Reasons to Believe emerged from my passion to research, develop, and proclaim the most powerful new reasons to believe in Christ as Creator, Lord, and Savior and to use those new reasons to reach people for Christ. I also am eager to equip Christians to engage, rather than withdraw from or attack, educated non-Christians. One of the approaches I’ve developed, with the help of my RTB colleagues, is a biblical creation model that is testable, falsifiable, and predictive. I enjoy constructively integrating all 66 books of the Bible with all the science disciplines as a way to discover and apply deeper truths. 1 Peter 3:15–16 sets my ministry goal, "Always be prepared to give an answer to everyone who asks you to give the reason for the hope that you have. But do this with gentleness and respect, keeping a clear conscience." Hugh Ross launched his career at age seven when he went to the library to find out why stars are hot. Physics and astronomy captured his curiosity and never let go. At age seventeen he became the youngest person ever to serve as director of observations for Vancouver's Royal Astronomical Society. With the help of a provincial scholarship and a National Research Council (NRC) of Canada fellowship, he completed his undergraduate degree in physics (University of British Columbia) and graduate degrees in astronomy (University of Toronto). The NRC also sent him to the United States for postdoctoral studies. At Caltech he researched quasi-stellar objects, or "quasars," some of the most distant and ancient objects in the universe. Not all of Hugh's discoveries involved astrophysics. Prompted by curiosity, he studied the world’s religions and "holy books" and found only one book that proved scientifically and historically accurate: the Bible. Hugh started at religious "ground zero" and through scientific and historical reality-testing became convinced that the Bible is truly the Word of God! When he went on to describe for others his journey to faith in Jesus Christ, he was surprised to discover how many people believed or disbelieved without checking the evidence. Hugh's unshakable confidence that God's revelations in Scripture and nature do not, will not, and cannot contradict became his unique message. Wholeheartedly encouraged by family and friends, communicating that message as broadly and clearly as possible became his mission. Thus, in 1986, he founded science-faith think tank Reasons to Believe (RTB). He and his colleagues at RTB keep tabs on the frontiers of research to share with scientists and nonscientists alike the thrilling news of what's being discovered and how it connects with biblical theology. In this realm, he has written many books, including: The Fingerprint of God, The Creator and the Cosmos, Beyond the Cosmos, A Matter of Days, Creation as Science, Why the Universe Is the Way It Is, and More Than a Theory. Between writing books and articles, recording podcasts, and taking interviews, Hugh travels the world challenging students and faculty, churches and professional groups, to consider what they believe and why. He presents a persuasive case for Christianity without applying pressure. Because he treats people's questions and comments with respect, he is in great demand as a speaker and as a talk-radio and television guest. Having grown up amid the splendor of Canada's mountains, wildlife, and waterways, Hugh loves the outdoors. Hiking, trail running, and photography are among his favorite recreational pursuits - in addition to stargazing. Hugh lives in Southern California with his wife, Kathy, and two sons.



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