SOS Forests

James D. Hays Awarded 2010 Milutin Milankovic Medal

The European Geosciences Union (EGU) has awarded Dr. James D. Hays, professor of Earth and environmental sciences at Columbia University [here], the 2010 Milutin Milankovic Medal [here].

The Milutin Milankovitch Medal is awarded to James D. Hays for his pioneering, fundamental and continuous work on the reconstruction of Cenozoic climates and for his Science 1976 seminal paper on the astronomical theory of palaeoclimates.

The Milutin Milankovitch Medal is reserved for scientists for their outstanding research in long term climatic changes and modeling. Originally established by European Geophysical Society in 1993, the Milankovitch Medal has been awarded to some of the world’s greatest paleoclimatologists, including Sir Nicholas J. Shackleton, John Imbrie, André L. Berger, George Kukla, and Pinxian Wang. (The EGU was established by the merger of the European Geophysical Society (EGS) and the European Union of Geosciences (EUG) on 7 September 2002.)

Dr. Hays was the lead author of J.D. Hays, J. Imbrie, and N.J. Shackelton, 1976. “Variations in the Earth’s Orbit: Pacemaker of the Ice Ages,” Science, Vol. 194, pp. 1121-32 [here], now recognized as one the greatest breakthrough papers of modern science. His research proved that the timing of major ice ages is controlled by variations in Earth’s orbit around the sun, known as Milankovitch Cycles.

In 1938 Serbian mathematician Milutin Milankovitch published “Astronomical Methods for Investigating Earth’s Historical Climate”. His theory was that variations in the Earth’s dance around the Sun caused fluctuations in the global climate of the Ice Ages, one such fluctuation being our current Holocene.

Milankovitch described and calculated three astronomical “wobbles” in the shape of the orbit of the Earth around the Sun, in the degree of tilt of the Earth’s axis, and in the direction (into the cosmos) that the axis points toward [here].

When Milankovitch presented his theory, it was received with skeptical curiosity. There was no way of dating fossils past 40,000 years or so, the limit of the carbon-14 method. That method was still in its earliest development, so it was impossible to test his theory.

By the 1970’s, however, researchers were extracting mud cores from ocean bottoms. The sediment cores were color-banded by different fossil planktons, each assemblage indicating ocean temperatures at the time of deposition. Some long cores dated all the way back to the Matuyama-Brunhes geomagnetic polarity reversal of 780,000 years ago. Using that marker, the bands in the cores could finally be dated. The types of fossil plankton in each band, and later their oxygen isotope ratios, allowed researchers to estimate global temperatures back deep into the Pleistocene.

The researchers came up with a graph of global temperature verses paleo-time. Lo and behold, the graph had fluctuations of 100,000 years, 41,000 years, and in faint signals, 23,000 and 19,000 years, matching Milankovitch’s predictions.

Milankovic’s theory turned out to be correct. The astronomically induced changes in insolation, the energy received by the Earth from the Sun, were indeed the primary cause for the waxing and waning of the Quaternary ice sheets.

The researchers (three in particular: John Imbrie, Nicholas Shackleton, and James Hays) had unlocked a fundamental key to paleoclimate and to present and future climate, too. It was a scientific discovery akin to the unraveling of the structure of DNA, or of continental drift and plate tectonics.

From the EGU website [here]

James D. Hays, Columbia University Ph.D. 1964, spent the late ‘60’s developing, in cooperation with Lamont colleagues, a chronostratigraphic framework for deep-sea sediments by connecting the land-dated record of Earth’s magnetic field reversals with marine stratigraphic datums. This established a near-global, Plio-Pleistocene chronology for deep-sea sediments and recognized and dated for the first time the 100K-year climate cycle.

By 1970 Hays realized that this marine chronostratigraphy, combined with the Imbrie-Kipp technique, which transforms marine microfossil assemblage data into estimates of past sea surface temperature, if applied to the extensive Lamont Core collection, could form the basis of a global study of Pleistocene climates. He asked John Imbrie to join the Lamont group and the CLIMAP project was born. Hays then asked Nick Shackelton to join CLIMAP and generate an oxygen isotope record of benthic and planktonic microfossils in a Pacific core.

From this work Shackelton and Opdyke showed that the marine oxygen isotopic record is dominated by changes in the isotopic composition of seawater, caused by the waxing and waning of the great ice sheets. This near synchronous isotopic signal was then used by CLIMAP to correlate calcareous records, further refine the dating of biostratigraphic datums and when correlated with siliceous indicators, extend time control to non-calcareous sediments. This allowed the construction of global maps of past sea surface temperature at specific times.

It was this careful pre-CLIMAP and early CLIMAP chronostratigraphic work that allowed Hays, Imbrie and Shackelton to show, through analyses in both the frequency and time domains, that Earth’s orbital variations control the timing of climate change on ice age time scales, proving the theory that Milankovitch contributed so much to developing.

Modern theories of anthropogenic global warming (AGW) have not been proved. Indeed, there is much debate regarding whether human activities can affect climate. But there is little debate that the astronomical changes in insolation have caused Ice Age glacial periods at regular intervals over the last 1.8 million years.

The last insolation peak in the Milankovitch Cycle was 10,000 years ago. Since then insolation has been steadily declining. The Earth is in a neo-glaciation era; the next Ice Age glaciation is on its way. The pattern is written in the heavens, in the music of the spheres, the movements of celestial bodies.

It has been 40 years since James Hays made his paradigm-shattering discoveries. It is high time he was honored for those. The Milankovitch Medal could not go to a more deserving recipient.