Core aspects of climate models are sound — the proof’s in the plankton

The study, published this week in Proceedings of the National Academy of Sciences, and led by Yale University, offered a novel way of examining plankton shells to better gauge the accuracy of climate models and the Earth’s temperature gradients.

As plankton shells carry an imprint of the seawater conditions at the time they were formed, researchers were able to use them to track the evolution of Earth’s climate system by calculating the temperature difference between oceans in higher and lower latitudes.

Co-author Dr Charlotte O’Brien (UCL Geography) helped design the research study and compiled planktic and benthic oxygen isotope data which she then helped analyse.

Dr O’Brien said: “The ability to combine robust, high-resolution temperature records covering 95 million years of Earth’s history with the results of up-to-date climate models is key for understanding the numerous responses of the global climate system to past and future climate conditions.”

The global climate system can be described as a giant ‘heat engine’ that attempts to redistribute the sun’s heat from lower latitudes near the Equator to higher latitudes near the North and South poles.

The latitudinal temperature gradient (LTG) — or the difference in sea-surface temperatures between low and high latitudes — is an important measure of how well Earth’s heat engine is working. 

It is also an important factor in gauging how well climate models work to reconstruct the climate of Earth’s past and predict the climate of the future.

Previously, scientists struggled to nail down reliable surface temperature data to test models, due to there being relatively few geological or biochemical proxies for past temperatures, and disagreements between those proxy temperature estimates and climate models.

Through the new study, the team used a combination of fossils from a single-celled organism called foraminifera to create a continuous, 95-million-year record of LTGs. 

First author, doctoral student Daniel Gaskell (Yale University), said: “There are so many interlocking parts to climate science. What we’re doing here is trying to improve the foundations by testing some of the underlying dynamics of climate models that are used to predict future climate.”

Co-author Assistant Professor Pincelli Hull (Yale University), added: “Our results show that the behavior of this temperature difference has been remarkably consistent over time. When the climate warms, the temperature gradient goes down in almost a straight line, regardless of continental configuration or global ice volume.” 

Gaskell said the models ‘work better than we thought they might’, adding: “It means we understand this aspect of the climate system pretty well and it implies that some of the more extreme scenarios are not as likely to happen.”

Other partners involved in the study were Purdue University, the University of Michigan and the University of Southampton.

Links

Full paper in PNAS
Dr Charlotte O’Brien’s academic profile 
UCL Geography 
UCL Faculty of Social & Historical Sciences

Source

Yale press release

Image

A living foraminifera in culture, surrounded by a halo of symbiotic algae along its spines (in golden dots). Fluffy material in the background is an Artemia nauplius that the foraminifera is eating. Credit: Daniel Gaskell.

Media contact

Sophie Vinter

Tel: +44 (0)20 3108 7787

Email: s.vinter [at] ucl.ac.uk