No evidence of polar warming during penultimate interglacial

Jul 18, 2012

The Atlantic Meridional Overturning Circulation (AMOC), driven by temperature and salinity gradients, is an important component of the climate system; it transfers an enormous amount of heat via ocean currents and atmospheric circulation to high northern latitudes and hence has bearing on climate in the region.

Freshening of the surface ocean could weaken the AMOC. But during warm interglacial periods the effect of a fresh surface ocean on the AMOC may be muted. In fact, climate models predict that heat transfer from the North Atlantic to the Arctic may increase over the 21st century. A series of interconnected processes in the North Atlantic, known as polar amplification, could cause the Arctic to warm up faster compared to the rest of the world. It could even lead to ice-free conditions in the Arctic.

Previous paleoclimatic reconstructions indicate that the sub-Arctic may have been warmer by about 5 degrees Celcius (9 degrees Fahrenheit) with little summer sea ice cover during the Eemian, the penultimate interglacial centered around 125,000 years ago. Climate models favoring polar amplification use the Eemian as an analog of the present. In a new study, Bauch et al. compare reconstructed temperatures and water masses from two that record the flow of meltwater in the subpolar and polar North Atlantic over the past 135,000 years. They do not find evidence of extreme warmth in the sub-Arctic during the Eemian interglacial period.

In fact, the Arctic may have been colder during the Eemian, with lower heat transfer from the North Atlantic. On the basis of their finding, the authors suggest that previous records may reflect other phenomena and caution against the use of the Eemian as an analog of the present. Their finding also challenges that predict extreme warmth and ice-free conditions in the Arctic in response to greenhouse gas warming in the 21st century.

Explore further: NASA image: Volcanoes in Guatemala

More information: Contrasting ocean changes between the subpolar and polar North Atlantic during the past 135 ka, Geophysical Research Letters, doi:10.1029/2012GL051800, 2012

add to favorites email to friend print save as pdf

Related Stories

Arctic Ocean waters warm suddenly

Oct 07, 2005

Water flowing from the North Atlantic Ocean into the Arctic provides evidence that the Arctic Ocean is warming, according to U.S. and European researchers.

Declining sea ice to lead to cloudier Arctic: study

Mar 31, 2012

Arctic sea ice has been declining over the past several decades as global climate has warmed. In fact, sea ice has declined more quickly than many models predicted, indicating that climate models may not be correctly representing ...

Bering Strait may be global temperature stabilizer

Apr 10, 2012

(Phys.org) -- A diverse group of climate researchers has found after running computer simulations that the strait that separates North America and Russia might be serving as a global temperature stabilizer. ...

Recommended for you

How productive are the ore factories in the deep sea?

2 hours ago

About ten years after the first moon landing, scientists on earth made a discovery that proved that our home planet still holds a lot of surprises in store for us. Looking through the portholes of the submersible ...

NASA image: Volcanoes in Guatemala

7 hours ago

This photo of volcanoes in Guatemala was taken from NASA's C-20A aircraft during a four-week Earth science radar imaging mission deployment over Central and South America. The conical volcano in the center ...

NASA sees last vestiges of Tropical Depression Jack

Apr 23, 2014

Tropical Cyclone Jack had weakened to a tropical depression when NASA and JAXA's Tropical Rainfall Measuring Mission (TRMM) satellite passed above on April 22, 2014 at 1120 UTC/7:20 a.m. EDT.

User comments : 0

More news stories

Untangling Brazil's controversial new forest code

Approved in 2012, Brazil's new Forest Code has few admirers. Agricultural interests argue that it threatens the livelihoods of farmers. Environmentalists counter that it imperils millions of hectares of forest, ...

How productive are the ore factories in the deep sea?

About ten years after the first moon landing, scientists on earth made a discovery that proved that our home planet still holds a lot of surprises in store for us. Looking through the portholes of the submersible ...

Genetic code of the deadly tsetse fly unraveled

Mining the genome of the disease-transmitting tsetse fly, researchers have revealed the genetic adaptions that allow it to have such unique biology and transmit disease to both humans and animals.

Ocean microbes display remarkable genetic diversity

The smallest, most abundant marine microbe, Prochlorococcus, is a photosynthetic bacteria species essential to the marine ecosystem. An estimated billion billion billion of the single-cell creatures live i ...