New Southern Hemisphere climate data provides clearer global picture

Mar 31, 2014 by Rebecca Scott
Field work in the Indian Ocean - This coral off the Broome coast, Western Australia, stores information about past climate. Credit: Eric Matson Australian Institute of Marine Science

A new international study has published the most comprehensive Southern Hemisphere reconstruction of past climate records, revealing a clearer climate picture of the globe's temperature history than ever before.

The study revealed that over the past 1000 years temperature variations have differed greatly between the two hemispheres, yet it confirmed they shared the one warm period after the 1970s.

Led by the Oeschger Centre at the University of Bern, the Swiss Federal Research Institute WSL and the University of Melbourne, the study Inter-hemispheric temperature variability over the past millennium was published today in the journal Nature Climate Change.

Co-author Dr Joelle Gergis, ARC Fellow from the University of Melbourne, said the study finally put the Southern Hemisphere on the map in terms of recording past variations over the past 1000 years.

"Our findings showed there were considerable decade-to-decade regional temperature variations in the Southern Hemisphere, that were different to the Northern Hemisphere,'' she said.

"The Southern Hemisphere is a vast oceanic region that is influenced by ocean circulation features such as El Niño. Our study showed that these internal climate cycles may have played a role in influencing regional climate compared to the land-dominated Northern Hemisphere, where external changes in volcanic and solar variations have a more direct influence.

"But despite the two hemispheres behaving differently over the past 1000 years, what is consistent is the recent warming in the last 40 years.

"This study provided an opportunity to refine regional climate model predictions in the Southern Hemisphere for countries like Australia and South America by extending our understanding of natural recorded since 1850 back over the past 1000 years," she said.

The study involved the coordination of an international scientific team with expertise in past climate information from tree-rings, lake sediments, corals, ice cores and climate modelling.

Scientists compiled climate data from hundreds of different locations and used a range of methods to estimate Southern Hemisphere temperatures over the past 1000 years.

In 99.7 percent of the results, the warmest decade of the millennium occurred after 1970.

And surprisingly, only twice over the entire past millennium have both hemispheres simultaneously shown extreme temperatures.

One of these occasions was a global cold period in the 17th century; the other was the current warming phase.

Lead author Dr Raphael Neukom from Switzerland said the study showed the 'Medieval Warm Period', as identified in some European chronicles, was a regional phenomenon.

"During the same period, temperatures in the Southern Hemisphere were only average. Our study revealed it was not a common climate event that many people have previously assumed," he said.

The study showed that regional differences such as these were larger than previously thought.

Explore further: Solar activity not a key cause of climate change, study shows

More information: Inter-hemispheric temperature variability over the past millennium, Nature Climate Change (2014) DOI: 10.1038/nclimate2174

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User comments : 11

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runrig
4.1 / 5 (13) Mar 31, 2014
"Lead author Dr Raphael Neukom from Switzerland said the study showed the 'Medieval Warm Period', as identified in some European chronicles, was a regional phenomenon.

"During the same period, temperatures in the Southern Hemisphere were only average. Our study revealed it was not a common climate event that many people have previously assumed," he said. "

Exactly so.
Otherwise it would have to have been the Sun.
It wasn't then and it isn't now.
DistortedSignature
not rated yet Mar 31, 2014
@runrig What exatcly are you trying to say? Are you saying that temperature changes are regional only? And that the world isn't warming as whole?

"But despite the two hemispheres behaving differently over the past 1000 years, what is consistent is the recent warming in the last 40 years...


This article is talking about the cataloging of the history of the southern hemisphere and how temperature fluctuates doesn't seem to match the northern hemisphere except in two instances. One was in the 17th century, and the other which is happening currently for the past 4 decades, including now. The two paragraphs you quote weren't being tied in to the present at all, in fact it mentions what those two paragraphs mean right after.
The study showed that regional differences such as these were larger than previously thought.
i.e. The southern hemisphere history showed that it was regionally phenomenon but encompassed a bigger area than what was recorded.
runrig
4.3 / 5 (12) Mar 31, 2014
@runrig What exatcly are you trying to say? Are you saying that temperature changes are regional only? And that the world isn't warming as whole?


No, I am saying that the world is currently warming because of AGW. And that the MWP was a regional phenomenon.
For it to have been worldwide then it must have been the Sun that caused it (as in a greater output ). That was not the case then and it is not now.
What can cause regional temperature changes can involve the small (~1%) variation of Solar energy change in the Sun's 11 year cycle, whereby the winter Arctic Stratospheric vortex can be weakened/disrupted. This merely leads to an outflow of frigid Arctic air to more southerly and preferred locations.
ubavontuba
1.4 / 5 (12) Mar 31, 2014
No, I am saying that the world is currently warming because of AGW.
But it's not.

http://www.woodfo...14/trend

LagomorphZero
4.6 / 5 (9) Mar 31, 2014
@ubavontuba: nice cherry picking of data for your graph there..

In regards to the articles claim: "what is consistent is the recent warming in the last 40 years."

I present the same data and graph as uba, but actually include 40 years of data. Note the positive trendline.

http://www.woodfo...14/trend

Maggnus
4.1 / 5 (9) Mar 31, 2014
No, I am saying that the world is currently warming because of AGW.
But it's not.

http://www.woodfo...14/trend



Whack-a-mole!
ubavontuba
1.4 / 5 (10) Apr 01, 2014
No, I am saying that the world is currently warming because of AGW.
But it's not.

http://www.woodfo...14/trend


Whack-a-mole!
And again, Maggnus has no argument to make, ergo he agrees there's been no global warming in more than a dozen years. He just doesn't like it.

Therefore, Maggnus doesn't really care about global warming, as he isn't happy the globe is cooling.

Therefore, Maggnus must be in it for selfish reasons.

Maggnus, are you getting paid for your posts?

.

Maggnus
4.5 / 5 (8) Apr 01, 2014
And again, Maggnus has no argument to make, ergo he agrees there's been no global warming in more than a dozen years. He just doesn't like it.

Therefore, Maggnus doesn't really care about global warming, as he isn't happy the globe is cooling.

Therefore, Maggnus must be in it for selfish reasons.

Maggnus, are you getting paid for your posts?


And again, Ubamoron with more misrepresentation and games of whack-a-mole.

It's not worth responding to you, you denialist moron, you just post the same zombie BS over and over, and over and over......
shavera
4.4 / 5 (7) Apr 01, 2014
science: *presents data supporting AGW*

deniers: "nuh uh"

What literally happened above.
ubavontuba
1 / 5 (5) Apr 02, 2014
@ Maggnus
you just post the same zombie BS over and over, and over and over......
Which is my complaint with you. "Whack-a-mole!" is not an argument. They're just B.S. buzz words you use when you don't like the data.

So, why don't you like the data? Don't you care about the environment?

ubavontuba
1 / 5 (5) Apr 02, 2014
science: *presents data supporting AGW*

deniers: "nuh uh"

What literally happened above.
If warmists were really concerned about global warming, why aren't they happy the globe is cooling?

http://www.woodfo....1/trend

Obviously the warmists don't really care about the environment. as they fight tooth and claw to hide this fact from the populace. Therefore it appears they're in it for the money and political control.