Could Global Warming Change Earth's Tilt?
2009 08 22

By Rachel Courtland | NewScientist.com

Warming oceans could cause Earth's axis to tilt in the coming century, a new study suggests. The effect was previously thought to be negligible, but researchers now say the shift will be large enough that it should be taken into account when interpreting how the Earth wobbles.

The Earth spins on an axis that is tilted some 23.5° from the vertical. But this position is far from constant – the planet's axis is constantly shifting in response to changes in the distribution of mass around the Earth. "The Earth is like a spinning top, and if you put more mass on one side or other, the axis of rotation is going to shift slightly," says Felix Landerer of NASA's Jet Propulsion Laboratory in Pasadena, California.

The changing climate has long been known to move Earth's axis. The planet's north pole, for example, is migrating towards 79 °W – a line of longitude that runs through Toronto and Panama City – at a rate of about 10 centimetres each year as the Earth rebounds from ice sheets that once weighed down large swaths of North America, Europe, and Asia.

The influx of fresh water from shrinking ice sheets also causes the planet to pitch over. Landerer and colleagues estimate that the melting of Greenland's ice is already causing Earth's axis to tilt at an annual rate of about 2.6 centimetres – and that rate may increase significantly in the coming years.

Now, they calculate that oceans warmed by the rise in greenhouse gases can also cause the Earth to tilt – a conclusion that runs counter to older models, which suggested that ocean expansion would not create a large shift in the distribution of the Earth's mass.

Tracking sea levels

The researchers modelled the changes that would occur if moderate projections made by the Intergovernmental Panel on Climate Change – a doubling of carbon dioxide levels between 2000 and 2100 – were to become reality.

The team found that as the oceans warm and expand, more water will be pushed up and onto the Earth's shallower ocean shelves. Over the next century, the subtle effect is expected to cause the northern pole of Earth's spin axis to shift by roughly 1.5 centimetres per year in the direction of Alaska and Hawaii.

The effect is relatively small. "The pole's not going to drift away in a crazy manner," Landerer notes, adding that it shouldn't induce any unfortunate feedback in Earth's climate.

But he says the motion is strong enough that it needs to be taken into account when interpreting shifts in Earth's axis. Tracking the motion of the poles could help place limits on the total amount of sea level rise over decades.

"The oceans take up at least 80 per cent of the heat that is added from greenhouse gases," Landerer told New Scientist. "They have a huge heat capacity, so this effect is going to be there for quite a bit."

Faster spin

Maik Thomas of the German Research Centre for Geosciences in Potsdam, who was not affiliated with the study, says the new work overturns previous ideas. "Up to now, people had believed that height variations [from ocean temperature changes] gave no contribution to polar motion," he told New Scientist. "This is an effect that now has to be considered."

But Thomas notes that polar motion is unlikely to yield a good measurement of sea level rise, whose signal may be difficult to disentangle from a host of other factors that contribute to changes in Earth's tilt, from movements in Earth's crust and mantle to the periodic effects of El Niño, an oscillation of the ocean-atmosphere system in the Pacific.

And climate change can also affect the Earth's spin. Previously, Landerer and colleagues showed that global warming would cause Earth's mass to be redistributed towards higher latitudes. Since that pulls mass closer to the planet's spin axis, it causes the planet to rotate faster – just as an ice skater spins faster when she pulls her arms towards her body.

Article from: NewScientist.com



The Great Global Warming Swindle (Video)

Red Ice Creations Radio - Susan Joy Rennison - Cosmic Origins of Global Warming

Global Warming or Global Governance? (Video)

Micheal Sunanda - Extreme Weather, Global Warming & Permaculture

Red Ice Creations Radio - Jerry E. Smith - The "Green" Conspiracy (Subscription)

Edmund Marriage - Sun, Earth, Global Cooling and Neuro-Therapy (Subscription)



Related Articles
Greenpeace Leader Admits Organization Put Out Fake Global Warming Data
EPA May Have Suppressed Anti-Global Warming Study
EPA dismissed an analyst's report questioning the science behind global warming
Scientists: No link cloud coverage and global warming?
Media Ignore Al Gore’s Financial Ties to Global Warming
Viewpoint: Global warming is a scam, not a crisis
2008 was the year man-made global warming was disproved
IPCC Scientists Caught Producing False Data To Push Global Warming
Global warming: pretext for weather warfare?
Was Katrina A 'Man-Made Storm' For Profits?


Latest News from our Front Page

NATO Exercise in Ukraine Coincided with MH-17 Shoot-down
2014 07 24
Rapid Trident was omitted from the flurry of coverage on the shoot-down MH-17. From the U.S. Army in Europe website: Rapid Trident supports interoperability among Ukraine, the United States, NATO and Partnership for Peace member nations. The exercise helps prepare participants to operate successfully in a joint, multinational, integrated environment with host-nation support from civil and governmental agencies. ...
Warning of ’imminent’ terror attack in Norway
2014 07 24
Norwegians were warned Thursday of the concrete possibility of a terror attack occurring in that country at the hands of people with connections to an extremist group in Syria. A press conference was called in Oslo, Norway on Thursday where an announcement was made of a "possible concrete threat" to national security in that country from terrorists related to an extremist ...
Judge says government can access everything in a Gmail account
2014 07 24
All your emails are belong to us. At least that’s what the latest court order from a judge in New York says. The warrant, granted on June 11, states that the government can access all the content and files contained in a Gmail account. Yes, this is a significant blow to privacy. The subject of this specific search relates to a money laundering ...
Scotland Yard Spied on Grieving Families: secret surveillance after police victim shot seven times in head ’by mistake’
2014 07 24
More terror from the ’anti-terror’ brigade. Undercover police gathered evidence on 18 grieving families By Rob Evans and Vikram Dodd | The Guardian Undercover police officers secretly gathered intelligence over two decades on 18 families fighting to get justice from the police, it was revealed on Thursday. The intelligence covering high-profile campaigns was collected between the mid-1980s and 2005, and affected grieving families ...
Air Algerie AH5017 with 116 onboard goes missing for hours, found crashed in Mali
2014 07 24
An Air Algerie flight carrying 110 passengers and six crew members has reportedly crashed in Mali after having disappeared from radar early on Thursday morning between Burkina Faso and Algeria. A French Ministry of Defense official told Fox News that the two French fighter jets located the wreckage of the plane, which had crashed in Mali. An airport official additionally confirmed ...
More News »