CLIMATE CHANGE MIGHT BE WORSE THAN WE THINK AFTER SCIENTISTS FIND HUGE MISTAKE IN TEMPERATURE ESTIMATES OF EARTH'S ANCIENT OCEANS...

Climate change might be even worse than we think, according to a new study that is challenging the way we measure ocean temperatures. Pictured is Ceverville Island in Antarctica

 

Climate change might be even worse than we think, according to a new study that is challenging the way we measure ocean temperatures...

  • Until now, ocean temperatures were based on the oxygen content in fossils
  • But a new study suggests oxygen level may change regardless of temperature
  • Findings suggest that oceans in the past were much colder
  • This indicates that ocean temperatures are now rising quicker than realised 

Scientists suggest that the method used to understand sea temperatures in the past is based on a mistake, meaning our understanding of climate change may be flawed.

The findings indicate that oceans in the past were much colder than thought, meaning that temperatures may be increasing quicker now than realised.

FLAWS IN THE PREVIOUS METHOD

For over 50 years, scientists based their estimates on what they learned from foraminifera - fossils of tiny marine organisms found in sediment cores taken from the ocean floor.

Foraminifera form shells called tests, in which the content of a form of oxygen, called oxygen-18, depends on the temperature of the water.

So changes in the ocean's temperature over time were calculated on the basis of the oxygen-18 content of the fossil foraminifera tests found in sediment.

According to these measurements, the ocean's temperature has fallen by 15°C over the past 100 million years.

But these estimates were based on the principle that the oxygen-18 content of the foraminifera tests remained constant while the fossils were in the sediment.

To test whether oxygen-18 levels changed, the researchers exposed foraminifera to high temperatures in artificial sea water that contained only oxygen-18.

An instrument called NanoSIMS was then used to analyse the chemical content of the fossils.

Results show that the level of oxygen-18 changed without leaving a visible trace.

According to the methodology widely used by the scientific community, the temperature of the polar oceans 100 million years ago were around 15°C higher than current readings.

But in a new study, researchers from the French National Center for Scientific Research (CNRS) are challenging this method.

Instead, they suggest that ocean temperatures may in fact have remained relatively stable throughout this period, which raises serious concerns about current levels of climate change.

Dr Anders Meibom, one of the researchers who worked on the study, said: 'If we are right, our study challenges decades of paleoclimate research.'

'Oceans cover 70 per cent of our planet. They play a key role in the earth's climate.

'Knowing the extent to which their temperatures have varied over geological time is crucial if we are to gain a fuller understanding of how they behave and to predict the consequences of current climate change more accurately.' 

For over 50 years, scientists have based their estimates on what they learned from foraminifera - fossils of tiny marine organisms found in sediment cores taken from the ocean floor.

Foraminifera form shells called tests, in which the content of a form of oxygen, called oxygen-18, depends on the temperature of the water in which they live.

So changes in the ocean's temperature over time were calculated on the basis of the oxygen-18 content of the fossil foraminifera tests found in the sediment.

According to these measurements, the ocean's temperature has fallen by 15°C over the past 100 million years.

But these estimates were based on the principle that the oxygen-18 content of the foraminifera tests remained constant while the fossils were in the sediment.

To test whether oxygen-18 levels changed, the researchers exposed foraminifera to high temperatures in artificial sea water that contained only oxygen-18.

For over 50 years, scientists based their estimates on what they learned from foraminifera - fossils of tiny marine organisms found in sediment cores taken from the ocean floor (pictured)

For over 50 years, scientists based their estimates on what they learned from foraminifera - fossils of tiny marine organisms found in sediment cores taken from the ocean floor (pictured)

DISTANT VOLCANOES MAY MELT ICE SHEETS

Research published this week found that ice sheets may melt rapidly as a result of volcanic eruptions thousands of miles away. 

While volcanic eruptions have been known to cool the global climate, the findings suggest that they can also speed up the melting of ice sheets.

Researchers from Columbia University looked at ice sheets that covered much of northern Europe at the end of the last ice age, around 12,000 to 13,000 years ago.

They found that ancient eruptions caused 'immediate and significant' melting of the ice sheet which suggests modern ice sheets could also be vulnerable.

An instrument called NanoSIMS was then used to analyse the chemical content of the fossils.

Results show that the level of oxygen-18 present changed without leaving a visible trace.

Dr Sylvain Bernard, lead author of the study, said: 'What appeared to be perfectly preserved fossils are in fact not.

'This means that the paleotemperature estimates made up to now are incorrect.'

Rather than showing a gradual decline in temperature over the past 100 million years, the researchers suggest that the foraminifera had changed their oxygen-18 levels simply to equilibrate with the surrounding water.

The findings indicate that temperature in the oceans have been overestimated.

In terms of next steps, Dr Meibom added: 'To revisit the ocean's paleotemperatures now, we need to carefully quantify this re-equilibration, which has been overlooked for too long.

'For that, we have to work on other types of marine organisms so that we clearly understand what took place in the sediment over geological time.'

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David Pike, Editor