Is this finally proof we’re NOT causing global warming? The whole of the Earth heated up in medieval times without human CO2 emissions, says new study

Current theories of the causes and impact of global warming have been thrown into question by a new study which shows that during medieval times areas as far apart as Europe and Antarctica both warmed up.
It then cooled down naturally and there was even a ‘mini ice age’.
A team of scientists led by geochemist Zunli Lu from Syracuse University in New York state, has found that the ‘Medieval Warm Period’ approximately 500 to 1,000 years ago wasn’t just confined to Europe.
In fact, it extended all the way down to Antarctica.
At present the Intergovernmental Panel on Climate Change (IPCC) argues that the Medieval Warm Period was confined to Europe.
However, Professor Lu has shown that this the Medieval Warm Period had a much broader reach – and the evidence lies with a rare mineral called ikaite, which forms in cold waters.
‘Ikaite is an icy version of limestone,’ said Lu. ‘The crystals are only stable under cold conditions and actually melt at room temperature.’
It turns out the water that holds the crystal structure together – called the hydration water – traps information about temperatures present when the crystals formed.
This finding by Lu’s research team establishes, for the first time, ikaite as a reliable way to study past climate conditions.
The mineral proved that Antarctica did warm up.
Lu says that his research has no direct bearing on the current climate, and points out that his research is restricted to one area in Antarctica, and is not in itself proof that the whole Earth warmed up.
The scientists studied ikaite crystals from sediment cores drilled off the coast of Antarctica. The sediment layers were deposited over 2,000 years.
The scientists were particularly interested in crystals found in layers deposited during the ‘Little Ice Age,’ approximately 300 to 500 years ago, and during the Medieval Warm Period before it.
Both climate events have been documented in Northern Europe, but studies have been inconclusive as to whether the conditions in Northern Europe extended to Antarctica.
Lu’s team found that in fact, they did.
They were able to deduce this by studying the amount of heavy oxygen isotopes found in the crystals.
During cool periods there are lots, during warm periods there aren’t.
‘We showed that the Northern European climate events influenced climate conditions in Antarctica,’ Lu says. ‘More importantly, we are extremely happy to figure out how to get a climate signal out of this peculiar mineral. A new proxy is always welcome when studying past climate changes.’
The research was recently published online in the journal Earth And Planetary Science Letters and will appear in print on April 1.