ON “signal” is defined as glacial changes caused

ON THIN ICE: The likelihood that
climate change is causing glacial retreat is 99 percent

 

It is ‘virtually certain’ that global
glacial retreat is a result of climate change, a new study suggests.

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By Y3608627 |
JAN 02, 2017 — 15:27 PM ET

A new study published last month by researchers from
the Earth and Space Sciences department at the University of Washington concluded
that there is a very small chance that the dwindling
of mountain glaciers in five continents could have occurred
without the influence of climate change.

In
2013 the Intergovernmental Panel on Climate Change
(IPCC)1 believed the connection between glacial retreat and
climate change to be only “likely”, or at least a 66% probability. However, by
comparing the long-term decline of 37 glaciers, researchers propose that all
but one are “very likely” – or
to be more than 90% probable– to have retreated due to
the human-caused change in climate.

Yet,
the results from 21 of the 37 glaciers are
even more worrying. Roe and his colleges find
that it is over 99% likely – or “virtually certain” – that glacier retreat is
being driven by climate change.

Previously,
pinpointing any one glacier’s retreat to
climate change has been challenging due to the short glacial records and glaciers’ great natural variations. The new study
overcomes this by applying their data to a statistical ratio known as “signal-to-noise”,
where “signal” is defined as glacial changes caused by climate
change and “noise” as the usual glacial fluctuations driven by the year to year
weather conditions. This ratio allowed the
researchers to calculate the likelihood that each glacier’s observed retreats would have happened
even without any background climate change.