Climate change IS to blame for rising sea levels – as risk of ‘megatsunamis’ grows
There's more reason than ever before to worry about climate change
SEA LEVELS rising unevenly across Earth has been blamed on climate change.
The rise – which has been documented over the last 25 years – is "human-caused" according to scientists, and it could have devastating results if it continues.
Rising sea levels are a major concern for the global community – and scientists have now issued a fresh warning.
A new study published in the PNAS journal suggests that areas of the world with "higher than average" sea level rises can "expect the trend to continue" as the climate warms.
John Fasullo, of the National Centre for Atmospheric Research, said the new findings are extremely important.
"By knowing that climate change is playing a role in creating these regional patterns, we can be more confident that these same patterns may linger or even intensify in the future if climate change continues unabated," Fasullo explained.
He continued: "With sea level project to rise a couple of feet or more this century on average, information about expected regional differences could be critical for coastal communities as they prepare."
We know sea levels are rising – but they're rising at different levels around the world.
For instance, areas near Antarctica and the USA's West Coast have had lower-than-average sea level rise.
But some parts of the world as experiencing the opposite, including the USA's East Coast, the Philippines and Indonesia.
This is based on satellite data, which has measurements of the sea's surface heights going back to 1993.
It's possible to explain why sea level rises are different depending on the region based on where heat is stored in the ocean. That's because warm water expands to fill more space than cold water.
Uneven sea levels can also be explained by melting ice sheets.
Rising sea levels – what's the problem?
Here's what you need to know...
- The global sea level has been gradually rising over the past century
- Sea levels rise due to two main reasons
- The first is thermal expansion – as water gets warmer, it expands
- The second is melting ice on land, adding fresh water into seas
- This has a cyclical effect, because melting ice also warms up the planet (and oceans), causing more even ice to melt and boosting thermal expansion
- It's currently rising at a rate of around 0.3cm per year
- The sea is huge, so that might sound harmless
- But rising sea levels can have a devastating effect over time
- Low-lying coastal areas can disappear completely, even putting areas of the UK at risk
- It can also mean sea storms and tsunamis can have a more devastating effect, reaching further in-land than they would have previously
- There's also an increased risk of flooding
Scientists have documented a natural shift in the ocean cycle called Pacific Decadal Oscillation.
But what is tricky is separating these natural shifts from climate change-induced sea level rises.
To solve this problem, scientists created computer climate models – which mapped out sea level rises over the last 25 years.
By running the simulations over and over again, it was possible to separate "natural variability from the impacts of climate change".
Scientists found that for regions affected with above-average sea level change, as much as half of the variation could be attributed to climate change.
"It turns out the sea level rise response to climate change in the Pacific resembles what happens during a particular phase of the Pacific Decadal Oscillation," said Fasullo.
"This explains why it's been so difficult to determine how much of the pattern was natural or not, until now."
It's an exciting finding, particularly for local officials who are keen to get improved forecasts of local sea level rises.
Typically, people have had to rely on global rates of sea level rises (around 3 millimetres a year), rather than localised information.
"We now have a new tool – long-term satellite altimeter measurements – that we can use to help stakeholders who need information for specific locations," said Steve Nerem, of the University of Colorado Boulder, who worked on the study.
Rising sea levels can have a major impact for life on Earth.
Earlier this year, scientists issued a warning about the risk of “devastating tsunamis” caused by climate change.
Research in Science Advances suggested that rising sea levels – caused by global warming – significantly increase the threat of giant killer waves.
Experts modelled the impact of tsunamis based on sea level increases, and discovered worrying results.
It found that rising sea levels allowed tsunamis to reach much further inland, significantly increasing the risk of floods.
This means small tsunamis that might not be deadly today could wreak havoc in the future.
“Our research shows that sea-level rise can significantly increase the tsunami hazard, which means that smaller tsunamis in the future can have the same adverse impacts as big tsunamis would today,” said Robert Weiss, a professor of geosciences at Virginia Tech.
And if you think Britain is safe from tsunamis, think again.
Recent research revealed that deadly tsunamis crashing into the UK is more common than previously thought.
Scientists believe three killer waves have hit the UK within the last 10,000 years – raising the possibility that another one may be due.
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We already knew about one of these: around 8,200 years ago, the Storegga submarine landslide off the coast of Norway sparked a 20-metre high tsunami that swept across Shetland.
Now experts have discovered evidence of two additional tsunamis that took place even more recently.
Researchers from Dundee University and the British Geological Survey found sands on Shetland that prove two separate tsunamis hit Britain in fairly recent history.
“We found sands aged 5,000 and 1,500 years old at multiple locations in Shetland, up to 13m above sea level,” said Dr Sue Dawson, of the University of Dundee.
Are you worried about climate change? Let us know in the comments!
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