(CNN) Severe cold is still gripping UK and parts of Europe as Storm Emma collides with the "Beast of the East" causing transport delays and disruptions.

Air travelers are urged to check with their airline before they set out for the airport in case of flight delays and cancellations.

In the UK police were urging commuters to avoid non-essential travel after a number of people had to be rescued from cars overnight. Police declared a "major incident" Thursday after 100 vehicles became stuck in snow in Somerset, South West England.

Key developments, last updated 7.45 a.m. GMT

Ireland: All flights are suspected to and from Dublin Airport until Saturday March 3. Aer Lingus and Ryanair have canceled flights from Cork Airport and Kerry Airport until Saturday.

All flights are suspected to and from Dublin Airport until Saturday March 3. Aer Lingus and Ryanair have canceled flights from Cork Airport and Kerry Airport until Saturday. England: Most major airports remain open but a large number of flights are delayed or canceled. East Midlands Airport has reopened but flights are at the discretion of airlines. London City Airport is advising passengers to expect delays and cancellations and to check the status of flights ahead of travel.

Mainland Europe: Geneva Airport was briefly closed Thursday morning, but departures have now resumed. The first landings are expected Thursday afternoon. Some other airports across Europe, including Montpellier in France and Amsterdam's Schiphol airport are also experiencing disruption.

Geneva Airport in Switzerland was temporarily closed Thursday morning because of snow.

'Risk to life'

After issuing a rare red weather warning Thursday, the UK Met Office has downgraded its alert to amber and yellow warnings across most of the UK.

#AmberWarnings remain in force across much of the UK - please take extra care out and about, only travel if absolutely necessary and follow the advice of local authorities and emergency services. Stay #weatheraware pic.twitter.com/6HgllVfmhy — Met Office (@metoffice) March 2, 2018

Frequent and heavy snow showers could block roads and cause transport delays. Some rural communities could be cut off for days, the Met Office warns.

Up to 50 centimeters of snow are expected in Dartmoor, Exmoor and upland parts of southeast Wales on Friday morning.

Storm Emma is expected to hit Ireland particularly hard. A red weather warning was issued for the whole of the Republic of Ireland late Wednesday night and is valid until Friday afternoon.

Weather warnings are also still in place across much of central and southern Europe, with red warnings for extreme low temperatures or snow and ice issued in Hungary and Serbia, according to Meteoalarm

Both British Airways and Ryanair, which have canceled multiple flights to and from British airports, said they are working to rebook customers on future flights.

Rail travelers in the UK are also facing significant disruption. London's Paddington Station was closed temporarily Thursday morning because of a build-up of ice and snow on the platforms and multiple routes across the country are affected.

Drivers were urged not to venture out in areas hit by deep snow.

Please don't use the region's roads this morning as conditions are still dangerous. More #snow & #ice is expected today.



Last night, a major incident was declared and an operation was launched to rescue people stranded in vehicles. https://t.co/F4qdoi7Rt2#StormEmma pic.twitter.com/wQWwhp8MQG — Avon&Somerset Police (@ASPolice) March 2, 2018

National Grid UK, which manages the distribution of electricity and gas across England and Wales, said Thursday there were gas supply losses overnight "due to the extreme weather conditions" and issued a gas deficit warning.

Blizzards brought traffic to a halt on one of Scotland's major motorways overnight.

Why is this extreme weather happening?

Much of Europe has been blanketed in snow this week, with rare falls of the icy stuff in the south of France, Spain and Italy.

According to Simon Clark , researcher of stratosphere-troposphere interactions in Bristol, England, the current cold snap was triggered by a disruption to the stratospheric polar vortex -- a doughnut of air 6,000km (3,800 miles) across that forms high up in the atmosphere above the Arctic Circle every winter.

Now and again -- perhaps six times every decade -- the vortex gets split in two, a phenomenon known as sudden stratospheric warming.

Venice has seen an unusual amount of snow this week.

The disruption allows icy Arctic air to spread further south, often lowering temperatures across much of the northern hemisphere.

"That big mass of Arctic air -- which is normally trapped over the poles, so it's really freezing cold -- is then able to spill further south," Clark told CNN.

Storm Emma, currently making its way across the UK from the southwest, is a normal phenomenon for this time of year, and would usually result in heavy rainfall.

But as it meets the freezing polar air swirling around much of Britain, the storm is much more likely to dump its moisture as snow, Clark explained.

While mainland Europe "will still be affected by Emma... we (in the UK) are probably going to take the brunt of the moisture," said Clark.

Conditions are expected to improve by the end of the weekend, but average temperatures across the UK could remain lower than normal over the next month as the polar air gradually returns to the Arctic.

Clark expects Europe to feel the effects of disruptions to the vortex more often as the global climate continues to warm.

"It's very difficult to say for sure whether this one event was caused by climate change," he said, "but as the climate warms, we expect the polar vortex to get weaker.... We will then see more of these sudden warmings."

Precise predictions are difficult, however, due to the rate at which the climate is changing. "It's changing faster than we can collect data on it," Clark said.