A state of emergency has been declared in the Canadian western province of British Columbia after a major storm cut road and rail links in the region.

The Canadian Armed Forces are being deployed to help thousands of stranded residents who have been trapped since the storm hit overnight on Sunday.

Prime Minister Justin Trudeau pledged assistance during a visit to Washington DC and said troops would help rebuild.

One woman was killed in a landslide, and two people are missing.

Thousands remain evacuated after an "atmospheric river" - a long strip of moisture in the air that transports water from tropical areas towards the poles - dumped the region's monthly rainfall average in 24 hours.

Officials in the region have attributed the natural disaster to the effects of climate change.

The impact of climate change on the frequency of storms is still unclear, but we know that increased sea surface temperatures warm the air above and make more energy available to drive hurricanes, cyclones and typhoons. As a result, they are likely to be more intense with more extreme rainfall.

The world has already warmed by about 1.2C since the industrial era began and temperatures will keep rising unless governments around the world make steep cuts to emissions.
'We need to act now'

British Columbia Premier John Horgan said the emergency order took effect at 12:00 local time (20:00GMT) in a news conference on Wednesday.

He said that travel restrictions will keep people off flooded roads, and ensure that essential goods will "reach the communities that need them".

"There's not a person that hasn't been affected or will not be affected by the events of this past weekend," he said, adding: "These events are increasing in frequency due to human caused climate change."

Mr Horgan said British Columbia must "bring the seven billion other souls that live on this planet to understand that we need to act now… to protect us from these types of events that will happen in the future".

University of British Columbia atmospheric scientist Rachel White told the BBC that the massive devastation caused by this storm can likely be attributed to a combination of human-caused factors.

"As we warm up the climate, heavy rainfall events such as these are going to get more intense," she said.

"As we warm up the atmosphere, as we warm up the oceans - more water is evaporated from the oceans. So then when we have these atmospheric river events, essentially the atmosphere can carry more water towards our mountains." This then condenses into rain.

Logging and wildfires have also removed old-growth trees with deep roots, leading to a higher risk of landslides when it rains. Human development in flood plains, and the increase of non-absorbent asphalt also increases risks of flooding, Prof White said.

The extreme weather in Canada comes days after world leaders met for the COP26 climate conference in Glasgow.

The same region, British Columbia, suffered a record high heat wave in the summer that killed more than 500 people as well as wildfires, including one that destroyed the village of Lytton.
'Not out of this yet'

The rains and winds had largely finished by Tuesday afternoon, but several communities remain stranded. More rain is forecast later in the week, and officials have warned that the death toll is likely to rise.

Helicopters on Wednesday dropped food supplies to stranded mountain communities after slides destroyed roads and floods submerged major highways.

The town of Tulameen has about 400 people trapped there, according to Reuters news agency.

Some communities at higher elevations have seen temperatures drop below freezing. Farmers and ranchers at lower elevations have struggled with widespread flooding and thousands of animals have died.

Approximately 1,500 travellers became stranded in the town of Hope after roads closed, Grace Baptist Church Pastor Jeff Kuhn told BBC News in an email on Wednesday.

Premier Horgan has called on residents to stay at home, and to not hoard items. "What you need your neighbours need as well," he said.

Residents of some neighbourhoods in the city of Abbotsford were told on Tuesday to leave immediately as rising water levels posed "a significant risk to life".

In a press conference on Wednesday, Mayor Henry Braun said water levels in the nearby Fraser River were dropping but warned: "We're not out of this yet.

"If we have another weather event like we just went through, we're in deep doo-doo," he said.

Rescue operations are still under way in the area, and aerial assessments of the damage are being conducted.
Members of a search and rescue team speak with the pilot of a hovercraft parked on the flooded Trans-Canada Highway after rainstorms caused flooding and landslides in Abbotsford, British Columbia, Canada November 16, 2021.