Storm Ida kills dozens across US north-east
US President Joe Biden says "historic investment" is needed to deal with the climate crisis, as the north-east reels from flash flooding and tornadoes that have killed at least 41 people.
The US is facing climate-related destruction across the country and tackling it is "a matter of life and death", the president said.
New York City and New Jersey saw unprecedented levels of rainfall.
Some residents became trapped in flooded basements and cars.
Four states suffered loss of life:
New Jersey Governor Phil Murphy said at least 23 people had died in his state - most of them stuck in their vehicles as the waters rose
At least 14 people lost their lives in New York City, including a two-year-old boy. Eleven of them drowned while trapped in their flooded basements, officials said
Three people died near Philadelphia, Pennsylvania, while one person was killed in Connecticut
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.
'Niagara Falls level of water'
New York City Mayor Bill de Blasio criticized weather experts, saying their forecasts were being "made a mockery of in a matter of minutes". He said he had been warned to expect between three and six inches (7.5 and 15cm) of rain over the course of the day. However a record 3.15 inches fell in Central Park in just one hour.
"We need to start communicating to people that things will be much worse in literally every situation," he said.
New York Governor Kathy Hochul said: "We did not know that between 8:50 and 9:50 p.m. last night, that the heavens would literally open up and bring Niagara Falls level of water to the streets of New York."
Residents have been assessing the damage to property.
One man in Flushing, New York, said his residence was prone to flooding "but what I saw last night is unimaginable". "I have never seen water coming in all directions," Tedla Asfaw, 60, told the BBC. "There's huge damage here. It's a big hit for us."
In New Jersey, a tornado flattened the state's largest dairy farm, ripping roofs of buildings and toppling several large silos.
Many cows were trapped under fallen sheds and some died, the owners of Wellacrest Farm wrote on their Facebook page. "Along with the devastating loss of homes in our neighborhoods - we, as a community, suffered a great loss with the destruction of our farm."
Many of New York City's subway lines remain closed after social media pictures showed water gushing into the underground stations.
Other footage showed cars floating down flooded roads, with cries of "help" being heard from inside.
Passengers on trains, planes and buses found themselves stuck for hours without moving as the flooding made travelling impossible.
