BECCLES, England — This winter a 50-foot-wide strip of Roger Middleditch’s sugar-beet field fell into the North Sea, his rich East Anglian lands reduced by a large fraction of their acreage. The adjacent potato field, once 23 acres, is now less than 3 — too small to plant at all, he said.

Each spring Mr. Middleditch, a tenant farmer on the vast Benacre Estate here, meets with its managers to recalculate his rent, depending on how much land has been eaten up by encroaching water. As he stood in a muddy field by the roaring sea recently, he tried to estimate how close he dared to plant this season.

“We’ve lost so much these last few years,” he said. “You plant, and by harvest it’s fallen into the water.”

Coastal erosion has been a fact of life here for a century, because the land under East Anglia is slowly sinking. But the erosion has never been as quick and cataclysmic as it has been in recent years, an effect of climate change and global warming, many scientists say. To make matters worse for coastal farmers, the government has stopped maintaining large parts of the network of seawalls that once protected the area.