In Iowa, soaked by its wettest 36-month period in 127 years of recordkeeping, floodwaters from three nights of rain this week forced hundreds from their homes and killed a 16-year-old girl.
The international climate panel projected increased U.S. precipitation this century—except for the Southwest—and more extreme rain events causing flooding.
Researchers last week spotted a 100-square-mile (260-square-kilometer) chunk of ice calved off from the great Petermann Glacier in Greenland's far northwest. It was the most massive ice island to break away in the Arctic in a half-century of observation.
The huge iceberg appeared just five months after an international scientific team published a report saying ice loss from the Greenland ice sheet is expanding up its northwest coast from the south.
Changes in the ice sheet "are happening fast, and we are definitely losing more ice mass than we had anticipated," said one of the scientists, NASA's Isabella Velicogna.
In the Arctic Ocean itself, the summer melt of the vast ice cap has reached unprecedented proportions in recent years. Satellite data show the ocean area covered by ice last month was the second-lowest ever recorded for July.
The melting of land ice into the oceans is causing about 60 percent of the accelerating rise in sea levels worldwide, with thermal expansion from warming waters causing the rest. The WMO'S World Climate Research Program says seas are rising by 1.34 inches (34 millimeters) per decade, about twice the 20th century's average.
Worldwide temperature readings, meanwhile, show that this January-June was the hottest first half of a year since recordkeeping began in the mid-19th century. Meteorologists say 17 nations have recorded all-time-high temperatures in 2010, more than in any other year.
Scientists blame the warming on carbon dioxide and other heat-trapping gases pouring into the atmosphere from power plants, cars and trucks, furnaces and other fossil fuel-burning industrial and residential sources.
Experts are growing ever more vocal in urging sharp cutbacks in emissions, to protect the climate that has nurtured modern civilization.
"Reducing emissions is something everyone is capable of," Nanjing-based climatologist Tao Li told an academic journal in China, now the world's No. 1 emitter, ahead of the U.S.
But not everyone is willing to act.
The U.S. remains the only major industrialized nation not to have legislated caps on carbon emissions, after Senate Majority Leader Harry Reid last week withdrew climate legislation in the face of resistance from Republicans and some Democrats.
The U.S. inaction, dating back to the 1990s, is a key reason global talks have bogged down for a pact to succeed the expiring Kyoto Protocol. That is the relatively weak accord on emissions cuts adhered to by all other industrialized states.
Governments around the world, especially in poorer nations that will be hard-hit, are scrambling to find ways and money to adapt to shifts in climate and rising seas.
The meetings of climatologists in the coming weeks in Paris, Britain and Colorado will be one step toward adaptation, seeking ways to identify trends in extreme events and better means of forecasting them.
A U.N. specialist in natural disasters says much more needs to be done.
Salvano Briceno of the U.N.'s International Strategy for Disaster Reduction pointed to aggravating factors in the latest climate catastrophes: China's failure to stem deforestation, contributing to its deadly mudslides; Russia's poor forest management, feeding fires; and the settling of poor Pakistanis on flood plains and dry riverbeds in the densely populated country, squatters' turf that suddenly turned into torrents.
"The IPCC has already identified the influence of climate change in these disasters. That's clear," Briceno said. "But the main trend we need to look at is increasing vulnerability, the fact we have more people living in the wrong places, doing the wrong things."