Environment

CNN - Humanity has thrown the global water cycle off balance “for the first time in human history,” fueling a growing water disaster that will wreak havoc on economies, food production and lives, according to a landmark new report.Decades of destructive land use and water mismanagement have collided with the human-caused climate crisis to put “unprecedented stress” on the global water cycle, said the report published Wednesday by the Global Commission on the Economics of Water, a group of international leaders and experts.

The water cycle refers to the complex system by which water moves around the Earth. Water evaporates from the ground — including from lakes, rivers and plants — and rises into the atmosphere, forming large rivers of water vapor able to travel long distances, before cooling, condensing and eventually falling back to the ground as rain or snow.Disruptions to the water cycle are already causing suffering. Nearly 3 billion people face water scarcity. Crops are shriveling and cities are sinking as the groundwater beneath them dries out.

The consequences will be even more catastrophic without urgent action. The water crisis threatens more than 50% of global food production and risks shaving an average of 8% off countries’ GDPs by 2050, with much higher losses of up to 15% projected in low-income countries, the report found.“For the first time in human history, we are pushing the global water cycle out of balance,” said Johan Rockström, co-chair of the Global Commission on the Economics of Water and a report author. “Precipitation, the source of all freshwater, can no longer be relied upon.”

Popular Science - Picking out what to wear during the fall or spring can be tough. It might be sweater weather in the morning, only to feel more like summer heat by lunchtime. Or temperatures may start out in winter’s biting chill and suddenly warm up. It can be difficult to see 60 or 65 degrees Fahrenheit during a morning forecast and accurately anticipate what that will even feel like. There is actually a meteorological and a biological reason why the same temperature can feel different depending on the season.

“In the summer, the ground is warm. As we start to cool and get into the cooler seasons, the ground changes temperature slower than the air around us,” New Hampshire-based meteorologist Cyrena Arnold tells Popular Science. “If you were to look at a graph of how the ground temperature changes with the seasons, and has less fluctuation, and it’s always kind of behind the seasons.”