Climate

NY Times - After the warmest winter on record for many states and a blistering March heat wave that left almost no snow in parts of the American West, the region is facing a summer of serious wildfire risks and a drought that could force broad water restrictions.

New measurements this month show most of the Mountain West won’t be able to rely on melting snow, the region’s largest water source, because there’s hardly any snowpack there. And while some rain is forecast in the coming weeks, any spring precipitation will likely be too little, too late, scientists said.

“It’s going to be a seriously dry summer ahead,” said Nels Bjarke, a research scientist with the Western Water Assessment at the University of Colorado, Boulder.

Scientists in many parts of the West found a snow drought this month unlike any they had seen. Almost the whole region was affected, rather than just isolated pockets, said Noah Molotch, a professor of hydrology at the University of Colorado, Boulder.

At one key snowpack measurement site in California’s Sierra Nevada, scientists last week found only traces of snow. In parts of western Colorado, mountain slopes where researchers have always measured at least 6 inches of snowpack at this time of year were virtually snowless. Across that state, snowpack was less than half of normal.

Those findings were the product of a record-warm winter for many western states. Through much of the winter, temperatures were simply too warm for it to snow, and precipitation fell as rain instead, unlike in previous low-snow years caused by a general lack of moisture, said Karla Nemeth, director of the California Department of Water Resources. Snowpack, which builds up over the winter and spring, provides a larger, steadier and less ephemeral source of water than rain.

Discover Wildlife - Every year since 2002, Greenland has lost 264 gigatons of ice, causing sea levels to rise by 0.8mm annually. This may not initially seem like a huge rise, but when you consider that 10% of the world’s population live within 5km of the coast at elevations near sea level, it soon becomes an alarming statistic.

The loss of Greenland’s ice is largely driven by warming air and sea temperatures linked to anthropogenic global warming. However, a new study led by the University of Leeds has just highlighted a relatively unexplored feature that is amplifying this loss - the meltwater lakes forming at the end of Greenland’s retreating glaciers.

As a glacier melts and retreats up the valley it formed in, it exposes deep, bowl-shaped hollows in the surrounding landscape that quickly fill with meltwater. These lakes are known as ice-marginal lakes (or IMLs) and they can grow as large as 117km2, which is roughly the same area occupied by the urban subdivision of Leeds in England.

The recent study, published last week in the journal Communications Earth and Environment, demonstrates IMLs aren’t just the results of retreating glaciers, but rather active agents in their demise, destabilising them, triggering movement, and increasing thinning, all of which contribute to ice loss.

When a glacier flows into an IML, its front is partly lifted, exposing its underside to increased melting. This reduces the friction that typically slows the glacier’s flow and increases the likelihood of large slabs breaking away via a process known as ‘calving’.