California wildfires spawn first ‘gigafire’ in modern history

California’s extraordinary year of wildfires has spawned another new milestone – the first “gigafire”, a blaze spanning 1m acres, in modern history.

On Monday, the August complex fire in northern California expanded beyond 1m acres, elevating it from a mere “megafire” to a new classification, “gigafire”, never used before in a contemporary setting in the state.

At 1.03m acres, the fire is larger than the state of Rhode Island and is raging across seven counties, according to fire agency Cal Fire. An amalgamation of several fires caused when lightning struck dry forests in August, the vast conflagration has been burning for 50 days and is only half-contained…

Moving delta rivers to bring floods to new places

The same team has now discovered that a perfect storm of factors—including larger floods and finer sediment size—will enable these destructive events to occur farther and farther inland. The results, which appear in Geophysical Research Letters, warn of major disasters poised to hit many urban centers that historically never had to worry about these issues. The prior finding appears in PNAS.

On large, relatively flat rivers, avulsions tend to occur in the backwater region, explains

geomorphologist Vamsi Ganti of the University of California, Santa Barbara. “This is the zone over which the river flow feels the effect of the sea level.” This region begins at the river mouth and can extend relatively far inland. For instance, the Mississippi River’s backwater reach stretches 500 kilometers (311 miles) from the coast…