The drought in the southwestern U.S. isn't new - it's actually a couple of decades old now.

Drought, wildfires, declining water supplies, threats to human health made even more dangerous by urban design flaws and socioeconomic inequities — the climate crisis has already hit the Southwest hard. And it’s only going to get worse.

On Monday, the US government announced a water shortage for the first time in the Colorado River, in the southwest of the country. Western North America has been ravaged by drought and wildfires for months.

The drought in the southwestern U.S. isn’t new - it’s actually a couple of decades old now.

At more than 420 parts per million (ppm) in May, scientists measured the highest levels of carbon in the atmosphere since they started taking direct measurements 63 years ago at Hawaii's Mauna Loa Observatory.

The largest reservoir in the US has fallen to the lowest level in history.

Climate and business experts say tough decisions must be made in the next few months, as the Western drought intensifies and water resources dry up.

Lake Mead, the reservoir in Nevada created by Hoover Dam, has sunk to its lowest level ever, underscoring the gravity of the extreme drought across the US west.