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As Arizona ends one of its driest monsoons on record, many may wonder how climate change is affecting the source of one-third to one-half of the state’s rainfall.

Earth's atmospheric carbon dioxide levels averaged over 417 ppm in 2022, and even recently reached a daily reading of over 424 ppm. When this story first published in 2019, CO2 levels hovered around 412 ppm. They keep rising, relentlessly.

Spread between Nevada and Arizona—Lake Mead, the largest man-made reservoir in the U.S.—is best known for its rapidly declining water levels due to the ongoing megadrought gripping the western states. The lake is integral to surrounding communities, as it is also formed by the Hoover Dam on the Colorado River—which generates electricity for thousands of people. If the water levels continue to decline, the consequences could be catastrophic.

Across the western United States, many areas are drying up, and Lake Powell and Lake Mead continue to reach historic lows.

At the end of June, the Bureau of Reclamation (BOR) gave the seven states along the Colorado River 60 days to make serious cuts to water usage or the bureau would do it for them.

Dramatic before-and-after photos of Lake Mead are providing visual evidence to the alarming rate in which the water levels at the largest reservoir in the country are receding.

Dramatic before-and-after photos of Lake Mead are providing visual evidence to the alarming rate in which the water levels at the largest reservoir in the country are receding.

Twenty-nine states are under excessive heat warnings today as the Southwest suffers through record drought. ABC News’ Christie Ileto has the latest.