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The evidence of how climate change is already affecting our world seems to grow more pronounced with every passing day.
At least 2,000 cows at a Kansas feedlot were killed this week by excessively high temperatures, as the latest record-breaking spring heat wave pushed east across the country.
“This was a true weather event — it was isolated to a specific region in southwestern Kansas," A.J. Tarpoff, a cattle veterinarian with Kansas State University, told the Associated Press. “Yes, temperatures rose, but the more important reason why it was injurious was that we had a huge spike in humidity ... and at the same time, wind speeds actually dropped substantially, which is rare for western Kansas.”
On Wednesday, the National Weather Service advised more than one-third of the U.S. population to remain indoors to protect themselves against that same potentially deadly combination of heat and humidity. Scientists have termed that lethal mix the "wet-bulb" effect. When the body gets hot, it sweats, and the evaporation of that sweat helps cool the body. But when the humidity in the atmosphere is too high, that evaporation isn't possible, and the sweat doesn't help cool the body down.
“We need a differential between the human body and the environment, and if the air is already holding as much moisture as it can, you don't have that gradient,” Radley Horton, Lamont Research Professor at Columbia University’s Lamont-Doherty Earth Observatory, told Vice News. “Your body's not able to get the atmosphere to take that moisture from it.”
While climate scientists had previously predicted that such high temperatures and humidity would not arrive on Earth until the mid-21st century, recent studies have found that "extreme humid heat overall has more than doubled in frequency since 1979."
On Monday, 10,000 visitors to Yellowstone National Park had to be evacuated after an excess of rainfall unprecedented for June. Roads, bridges and homes in the park were washed away, the park remains closed, and on Thursday, President Biden issued federal disaster assistance to Montana.
The rain unleashed on Montana was part of a so-called atmospheric river that broke records in Washington state shortly before it pushed east. Studies have linked an increase in those records to rising air and water temperatures caused by climate change.
More generally, research has linked rising global temperatures to higher levels of atmospheric moisture, what's known as the Clausius-Clapeyron relation. When conditions are right, that excess moisture is released, causing severe downpours and storms like the ones that hit the Midwest this week, knocking out power to half a million people amid triple-digit temperatures, and making the need for air conditioning acutely felt.
Meanwhile, the extreme drought that has gripped the American West continues apace. The last 20 years have been the driest two decades in the past 1,200 years. As a result, rivers, lakes and reservoirs are drying up at alarming speed.
The Senate Energy and Natural Resources Committee held a hearing this week on the dwindling water supply in the Colorado River and its reservoirs, including Lake Mead and Lake Powell. In all, 40 million people across the West rely on the Colorado for water.
“What has been a slow-motion train wreck for 20 years is accelerating, and the moment of reckoning is near,” John Entsminger, general manager of the Southern Nevada Water Authority, testified at the hearing. “We are 150 feet from 25 million Americans losing access to the Colorado River, and the rate of decline is accelerating.”
Water-rationing restrictions have been put in place in California and are likely to be extended there and in other states in the coming months.
The science is crystal clear about why these weather-related disasters continue to pile up: Human beings are pumping greenhouse gases like carbon dioxide into the atmosphere, which traps the sun's radiation, warming temperatures.
For years now, the Scripps Institute of Oceanography at the University of California, San Diego, has measured that buildup at the Mauna Loa Observatory in Hawaii, charting the steady rise on a graph known as the Keeling Curve.
Ultimately, researchers say, until mankind reduces the amount of carbon dioxide in the atmosphere, the consequences being witnessed this spring will persist. Just as certainly, they will worsen along with the rise of atmospheric carbon dioxide.
Yet there is still much that we don't know about how climate change will play out in the coming decades. A study published in April in the Cornell University astrophysics journal arXiv concluded that mankind is ushering in an unprecedented shift in the Earth's climate system. Those changes, contrary to the claim of Rep. Marjorie Taylor Greene, R-Ga., earlier this week, are not likely to prove "healthy for us."
"The implications of climate change are well known (droughts, heat waves, extreme phenomena, etc)," researcher Orfeu Bertolami told Live Science in an email. "If the Earth System gets into the region of chaotic behavior, we will lose all hope of somehow fixing the problem."