Temperature & southwest drought: an unseen climate disaster in 1,200 years

In June 1988, when James Hansen, a Nasa climatologist, testified to Congress about a warming planet in Washington DC it reached a record 100 degree F. This was the summer of unprecedented heatwaves, and 40 states were suffering from drought. His warning was viewed as a historical wake-up call. But instead of listening to the existential smoke alarm, the US took out the batteries and continued cooking. Nearly forty years later, the effects of a scorching Earth are being felt in the US's southwest and mountain-west - which includes states from California to Colorado. The past 20 years have seen extreme heat and decreasing moisture levels combine to create the dryest period in 1,200 years. [caption id="attachment_39252" align="aligncenter" width="1200"] Dry land that would be underwater when the lake is full is seen next to Gregory Butte in Arizona’s Lake Powell. Photograph: Rick Wilking/Reuters[/caption] As once rare conditions are becoming the norm, the west is in new territory. The world's largest reservoirs, Lake Mead (and Lake Powell) are at an all-time low and slowly shrinking. Cities like Phoenix, Arizona and Las Vegas (Nevada) are almost unlivable during the summer heatwaves. Wildfires are now more likely to ignite year round, as the grasslands and forests that have been dry for so long are more ready than ever. The Washington Post recently conducted an analysis and found that in certain parts of the southwest average annual temperatures have risen by more than 1.5C. This threshold is widely believed to be the tipping point where catastrophic consequences for the environment and people can occur. These extraordinary conditions are a warning sign of what lies ahead in other arid areas that cross this line. This is a reminder that despite all the innovations made to avoid an unforgiving climate and if drastic measures are not taken soon, drought could once again rule the region. Bill McKibben is a journalist and climate activist who says that climate scientists gave us an excellent warning. "And yet, rather than demonstrating the will to act, our political, economic, and social systems rallied to nothing." [caption id="attachment_39256" align="aligncenter" width="1200"] A dead Joshua tree affected by worsening drought in Arizona. Large portions of the west are now classified as being in exceptional drought. Photograph: David McNew/Getty Images[/caption] Tim Kohler is an archaeologist who is also a professor at Washington State University. He says that the megadrought of today is unlike prehistoric dry periods. He says, "This drought seems to be worse than any of the other droughts, and it lasts just as long." The bad news is that all previous megadroughts occurred without increasing greenhouse gas emissions. Scientists don't know what we can expect. Recent research has demonstrated how these compelling forces play out on the ground.