Quote:

Water Resources Research March 2017 Pages 2404–2418 Research Article The twenty-first century Colorado River hot drought and implications for the future history ABSTRACT Between 2000 and 2014, annual Colorado River flows averaged 19% below the 1906–1999 average, the worst 15-year drought on record. At least one-sixth to one-half (average at one-third) of this loss is due to unprecedented temperatures (0.9°C above the 1906–1999 average), confirming model-based analysis that continued warming will likely further reduce flows. Whereas it is virtually certain that warming will continue with additional emissions of greenhouse gases to the atmosphere, there has been no observed trend toward greater precipitation in the Colorado Basin, nor are climate models in agreement that there should be a trend. Moreover, there is a significant risk of decadal and multidecadal drought in the coming century, indicating that any increase in mean precipitation will likely be offset during periods of prolonged drought. Recently published estimates of Colorado River flow sensitivity to temperature combined with a large number of recent climate model-based temperature projections indicate that continued business-as-usual warming will drive temperature-induced declines in river flow, conservatively −20% by midcentury and −35% by end-century, with support for losses exceeding −30% at midcentury and −55% at end-century. Precipitation increases may moderate these declines somewhat, but to date no such increases are evident and there is no model agreement on future precipitation changes. These results, combined with the increasing likelihood of prolonged drought in the river basin, suggest that future climate change impacts on the Colorado River flows will be much more serious than currently assumed, especially if substantial reductions in greenhouse gas emissions do not occur.

http://onlinelibrary.wiley.com/doi/10.1002/2016WR019638/full

For those struggling with scientific papers read:
http://grist.org/article/climate-change-spells-dry-times-ahead-for-the-west/

For those who are frightened by AGW and its implications (Hi ’Erbert!) just keep your heads safely buried in the sand.

You mean AGW will cause the extra water vapour to remain in the atmosphere?


Jovial Monk wrote on May 19^th, 2017 at 5:40pm:

Whereas it is virtually certain that warming will continue with additional emissions of greenhouse gases to the atmosphere, there has been no observed trend toward greater precipitation in the Colorado Basin, nor are climate models in agreement that there should be a trend.

And also probably climate models show no trend for less precipitation.

https://pubs.usgs.gov/fs/2004/3062/images/fig3.gif

"Thus, variability in the flow values is due both to climatic fluctuations as well as to changes in consumptive water use upstream from the Lee’s Ferry station."

https://pubs.usgs.gov/fs/2004/3062/

" Recently published estimates of Colorado River flow sensitivity to temperature combined with a large number of recent climate model-based temperature projections "

oh, models. ;)

Perhaps they should tell those near the head of the river not to irrigate so much.