monsoon-shifts | GarryRogers Nature Conservation

GR: The article below illustrates the value of scientific analysis. The Southwest Monsoon has always caused flooding. However, memory alone is an unreliable indicator of changes in storm strength; numerical comparison of time periods is better. The analysis mentioned in this article confirms the assertion that climate-change is bringing stronger storms to the Southwest.

Flooding is the primary danger from intense monsoon storms, but around my house you sometimes have to dodge falling branches too. Combining wind and rain-soaked leaves often breaks the brittle branches of the weeping willows surrounding my place. The one below fell on Sunday. It only weighs a few hundred pounds, but over recent years, branches weighing several tons have fallen. The ominous sounds of cracking and crashing lend wings to one’s feet.

Fallen weeping willow branch.

From LabRoots:

“A new study published recently in the Journal of Applied Meteorology and Climatology suggests that the North American Monsoon (NAM) is becoming more intense in the United States Southwest, particularly in Arizona. Their results show that while storms are not as frequent as they have been in the last 60 years, the rain episodes are heavier and include high winds, dust storms, and flooding, which often threaten residents and property. This pattern, the study concludes, is consistent with flux caused by climate change.

Monsoons often come on suddenly. Photo: The Arizona Experience

“Because of specific Department of Defense installations in the Southwest, and because the existing models of the NAM do not represent patterns in the climate accurately, the team analyzed Arizona rainfall data from 1950-1970 and compared it with data from 1991-2010. Defining severe weather events as days when the highest atmospheric instability and moisture occur within a long-term regional climate simulation, the scientists found that while the mean precipitation for the region stayed the same during the different time epochs, the later time period had more heavy-rain storms.” –Kathryn DeMuth Sullivan (More: American Southwest threatened by heavy-rain monsoons).

GR: This warning is worth repeating. It needs to reach the ears of the climate-change deniers whose willful ignorance is endangering all of us and all the creatures sharing this ride with us. Storms, floods, and droughts will get worse.

Cloudburst, North Vancouver: Wet or dry, extremes will become more intense. Image: Terence Thomas via Wikimedia Commons

“Wet and dry extremes across the world will become more marked as the planet heats up, evidence from past climates shows.”

“Two US scientists have once again confirmed one of the oldest predictions of climate change: that those regions already wet will become wetter, while the arid zones will become drier.

“This time the reasoning comes not just from computer models of future climate, but also from the evidence of the past.

“Because the northern hemisphere will warm faster than the southern, the temperature difference will drive the planet’s rainbelts northwards, at least during the winter months. The tropics will become wetter, while the subtropics and the mid-latitudes will become drier, and this will be most noticeable in June, July and August.

“The predictions – made in the journal Science Advances – come from two researchers. Aaron Putnam is a glaciologist who studies ancient climates at the University of Maine. Wallace Broecker is an oceanographer at the Lamont-Doherty Earth Observatory of Columbia University, and one of the pioneers of climate research.” –Tim Radford (Learn more: Warmth will worsen wet and dry extremes – Climate News NetworkClimate News Network.)