Great piece by Daniel Collins today on Pinus edulis (our beloved piñon) and decadal-scale climate variability.

[T]his episodicity was driven not by natural population processes but by the progression of strong decadal wet and dry regimes, as evidenced by the tree ring data. During pluvial events (pluvial is the opposite of drought), abundant soil moisture promoted pinyon germination and seedling survival. Soil moisture is critical at these developmental stages. Decadal-scale climate variability might have also regulated pinyon pine expansion through its effects on seed masting, the abundance and activity of animal dispersers, or even the movements of Native Americans (pine nuts were a staple food).

Talking about drought with Mom and Dad at dinner tonight (my poor family), I brought up the “Civil War Drought”, which hit the middle of North America in the late 1850s and ’60s. Dad wanted to know more about where it hit, and I wasn’t sure. I found out. I could just call and tell him, but why not just broadcast it to the WorldWeb?

At the risk of everything currently looking like a nail to me, given the particular climate variability hammer I have in my hand, it turns out that the Civil War Drought is yet another example of what happens when people adjust to a wet climate and then get whacked when it gets dry. That’s according to the story told by Richard Seager and Celine Herweijer, who have an excellent web page on their work on this:

In the preceding decades the Indian population had increased as they moved onto the Plains in the face of the westward expansion of European settlement. Indians made this decision during an unusually wet period when grasses were high, bisons abundant, and a switch to a horse and hunting-based lifestyle seemed viable. At the same time European emigrants were heading across the Plains bound for the West accompanied by large numbers of horses, mules and oxen. The U.S. Army had also spread across the region.

This peopling of the Plains greatly impacted the bison through an increased competition for resources. During drought the bison would move to the river valleys where grasses would still survive. But these valleys now also were home to Indian camps and the emigrants headed West and their animals, all for the same reason of better water supply.

From the mid 1850s to the mid 1860s the West and Plains were struck by a severe drought.

The map (a tree ring reconstruction of drought conditions – not enough rain gauges yet) shows a bullseye in the middle of the United States, with just the northeast and the deep south escaping drought.

Nick Brooks kindly dropped by a few weeks back with a comment that’s worth pulling out and highlighting in its entirety. Brooks is assistant director of the University of East Anglia’s Saharan Studies Programme, and I’d commented on a paper of his on cultural response to climate change. Nick’s comment:

Flattering that you guys are discussing my paper in this capacity. It seems to me that people are reading what they want into my work, based on their existing views of civilisation and progress. If we accept the substantial evidence that the first large urban, state-level civilisations emerged in large part as a response to climatic deterioration, we might think that this was a good thing, if we believe in progress based on technological and political innovation.

Continue reading ‘Brooks on Climate, Society and “Progress”’ »

This is a great example of the issue Daniel Collins raised a couple of days ago in a discussion of the definition of drought – the extent to which the demand side of the equation must be taken into consideration. It’s a Reuters story about Prince Edward’s visit to northwest Kenya, “where drought has decimated livestock and caused widespread hunger.”

Already leading tough subsistence lives, Turkana’s population of half a million mainly nomadic herders have suffered further from a drought under way since last year, losing up to half of their precious livestock in some places.

Cattle-rustling and clashes between tribes over scant resources are common, especially on the border.

Child malnutrition levels have reached 30 percent.

“Of the children who are picked up and come here for treatment, recovery is fifty-fifty,” said district public health officer Chris Lirunde at the Lodwar District Hospital.

“But there are remote areas where nobody knows what is going on. There, the people are at the mercy of God.”

I’ll refer again to the Standardized Precipitation Index, which suggests that, while folks in neighboring Uganda, Sudan and the Congo are suffering potentially serious precipitation deficits over the last year, northwest Kenya is not.

I’m not going to begrudge these people their drought. Here in New Mexico, “drought” means a bad ski season and some economic hardship for farmers. In northwest Kenya, children die. A third of Kenya’s population is malnourished. Call it whatever, that’s bad. But this again illustrates that a big part of what people perceive as drought is not entirely related to how much rain falls from the sky.

(The caveat: I’m using SPI, which Daniel points out only captures precipitation, and not things like evaporation and soil moisture, which are important to farmers and people making their living raising cattle. In this case, it’s the best I’ve got. If anyone knows a source of Palmer-like drought indexes for Africa, I’d be most appreciative.)

Heard on a local TV ad today:

Skiers and snowboarders! El Niño is back, and it’s gonna be a great year!