A Creeping Reaper...

The 100th meridian west (solid line) coincides with the climate divide between the relatively moist eastern U.S. and the more arid West. Climate change may already be pushing the divide eastward (dotted line).
Credit: Richard Seager Lamont-Doherty Earth Observatory

Topics: Climate Change, Greenhouse Gases, Weather

I used to live in Central Texas where an average summer temperature is 110 degrees Fahrenheit and a "cold front" is 90 degrees in comparison. I also suffered mightily from "Cedar Fever," a pollen from a popular local genus of tree. I also remember it being particularly lethal for senior and younger citizens as temperatures climbed. My wife has had her bouts with pine in New York and now North Carolina.

So CBS News reported in March that the intensity of allergy seasons may be extended by climate change as well as associated health risks from malaria to kidney stones and waterborne parasites. It makes it personal; denial hard to do when you're on an antibiotic more than you'd like to be.

The unfortunate part is, I think through denial and selfishness, we've waited beyond a window where we could do anything about it.

*****

To travel westward across the U.S. is to experience a striking landscape metamorphosis. Stately hardwood trees give way to squat shrubs, verdant cornfields to brown wheat and lush grasslands to cacti and creosote bush. The air dries out and the land is often parched. This rather abrupt shift from the humid east to arid west occurs along a border that slices neatly through the Canadian province of Manitoba, then the Dakotas, Nebraska, Kansas, Oklahoma, Texas and into eastern Mexico. The divide is so stark airline passengers can see it—a patchwork quilt of green farms on one side, a vast expanse of brown and gold on the other.

And now this boundary is on the move, creeping east as global temperatures rise, according to new research published last month in Earth Interactions. Given the line’s historical role in shaping U.S. westward expansion, its shift could alter the agriculture that plays a crucial role in the economy of the Great Plains states. [1]

Methane (CH4) is a potent greenhouse gas that is roughly 30 times more harmful to the climate than carbon dioxide (CO2). Both gases are produced in thawing permafrost as dead animal and plant remains are decomposed. However, methane is only formed if no oxygen is available. Until now, it was assumed that larger amounts of greenhouse gases are formed when the ground was dry and well aerated—when oxygen was available. Christian Knoblauch and his colleagues have now demonstrated that water-saturated permafrost soils without oxygen can be twice as harmful to the climate as dry soils—which means the role of methane has been greatly underestimated.

Knoblauch has, for the first time, measured and quantified in the laboratory the long-term production of methane in thawing permafrost. The team had to wait for three years before the approximately 40,000 year-old samples from the Siberian Arctic finally produced methane. The team observed the permafrost for a total of seven years, an unprecedented long-term study.

They found that without oxygen, equal amounts of methane and CO2 are produced. But since methane is a far more potent greenhouse gas, it is more significant. Because methane production couldn't be measured, it was assumed that in the absence of oxygen only very small amounts of it can be formed. "It takes an extremely long time until stable methane-producing microorganisms develop in thawing permafrost," explains Knoblauch. "That's why it was so difficult to demonstrate methane production until now." [2]

1. A Nation Divided: Arid/Humid Climate Boundary in U.S. Creeps Eastward, Shannon Hall, Scientific American
2. Thawing permafrost produces more methane than expected, Helmholtz Association of German Research Centres, Phys.org