July 5th, 2017

2100 AD

Summers around the world are already warmer than they used to be, and they’re going to get dramatically hotter by century’s end if carbon pollution continues to rise. That problem will be felt most acutely in cities. The world’s rapidly growing population coupled with the urban heat island effect — which can make cities up to 14°F (7.8°C) warmer than their leafy, rural counterparts —  add up to a recipe for dangerous and potentially deadly heat. Currently, about 54 percent of the world’s population lives in cities, and by 2050 the urban population is expected to grow by 2.5 billion people. As those cities get hotter, weather patterns may shift and make extreme heat even more common. That will in turn threaten public health and the economy.

Under the high-pollution scenario, currently mild Ottawa, Canada could have the tropical climate of Belize City by 2100. The average land temperature is projected to rise 8.6°F (4.8°C), but due to the vagaries of geography, some cities will warm much more. Sofia, Bulgaria has the biggest overall temperature shift, with temperatures rising nearly 15°F (8.4°C) by 2100. Up to a dozen cities will heat up so much, their summers will have no analog currently on Earth. Reducing carbon emissions still means temperatures will rise in cities (and everywhere else). Dealing with less extreme heat makes adaptation easier and less expensive, and given that choice, perhaps it’s no surprise cities are leading the charge on climate change. They face the worst impacts of extreme heat and are home to billions. That’s why thousands of mayors from around the world have banded together and pledged to reduce their emissions.

That includes multitudes of U.S. cities committing to meet the Paris Agreement goals after President Trump announced he was pulling the U.S. from the pact, and even more ambitious moves like Oslo’s pledge to nearly zero its emissions by 2030.

Kemo D. 7

credit: LiveScience
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Our Tangled Ancestry

According to a report in Science, researchers led by Johannes Krause and Cosimo Posth of the Max Planck Institute for Human History have made the surprising discovery that Neanderthals may have decended from a female member of the lineage of modern humans. They sequenced mitochondrial DNA, which is inherited through the maternal line, from a 120,000-year-old Neanderthal femur excavated from southwest Germany’s Hohlenstein-Stadel Cave in 1937. They then compared the data with the mitochondrial DNA of other Neanderthals and Neanderthal ancestors, Denisovans—a hominin closely related to Neanderthals, and modern humans. The study suggests that sometime between 470,000 and 220,000 years ago, a female relative of modern humans interbred with a male Neanderthal, possibly in the Middle East. Over many generations, her mitochondrial DNA may have eventually replaced Neanderthals’ ancestral mitochondrial DNA. The study could explain why Neanderthals and Denisovans, who have similar nuclear DNA, do not share similar mitochondrial DNA.

Critics say analysis of mitochondrial DNA from additional Neanderthal samples is needed in order to show the material wasn’t inherited from a common ancestor of Neanderthals and modern humans.

Kemo D. 7
credit: Archaeology Magazine