A new estimate of biodiversity on Earth

by University of Chicago Press Journals, August 30, 2017 in ScienceDaily


To date, about 1.5 million species have been formally described in the scientific literature, most of them insects. Proportionally, bacteria comprise less than 1% of all described species.

In a new paper published in The Quarterly Review of Biology (September 2017), researchers from the University of Arizona have estimated that there are roughly 2 billion living species on Earth, over a thousand times more than the current number of described species.

The onset of widespread marine red beds and the evolution of ferruginous oceans

by Haijun Song et al., August 2017, in Nature


Banded iron formations were a prevalent feature of marine sedimentation ~3.8–1.8 billion years ago and they provide key evidence for ferruginous oceans. The disappearance of banded iron formations at ~1.8 billion years ago was traditionally taken as evidence for the demise of ferruginous oceans, but recent geochemical studies show that ferruginous conditions persisted throughout the later Precambrian, and were even a feature of Phanerozoic ocean anoxic events.

Soil carbon debt of 12,000 years of human land use

by J. Sanderman et al., July 2017 in PNAS


Human appropriation of land for agriculture has greatly altered the terrestrial carbon balance, creating a large but uncertain car- bon debt in soils. Estimating the size and spatial distribution of soil organic carbon (SOC) loss due to land use and land cover change has been difficult but is a critical step in understand- ing whether SOC sequestration can be an effective climate mitigation strategy.

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Volcanic eruptions drove ancient global warming event

by Marcus Gutjah et al., August 30,  2017 in PhysOrg


A natural global warming event that took place 56 million years ago was triggered almost entirely by volcanic eruptions that occurred as Greenland separated from Europe during the opening of the North Atlantic Ocean,

The amount of carbon released during this time was vast—more than 30 times larger than all the fossil fuels burned to date and equivalent to all the current conventional and unconventional fossil fuel reserves we could feasibly ever extract.” Ridgwell said.

An unexpected finding was that enhanced organic matter burial was important in ultimately sequestering the released carbon and accelerating the recovery of the Earth’s ecosystem without massive extinctions.

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Climate-driven variability in the occurrence of major floods across North America and Europe

by Glenn A. Hodgkins et al., September 2017 in Journal of Hydrology


 

Trends in major-floods from 1204 sites in North America and Europe are assessed.

Trends based on counting exceedances of flood thresholds for groups of gauges.

The number of significant trends was about the number expected due to chance alone.

Changes in the frequency of major floods are dominated by multidecadal variability.

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Texas Major Hurricane Intensity Not Related to Gulf Water Temperatures

by Ph.D. Roy Spencer, August 29, 2017 in GlobalWarming


As the Houston flood disaster is unfolding, there is considerable debate about whether Hurricane Harvey was influenced by “global warming”. While such an issue matters little to the people of Houston, it does matter for our future infrastructure planning and energy policy.

Let’s review the two basic reasons why the Houston area is experiencing what now looks like a new record amount of total rainfall, at least for a 2-3 day period over an area of tens of thousands of square miles.

Water Intrusion in the Chesapeake Bay Region: Is It Caused by Climate-Induced Sea Level Rise?

by Roger H. Bezdek, August 2017 in SciRes


Our findings indicate that the water intrusion problems in the region are due not to “sea level rise”, but primarily to land subsidence due to groundwater depletion and, to a lesser extent, subsidence from glacial isostatic adjustment. We conclude that water intrusion will thus continue even if sea levels decline. These findings are critical because the water intrusion problems in the Chesapeake Bay—and elsewhere—cannot be successfully solved unless their causes are correctly identified and appropriate remedies are devised.

Quantifying the causes of the recent decrease in US CO2 emissions

by Roger Andrews, August 23, 2017 in Energy Matters (blog)


Between 2007 and 2015 total annual US CO2 emissions decreased by 740 million tons (12%). An updated analysis shows that 35% of this decrease was caused by natural gas replacing coal in electricity generation, 30% by lower fuel consumption in the transportation sector, 28% by renewables replacing