Oxygen on EARTH Magazine

Comment: Could NASA find evidence of extraterrestrial life by 2050?

Tue, 01 May 2018 12:26:02 -0400

The Transiting Exoplanet Survey Satellite, which launched in April, is the successor to the Kepler Space Telescope and is the most sophisticated exoplanet-hunting spacecraft yet. Credit: NASA Goddard Space Flight Center.

by Jacob Haqq-Misra

A flammable planet: Fire finds its place in Earth history

Tue, 09 Jan 2018 07:07:24 -0500

For hundreds of millions of years, wildfires have shaped the planet. Credit: Naomi Kelly.

We owe Earth as we know it to fire. Fire-prone ecosystems cover 40 percent of the land surface today, and fires play a key role in maintaining many of the world’s major biomes, including grasslands, savannas, shrublands and boreal forests. It’s thought that global forests would double in extent in the absence of fire.

Ocean oxygen levels control seafloor carbon burial

Thu, 12 Nov 2015 09:14:26 -0500

A converted local ferry became a research vessel on Lake Matano in Indonesia, where researchers studied organic carbon from lake-floor sediments. Credit: Sergei Katsev.

Residual organic carbon from dead marine phytoplankton and other oceanic life can follow two pathways: It can be deeply buried in seafloor sediments or it can be oxidized, either in the water column or in shallow sediment layers. The balance between these two processes and the extent of organic carbon burial over time are crucial in the global carbon cycle, but a complete understanding of the factors and rates controlling organic carbon burial versus oxidation in the oceans has been lacking. In a recent study in Geology, scientists improved on an approach to quantify organic carbon oxidation and provided a glimpse of marine organic carbon burial in the Precambrian, when the oceans were anoxic and Earth’s atmosphere was in the early stages of oxygenation.

Benchmarks: Sept. 26, 1912: Birth of Preston Cloud, geologist who deciphered banded iron formations

Mon, 15 Dec 2014 14:24:31 -0500

Public domain.

Banded iron formations (BIFs) represent some of the earliest, and most controversial, evidence that the early Earth was devoid of oxygen. These deposits — consisting of thin layers of iron, primarily magnetite and hematite, interspersed with chert, shale and quartz — were recognized for their economic value in the mid-1800s. But it wasn’t until the late 1960s when Preston Cloud, the eminent 20th-century American geologist, focused his vast and wandering intellect on their origins that they assumed their prominent role in the revelation of early Earth history.

Nutrient runoff feeding Baltic Sea dead zone

Tue, 19 Aug 2014 11:04:52 -0400

Hypoxic (red) and anoxic (black) deep waters in the Baltic Sea extend over a far larger area today than they have historically. Credit: J. Carstensen et al. Proceedings of the National Academy of Sciences, 2014.

Low-oxygen, or hypoxic, deep waters now extend over an area of about 60,000 square kilometers in the Baltic Sea, a tenfold increase compared to 115 years ago, according to a recent study published in Proceedings of the National Academy of Sciences. The hypoxic zone has fluctuated substantially in that period, but much of the expansion has occurred in recent decades as a result of large inputs of nutrients like nitrogen and phosphorus from human activities such as agriculture, reported Jacob Carstensen of Aarhus University in Denmark and colleagues.

Trial by Fire

Thu, 05 Jan 2012 06:41:58 -0500

What makes a fire burn? In addition to fuel (such as wood or paper) and heat, fires need oxygen. If there isn’t enough oxygen in the atmosphere, combustion simply won’t happen.

That was as true hundreds of millions of years ago as it is today. So wildfires, scientists say, can provide a unique way to estimate how much oxygen was in Earth’s atmosphere throughout its history.