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Human activities currently add about nine gigatons of carbon to the atmosphere yearly. Photosynthetic organisms on land and in the ocean absorb about five of those gigatons through the natural uptake of CO2, leaving to humans the task of dealing with the rest. But no matter how much carbon there is, capturing it and preventing it from reentering the atmosphere is an immense engineering challenge; even today's best technology is orders of magnitude less effective than photosynthesis at trapping atmospheric carbon.

The Miller-Urey experiment was the first attempt to scientifically explore ideas about the origin of life. Stanley Miller simulated conditions thought be common on the ancient Earth. The purpose was to test the idea that the complex molecules of life (in this case, amino acids) could have arisen on our young planet through simple, natural chemical reactions. The experiment was a success in that amino acids, the building blocks of life, were produced during the simulation. The finding was so significant that it kick started an entirely new field of study: Prebiotic Chemistry. Scientists now have reason to believe that the gases used in the Miller-Urey simulation were not actually the same as those of the ancient atmosphere. Because of this, many experiments have since been done, testing a wide variety of atmospheres and different environmental conditions. The results are overwhelming: the molecules of life can form under a wide variety of ancient Earth-like conditions. Many questions about the origin of life remain to be answered but these findings give strong support to the idea that the first living cells on Earth may have emerged from natural chemical reactions.

This interactive activity adapted from the University of Alberta illustrates how, through a process called fixation, nitrogen flows from the atmosphere, into the soil, through various organisms, and back to the atmosphere in a continuous cycle.

While surveying the seafloor last fall, a research vessel spotted bubbles rising from the depths. Now, another ship has gone back to investigate, and found a variety of life on the seafloor surrounding a methane seep, according to an update from researchers with the National Oceanic and Atmospheric Administration (NOAA).

Researchers working with the National Oceanic and Atmospheric Administration say warmer, more acidic oceans may reduce the number of stone crab hatchlings as the availability of the popular, pricey delicacy dwindles.

Data from three major climate-tracking groups agree: The combined land and ocean surface temperatures hit new highs this year, according to the United States' National Oceanic and Atmospheric Administration (NOAA), the United Kingdom's Met Office and the World Meteorological Association.

Nitrogen is one of the primary nutrients critical for the survival of all living organisms. Although nitrogen is very abundant in the atmosphere, it is largely inaccessible in this form to most organisms. This article explores how nitrogen becomes available to organisms and what changes in nitrogen levels as a result of human activity means to local and global ecosystems.

National Oceanic&Atmospheric Administration, Global Greenhouse Gas Reference Network

In this interrupted case study developed for use in a flipped classroom, students read about a picnic that takes place in autumn during the peak of fall color and along the way learn about light absorption by photosynthetic pigments, why leaves turn color in the fall, atmospheric CO2 concentrations and their effect on photosynthesis, and the C3, C4, and CAM photosynthetic pathways. The case is designed to provide introductory biology students with a basic understanding of photosynthetic pathways and how environmental factors affect plants using these pathways. The activity could also be used in an advanced high school biology course covering photosynthesis. The case includes several short videos that students watch as homework before coming to class so that they are prepared to work together in class in small groups to answer the case questions.

Séguin, a research scientist in forest genomics with the Canadian Forest Service, inserted bacterial DNA into spruces that effectively made them immune to spruce budworm, a pest that can chew needles off tens of millions of hectares of trees in a single outbreak. While there is controversy over genetic engineering, some scientists say it could also help fight climate change by creating trees that grow bigger, faster, resist disease and can even turn carbon into a stable white powder that falls to the ground - in other words, trees that would be better at pulling carbon from the atmosphere.

The online textbook provides a background to understand and discuss the natural functioning of the different Earth systems; it introduces humans as part of the overall ecosystem and explores what is needed to sustain human life; and it looks at the effects that human actions have on different natural systems. The online textbook also includes full-color images of related figures, glossary terms, and a bibliography for further reading.