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Weekly Climate Science Roundup: March 1-7

By David Kroodsma, Climate Central

Macaws, the world's largest parrots, are an endangered species. Credit: istock

Nearly every week it seems there are new papers on how ecosystems are responding to climate change, as well as how climate change is affecting species extinction rates. Last week was no different: one paper shows shifting biomes in Alaska, and another compares modern rates of extinction to the “great” extinctions of Earth’s history. The paper on extinction makes for a fascinating read, addressing the key question: how do today’s human-driven extinctions compare to the major biodiversity catastrophes of the past?

Other studies, detailed below, increase our knowledge of the world's largest ice sheets, and one study reveals more complexities of growing crops for use as biofuels. These studies, and a number of others published between March 1-7, are summarized here:

Paper Title: Has Earth’s sixth mass extinction already arrived?
Journal: Nature
Authors: Anthony D. Barnosk and 11 others

The Gist: Paleontologists have identified five periods in Earth’s history when the majority of the planet’s life perished — massive extinctions that claimed over half of the planet’s species of plants and animals. The most well-known of these events occurred 65 million years ago, when the dinosaurs succumbed to what was likely a massive meteor strike. Other mass extinction events occurred 205 million, 251 million, 360 to 375 million, and 440 to 450 million years ago. Today, due to human activities, we are causing massive biodiversity loss. How does this modern era compare to the historical record? By analyzing current and historic extinction rates, the study's authors find that although we have not yet seen extinctions on the scale of these past events, the current rate of species loss is alarming. If species continue to go extinct at their current rate, the authors warn, the next few hundred years could be as calamitous for Earth’s biodiversity as the other five major events.

Climate Central's Alyson Kenward has a more in depth analysis of this paper.

Paper Title: Changes in forest productivity across Alaska consistent with biome shift
Journal: Ecology Letters
Authors: Pieter S.A. Beckand and eight others

The Gist: Vegetation models predict that the boreal forests of Alaska are particularly sensitive to climate change, and that the forests should shift north as the climate warms. This paper analyzes satellite images and tree-ring data from the past 30 years to find that we are already seeing this northward shift.

Paper Title: Acceleration of the contribution of the Greenland and Antarctic ice sheets to sea level rise
Journal: Geophysical Research Letters
Authors: E. Rignot, I. Velicogna, M. R. van den Broeke, A. Monaghan, and J. Lenaer

The Gist: These authors used two techniques to get a highly accurate measure of how much ice is melting in Greenland and Antarctica: these two ice sheets are losing about 500 billion metric tons of ice every year, raising sea levels by a bit more than a millimeter per year. The amount of ice lost, though, is increasing by about 35 billion metric tons per year. Climate Central's Michael Lemonick has more details.

Journal: Science
Authors: Robin E. Bell and 11 others.

The Gist: This paper shows that Antarctica accumulates ice not only from snowfall, but also from “wicking” up water from beneath the ice cover. The authors used radar to reveal some of these fascinating structures on the bottom of the ice sheet, which significantly alters their understanding of how land-based ice sheets grow. Michael Lemonick has a more detailed description of the surprising findings here.

Paper Title: Direct climate effects of perennial bioenergy crops in the United States
Journal: PNAS
Authors: Matei Georgescu, David B. Lobell, and Christopher B. Field

The Gist: Greenhouse gases affect the climate, but so does vegetation. Vegetation that is brighter will reflect more sunlight back into space and make a region cooler. Also, vegetation that draws up water from the soil will create more evaporation, cooling the surrounding area in much the same way your body cools off when you sweat. This study analyzes these effects for a perennial crop in the Midwest that is used for growing biofuels. The authors found that the physical effects — the evaporation and increased reflectivity — had a larger effect on the climate than using the crops to offset fossil fuel use. Another paper this week in PlosOne analyzes how this type of crop would affect migrating bird populations.

Are people's lives in industrial countries improved by using more energy? Above, New York City lights. Credit: jenschapter3/flickr

Paper Title: Does increasing energy or electricity consumption improve quality of life in industrial nations?
Journal: Energy Policy
Author: Allan Mazu

The Gist: It’s fairly clear that people in developing countries are better off when they use more energy. Electric lighting, mechanization, and transportation improve lives. But what about in developed countries, where energy use is already very high? Are people's lives improved by using more energy? This study looks at increases in per capita energy use since 1980 in developed countries and measures how this increase has correlated with well-being. Well-being is measured by a basket of 13 indicators, which range from per capita gross domestic product (GDP) to the societal divorce rate. Of course, any measure of quality of life is highly subjective. Nonetheless, the author finds that in developed countries, increases in energy use do not correlate with increases in well-being.

Paper Title: Air Pollution and climate change co-benefit opportunities in the road transportation sector in Durban, South Africa
Journal: Atmospheric Environment
Authors: Tirusha Thambiranand Roseanne D. Diab

The Gist: The combustion of fossil fuels creates both carbon dioxide (CO2), which contributes to global climate change, and pollutants that contribute to smog formation. Local air pollution is often worse in developing countries, which are also seeing their greenhouse gas emission grow rapidly. This study analyzes the opportunities to reduce both greenhouse gas pollution and local air pollution in South Africa. The paper finds that the best opportunities to do so are to improve the efficiency of the trucking industry, and also to reduce the number of miles private vehicles have to travel.


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