Most-recent articles

High quality satellite remote-sensing data lowers estimates of global emissions from deforestation by 40%

Submitted by: Geoff Zeiss - Published At: 2016-01-18 22:26 - (167 Reads)
Forestry and Agriculture
In 2007 the IPCC concluded that deforestation was the second largest contributor of anthropogenic carbon dioxide emissions, after energy. Over the past decade data from earth observation satellites have increasingly been used to clarify how deforestation is defined (for example, by providing more and higher quality data on forest degradation and forest regrowth) and to augment and check the national data compiled by the FAO. A 2012 paper by Harris et al. estimated carbon emissions due to deforestation using only satellite data, without recourse to any FAO data. The new higher quality satellite data and the work by Harris et al. (and other peer reviewed work) has resulted in a significant lowering of the estimated carbon emissions from deforestation by both the FAO's most recent Global Forest Resource Assessment (FRA 2015) and the IPCC's 2015 Assessment Review 5 (AR5). The new estimates have directly affected assessments of where to focus future climate remediation efforts.

Accelerating retreat of massive Greenland glacier detected by remote sensing technologies

Submitted by: Geoff Zeiss - Published At: 2015-11-18 22:54 - (417 Reads)
The massive Zachariæ Isstrøm (ZI) glacier entered a phase of accelerated retreat in fall 2012. Since then its ice velocity has tripled and it is now losing mass at about 5 gigatonnes per year (Gt/yr). ZI, which is in northeast Greenland, holds enough water to raise global sea level by half a meter. In this study data collected with a number of different remote sensing technologies have been used to construct a high resolution profile of the accelerating retreat of the glacier including glacial ice front positions, glacier grounding lines (where the base of the glacier meets the sea), surface velocity, ice thickness and surface elevation since 1992 and even earlier for some data. By combining surface velocity and ice thickness the researchers have been able to calculate the glacier ice discharge from 1976 to 2015. This is an example of how satellite remote sensing has become an essential tool for studying glaciers and ice sheets by allowing research to be conducted over large inaccessible areas even during winter.

5 trillion pieces of plastic floating on World's oceans

Submitted by: Rick Higgins - Published At: 2015-04-26 00:20 - (1592 Reads)
Marine and Oceans
A recent evidence-based study(external link) has been released which estimates the amounts of plastics floating on the oceans. The study is based on extensive surveys from 24 expeditions across the five major rotating ocean current regions (known as ocean gyres) of the sub tropics as well as coastal Australia, the Bay of Bengal and the Mediterranean Sea. The study estimates ("our estimates are highly conservative") there are in the order of 5.25 trillion pieces of plastic weighing around 270,000 tonnes currently floating on the surface of the oceans. As around 8 million tonnes of plastic waste is added to the World's oceans annually the majority of it sinks to the ocean floor. Plastics take in the order of 5 to 40+ years to break up and degrade/decompose in the oceans, depending on their chemical and physical composition. Some are ingested by marine life and some eventually find their way into the food chain for human consumption. Every year around 100,000 marine mammals and turtles are killed by plastic litter. A second recent study(external link) takes available data on plastics entering the oceans from major sources and models the dynamics of how the plastics are flushed from these land sources into the major ocean regions and demonstrates the subsequent transport of plastics by wind and current around the World. Together these 2 studies provide new, more robust estimates of the global situation.

Does rapid Arctic warming cause extreme weather in mid- latitudes ?

Submitted by: Geoff Zeiss - Published At: 2015-03-22 15:57 - (1451 Reads)
This article investigates the conjecture that the rapidly warming Arctic is more important in determining Northern Hemisphere weather patterns than conventional climate dynamics theory holds. We have discussed a previous 2009 article in which Jennifer Frances and colleagues investigated correlations between summer ice extents in the Arctic and broader Northern Hemisphere weather patterns(see Extent of summer Arctic sea ice may help predict Northern Hemisphere weather patterns(external link)). In this 2012 paper Jennifer Francis and Stephen Vavrus propose a mechanism by which Arctic amplification affects broader Northern Hemisphere weather patterns. They provide evidence that a rapidly warming Arctic weakens the pressure gradient between the Arctic and mid-latitudes which slows the jet stream and increases its waviness. Increased waviness in the jet stream has been statistically linked by recent independent studies to extreme weather in the mid-latitudes. This research is still in its early stages and the detailed mechanism proposed in this paper has not yet been widely accepted.
Jennifer Francis, Stephen Vavrus, Evidence linking Arctic amplification and extreme weather in mid-latitudes 2012(external link)

Extent of summer Arctic sea ice may help predict Northern Hemisphere weather patterns

Submitted by: Geoff Zeiss - Published At: 2015-02-26 01:57 - (1537 Reads)
The Arctic Ocean, which is a small body of water compared to the Pacific or the Atlantic oceans, is not considered to be a major determinant of global weather patterns. But in 2009 Jennifer Francis and her colleagues published a paper presenting evidence that the recent faster warming in the Arctic, called Arctic amplification, is changing broader Northern Hemisphere weather patterns. The authors hypothesize possible mechanisms by which the Arctic could influence broader weather patterns. The most controversial of these is the suggestion that decreasing ice extents reduces the temperature gradient between high and mid-latitudes which results in slowing the jet stream which has important implications for Northern Hemisphere weather patterns. A potential application of this research is that summer sea extents could be used to predict Northern Hemisphere weather in the following autumn and winter which would be of value for weather forecasting in the Northern Hemisphere. Francis et al (2009), Geophys. Res. Lett., 36,L07503.(external link)