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New evidence that changes in ocean currents triggered abrupt Northern hemisphere warming

Author: Geoff Zeiss - Published At: 2016-07-30 19:38 - (81 Reads)
Climate
An important climate research question is what causes the warming and cooling cycles observed in the last million years of the Earth's paleohistory. One conjecture suggests that variations in the Atlantic Meridional Overturning Current (AMOC), which draws southern tropical surface waters to the North Atlantic where they become increasingly saline and sink to become deep water and flow south, has played a central role in abrupt warming (8–16 °C) events and cooling periods during the last ice age. This new study reports measurements from ocean floor sediments that provide the first direct evidence that changes in ocean currents have triggered abrupt northern hemisphere warming. North Atlantic ocean circulation and abrupt climate change during the last glaciation, L. G. Henry et al., Science 29 Jul 2016, Vol. 353, Issue 6298, pp. 470-474, DOI: 10.1126/science.aaf5529

Rising U.S. emissions responsible for half of increase in global atmospheric methane

Author: Geoff Zeiss - Published At: 2016-05-09 13:53 - (279 Reads)
Waste
Since 2007 global methane emissions have risen again, after stabilizing for several years. A new study suggests that growing U.S. anthropogenic methane emissions could account for 30–60% of the renewed growth in global atmospheric methane. The study, which analyzed GOSAT satellite observations of atmospheric methane, found that U.S. methane emissions have increased by more than 30% over the 2002–2014 period. It was not been possible to identify the source of the increased methane emissions because of the geographic overlap of livestock production and oil and gas production in the U.S. and the limited resolution of the spatial pattern of the methane increase seen by satellite. Turner, A. J., D. J. Jacob, J. Benmergui, S. C. Wofsy, J. D. Maasakkers, A. Butz, O. Hasekamp, and S. C. Biraud (2016), A large increase in U.S. methane emissions over the past decade inferred from satellite data and surface observations, Geophys. Res. Lett., 43, 2218–2224, doi:10.1002/2016GL067987.

7 million people die every year from air pollution – Double previous estimates

Author: Rick Higgins - Published At: 2016-04-16 13:49 - (490 Reads)
The World Health Organization (WHO) estimates that more than seven million deaths every year are linked to air pollution exposure from household and ambient (outdoor) air pollution according to the latest (2014) study. Based on the latest results from WHO air pollution is now the world’s largest single environmental health risk, linked to 12% of all global deaths. Around 4.3 million deaths every year are attributed to exposure to household (indoor) air pollution, from heating, cooking and lighting using solid fuels. Around 3.7 million deaths every year are linked to outdoor air pollution , including exposure to fine particulate matter from fuel combustion from vehicles and from power plants, industry and biomass burning. The burden of deaths from ambient air pollution falls most heavily on the low and middle income countries of SE Asia and the Western Pacific (including China). In the case of indoor air pollution women and children suffer the greatest mortality rates. Burden of disease from ambient and household air pollution. UN WHO

Adaptation by plants may slow down growth in atmospheric CO2

Author: Geoff Zeiss - Published At: 2016-04-10 16:50 - (264 Reads)
Climate
On land plant respiration produces an annual flow of carbon dioxide (CO2) to the atmosphere that is six times as large as the emissions from burning fossil fuels, hence changes in plant respiration can have a major impact on the global climate. The amount of CO2 removed from the atmosphere by photosynthesis increases with warming, but CO2 from plant respiration is expected to rise faster which can accelerate global warming. In this article the authors provide evidence that plants adapt their respiration rates which reduces their CO2 emissions stimulated by warming by 80% in northern and temperate forests. If this is generally true, then CO2 emissions from boreal and temperate forests may not increase in response to warming as much as anticipated. This implies that warming Northern forests may not accelerate global warming. Boreal and temperate trees show strong acclimation of respiration to warming, Peter B. Reich et al., Nature 531, 633–636(31 March 2016)

Changes in methodology doubles WHO estimates of deaths linked to environmental risk factors

Author: Geoff Zeiss - Published At: 2016-03-22 18:13 - (477 Reads)
Waste
The World Health Organization (WHO) has recently released a report with an infographic that headlines as “fact” that 23% of all global deaths are linked to the environment, approximately 12.6 million deaths a year. Since these estimates are widely used to support policy decisions, this article aims to elucidate some of the key sources of uncertainty in their calculation. In particular these estimates include limited and unreliable statistics on cause of death, a reliance on generalizing from epidemiological studies in the U.S. and Western Europe to the rapidly developing cities of Asia, and the limited data about the health effects of the different chemical composition of air pollution in different localities. Our conclusion is that while the latest WHO report is based on the best evidence available, there are still important gaps and concerns with the data underlying the estimates.Preventing Disease through Healthy Environments Second Edition 2016



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