Bäume verbrauchen zuviel Wasser: Umhauen!

Spiegel Online am 18. April 2018:

Kritik des Bundesrechnungshofs Regierung weiß nicht, was Energiewende kostet
Das Wirtschaftsministerium koordiniert Dutzende Gesetze zur Energiewende. Doch es hat laut Bundesrechnungshof keinen Überblick über deren Kosten. Dabei wird genau das seit mehr als einem Jahr angemahnt.

Weiterlesen auf Spiegel Online

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Die Welt am 17. April 2018:

Altmaier akzeptiert den wahren Zustand der Energiewende
Erstmals hat der neue Bundeswirtschaftsminister zur Energiepolitik gesprochen. Dabei hätte er relativ einfach Applaus einsammeln können. Doch Altmaier verzichtete auf das Erzählen eines alten deutschen Klima-Märchens.

Weiterlesen auf welt.de

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Das Barcelona Institute for Global Health warnte am 25. April 2018 vor Krebsgefahr bei Verwendung von energiesparenden weißen LEDs (via EurekAlert!) :

Study links night exposure to blue light with breast and prostate cancer

Researchers used images taken by astronauts to evaluate outdoor lighting in Madrid and Barcelona

A study performed by an international team led by the Barcelona Institute for Global Health (ISGlobal), a centre supported by the “la Caixa” Foundation, reports a link between exposure to blue light at night and higher risk of developing breast and prostate cancer. Blue light is a range of the visible light spectrum emitted by most white LEDs and many tablet and phone screens. The results have been published in Environmental Health Perspectives.

“WHO’s International Agency for Research on Cancer (IARC) has classified night shift work as probably carcinogenic to humans. There is evidence pointing to an association between exposure to artificial light at night, disruption of the circadian rhythm, and breast and prostate cancers. With this study we sought to determine whether night exposure to light in cities can affect the development of these two types of cancer”, explains Manolis Kogevinas, ISGlobal researcher and coordinator of the study. “We know that depending on its intensity and wave length, artificial light, particularly in the blue spectrum, can decrease melatonin production and secretion”, says Martin Aubé, physics professor at CÉGEP in Sherbrooke, Canada and study co-author.

The study was conducted within the framework of the MCC-Spain project cofunded by the ‘Consorcio de Investigación Biomédica en Red de Epidemiología y Salud Pública’ (CIBERESP), and includes medical and epidemiological data of more than 4,000 people between 20 and 85 years of age in 11 Spanish regions. Indoor exposure to artificial light was determined through personal questionnaires, while outdoor levels of artificial light were evaluated for Madrid and Barcelona, based on nocturnal images taken by astronauts aboard the International Space Station. Results obtained for both cities show that participants exposed to higher levels of blue light had a 1.5 and 2-fold higher risk of developing breast and prostate cancer, respectively, as compared to the less-exposed population.

Ariadna García, ISGlobal researcher and first author of the study, says: “Given the ubiquity of artificial light at night, determining whether it increases or not the risk of cancer is a public health issue”. At this point, further studies should include more individual data using for instance light sensors that allow measuring indoor light levels. It would also be important to do this kind of research in young people that extensively use blue light emitting screens”.

“Currently, the images taken by the astronauts on the Space Station are our only way of determining the colour of outdoor lighting at a large scale, and the spread of blue light-emitting white LEDs in our cities”, comments Alejandro Sánchez de Miguel, scientist at the Astrophysics Institute in Andalucía-CSIC and Exeter University.

Reference: Garcia-Saenz A., Sánchez de Miguel A., Espinosa A., Valentín A., Aragonés N., Llorca J., Amiano P., Martín Sánchez V., Guevara M., Capelo R., Tardón A., Peiró-Pérez R., Jiménez-Moleón JJ., Roca-Barceló A., Pérez-Gómez B., Dierssen-Sotos T., Fernández-Villa T., Moreno-Iribas C., Moreno V., García-Pérez J., Castaño-Vinyals G., Pollán M., Aubé M., Kogevinas M. Evaluating the association between artificial light-at-night exposure and breast and prostate cancer risk in Spain (MCC-Spain study). April 2018. DOI:10.1289/EHP1837. Environmental Health Perspectives

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Kurios: Weil Bäume Wasser brauchen, sollen sie jetzt in einigen Gegenden der Welt umgehauen werden, um die Wasserressourcen zu schonen. Pressemitteilung der US-amerikanischen National Science Foundation (NSF) vom 23. April 2018:

Billions of gallons of water saved by thinning forests

Too many trees in Sierra Nevada forests stress water supplies, scientists say

There are too many trees in Sierra Nevada forests, say scientists affiliated with the National Science Foundation (NSF) Southern Sierra Critical Zone Observatory (CZO). That may come as a surprise to those who see dense, verdant forests as signs of a healthy environment. After all, green is good, right? Not necessarily. When it comes to the number of trees in California forests, bigger isn’t always better. That’s in part because trees use lots of water to carry out basic biological tasks. In addition, they act as forest steam stacks, raking up water stored in the ground and expelling it as vapor into the atmosphere, where it’s accessible to humans and forest ecosystems only when it falls back to Earth as rain and snow.

That process — by which plants emit water through tiny pores in their leaves — is known as evapotranspiration. And according to researchers, excessive evapotranspiration may harm a fragile California water system, especially during prolonged, warm droughts. New research published this week in the journal Ecohydrology shows that water loss from evapotranspiration has decreased significantly over the past three decades. That’s due in large part to wildfire-driven forest thinning — a finding with important implications for forest and water management. A century of forest management had kept wildfires to a minimum. But without fire, Sierra forests grew very dense. In recent decades, new policies have allowed nature to take its course, with wildfires helping to thin out overgrown forests.

“Forest wildfires are often considered disasters,” said Richard Yuretich, director of NSF’s CZO program, which funded the research. “But fire is part of healthy forest ecosystems. By thinning out trees, fires can reduce water stress in forests and ease water shortages during droughts. And by reducing the water used by plants, more rainfall flows into rivers and accumulates in groundwater.” Using data from CZO measurement towers and U.S. Geological Survey satellites, researchers found that over the period 1990 to 2008, fire-thinned forests saved 3.7 billion gallons of water annually in California’s Kings River Basin and a whopping 17 billion gallons of water annually in the American River Basin — water that would otherwise have been lost through evapotranspiration.

Forest thinning has increased in recent decades in an effort to stave off disastrous wildfires fueled by dense forests. This study shows that restoring forests through mechanical thinning or wildfire can also save California billions of gallons of water each year. “The need for forest restoration is being driven largely by the need to lower the risk of high-intensity wildfires and restore forest health,” said University of California Merced scientist Roger Bales, director of the Southern Sierra CZO and study co-author. “Downstream users who benefit from the increased water yield are an important potential revenue stream that can help offset some of the costs of restoration.”

Forested areas needing restoration are large, Bales said, but potential changes in water availability are significant. The total effect of wildfires over a 20-year period suggests that forest thinning could increase water flow from Sierra Nevada watersheds by as much as 10 percent. The U.S. Forest Service says that 6 to 8 of the 21-million acres it manages in California need immediate restoration. Another 58 million acres nationally also require restoration. For California alone, restoration costs are estimated at $5 to $10 billion. But, according to the study authors, the restoration might help pay for itself. “We’ve known for some time that managed forest fires are the only way to restore the majority of overstocked western forests and reduce the risk of catastrophic fires,” said James Roche, a National Park Service hydrologist and lead author of the new study. “We can now add the potential benefit of increased water yield from these watersheds.”