Un nuevo estudio dirigido por la Universidad de Yale cuantifica por primera vez las principales causas de la "isla de calor urbana " (ICU), un fenómeno común que hace que las áreas urbanas del mundo sean considerablemente más calientes que los alrededores y puede incrementar los riesgos de salud para los residentes de la ciudad.
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Astrobiologists from the United States and Germany recorded the highest known level of solar UV radiation to reach Earth's surface. This was around 10 years ago.
On December 29, 2003, the UV Index (UVI) peaked, reaching the blistering number of 43.3 over the Andes Mountains in Bolivia. To put this in context, a beachgoer in the United States would expect a UVI of 8 or 9 on a summer day. Even with an 8 or a 9, one may not escape the day without sunburn.
Nonetheless, it has taken scientists 10 years to detail a report of this data while taking into account all of the variables and anomalies monitored from an international network of dosimeters – or Eldonets (European Light Dosimeter Network) – that measure UV radiation worldwide. This system is comprised of more than 100 stations across 5 continents to account for variation in the atmosphere above each station.
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The Amazon is the largest tropical forest on the planet, covering about 6.5 million square kilometers, although much has been lost (around 18-20 percent) in recent decades. The great forest also, very likely, contains the highest biodiversity of species on land; for example a single hectare in Yasuni National Park contains more tree species than all of the U.S. and Canada combined. Yet new research published in the Proceedings of the National Academy of Sciences (PNAS) finds that quite recently—just 500 years ago—a significant portion of the southern Amazon was not the tall-canopied forest it is today, but savannah.
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A new Yale-led study quantifies for the first time the primary causes of the "urban heat island" (UHI) effect, a common phenomenon that makes the world's urban areas significantly warmer than surrounding countryside and may increase health risks for city residents. In an analysis of 65 cities across North America, researchers found that variation in how efficiently urban areas release heat back into the lower atmosphere — through the process of convection — is the dominant factor in the daytime UHI effect. This finding challenges a long-held belief that the phenomenon is driven principally by diminished evaporative cooling through the loss of vegetation.
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Extreme weather events and other natural disasters claimed the lives of more than 2,700 people and caused around US $42 billion in damage worldwide in the first half of 2014, but this was well below the first half of last year and a 10-year average, according to new research from reinsurer Munich Re. However, the briefing report warns that towards the end of the year the natural climate phenomenon El Niño may impact regions differently in terms of the number and intensity of weather extremes.
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