Global warming and volcanic impact

Climate researchers have shown that large volcanic eruptions in the past 450 years have helped temporarily cool the climate in tropical regions, but they also claim that those effects have not been received. seen in the 20th century because of the rise in global temperature. Their article, showing that higher latitudes are more sensitive to volcanoes, was published in Nature Geoscience.

Scientists have agreed that large eruptions contribute to lower temperatures in high latitudes in recent centuries, because volcanic particles reflect sunlight into space.For example, in 1816, the year after the Tambora eruption in Indonesia, it became known as 'The Year Without Summer' after low temperatures caused crop failures in Northern Europe and Eastern North America. Other evidence comes from wood veins, which become thinner in low-temperature years.

This is one of the first studies to show the reaction of the tropics, lead author Rosanne D'Arrigo, scientist at the Wood Grain Laboratory at Columbia University's Lamont-Doherty Earth Observatory for know. He added: 'This is important because it gives us more information about the tropical climate's response to the agents that alter the impact of solar radiation.' Other authors include Rob Wilson of Lamont and the University of St. Louis. Andrews, Scotland; and Alexander Tudhope of Edinburgh University, Scotland.

This is Mount Bromo, an active volcano in East Java, Indonesia. (Photo:: Paul Krusic, Lamont-Doherty Earth Observatory)

Along with the wood grain, researchers analyzed ice cores from alpine glaciers, and corals were taken from a large tropical area. As the temperature decreases, not only does the plant grow poorly, but the oxygen isotope in corals and ice can change. All showed that low latitude temperatures declined for several years after major tropical eruptions. Specimens were collected from Nepal down to Indonesia and through the Indian and Pacific Oceans, ice cores were taken from Peru's Andes. The researchers used the materials they collected, as well as samples collected by other scientists.

Data show that the coolest climate maintained for the longest is due to two events: the eruption in 1809 in the tropics, but the exact location is unknown, and erupts Tambora in 1815, one of the most intense eruptions recorded in human history. After Tambora, from 1815 to 1818, tropical temperatures decreased by 0.84 degrees C (1.5 degrees F). A greater reduction in temperature was in 1731 - 0.9 degrees C (1.6 degrees F). The researchers say this phenomenon may be related to eruptions of Lanzarote volcano of the Canary Islands, and Sangay in Ecuador.

The study also found that higher latitudes are often more sensitive than the tropics. Some temperature reductions in the northern region after the eruptions are usually three times larger. D'Arrigo said the high-latitude sensitivity of these areas comes from complex feedback mechanisms that make these areas vulnerable to temperature changes. This phenomenon is also consistent with evidence from other researchers, that when the earth warms, the greatest effects are seen from the melting of glaciers, sea ice and tundra in high latitudes. .The authors say, overall, eruptions in the 20th century created less impact on the tropics. They claim that it may be due to the few major events that occurred in this century - but they also emphasized the broad impact of the warming phenomenon in the 20th century.

D'Arrigo concluded: 'A decade with warm climate has obscured the cooling effect of some volcanic events'. She stressed that very few records existed before this time: 'This study provides a small amount of comprehensive information about the response of tropical climate systems to fire eruptions'.

Refer:

Rosanne D'Arrigo, Rob Wilson & Alexander Tudhope.Impact of volcanic để định vị lại khi thời gian trong thời gian cuối thứ four.Nature Geoscience, [link]