Why the world hit the Winter during the Spring? Science provides an unexpected answer!

  
Millions of people in northern Europe struggles with snow and ice, which makes them wonder why experiencing low temperatures in a period in which - at least officially - spring has arrived and the Earth experiencing global warming.
Scholars offer an answer: why we are facing the fourth consecutive year in which Europe and North America have some snow and cold so late is even global warming!
Researchers say that global warming affects a complex relationship between the ocean and atmosphere, which makes the air pol icy to go down south.
"This relationship is becoming increasingly clear, even if the evidence is not 100% conclusive yet," said Dim Coumou, specialist in the Potsdam Institute for Climate Impact Research, research center located near Berlin.
Scientists theory is based on a phenomenon studied in depth arctic called "positive feedback" - in other words, a vicious circle.
Increasing temperatures lead to melting ice in the Arctic, especially in summer. In 1979, when they were first made satellite measurements, ice in Arctic summer stretched seven million square kilometers, equivalent to 90% of Australia. Measurements taken in September 2012 showed that ice extent reached a minimum of just 3.4 million square kilometers.
The disappearance of ice reflecting sunlight reveals a larger amount of dark water that absorbs solar radiation, which accelerates melting ice - continuing the vicious circle.
Theory researchers suggest that this additional heat, stored in a large surface area of ​​water is slowly released into the atmosphere during the fall Arctic. Pressure increases heat and moisture in the Arctic, reducing the temperature difference from lower latitudes.
For this reason, the polar vortex, a circular wind that maintain strong Arctic air north of the planet begins to weaken. Therefore polar air manages to escape, leading to the south a cold and humid air mass, resulting in snow and cold in North America and Europe. However, this cold air mass tends to stay there because of the wind.

Instead of enclosing the northern hemisphere in a predictable manner, the wind that is at high altitude began to take a zigzag route over U.S. Atlantic and Europe. Located on the southern side of the zig-zag part in the cold weather that remains locked in place.

"The heat that is stored in the Arctic is rapidly transferred into the atmosphere and it affects weather patterns in the northern hemisphere," said Coumou.
"We had a few winters in Europe where there were cold periods 10-20-30 days. The same thing happened in the U.S. and Canada, where forecasters have witnessed the cold period bizarre, but something shorter, "says Coumou.
Charles Greene, director of the Ocean Resources and Ecosystems Program at Cornell University in New York, said that Arctic warming lead to unpredictable changes in climate.
"The changes made in the ice leading to an increase in the probability of arctic cold air to descend south. But it is difficult to predict which regions will drop this cold air, because we do not know how to interact with other parts of the climate system such as El Nino or La Nina, "says Greene.
However, the theory is not embraced by all climatologists, some requiring more evidence in its favor, especially as a result of accumulated data over longer periods

Global warming is the rise in the average temperature of Earth's atmosphere and oceans since the late 19th century and its projected continuation. Since the early 20th century, Earth's mean surface temperature has increased by about 0.8 °C (1.4 °F), with about two-thirds of the increase occurring since 1980.Warming of the climate system is unequivocal, and scientists are more than 90% certain that it is primarily caused by increasing concentrations of greenhouse gases produced by human activities such as the burning of fossil fuels and deforestation^.These findings are recognized by the national science academies of all major industrialized nations.
Climate model projections were summarized in the 2007 Fourth Assessment Report (AR4) by the Intergovernmental Panel on Climate Change (IPCC). They indicated that during the 21st century the global surface temperature is likely to rise a further 1.1 to 2.9 °C (2 to 5.2 °F) for their lowest emissions scenario and 2.4 to 6.4 °C (4.3 to 11.5 °F) for their highest.The ranges of these estimates arise from the use of models with differing sensitivity to greenhouse gas concentrations.
Future warming and related changes will vary from region to region around the globe.The effects of an increase in global temperature include a rise in sea levels and a change in the amount and pattern of precipitation, as well a probable expansion of subtropical deserts.Warming is expected to be strongest in the Arctic and would be associated with the continuing retreat of glaciers, permafrost and sea ice. Other likely effects of the warming include a more frequent occurrence of extreme weather events including heat waves, droughts and heavy rainfall, ocean acidification and species extinctions due to shifting temperature regimes. Effects significant to humans include the threat to food security from decreasing crop yields and the loss of habitat from inundation.
Proposed policy responses to global warming include mitigation by emissions reduction, adaptation to its effects, and possible future geoengineering. Most countries are parties to the United Nations Framework Convention on Climate Change (UNFCCC), whose ultimate objective is to prevent dangerous anthropogenic (i.e., human-induced) climate change.Parties to the UNFCCC have adopted a range of policies designed to reduce greenhouse gas emissions and to assist in adaptation to global warming.Parties to the UNFCCC have agreed that deep cuts in emissions are required,and that future global warming should be limited to below 2.0 °C (3.6 °F) relative to the pre-industrial level.Reports published in 2011 by the United Nations Environment Programme and the International Energy Agency suggest that efforts as of the early 21st century to reduce emissions may be inadequate to meet the UNFCCC's 2 °C target.
Sursa : wikipedia.org