Wildfires occurs on every continent, except Antarctica. They can occur in periodic intervals and may cause extensive damage, but they also have various beneficial effects on wilderness areas. Some plant species depend on the effects of fire for growth and reproduction, although large wildfires will also have negative ecological effects.The most common cause of natural wildfires is lighting, but high temperatures can cause wildfires too. When: 2005Category: 3Cost: $ 108 billionHurricane Katrina hit the southern coast of the United States with overwhelming force onAugust 25, killing more than a thousand people and forcing the evacuation of half a million. New Orleans was the city most affected. Some of the levees that protected itfailed to contain the waters of Lake Pontchartrain, which surged inland floodingmunicipality at least 80% of its territory. Entire neighborhoods were almost submerged.Without money or car to leave the city, many residents simply remained in town to face the storm. Occurred during the Bush administration, the tragedy exposed the country'seconomic inequalities and poverty in which much of the population lived in New Orleans, which was formed mainly by blacks. Even today, the city tries to recover from the damage and losses caused by Katrina. In Sendai, one of the hardest hit regions, one year later, reconstruction work is admirable, but there is still much work ahead.Sunday was a day of tributes in Japan and worldwide. Tributes to the dead in the wake of tragedies that devastated Japan - the earthquake, the tsunami and the nuclear accident at Fukushima.In Sendai, one of the hardest hit regions, one year later, reconstruction work is admirable, but there is still much work ahead.The recovery of the infrastructure has been widely shown. Ports, airports and roads were completed in record time. But the reconstruction of cities is long overdue. Little or nothing was done.The Japanese government has been heavily criticized for this reason. One reason is the amount of rubbish left by the tsunami in these cities. Some cities have mountains of debris equivalent to a production of waste a hundred years.Other Japanese cities that were not affected refuse to receive the debris, because they fear they are contaminated by radiation from the Fukushima plant.On Monday (12), the prime minister gave an earful sort of in the country. He said the Japanese, who at the weekend showed so much solidarity, must show in practice, getting the garbage to incinerate or recycle.There were tributes at the weekend in Japan and various countries.In New York , the tribute was in a church. In Germany , there were demonstrations in several cities. The country said it would abandon nuclear power after the accident at Fukushima. InParis , thousands of people took minutes of silence. There were also demonstrations in Hong Kong , Philippines and Thailand . More than a year after deadly floods and mudslides devastated the city of Nova Friburgo, Brazil, people are still in shock.People are traumatized, Marie-Anne Pinheiro, a Swiss teacher and social anthropologist living in Nova Friburgo, said in a telephone interview. When it rains, they are so terrified they stay at home and