Answer the question

Questions: In the preceding article the author has provided several examples of abrupt fluctuations in climate that have occurred within the last 110,000 years. One such warm spell occurred 11,500 years ago with a sudden 10 degree C warming indicated by high levels of methane in air bubbles trapped in the Greenland ice. Explain why methane levels would increase in the atmosphere during a warm spell. The author has linked the collapse of the Mayan Civilization 1100 years ago, the migration of the Vikings out of Greenland around 1400 AD and the drying of the Sahara 5000 years ago to abrupt shifts in climate. Discuss what might have caused each of these outcomes. “Cold, wet times in Greenland correlate with particularly cold, dry, windy conditions in Europe and North America; they also coincide with anomalously warm weather in the South Atlantic and Antarctica.” Why do you think there is such a climatic contrast between the northern and southern continents? “Global warming should be more of a worry than ever: it could be pushing the earth’s climate faster toward sudden shifts.” Explain what the author means by this statement. Explain how slowing down the ocean currents in the North Atlantic might cause widespread famine in Africa and Asia. Humans have altered the land cover with cultivation, changed the amount of water that rivers carry to the ocean by extracting groundwater and altered the composition of the trace gases in the atmosphere by burning fossil fuels. Can you think of other ways in which humans are pushing certain aspects of climate closer to the thresholds that could unleash sudden changes that we will regret?