On Monday, actor and environment activist Robert Redford appeared in UN and said that a big tragedy could occur in future if necessary steps are not taken at the UN Climate Summit. He said that this could be the last chance to tackle with the problem. The world is needed to be saved before things get worse, he added.

Over 2,300 lives have already become victim of the heat wave in India and Pakistan. Destructive tornadoes, hurricanes, crippling floods are also adding to the problem. Moderate weather is getting affected all over the world.

It has been reported by History. com that two of the most deadly heat waves took place in 1896 and 1936. In 1896, nearly 1,300 New Yorkers died in consequence of a strong 10-day heat wave. It is expected that more than 1,000 horses have died in the heat. During the course of one burning summer in 1936, over 5,000 Americans died.

As per the Weather Channel, in approximately ten years, a large hurricane hasn't made landfall in the United States.

According to Britannica, the Huang He River floods in 1887, and 1931 were the two deadliest floods in recorded history. The minimum estimated death toll was 1.75 million people in both the floods combined.

According to Larry Bell of Forbes, severe trends in global temperature are not new. Bell added, "As recently as 1,000 years ago, Icelandic Vikings were raising cattle, sheep and goats in grasslands on Greenland's southwestern coast. Then, around 1200, temperatures began to drop, and Norse settlements were abandoned by about 1350".