World Heats up

Last Updated: Saturday 04 July 2015

A new study by the National Aeronautics and Space Administration (nasa) scientists has found that the world temperature is reaching a level that has not been seen in thousands of years. The study, led by James Hansen of nasa 's Goddard Institute for Space Studies, along with scientists from other organisations says that because of a rapid warming trend over the past 30 years, the Earth is now reaching and passing through the warmest levels in the current interglacial period, which has lasted nearly 12,000 years. The study also revealed that recent warming is forcing plant and animal species to move towards the north and south poles.

The study used temperatures around the world taken during the last century. Scientists concluded that these data showed the Earth has been warming at the remarkably rapid rate of approximately 0.2c per decade for the past 30 years. "This evidence implies that we are getting close to dangerous levels of human-made pollution," said Hansen. In recent decades, human-made greenhouse gases have become the most significant climate change factor. Greenhouse gases trap heat in the Earth's atmosphere and warm the surface. Some greenhouse gases, which include water vapour, carbon dioxide, methane, nitrous oxide, and ozone, occur naturally, while others are due to human activities.

The study notes that the world's warming is greatest at high latitudes of the Northern Hemisphere and it is larger over land than over oceans. The enhanced warming at high latitudes is attributed to effects of ice and snow. As the Earth warms, snow and ice melt, uncovering darker surfaces that absorb more sunlight and increase warming, a process called a positive feedback. Warming is less over oceans than land because of the great heat capacity of the deep-mixing ocean, which causes warming to occur more slowly there.

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