Earth may soon become a ‘hothouse’

NEWDELHI: Keeping global temperatures below 2 degrees Celcius as recommended by the Paris climate accord may be more difficult than expected as the planet risks entering “hothouse” conditions that will keep the average global temperatures at 4-5 degrees Celsius above the pre-industrial levels and sea levels 10-60 metres higher than today, scientists said in a new study.

The current global average temperature is 1oc above the preindustrial levels and is increasing at 0.17oc each decade.

The hothouse effect of the climate feedback mechanisms that amplify or diminish the effects of change in temperature. For example, when rising temperatures melt ice caps, the “darker” areas under the ice trap more of the sun’s heat, resulting in further increase in temperature.

This triggers a domino effect resulting in permafrost thaw, the loss of methane hydrates from the ocean floor, weaker land and ocean carbon sinks, the loss of Arctic summer sea ice, and the reduction of Antarctic sea ice and polar ice sheets, according to the study published in Proceedings of the National Academy of Science.

“It may be very difficult or impossible to stop the whole row of dominoes from tumbling over. Places on Earth will become uninhabitable if “Hothouse Earth” becomes the reality,” said co-author Johan Rockström, former executive director of the Stockholm Resilience Centre, in a release.

It will lead to massive displacements in India, say experts. “Even in the Himalayas, a 2oc rise in temperature pushes up the permanent snowline, the level at which there is snow throughout the year. It also pushes up the tree line and the grasslands. That means, we will have mangoes and pomegranates at higher altitudes, where these crops were unheard of a few decades ago.