Geneva: The UN Intergovernmental Panel on Climate Change (IPCC) on Monday said the planet will reach the crucial threshold of 1.5 degrees Celsius above pre-industrial levels by 2030, precipitating the risk of extreme drought, wildfires, floods and food shortages for hundreds of millions of people.

In a report, the IPCC said that governments around the world must take “rapid, far-reaching and unprecedented changes in all aspects of society” to avoid disastrous levels of global warming, CNN reported.

The date, which falls well within the lifetime of many people alive today, is based on current levels of greenhouse gas emissions.

The planet is already two-thirds of the way there, with global temperatures having warmed about 1 degree Celsius. Avoiding going even higher will require significant action in the next few years, the report said.

Global net emissions of carbon dioxide would need to fall by 45 per cent from 2010 levels by 2030 and reach “net zero” around 2050 in order to keep the warming around 1.5 degrees Celsius.

Lowering emissions to this degree, while technically possible, would require widespread changes in energy, industry, buildings, transportation and cities, according to the report.

“One of the key messages that comes out very strongly from this report is that we are already seeing the consequences of 1 degree Celsius of global warming through more extreme weather, rising sea levels and diminishing Arctic sea ice, among other changes,” said Panmao Zhai, co-chair of IPCC Working Group I.

Coral reefs will also be drastically effected, with between 70 and 90 per cent expected to die off, including Australia’s Great Barrier Reef.

Countries in the southern hemisphere will be among the worse off, the report said, adding “projected to experience the largest impacts on economic growth due to climate change should global warming increase”.

“Every extra bit of warming matters, especially since warming of 1.5 degrees C or higher increases the risk associated with long-lasting or irreversible changes, such as the loss of some eco-systems,” CNN quoted Hans-Otto Pörtner, Co-Chair of IPCC Working Group II, as saying.

Monday’s report is three years in the making and is a direct result of the 2015 Paris Climate Agreement.

In the Paris accord, 197 countries agreed to the goal of holding global temperatures “well below” 2 degrees Celsius above pre-industrial levels and to pursue efforts to limit it to 1.5 degrees Celsius.

More than 90 authors from 40 countries were involved in leading the report, helped by 133 contributing authors.