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UN report says humans are causing catastrophic climate change

The UN’s new IPCC report says that humans have already caused ‘unprecedented’ changes to the climate, and the effects are going to get worse

Floods, heatwaves, and sea level rise will all get worse, according to the latest climate science.
Floods, heatwaves, and sea level rise will all get worse, according to the latest climate science. (Getty Images)

The UN’s apex climate science body, the Intergovernmental Panel on Climate Change (IPCC), today released the first of its current round of reports focusing on the state of the climate crisis. The report, which assesses the latest science and data, says that human CO2 and other greenhouse gas (GHG) emissions have caused irreversible changes to the global climate.

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The Climate Change 2021: The Physical Science Basis report, begins with a stark warning: “It is unequivocal that human influence has warmed the atmosphere, ocean and land.” It goes on to state that if current GHG emissions persist, then the world will definitely breach the 1.5 degree Celsius heating barrier within the next 20 years. It also says that unless there’s rapid, large-scale and immediate reductions in GHG emissions, limiting warming to 1.5 degree Celsius, or even 2 degree Celsius (above 1850-1900 levels) will be impossible.

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The report states that in the past 150 years, the world has already heated up by 1.1 degree Celsius, leading to the climate catastrophes that are being observed around the world. At 1.5 degrees of warming, heatwaves will increase, as well as the duration of warmer seasons. At 2 degree Celsius of warming, heat extremes would reach “critical tolerance” levels for humans. The report is very clear that the climate crisis is affecting every region around the world.

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The report is the first of the IPCC’s current cycle of Sixth Assessment Reports (AR6). Three more AR6 reports, including the concluding AR6 Synthesis Report, will be published by September next year. The new report states that some of the impacts of climate change, such as sea level rise and the melting of glaciers is already locked in as a result of the warming of the past 50 years. As bad as the current round of wildfires, floods and cyclones have been, they will get even more intense and regular in the next few decades once the effects of current heating get locked in. “We will only observe the impact of current warming in the decades to come. This year, we have observed some very unprecedented extreme events but we will not observe all the effects of the current warming right now but in the coming decades,” says IPCC lead author and associate director of the University of Oxford’s Environmental Change Institute, Fredericke Otto.

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The report also gives contextual evidence from earth’s climate history to show how unprecedented current levels of warming are. This is the hottest the world has been in the past 2,000 years, and heating to this extent was probably last experienced over 100,000 years ago. While those changes were very slow, and likely caused by changes in the earth’s orbit, the current warming has accelerated at an unnatural pace in the last 150 years. In 2019, atmospheric CO2 levels have been higher than any time in the past 2 million years, and methane in the past 800,000 years.

Also Read: The effects of global warming are here and we should be very scared

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The report also forecasts future scenarios depending on the amount of planet warming carbon emissions that we emit. In the best case scenario, where GHG emissions are drastically cut, resulting in net zero emissions by 2050 and negative emissions thereafter, global heating will stabilise to under 2 degree Celsius by 2100. Under intermediate and current levels of emissions, the world will heat up by 3.5 to 5.7 degree Celsius by the end of the century. This is the nightmare scenario, because for every .5 degree Celsius of warming, climate events like hot weather extremes, heatwaves, heavy rainfall, floods, drought and cyclones will become more frequent and more intense. “If we reduce emissions globally to net zero by 2040 there is still a two thirds chance to reach 1.5 degrees and if we globally achieve net zero emissions by the middle of the century, there is still a one third chance to achieve that. To limit global warming, strong, rapid and sustained reductions in CO2, methane and other greenhouse gases are necessary,” says Otto.

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The ramifications for India couldn’t be starker. With greater heating, there will be a more severe increase in rainfall in southern parts of the country. A 2 degree Celsius warming would see a 20% annual increase in rainfall on the south west coast. A 4 degree Celsius warming would see this jump to a 40% increase. At 2 degree Celsius warming, extreme heat events will occur 5 times more frequently than in the past. At 4 degree of warming, such extremes will occur nearly once every year.

Also Read: Why Arabian Sea cyclones have increased by 52% in twenty years

IPCC lead author and climate scientist at the Indian Institute of Tropical Meteorology, Pune (IITM), Swapna Panickal, says that the Indian Ocean is warming at a higher rate than the global average. “50% of the sea level rise is contributed by the thermal expansion, hence sea level over the Indian Ocean region is also rising. The global mean sea level is rising at a rate of around 3.7 millimeter per year, that is estimated between 2006-2018. At 1.5 degrees, the sea temperature is expected to increase by one degree,” she says.

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Ulka Kelkar, Director, Climate Program, World Resources Institute India (WRI) says that it is high time the climate science is heeded. “This new report comes amid consternation over extreme weather despite 30 years of warnings from the IPCC. For India, the predictions in this report mean people labouring in longer and more frequent heat waves, warmer nights for our winter crops, erratic monsoon rains for our summer crops, destructive floods and storms that disrupt power supply for drinking water or medical oxygen production,” she says.

Also Read: Will rich nations finally wake up to climate action?

Energy expert Ajay Mathur, who is also the Director of the India-led International Solar Alliance says that the new report is both more stark and more certain about the effects of human CO2 emissions on the climate. “The global energy sector accounts for around 73% of our total emissions; it is also the engine behind every country’s economic and developmental plans—and ever more so in the emerging and developing economies where the quality of life, and the accompanying energy consumption is less than the global average. And so it becomes ever more important for us to be able to meet our growing energy needs without adding more CO2 to the atmosphere. Solar energy offers an ideal solution to all countries. The technology is ready and it is cost effective; we need global collaboration to scale it up exponentially and expeditiously.”

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