Earth to warm up by 1.5 deg C by 2030, a decade earlier
Human-induced global heating has arrived with a vengeance and will see Earth’s average temperature reach 1.5 degrees Celsius above pre-industrial levels around 2030, a decade earlier than projected just three years ago, according to a new UN climate-change assessment published on Monday.
In climate-vulnerable India, it means, the heat waves and humid heat stress will be more intense and frequent, while the annual and summer monsoon rainfall will increase and have more variability — and there will be increased rainfall events and more cyclonic activity, cautions the first part of IPCC’s Sixth Assessment Report (AR6) titled ‘Climate Change 2021: the Physical Science Basis’. The report has been finalised by a battery of scientists in collaboration with 195 Governments.
UN secretary-general Antonio Guterres called the report “a code red for humanity,” and said it must “sound a death knell for coal and fossil fuels before they destroy our planet.”
The report pointed out that global warming of 1.5 degrees is imminent in the next two decades unless there is a drastic move to eliminate greenhouse gas emission while the crucial threshold of 2 degrees Celsius will be exceeded during the 21st century in a “business as usual” scenario.
Even in the most ambitious emissions pathway, it will reach 1.5 degrees Celsius in the 2030s, overshoot to 1.6 degrees Celsius, before the temperature declines to 1.4 degrees Celsius at the end of the century, it said.
The report said warming over India is projected to track the global average and it is expected to see an increase in frequency and severity of hot extremes with an increase in annual mean precipitation.
Monsoon rainfall is also projected to witness exponential rise. The global mean sea level in the Indian Ocean is rising at 3.7 meters annually, said the report, adding that extreme sea level events that previously occurred once every 100 years, will now be seen nearly every year.
As per the report, on the southwest coast, rainfall could increase by around 20 per cent, relative to 1850-1900. If the planet warms by 4 degrees Celsius, India could see about a 40 per cent increase in rainfall annually. The increase in rainfall will be more severe over southern parts of the country.
There is more. Monsoon rainfall is projected to increase in the mid-to-long-term over South Asia. Globally, severe, heavy precipitation events that now occur on an average once every ten years, are projected to nearly double in frequency at 2 degrees Celsius (1.7 times in a ten-year period). At 4 degrees Celsius, the likelihood of these events will jump to 2.7 times in a ten-year period, warn the authors of the report.
“The key finding of the report is that climate change is a fact, global warming is a fact, and that the warming has taken place because of human influence is now well established. “We have seen rapid changes across the world, with heat waves, heavy rainfall events, droughts and compound events - or a mix of hot, dry and windy - preconditions for forest fires. We see this in every region of the planet. There is no going back from some of these changes. Even if we limit temperatures to 1.5 degrees Celsius from pre-industrial levels, we will continue to see extreme weather events,” said Dr Friederike Otto, who is the Associate Director of the Environment Change Institute, University of Oxford and one of the authors of the report.
Dr Otto added that some changes are locked in, such as rising sea levels and melting glaciers, which can now no longer be reversed. “For India, the increase in heat waves is marked by other emissions like aerosol emissions. If there is a reduction in aerosols, we will see a further increase in heat waves,” she said.
IITM’s Dr Swapna Panickal, another author of the report, said that India will experience an intensification of the water cycle which will affect rainfall patterns as well as increased monsoon precipitation. “In the Indian Ocean, the sea temperature is heating at a higher rate than other areas, and therefore may influence other regions. The Southwest Monsoon has declined over the past few decades because of the increase of aerosols, but once this reduces, we will experience heavy monsoon rainfall,” she said.
The report stated that the relative sea level in the Indian Ocean, around Asia, has increased faster than the global average, with coastal area loss and shoreline retreat. The Regional mean sea level will continue to rise, it added.
Regarding coastal areas, it said these will see continued sea level rise throughout the 21st century, contributing to more frequent and severe coastal flooding in low-lying areas and coastal erosion. For cities, some aspects of climate change may be amplified, including heat (since urban areas are usually warmer than their surroundings), flooding from heavy precipitation events and sea level rise in coastal cities.
CSE director general Sunita Narain who has been raising the issue of climate change threat for quite some time asserted that “there are no ‘maybes’ any more - the threat is real.”
The latest IPCC report confirms that we can no longer lose time in prevarication or in finding new excuses not to act, including empty promises of net zero by 2050, Narain said as she enlisted some key takeaways from the report - one, the world might be hurtling towards a 1.5 degrees temperature rise by 2040; two, the main trigger for climate change is, undoubtedly, human activities; and three, the efficiency of sinks to absorb emissions is going down.
“As far as India is concerned, we have a double burden now. We have to build resilience in our economy, infrastructure and social systems to deal with the increasing impacts of extreme weather events. At the same time, we have to act on mitigation measures,” added Chandra Bhushan, President & CEO, International Forum for Environment, Sustainability & Technology (iFOREST).
This WGI report is the first biggest update report of the IPCC (Working Group I (AR6 WGI) on the state of knowledge on climate science since the release of AR5 in 2014.