Monsoon clouds over the Chalakudy River. Photo: Jan Joseph George/Wikimedia Commons, CC BY-SA
- The Paris Agreement enjoins countries to limit the global mean surface temperature rise at the end of the century to 2º C above pre-industrial levels, and endeavour to limit it to 1.5º C.
- However, the new IPCC report estimates that the chances of limiting warming to 1.5º C are now extremely slim.
- India in particular should find the climatic changes that arise due to the 1º C difference between the ‘low emission’ and ‘current pledges’ scenarios more than worth fighting for.
On Monday, the Intergovernmental Panel on Climate Change (IPCC) released the first of the three parts of its flagship publication, the Sixth Assessment Report (AR6). To prepare the assessment reports, the first of which was published in 1990, experts examine the scientific literature and lay out the state-of-the-art in climate science. This time, some 234 scientists pored over more than 14,000 publications.
The report just published, entitled ‘Physical Science Basis of Climate Change’, was drafted by Working Group 1 of the AR6 team. It tells us about the sort of climatic changes we can expect in the coming decades.
India is particularly vulnerable to the physical and economic impacts of climate change for several reasons. With a high baseline mean temperature, even a small temperature rise will make for greater human discomfort and environmental change, leading to loss of livelihoods and in some cases even outright uninhabitability. The disruption of complex monsoon phenomena, on which India’s farmers depend for sustenance, is likely to cause additional widespread hardship.
As a developing country with much of its population still engaged in agriculture – and hence to be maximally impacted – India also has fewer resources to adapt to these changes than many other countries.
The Paris Agreement enjoins countries to limit the global mean surface temperature rise at the end of the century to 2º C above pre-industrial levels, and endeavour to limit it to 1.5º C – in order to avoid the most catastrophic impacts of climate change. However, even 1.5º C will precipitate unacceptable hazards and imperil lives and livelihoods.
The report estimates that the chances of limiting warming to 1.5º C are now extremely slim. Even if all countries met their current climate pledges, the world’s surface is on track for the years 2081-2100 to be at least 2.7º C warmer on average than it was in 1851-1900. And as the experience of the Kyoto Protocol and even the Paris Agreement has shown, setting targets is different from delivering on them.
To understand the impact of climate change on India as well as the importance of limiting warming, we can compare three scenarios in the IPCC report:
- SSP 1-2.6 – which limits the global mean surface temperature rise to 1.8º C and which we may call the ‘low emission scenario’
- SSP 2-4.5 – which is the trajectory of current climate commitments and limits warming to 2.7º C, i.e. the ‘current pledges scenario’
- SSP 5-8.5 – which represents complete inaction with emissions continuing to grow unabated, leading potentially to 4.4º C of warming, i.e. the ‘high emission scenario’
In the report’s datasets, the median figure for temperature rise in South Asia to emerge from the models for the three scenarios are, respectively, 1.9º C, 2.9º C and 5.1º C. The IPCC’s ‘Special Report on Global Warming of 1.5º C’, published in 2018, showed just how much worse the impacts of climate change could be with a rise of 0.5º C (1.5º to 2º C). So the 1º C difference in warming in South Asia between the ‘current pledges scenario’ and the ‘low emission scenario’ is more than worth fighting for.
This is particularly true for a hot country. And of course, we must prevent the catastrophic 5.1º C temperature rise at all costs.
Not only would the mean temperature rise: climate change will also bring more days of extreme heat. We can measure this by the number of days in a year reporting over 40º C temperature. In the ‘low emissions scenario’, such days are likely to increase by nearly 50% in South Asia – up from 40 days a year during 1850-1900 to 59 days a year during 2081-2100. The corresponding figures for the ‘current pledges scenario’ is 68 days. In the ‘high emissions scenario’, the temperature is likely to exceed 40º C for fully three months of every year.
In the ‘low emissions scenario’, the total precipitation between 2081 and 2100 is likely to be 10.2% higher than it was between 1850 and 1900. The same figures for the ‘current pledges’ and the ‘high emission’ scenarios are 12.9% and 27.6%, respectively.
But more eye-catching, and worrying, is the increase in the annual maximum one-day and five-day precipitation. This is a measure of the intensity of rain and a better indicator of the flood risk. The maximum one-day precipitation between 2081 and 2100 is expected to be higher than it was in 1850-1900 by 15.9% in the ‘low emissions scenario’, 24.% in the ‘current pledges scenario’ and a disturbing 47.8% in the ‘high emission scenario’.
The figures for the maximum five-day precipitation are similarly concerning – 14.1%, 20.8% and 40.1%, respectively, for the three scenarios. This increase in rainfall is likely to be higher over southern India. Both annual and summer monsoon precipitation will increase, as will the duration of the monsoon. Monsoon precipitation is also expected to increase in the medium to long term, though this will be less pronounced in the near term due to the concentration of aerosols over India.
Extreme weather events
The report estimates that globally, the likelihood of hot extreme events will likely increase from once every 10 years to 4.1 times in 10 years, at 1.5º C of warming; to 5.6 times at 2º C; and to 9.4 times at 4º C. (The last one essentially means one such event will take place nearly every year.) Similarly, the likelihood of 1-in-50-year extreme heat events will likely occur 8.6 times, 13.9 times and 39.2 times, respectively, under 1.5º C, 2º C and 4º C of warming. (The last one, again, means a one-in-50-year extreme heat event could take place every four out of five years.)
In South Asia in particular, heat waves and humid heat stress are set to intensify.
For the world as a whole, heavy precipitation that occurred once every 10 years is likely to happen 1.5 times in 10 years at 1.5º C of warming; 1.7 times at 2º C and 2.7 times at 4º C. Similarly, agricultural and ecological once-a-decade droughts (in drying areas) are likely to occur 2 times, 2.4 times and 4.1 times, respectively, after 1.5º C, 2º C and 4º C of warming. This doesn’t bode well for agriculture in India, which is already drought-prone.
India’s coastline is over 7,500 km long, so the country is particularly vulnerable to rising seas. According to the report, sea levels in South Asia are expected to rise by 0.4 m in the ‘low emissions scenario’, 0.5 m in the ‘current pledges scenario’ and 0.7 m in the ‘high emissions scenario’. In response, India will need to prepare with better urban planning and coastal defenses, as well as safeguard vital ecosystems such as mangroves from coastal flooding and associated erosion.
Over 240 million people (86 million of them in India) depend on glaciers in the Hindu-Kush Himalayan region for their water supply. These glaciers are expected to decline by two-thirds by 2100, heralding a crisis of domestic and irrigation water and putting the region’s – and the world’s – food supply in peril.
India has a growing urban population, so the IPCC’s verdict on cities is significant. Cities are typically hotter than their surrounding areas due to the urban heat island effect. Cities also alter the local water cycle, which may result in more rainfall and poorer drainage, thus increasing the overall flood risk.
The report has also observed that climate-driven changes to meteorological conditions generally favour extreme air pollution episodes in heavily polluted environments. Combating climate change could thus also help alleviate India’s air pollution problem as well. This problem is already significant in parts of the country due to pollution sources as much as climatic conditions.
Taken together, the verdict for India is clear: the country (along with the rest of the world) is hurtling towards a potential climate disaster. The world is already ‘locked in’ to some amount of warming and other climatic effects, given the historical and extant emissions. But even if all countries meet their climate targets – i.e. in the ‘current pledges scenario’ – the effects of climate change are set to proliferate as well as intensify by the end of the century.
India’s size, economy and socio-economic conditions together mean that the country is likely to be more impacted than many others. It’s crucial that it plans and implements a climate adaptation programme on a war footing. At the same time, India must moderate its own emissions even while pressing the ‘global north’ – which owes developing nations a carbon debt – to do its fair share, if not more. One way or another, the worst case scenario must not come to pass.