Attribution fundamental to climate litigation, say lawyers; scientists urge data, modelling fixes

New Delhi: Amid the likelihood of a rise in litigations following the Supreme Court's observation that climate change impacts the constitutional guarantee of the right to equality, scientists have urged for fixing inadequacies in data and modelling for attribution in such lawsuits.

Attribution science determines the likelihood of an extreme weather event due to climate change.

Environment lawyers and field experts agree that being evidence-based, attribution science will be crucial to climate litigation and play a key role in limiting baseless lawsuits.

"Attribution data has been important in litigation as it is scientific and evidentiary in nature. It definitely will help support a case," said Prachi Pratap, a Supreme Court advocate.

The Supreme Court on April 18 said that by impacting clean environment and health, climate change impacts the constitutional guarantee of the right to equality.

"Without a clean environment which is stable and unimpacted by the vagaries of climate change, the right to life is not fully realised. The right to health (which is a part of the right to life under Article 21) is impacted due to factors such as air pollution, shifts in vector-borne diseases, rising temperatures, droughts, shortages in food supplies due to crop failure, storms, and flooding," the bench said.

Shashank Pandey, a research fellow at the Vidhi Centre for Legal Policy, New Delhi, said, "Attribution will constitute the basic underpinning of the claims. All claims under this new right have to backed by scientific evidence, as seen in the recent European Convention on Human Rights (ECHR) rulings. Else there will be no restriction to the nature of claims made."

The ECHR on April 9 ruled against the Swiss government, saying it had violated its citizens' human rights by failing to do enough to combat climate change.

The Supreme Court ruling also gains relevance in light of a World Meteorological Organization (WMO) report that found Asia to be the world's most disaster-hit region in 2023, bearing the brunt of weather-, climate- and water-related hazards.

Extreme event attribution offers a "clean way to communicate the effects of climate change", according to Mariam Zachariah, a researcher at the Grantham Institute for Climate Change at the Imperial College, London, UK.

"Attribution quantifies whether and to what extent climate change -- driven primarily by human activities by continuing greenhouse gas and aerosol emissions -- has altered the chances and intensity of extreme weather events such as heat waves, extreme rainfall and droughts in the present climate, as compared to a past climate before humans began warming the planet," she said.

The idea of extreme weather attribution was first discussed by climate scientist Myles Allen in a 2003 paper in the Nature journal. The European heat wave of that year was the first event attribution study to be published.

However, long-term climate change attribution results started to become available since the mid-1990s as the field was made theoretically possible in the 1970s when Nobel Prize winning German scientist Klaus Hasselmann put forward a model for climate change detection and attribution.

In India, attribution still remains at a 'nascent stage', said Arpita Mondal, an associate professor at the Indian Institute of Technology - Bombay.

"It is primarily because of India's widely varying, diverse and very complex climate system. However, with increasing extreme events in India, and the growing importance of the role of climate change, I think more attribution studies are imperative," Mondal told PTI.

Heat waves in 2023, 2022 and 2020 were attributed to climate change whereas the Kerala floods of 2018 could not 'unequivocally' be attributed to climate change, she said.

Kerala recorded rainfall and flooding 'unprecedented' over a 66-year period in August 2018, Mondal and her colleagues had found.

The event had affected 54 lakh people and claimed more than 400 lives.

The 2005 drought in Maharashtra's Marathwada region was a complex study. While rainfall alone could not be attributed to climate change, the compounded hot-dry effect of abnormally high temperature and abnormally low rainfall could be 'unequivocally' attributed to climate change, Mondal explained.

While there are only a handful of experts in this field of climate science, merely increasing the number will not 'magically transform into more research' because the limitations typically are of data and modelling, said Krishna Achuta Rao, a professor at the Centre for Atmospheric Sciences in the Indian Institute of Technology - Delhi.

"The question is do we have enough data going back in history, at least more than 50 years, which can help us understand weather patterns and extremes then and how they've changed now?" asked Rao, who has been involved in attribution studies for around 25 years.

He said the daily data necessary for event attribution is not readily available and accessible.

"Curating data for this kind of work and making it useful and useable is a major undertaking. However, this is an exercise that does not seem to be a top priority," Rao said.

The other issue he pointed to is the infrastructure needed to perform modelling.

"Attribution also makes use of climate models and an extensive model database, which again is a resource-intensive business. I don't think we have the resources in India and this, clearly, has to improve," he said.

All three of Rao, Mondal and Zachariah work for the World Weather Attribution (WWA), a voluntary global initiative run by scientists in the UK and The Netherlands.

Results of rapid attribution studies performed in the wake of extreme weather events are released within the following couple of weeks.

The WWA was formed in 2015 and has more than 50 attribution studies on heat waves, extreme rainfall, drought, floods, wildfires and cold spells around the world.

Mondal acknowledged that they are more confident of attributing heat waves to climate change than events such as floods and droughts, made complex due to on-ground human operations such as managing water resources.

Zachariah said attribution results should be supported or supplemented with information of vulnerability and exposure of communities that can worsen the impacts of an extreme event.

However, there are also times when attribution cannot provide a conclusive result.

Mondal said there can be varied reasons for this, including a lack of scientific understanding of the physical processes at play during an extreme weather event or a lack of reliable data.

However, she believes attribution can inform legal proceedings, climate adaptation strategies and also government action.

She expects more litigations in the future grounded in attribution science.

Advocate Pratap welcomed the top court's ruling, saying structured reforms are needed and sometimes court cases can be the first step in that direction.

"This judgment will give a sense of empowerment to citizens to address issues when they feel their right related to effects of climate change is affected. It gives locus to more people in a situation where climate change is the crux of the problem," she said.

She, however, expects increased 'frivolous and luxury' litigations.

"It is true the first emotional reaction might be of blaming climate change but any report or news article which points to extreme weather will put the matter in perspective. A thin line has to be drawn. Yet there are umpteen cases where extreme weather is caused due to climate change," said Pratap.

Pandey believes that having issued the ruling, the Supreme Court is 'walking a very tight rope'.

"It will be difficult to limit and determine the contours of adverse effects of climate change, given that it has infiltrated every aspect linked with weather and climate. So, any affected individual or community can directly claim their right against adverse effects of climate change. How the courts interpret this right within the environmental jurisprudence is something that we have to look upon," he said.

Avinash Chanchal, Greenpeace India's campaign manager, called for a stronger legal framework to tackle climate change.

"There is an urgent need to introduce a climate change act that will integrate different laws and policies to safeguard our biodiversity and people," Chanchal said.

"The act should ensure clear targets and set timelines to achieve just legally binding energy transitions, adequate provisions for adapting to the impacts of climate change, and building resilience among vulnerable communities. It should also include mechanisms to hold polluting corporations accountable," he said.

Rao said, ultimately, the courts are going to look at the losses and how to quantify those. Here, the next stage of attribution, or end-to-end attribution, which is much more nuanced and sophisticated, will be helpful.

"For example, if a farmer's wheat crop yield was down by 30 per cent this year, was it all because of the heat wave or were there other factors too? We need to be able to strengthen this multi-step attribution," he said.