Delhi may suffer losses of Rs 2.75 trn by 2050 due to climate change

Delhi is projected to suffer losses of Rs 2.75 trillion by 2050 due to the impacts of climate change, with changes in precipitation and temperature patterns posing significant threats to the lives of the most vulnerable populations. The warning comes from the city government's draft action plan on climate change.

The plan, which is pending approval, highlights "heat waves/higher temperature and heavy precipitation events over fewer number of days" as major challenges that the city will confront in the upcoming years.

India introduced its National Action Plan on Climate Change (NAPCC) in 2008, following which state governments were instructed to create their own action plans. The State Action Plan on Climate Change (SAPCC) must be aligned with the strategies laid out in the NAPCC.

In January 2018, the central government directed the states to revise and strengthen their SAPCCs, taking into account the evolving national and international climate action, science and policy landscape.

Delhi's previous climate action plan was finalised in 2019 -- after a lengthy seven-year consultation with stakeholders -- rendering it obsolete.

"At an aggregate level, the total cost of climate change for Delhi by mid century is expected to be Rs 2.75 trillion," the draft action plan states.

It estimates the losses from the agriculture and allied sectors at Rs 80 billion, manufacturing at Rs 330 billion and services at Rs 2.34 trillion.

During the formulation of the new action plan, the Intergovernmental Panel on Climate Change Sixth Assessment Report (IPCC AR6) was examined, analysing the impacts of different climate scenarios on annual maximum and minimum temperatures and precipitation, an expert who contributed to the plan said.

The projections show a rise in maximum temperatures in Delhi by 1.5 degrees Celsius based on the RCP 4.5 scenario, and a 2.1-degree Celsius increase based on the RCP 8.5 scenario by mid-century.

Four Representative Concentration Pathways (RCPs) span a range of future global warming scenarios. RCPs quantify future greenhouse gas concentrations and the radiative forcing -- the difference between the incoming and outgoing radiation at the top of the atmosphere -- due to increases in climate change pollution.

Due to the different future concentrations of greenhouse gases, RCP2.6 will result in the least global warming and only limited climate change. RCP 8.5 will result in more rapid warming and climate change.

At the Paris climate talks in 2015, countries agreed to limit global warming to 1.5 degrees Celsius compared to pre-industrial levels to avoid the extreme, destructive and likely irreversible effects of climate change.

The Earth's global surface temperature has risen by around 1.15 degrees Celsius from pre-industrial levels and the CO2 spewed into the atmosphere since the start of the industrial revolution is closely tied to it. In the business-as-usual scenario, the world is heading for a temperature rise of around 3 degrees Celsius by the end of the century.

Excerpts of the draft action plan, reviewed by PTI, also indicate a decrease in cold days and nights, an anticipated reduction of 8.4 dry days, an increase of 1.4 consecutive wet days, and a rise of 0.9 heavy precipitation days compared to the baseline period of pre-industrial levels.

A detailed district specific vulnerability assessment has also been carried out as part of the plan's revision process.

A detailed district-specific vulnerability assessment was conducted as part of the process. The vulnerability rankings for all districts of the state will help policymakers prioritise adaptation strategies based on the extent and type of vulnerability, with south Delhi being identified as the most vulnerable and New Delhi the least.

On July 8-9, Delhi witnessed its highest single-day rainfall (153 mm) in the month since 1982 due to the interaction of a western disturbance, monsoon winds and a cyclonic circulation over northwest India. The city received an additional 107 mm of rain in the subsequent 24 hours.

In the 36 hours beginning at 8.30 am on July 8, Delhi recorded an unprecedented 260 mm of rainfall -- prompting the government to issue a flood warning and shut schools temporarily.

The heavy rain transformed roads into gushing streams, parks into watery labyrinths and marketplaces into submerged realms.

Subsequently, heavy rain in the upper catchment areas of the Yamuna, including Himachal Pradesh, Uttarakhand and Haryana, led to the river swelling to record levels.

The water level in the river reached 208.66 metres on July 13, surpassing the previous record of 207.49 metres set in September 1978 by a significant margin. It breached embankments and penetrated deeper into the city than it has in more than four decades.

The consequences of the floods have been devastating with more than 27,000 people evacuated from their homes. The losses incurred in terms of property, businesses and earnings have run into crores.

Experts attributed the unprecedented flooding to encroachment on the river's floodplain, extreme rainfall within a short span and silt accumulation that has raised the riverbed.

Delhi has three major drainage basins -- Najafgarh, Barapullah, and Trans-Yamuna.

During rainfall, stormwater on the eastern side of the central ridge directly flows into the Yamuna. On the western side, smaller drains merge into the Najafgarh drain, which eventually empties into the river.

The eastern region of Delhi is low-lying and was originally part of the Yamuna floodplain. The existing stormwater drainage system in Delhi is prone to congestion, primarily caused by waste and sewage, leading to sluggish water flow.

Different parts of Delhi experience annual flooding due to factors such as excessive concrete structures, the disappearance of water bodies, encroachments on the stormwater drains and the discharge of untreated sewage and waste.

The management of the drainage system involves multiple agencies, further complicating the situation, according to the city government's draft action plan for climate change.

The last drainage master plan for Delhi was created in 1976 when the city's population was approximately six million.

The government had asked IIT-Delhi to prepare a new 'Drainage Master Plan for the NCT of Delhi'. The institute submitted a final report in 2018 but a technical panel of the city government rejected it, citing "discrepancies in data".

Earlier this year, the government tasked the Public Works Department, which manages the largest part (2,064 kilometres of a total 3,741 kilometres) of the storm run-off system in Delhi, to prepare a new plan.

The draft action plan for climate change acknowledges a concerning lack of formal records and practices among various agencies responsible for stormwater drainage management in Delhi. Currently, there is no legislative mandate for these agencies to prepare comprehensive records of inundation extents in different parts of the capital territory.

The only exception to this is the Delhi Traffic Police, which records such events solely from the perspective of traffic movement. According to their records, there are 330 segments within the capital territory that can be designated as drainage hot spots.

To improve flood monitoring and enhance preparedness, the draft action plan proposes the installation of low-cost sensors at locations that are prone to perpetual flooding. These sensors would serve the purpose of issuing appropriate warnings and evaluating the effectiveness of flood reduction measures.

The plan outlines various measures to address urban flooding, including the de-silting of stormwater drains. It also suggests using drainage pumps in underpasses and low-lying areas to pump out excess water from the roads.

Additionally, the utilisation of mobile super sucker machines can be deployed at points witnessing heavy waterlogging. To expedite the response to such situations, the plan recommends the establishment of rapid response teams.

The drainage master plan report ranks the vulnerability of different districts to urban floods. Central, southwest, northeast, east Delhi and Shahdara are identified as highly vulnerable areas, while north, northwest, south, southeast Delhi and New Delhi are considered moderately vulnerable.