Government of India also Ban Plastic.
Government of India publish the Guide Book on Ban of Plastic and Thermacol which is given below.
Government of India publish the Guide Book on Ban of Plastic and Thermacol which is given below.
குமரி மாவட்டத்தில் கடல் சீற்றம் ஏற்பட்டு கடல் நீர் ஊருக்குள் புகுந்துள்ளது.
இதற்கு முக்கிய காரணம் புவி வெப்பமயமாதலால் கடல் மட்டம் உயர்வது தான். இந்த பகுதியை பார்த்தால் ஏற்கனவே கட்டிய கடல் அரிப்பு தடுப்பு சுவர்களை பெரும்பகுதி அழித்து ஒரு சிறு பகுதி மட்டுமே மிச்சம் இருப்பதை காணலாம்.
புவி வெப்பமயமாதலை தடுத்தலே இதற்கு நிரந்தர தீர்வாக அமையும். வைகுண்டராஜன் மீது கோபம் ஏற்படும் போது மட்டும் தான் ஊடகவியலாளர்கள் தாதுமணல் சுரங்க பணியால் தான் இம்மாதிரி இயற்கை சீற்றங்கள் ஏற்படுகிறது என எழுதுவார்கள்.
கேரளா மாநிலத்தில் 60 சதவீத கடற்கரை கடலரிப்புக்கு உள்ளாகி உள்ளது. விஞ்ஞானிகளின் ஆய்வு படி இந்த கடலரிப்புக்கு கடல் நீர் மட்டம் உயர்வது மற்றும் மழை காலங்களில் ஏற்படும் புயலால் உருவாகும் வருடாந்திர கடலரிப்பு மட்டும் காரணம் அல்ல. மாறாக நகரமயமாக்கல், சுற்றுலா, மற்றும் இயற்கைக்கு முரணான கடலரிப்பு தடுப்பு அமைப்புகள் ஆகியவையும் காரணம். இதனால் தேசிய பசுமை தீர்ப்பாயம் தற்போது உருவாக்கும் கடலரிப்பு தடுப்பு சுவர்களை அமைப்பதை நிறுத்தி வைக்க கேரளா, தமிழ்நாடு, ஆந்திரா முதலிய தென்மாநிலங்களுக்கு உத்தரவிட்டுள்ளது. இதற்கு விஞ்ஞானபூர்வாக எப்படி தடுப்பு அமைப்பது என ஒரு திட்டத்தை சமர்பிக்க உத்தரவிட்டுள்ளது.
கடலரிப்பில் பாதிக்கப் பட்டவர்களுக்கு மற்றும் கடற்கரையில் இருந்து 50 மீட்டருக்குள் உள்ள நபர்களுக்கு கேரளா அரசு வீடு கட்டிக் கொள்ள ஆறு லட்சம் ரூபாயும், நிலத்திற்கு நான்கு லட்சம் ரூபாயும் என மொத்தம் பத்து லட்சம் ரூபாய் வழங்குகிறது. ஆனால் அதனை பெற்றுக் கொண்டும் யாரும் கடற்கரையை விட்டு நகர தயாராக இல்லை. விரிவான செய்தி ஆங்கிலத்தில் கீழே.
*********
At 5 p.m. on February 10, at least 30 residents of Chellanam, a coastal village near Kochi in central Kerala, gathered on the side of the village road. The group was a motley of men and women of ages ranging from 40 to 75 — fishers, fishworkers, fish sellers, boat owners, and homeowners. They had set up a temporary shelter with bamboo, tarpaulin and bright green plastic chairs. Two speakers and a mic were also arranged. A huge banner with their cause and demands, and a whiteboard stating the day of protest – 837.
The group, part of a local non-profit forum Kochi Chellanam Janakeeya Vedi, were protesting the loss of their homes and livelihoods to coastal erosion and demanding that the government take proper action to protect their coastline. Their protest in Chellanam began on October 28, 2019, shortly after the village started experiencing severe erosion, and continues till date.
Chellanam is just one of the many villages affected by coastal erosion in the southern Indian coastal state. In November 2018, the National Centre for Earth Science Studies (NCESS) published a shoreline assessment study for southwest India. The study analysed the 1968-2014 period using multi-dated shoreline images and Survey of India (SOI) topographic charts. The analysis revealed that almost 60 percent of Kerala’s coastline is eroding. Apart from seal level rise, anthropogenic factors are a leading cause for an irreversible loss of land.

Coastal erosion and factors leading to damage
Kerala’s 590-kilometre long coastline, extending from Poovar in Thiruvananthapuram in the south till Thalapadi in Kasargod in the north is a dynamic coastal stretch. It lies sandwiched between the Arabian Sea on the west and the Western Ghats on the east. Its coast is intercepted by 41 rivers that originate from the Western Ghats and flow into the Arabian Sea through inlets that are connected to the sea via estuaries/lagoons.
Coastal erosion is the wearing away of the land by the sea. It is a long-term removal of sediment along the coastline. On dynamic shorelines, coastal erosion is a seasonal process. The littoral current is a combination of longshore currents that flow parallel to the shore and cross-shore currents that flow onshore-offshore. These currents transport sediment in both the directions and the beaches recede and accrete seasonally.
Kerala has three distinct seasons – pre-monsoon from February to May, the southwest monsoon from June to September and the northwest post-monsoon from October to January. The longshore currents generally flow north to south during the monsoon and in the opposite direction in other seasons. One of the primary reasons for erosion is the influence of monsoonal and non-monsoonal waves. The beaches, after being subjected to seasonal erosion, are capable of completely regaining their original shape.
But, over the years, as the NCESS study indicates, coastal development in the form of urbanisation, tourism, and “unscientific shoreline protection methods” has led to the coastline becoming unstable. Anthropogenic activities such as the construction of hard structures (breakwaters, seawalls, groynes), dredging of channels, beach/river sand mining, and damming of rivers have a negative impact on the coast. They obstruct the natural flow of the water, cause a shortage of sediment supply, and cause erosion on one part of the land and accretion on another part.

“Imagine a river of sand is flowing in a particular direction, just like a river,” said K.V. Thomas, geographer and former scientist and group head at NCESS, and former Dean, Kerala University of Fisheries and Ocean Studies, Kochi.
When one has structures protruding from the shore — breakwaters, harbours, jetties, or groynes — they block the natural flow of the sand, just like a dam blocks a river.
“When we intervene with the natural flow of sand on the up-drift side, the sediment gets blocked on that side. The down-drift side, where the sand is supposed to flow, now experiences scarcity. Thus, there is erosion on the down-drift side, and deposition on the up-drift side,” he explained. Once this displacement happens, there is no scope of sand coming back, as it is blocked by the structure. The erosion is irreversible.
Today, Kerala’s coast is dotted with one major port at Kochi, four intermediate ports at Thiruvananthapuram, Alappuzha, Kozhikode, Thalassery, an upcoming international port at Vizhinjam, 25 fishing harbours and breakwaters, and 106 groynes. Of the entire coastline, about 310 km is an artificial coast. An artificial coast is an eroding coast that is managed by man-made structures — seawalls running parallel to the shore, and groynes built perpendicular to the shoreline.
This is why fishers say that the “beaches would always come back. But not anymore.”

Chellanam is a narrow strip of low-lying land nestled between the Arabian sea and the backwaters of Vembanad Lake, the largest freshwater lake in Asia in the Ernakulam district of central Kerala. Cochin port lies to its north. The 17.5 km coastline has a harbour and a coastline that is partially covered with a seawall in dilapidated condition. Approximately 16,000 families live in the 812-hectare area. Large stretches of revenue land and property owned by the local community have been eroded over a period of 40-50 years in this area. Hundreds of families have lost their homes.
Sixty-two-year-old Filomena Joseph lives with her husband and two children in the Bazar ward of Chellanam. Her home, a broken, small pucca structure, lies barely 50 metres from the Arabian Sea; a wall of rocks separates it from the lashing waves. Nearly a year has passed since Cyclone Tauktae tore through the west coast. Huge waves overtopped the seawall, inundating the Chellanam village with floods. Some waves smashed through the seawall, sending stones flying into people’s homes. The Bazar ward, one of the worst affected parts of Chellanam, still looks like a disaster site. Nearly every house is either broken or filled with sand.
The row of houses next to Filomena’s are broken structures. They are the first in line, facing the sea, with the rocks between them. The beach that existed between the seawall and the sea is long gone. “Last monsoon, the waves were so big and strong, they crashed into the seawall, and the stones flew into people’s homes,” said Mary Jugunu, a resident of Chellanam and also the local translator for Mongabay-India.
“The depth is too high now. As you enter into the water, you will just fall,” she continued to explain. In her childhood, there used to be a beach in front of the seawall. In the presence of a beach, the waves break on the sand, and the energy gets absorbed, thus softening the waves. But now, there is no place for the waves to crash because there is no beach. The sand is gone, and the depth is so high that the waves directly crash into the seawall.
It is not that the waves themselves have become stronger, she added. It is just that they crash more heavily because of the high depth.
The sea by the beach of Shanghumugham, a fishing village near Trivandrum in south Kerala has layers of three distinct colours – a muddy brown near the shore, a teal, and a deep blue. The muddy brown is new, said Ajith Shanghumugham, a fisher, chef and activist from the village. “The sea has come closer. The beach used to stretch for miles and miles, and now it is barely 25-30 metres,” he said. A road running parallel to the shore, linking the beach to the city airport has been entirely damaged due to coastal erosion, making it tough for people to complete the last mile to the airport.
Fishing with kambavala, a large shore seine net requires up to 40 people at a time, and requires the fishers to hold the net from the sides, placing it near the shore. It is one of the oldest traditional fishing methods in south Kerala, and one that employs elderly fishers as well, as they don’t have to go into the sea. The net needs large swathes of land to spread out on. The shrinking beach has made it difficult for fishers to keep their nets, boats and equipment.

Many have even lost their homes to the sea, and have been shifted to relief camps.
On July 23, 2019, Celine Gerard’s home in Shanghumugham collapsed. It was a regular monsoon day. Rain thrashed. Waves crashed. “The waves came and took sand below my home and it just entirely caved in. No warning,” said Gerard. She now lives with thirty other refugees in a relief camp in Valiathura, a neighbouring village that is also facing the brunt of erosion. The camp is built of shipping containers, with 5ftx5ft cubicles fitting in 14 families, one kitchen, and two bathrooms.
The women want their homes back. Grief is a constant factor in their lives. They neither blame the sea nor the cyclone or the floods. They squarely blame the upcoming private port in Vizhinjam, about 20 km away.

While studies have proved that hard structures along the coastline cause irreversible coastal erosion, scientists insist that more site-specific studies are needed to understand the precise reasons, as the geomorphology of the coastline is different for each location.
In February 2022, Rafeeque M.K., a scientist studying coastal morphologies at NCESS presented a paper during the Oceans 2022 conference in Chennai. The draft, yet to be published, is titled Functional Performance of Coastal Protection Structures. Using scientific analysis and focus group discussions with indigenous fishers, his paper reveals that the shoreline trend analysis of the Trivandrum coast from 1968 to 2021 shows that 81 percent of the coastline is affected by coastal erosion. While the paper does not make any specific mentions about the Vizhinjam port, it does say that hard structures such as breakwaters, seawalls and promenades, and activities such as dredging cause irreversible erosion of the beaches. A 3.1 km breakwater is currently under construction at the port.

In Chellanam, central Kerala, the 2018 NCESS study shows that the region south of Cochin inlet (where Chellanam lies) has been under erosion for years. While activists and fishers blame the continuous dredging of the Cochin port for the coastal erosion, scientists also say that the renovated harbour breakwater could be increasing the rate of erosion. They also blame dredging.
For a port to maintain its shipping channel, it needs continuous dredging.
“Dredging is essentially the removal of sand from a beach,” said Thomas. “And they started dredging the tidal inlet (of Cochin) to deepen the channel, which changed the inlet dynamics and eventually the sediment dynamic,” he explained. The sand recharges the coast, it was deposited over thousands of years, and when we dredge it we are removing it. “The sediment is food for the coast and we are making it hungry,” he added.
And the first line of impact is the fishing communities that live on these stretches.

In December 2021, the Kerala government, through funding received by the Kerala Infrastructure Investment Fund Board, launched a Rs. 344 crore (Rs. 3.44 billion) project to build a seawall at Chellanam using tetrapods and rubble. The contract was given to Urangular Labour Contract Cooperative Society. The work is ongoing.
In Shanghumugham, a 350-metre long diaphragm wall is under construction to protect the airport road. A diaphragm wall is a continuous reinforced concrete wall constructed in the ground and acts as a retaining wall. The project was allotted Rs 6.39 crore (Rs. 63.9 million) under the Rebuild Kerala Initiative, a state government project to restore and rebuild Kerala after the 2018 floods. The work, here too, is ongoing.
This year, as part of their 2022-2023 budget, the government has allocated Rs 333 crore (Rs. 3.33 billion) for the coastal protection of the overall state.
But the government is keen on seawalls even when science has established that they are counter-effective. Seawalls have a long drawn history in Kerala, with the first one being constructed in 1890, south of Varkala cliff in Trivandrum in the southern district of the state. “The purpose of that seawall was to protect a canal that was being constructed at the time, not the coastline,” explained Thomas of NCESS.
Ever since, seawalls have been the go-to solution for any kind of protective measure. The erosion of the beach from the front of the seawall, explains Thomas, is often a result of the seawall being placed on the wrong site. “This is a micro-tidal and a high energy coast. A seawall cannot be the first option for protecting the coast in such a situation,” he said. “Once the waves hit the seawall, they will take the sand away, and over time the sediment will disappear from the spot. The waves will continue to get higher, and eventually overtop and break into the seawall.”

But, Thomas stressed that things are slowly changing. “Seawalls must only be used in dire emergencies, and the government is slowly understanding that,” he said.
In November 2021, the National Green Tribunal, southern zone, released an order demanding a shoreline assessment plan from Kerala, Tamil Nadu, Andhra Pradesh, Puducherry and Karnataka to devise a strategy to mitigate the problem of coastal erosion. The order emphasised that it has been proved that the construction of a seawall along the coastal zone is not a permanent measure for protecting the coast and each time state governments end up spending a huge amount on their construction. “It is high time for the coastal states to find out some scientific measures as to how this can be resolved so as to protect the coastal region…without affecting the persons who are depending on the sea for their livelihood,” the order stated.
Recently, on April 11, 2022, the NGT passed an order to stall the construction of all hard structures across India’s coastline, recommending to state governments to explore more eco-friendly solutions.
Queries sent to the Kerala state government regarding the seawall projects and shoreline assessment plans were unanswered at the time of publishing.
For rehabilitation and compensation, the state government has offered financial assistance with the “Punargeham project” which offers people Rs. 600,000 to buy new land and Rs. 400,000 to construct a home. The scheme is meant to rehabilitate 18,685 families living within 50-metre of the high tide line. Many people have found faults with the compensation because land prices are “too high” and they “do not want to move away from the sea.” On April 1, 2022, the fair value of land in the state went up by 220 percent from the time it was fixed in 2010.
“We also don’t get any loan from the banks because all of these coastal areas are vulnerable and no bank wants to take a risk. They have pushed us to the brink,” said 65-year-old Joseph, a fisherman whose home was completely destroyed in the cyclone last year. While some are suffering from the pain of losing their homes, residents like Filomena, who have parts of their houses intact, live by the sea with a sense of foreboding.
“We live in fear of the sea,” shared Filomena, whose front rooms are reduced to rubble, the switchboard is gone, the windows are broken, and all electrical appliances are rotting thanks to the seepage of seawater. She had 11 coconut trees, out of which seven were uprooted last year during the cyclone. She used a bit of her land to grow vegetables but she notes that saline water destroyed that livelihood. Her husband, a fisher, rarely goes to work because of dwindling fishing days thanks to bad weather.
But the sea is her home. “This is my homeland. This is my kadalamma (mother sea). I cannot leave this place. Our government needs to do better,” she said.
Banner image: A house damaged by Cyclone Tauktae and coastal erosion in Chellanam. Photo by Supriya Vohra/Mongabay.
தமிழகத்தில் தற்போது தான் பனைத்தொழிலுக்கு அரசின் சில ஊக்க அறிவிப்புகள் வந்துள்ளன. ஆனால் அதே நேரத்தில் நம் அண்டை தேசமான இலங்கையில் பனைத் தொழிலை ஊக்குவிக்க ஏராளமான ஆராய்ச்சிகள் சுமார் 40 ஆண்டுகளுக்கு முன்பாகவே மேற்கொள்ளப் பட்டு அதனை ஆவணப்படுத்தி உள்ளார்கள். அவ்வாறு ஒரு புத்தகம் ஒரு நண்பர் என்டிஆர் பவுண்டேசனில் பகிர்ந்து இருந்தார். அது அனைவரும் தெரிவதற்காக கீழே கொடுக்கப் பட்டுள்ளது.
புவி வெப்பமயமாதலால் உலகம் முழுவதும் பாதிக்கப் படுகிறது. அதற்கு அமெரிக்காவும் விதிவிலக்கு அல்ல. 2100 ஆண்டு வாக்கில் கடல் நீர் மட்டம் சுமார் ஒன்றரை மீட்டர் வரை உயரும் என்று எதிர் பார்க்கப் படுகிறது. இதனால் அமெரிக்காவில் ஏராளமான நகரங்கள் பாதிக்கப்பட வாய்ப்பு உள்ளது. மேலும் கடல் நீர் மட்ட உயர்வால் எவ்வளவு பகுதிகள் பாதிக்கப்பட்டுள்ளன என்ற விபரத்தையும், குடியிருப்புகள் எவ்வாறு பாதிக்கப் பட்டுள்ளன என்றும் இணைப்பில் உள்ள செய்தியும் படமும் தெரிவிக்கிறது.

அதிசயம். ஆனால் உண்மை.
தாது மணல் சுரங்க பணியால் கடலரிப்பு என்று சிலர் தி;ட்டமிட்டு பிரச்சாரம் செய்தார்கள். இது பற்றி நாங்கள் பல்வேறு நிபுணர்களிடம் கலந்து பேசி தாதுமணல் சுரங்க பணிக்கும் கடலரிப்பிற்கும் தொடர்பு இல்லை என்பதை தொடர்ந்து விளக்கி வந்தோம். தற்போது எங்கள் கருத்தை இந்திய அரசின் விஞ்ஞானம் மற்றும் தொழில் நுட்பதுறை கடந்த 26 வருடங்களாக இந்திய கடற்கரையில் ஏற்பட்டுள்ள மாற்றங்களை செயற்கைகோள் மூலம் படம் பிடித்து வந்து ஒரு அறிக்கையை பாராளுமன்றத்தில் சமர்பித்துள்ளார்கள். அது தொடர்பான செய்தி கீழே உள்ளது.
இதன்படி இந்தியாவில் சாதாரணமாக 41 சதவீத கடற்கரை கடலரிப்பால் பாதிக்கப் பட்டுள்ளது. இந்தியாவில் அதிகமாக கடலரிப்பால் பாதிக்கப் பட்ட மாநிலம் மேற்கு வங்காளம் (60 சதவீதம்). பாண்டிச்சேரி (56 சதவீதம்), கேரளா மற்றும் தமிழ்நாடு (41 சதவீதம்) ஆகும்.
இதில் முக்கியமாக கவனிக்கப் பட வேண்டியது மேற்கு வங்கம் மற்றும் பாண்டிச்சேரியில் தாதுமணல் சுரங்க பணி நடைபெறவில்லை. திருநெல்வேலி, தூத்துக்குடி மாவட்டங்களில் தனியார் தாதுமணல் சுரங்க குத்தகை உள்ள எந்த பகுதியிலும் கடலரிப்பு ஏற்படவில்லை. காரணம் அவர்கள் கடலோர மேலாண்மை விதிகளின் கீழ் பெற்ற சுற்றுச்சூழல் அனுமதியின் நிபந்தனைகளை தீவிரமாக கடைபிடிப்பது தான். எனவே அரசு கடலரிப்பை தடுக்க கோடிக்கணக்கில் செலவு செய்வதற்கு பதிலாக எல்லா கடலோர பகுதியிலும் தனியாருக்கு உரிய நிபந்தனையோடு சுரங்க குத்தகை வழங்கினால் கடலரிப்பை பாதுகாக்க முடியும். உள்ளுர் மக்களுக்கு வேலை வாய்ப்பு. அரசுக்கு வரி வருவாய். ஒன்றிய அரசுக்கு அன்னிய செலவாணி எல்லாம் கிடைக்கும். ஆனால் அரசியல்வாதிகளுக்கு கமிஷன் கிடைக்காது என்பதால் இதனை செய்ய மறுப்பதாக பொதுமக்களில் சிலர் கூறுவது உண்மை தானோ என்பது இந்த செய்தியை பார்க்கும் போது நினைக்க தோன்றுகிறது.
——————
The report said coasts of Kasaragod, Kannur, Malappuram, Ernakulam and Kollam are dominated by both erosion and stable condition with a few pockets of accretion.
Published: 12th December 2021 03:39 AM
THIRUVANANTHAPURAM: Giving enough reasons for the state to worry, a study report tabled in Parliament by the Ministry of Earth Sciences reveals that 41% of the coastline in Kerala is under varying degrees of coastal erosion. The National Centre for Coastal Research has monitored the shoreline changes along 6,632km of Indian coastline from 1990 to 2018. The results of the study are mainly classified into three different categories — erosion, stable and accretion.
The overall long-term (1990-2018) shoreline change result shows that about 32% of the coastline is under varying degrees of erosion, while 27% is of accreting nature and the remaining 41% is in a stable state. The state-wise shoreline analysis reveals that 60% of the West Bengal coast was noticed with varying degrees of erosion followed by Puducherry (56%), Kerala (41%) and Tamil Nadu (41%). Accretion was dominant along the Odisha coast with 51% followed by Andhra Pradesh (48%).
Another study, ‘Coastal Morphology and Long-term Shoreline Changes along the Southwest Coast of India’, conducted by the National Centre for Earth Science Studies and published in Journal Geological Society of India, revealed that almost 60% of the state’s coastline is eroding with about 29% showing an accreting trend. A 46-year-period from 1968 to 2014 was studied using multi-dated shoreline images and Survey of India topographic charts.
All these studies point to factors like construction of structures such as fishing harbours, ports, groynes, sea walls and beach sand mining for monazite ores for altering the nature of the coastline and induced changes.
M C Dathan, scientific advisor to the chief minister and a former director of ISRO’s Vikram Sarabhai Space Centre (VSSC), said, “Coastal erosion is more vigorous and rampant along the coastline of Kerala as more energy is stored in the waves of the Arabian Sea as compared to the Bay of Bengal. There are a lot of global factors which influence the sea surface temperature and wind patterns over the sea. We have been following various methods like construction of a sea wall, diaphragm wall etc here to dampen the force of waves. It is to some extent useful but, certainly, more needs to be done.”
மெர்காம் இந்தியா என்ற இணையதளத்தில் ஒரு அதிர்ச்சி செய்தி வெளியாகி உள்ளது. அதன் சுருக்கம்
2050-ல் இந்தியாவின் 30 பெருநகரங்கள் கடுமையான குடிநீர் தட்டுப்பாட்டை சந்திக்கும். அதிர்ஷ்டவசமாக தமிழ்நாட்டின் எந்த நகரமும் அந்த பட்டியலில் இல்லை. ஆனால் வடமாநில தொழிலாளர்களின் ஊடுருவல் தமிழ்நாட்டில் அதிகரித்தால் தமிழ்நாடும் இம்மாதிரி குடிநீர் தட்டுப்பாட்டை சந்திக்கும் நிலை ஏற்பட்டு விடும்.
அது வெளியிடும் இன்னொரு செய்தி சுமார் 1000 மெகாவாட் மின்சாரம் உற்பத்தி செய்யும் ஒவ்வொரு அனல் மின் நிலையமும் 6500-ல் இருந்து 8000 கிலோ லிட்டர் அளவிற்கு தினசரி நீரை உபயோகிக்கிறது என்ற அதிர்ச்சி செய்தியும் ஆகும். எனவே அனல் மின் நிலையங்கள் காற்றுமாசு மட்டும் ஏற்படுத்தவில்லை. நீர் தட்டுப்பாட்டையும் ஏற்படுத்துகிறது. தூத்துக்குடியை சுற்றி புதிதாக சுமார் நான்கு அனல் மின் நிலையங்கள் வந்ததும் தூத்துக்குடியின் பாதிப்பிற்கு ஒரு காரணம் என சில சமூக ஆர்வலர்கள் கூறுவது உண்மை தானோ என்பதை இந்த அறிக்கை சிந்திக்க வைக்கிறது.
இந்திய அரசின் நிதி ஆயோக் வெளியிட்ட தகவல் படி சுமார் ஆறு கோடி இந்தியர்கள் கடுமையான குடிநீர் தட்டுப்பாட்டை எதிர் நோக்கும் நிலை உள்ளது.
இப்போதே நாம் இதற்கு மாற்று வழியை சிந்திக்க வேண்டும். அரசியல்வாதிகளும், அதிகாரிகளும் இதற்கு ஆலோசனை கூற வேண்டும். மிக இலகுவான ஒரு வழி அனல் மின் உற்பத்தியை குறைத்து சூரிய மின் உற்பத்தியை கூட்ட வேண்டும். ஒவ்வொரு அடுக்குமாடி குடியிருப்பு அல்லது ஒரு மாடிக்கு மேல் உள்ள கட்டிடங்கள் புதிதாக கட்டுவதாக இருந்தால் அதற்கு தேவையான மின்சாரத்தை சூரிய மின் சக்தி மூலமே பெற வேண்டும். கூடுதல் உற்பத்தியை மின் வாரியத்திற்கு கொடுப்பதற்கு உரிய வசதியை செய்திருக்க வேண்டும். அந்த வசதிகள் இருந்தால் மட்டுமே கட்டிட அனுமதி வழங்க வேண்டும்.
அரசும் அனைத்து வீடுகளுக்கும் அரசு செலவிலேயே சூரிய மின்சக்தியை உற்பத்தி செய்யும் அலகுகளை 100 சதவீத மானியத்தோடு செயல்படுத்த வேண்டும். அனைத்து மின் விளக்குகளும் எல்இடி விளக்குகளாக மாற்றுவதற்கு அரசே செலவை ஏற்க வேண்டும். இதன் மூலம் அரசுக்கு மின்சார உற்பத்தி செலவு குறையும். மின்வாரிய பராமரிப்பு செலவு குறையும். உபயோகிப்பாளருக்கும் மின் கட்டணம் செலுத்தும் தேவை இருக்காது. மேலும் புவிவெப்பமயமாதல் தடுக்கப்படும். குடிநீர் தட்டுப்பாடும் தடுக்கப்படும்.
தமிழகத்தில் சுமார் 700 கிலோ மீட்டர் கடற்கரை உள்ளது. ஐந்து கிலோ மீட்டருக்கு ஒரு கடல் நீரை குடிநீராக்கும் தொழிற்சாலை வீதம் சுமார் 140 தொழிற்சாலைகள் அமைக்கப்பட வேண்டும். அந்த நீர் அப்பகுதியில் இருந்து சுமார் 10 கிலோமீட்டர் சுற்றளவு வரை உள்ள பகுதிகளுக்கு வீட்டிற்கு இலவசமாக வழங்க வேண்டும். எனவே அப்பகுதியில் ஆழ்துளை கிணறு மூலம் நிலத்தடி நீரை, குடிக்க, குளிக்க, கால்நடை உபயோகத்திற்கு மற்றும் பிற உபயோகங்களுக்கு எடுப்பது தடுக்கப் பட்டு இதனால் கடல் நீர் நிலத்தின் உள்ளே ஊடுறுவது தடுக்கப்படும். தற்போதைய தமிழக அரசு தொலை நோக்கு சிந்தனையோடு பல்வேறு செயல்களை செய்து வருகிறது. பல்வேறு நிபுணர்களையும் உபயோகப்படுத்துகிறது. எனவே இதனையும் செயல்படுத்தினால் குடிநீர் பிரச்சனையை தமிழகம் எக்காலத்திலும் சந்திக்க வேண்டிய தேவை இருக்காது.
இதற்கு ஒரு உதாரணம் முன்பு கோ.சி.மணி என்று ஒரு உள்ளாட்சி துறை அமைச்சர் திமுக ஆட்சியில் இருந்தார். ஒரு முறை நெல்லை மாவட்டம் வரும் போது இந்த குடிநீர் பிரச்சனையை கூறினார்கள். உடனடியாக அவர் தாமிரபரணி கூட்டு குடிநீர் திட்டத்தை அமுல் படுத்த உத்தரவிட்டதோடு ஒரு குடும்பத்திற்கு நாள் ஒன்றுக்கு 200 லிட்டர் தண்ணீர் கொடுக்க வேண்டும். அடுத்த 25 வருடங்களுக்கு இதில் எந்த மாற்றமும் இருக்க கூடாது என அதிகாரிகளிடம் கண்டிப்பாக கூறினார். ஆனால் செயல்படுத்திய அதிகாரிகள் 200 லிட்டர் என திட்டமிட்டு நடைமுறைக்கு வரும் போது 20 லிட்டர் தான் கொடுக்கப்படுகிறது. இவ்வாறு நல்ல மனம் கொண்ட அமைச்சர்கள் மற்றும் செயல் திறன் கொண்ட அதிகாரிகள் ஆகியோரை வைத்து முதல்வர் நீண்டகால திட்டமாக இவற்றை செயல்படுத்தினால் நிச்சயம் சரித்திரத்தில் தமிழக முதல்வர் பெயர் இடம் பெறும் என்பதில் ஐயம் இல்லை.
*************
The World Wide Fund (WWF), in its latest WWF Water Risk Filter report, said that 30 Indian cities face imminent water-related risks unless immediate actions are taken to mitigate and curb climate change.
These cities are Jaipur, Indore, Thane, Vadodara, Srinagar, Rajkot, Kota, Nashik, Visakhapatnam, Bengaluru, Kolkata (Calcutta), Ahmadabad, Jabalpur, Mumbai (Bombay), Lucknow, Hubli-Dharwad, Nagpur, Chandigarh, Amritsar, Ludhiana, Jalandhar, Pune (Poona), Dhanbad, Bhopal, Gwalior, Surat, Delhi, Aligarh, Kozhikode (Calicut), and Kannur.
Globally, the report said that the population from areas of high-water risk could rise from 17% in 2020 to 51% by 2050.
Climate change may alter the distribution and quality of India’s water resources. According to the report, some of the impacts include heavier rains, changed spatial and temporal distribution of rainfall, higher runoff generation, low groundwater recharge, melting of glaciers, changes in evaporative demands, and water use patterns in agricultural, domestic, and industrial sectors, etc. These impacts profoundly influence agricultural production and food security, ecology, biodiversity, river flows, floods, droughts, water security, human and animal health, and sea levels.
Water use in energy generation has been an area of concern in India. A government official had commented to Mercom that a 1,000 MW coal-powered thermal project would require between 6,500 to 8,000 kiloliters of water per day, which comes down to almost 6.5-8 kl/MW/day. This is nearly eight times the water required for solar projects.
Since water usage is minimal in solar, the government needs to include water in the equation along with CO2 reductions when formulating solar goals and establishing tariffs
Mercom had earlier reported that India is suffering from the worst water crisis in its history, and millions of lives are at risk. According to the NITI Aayog, 600 million Indians face high to extreme water stress, and about 0.2 million people die every year due to inadequate access to safe water. And the crisis is only going to get worse. The article further added that by 2030, the country’s water demand is projected to be twice the available supply, implying a severe water scarcity for hundreds of millions of people and an eventual ~6% loss in the country’s GDP.
While the coal industry is massively eroding India’s water resources, the solar industry finds innovative ways to save water. That said, solar projects do use some water primarily for cleaning panels. To address this, waterless and robotic module cleaning methods are slowly gaining traction.
Last year, the Ministry of New and Renewable Energy (MNRE) recommended efficient water utilization for cleaning utility-scale solar projects. The ministry said that project developers are currently using too much water to clean solar modules, and they should try and minimize wastage. MNRE also recommended the use of robotic cleaning technology.
எம்.ஐ.டி ஆராய்ச்சியாளர்களின் கட்டுரை சுருக்கம் கீழே கொடுக்கப் பட்டுள்ளது. இதில் உள்ள அதிர்ச்சி தகவல் 2050-க்கு பிறகு உலகில் உள்ள 52 சதவீத மக்கள் குடிநீர் தட்டுப்பாட்டை எதிர் நோக்கும் நிலை உள்ளது. மேலும் வேளாண்மை மற்றும் நீர் பாசனத்திற்கு உபயோகிக்கும் நீரில் சுமார் 80 சதவீதத்திற்கு மேல் இல்லாமல் போய் விடும் என்றும் சுமார் 39 நாடுகள் மிக கடுமையாக பாதிக்கப்படும் என்றும் குறிப்பிட்டு உள்ளார்கள். எனவே இப்போதே நாம் அனைவரும் இதற்கு நடவடிக்கை எடுக்க வேண்டும். புவி வெப்பமயமாதலை தடுத்தலும், அதற்கு ஏராளமான மரங்களை வளர்த்தலும், சுற்றுச்சூழலை பராமரித்தலும் நீரை வீணாக்காமல் சுருக்கமாக பயன்படுத்தி சேமிப்பதும் இப்போதே நாம் அனைவரும் தொடங்க வேண்டும். இதனை வருங்கால சந்ததியினருக்கும் பயற்சி கொடுக்க வேண்டும்.
***********
Some 52 percent of the world’s projected 9.7 billion people will live in water-stressed regions by 2050, MIT researchers say. The researchers used the MIT Integrated Global System Model Water Resource System (IGSM-WRS) to evaluate water resources and needs worldwide. The modeling tool also allowed researchers to measure how climate change and socioeconomics affect water stress.
Some 52 percent of the world’s projected 9.7 billion people will live in water-stressed regions by 2050, MIT researchers say.
The researchers used the MIT Integrated Global System Model Water Resource System (IGSM-WRS) to evaluate water resources and needs worldwide. The modeling tool also allowed researchers to measure how climate change and socioeconomics affect water stress.
The study found population and economic growth are the socioeconomic factors most responsible for increased water stress, resulting in an additional 1.8 billion people living in water-stressed areas. Of these additional people, 80 percent will live in developing countries.
Climate change, on the other hand, will have a bigger affect on water availability in developed nations, the study says.
Thirty-seven countries face “extremely high” levels of water stress, using more than 80 percent of their available water supply every year, according to the World Resources Institute’s water stress rankings published last month.
This means that more than 80 percent of the water available to agricultural, domestic and industrial users is withdrawn annually, which can hurt businesses, farms and communities, according to a WRI blog. As an example, the blog cites recent droughts, which threatened GDP growth in the US.
Source : https://waterfootprint.org/en/about-us/news/news/water-stress-affect-52-worlds-population-2050/
Tailpipe exhaust, Anchorage, Alaska, 2009. Credit: Daniel H. Bailey / Alamy Stock Photo.
The extent of the human contribution to modern global warming is a hotly debated topic in political circles, particularly in the US.
During a recent congressional hearing, Rick Perry, the US energy secretary, remarked that “to stand up and say that 100% of global warming is because of human activity, I think on its face, is just indefensible”.
However, the science on the human contribution to modern warming is quite clear. Humans emissions and activities have caused around 100% of the warming observed since 1950, according to the Intergovernmental Panel on Climate Change’s (IPCC) fifth assessment report.
Here Carbon Brief examines how each of the major factors affecting the Earth’s climate would influence temperatures in isolation – and how their combined effects almost perfectly predict long-term changes in the global temperature.
Carbon Brief’s analysis finds that:
Animation by Rosamund Pearce for Carbon Brief. Images via Alamy Stock Photo.
In its 2013 fifth assessment report, the IPCC stated in its summary for policymakers that it is “extremely likely that more than half of the observed increase in global average surface temperature” from 1951 to 2010 was caused by human activity. By “extremely likely”, it meant that there was between a 95% and 100% probability that more than half of modern warming was due to humans.
This somewhat convoluted statement has been often misinterpreted as implying that the human responsibility for modern warming lies somewhere between 50% and 100%. In fact, as NASA’s Dr Gavin Schmidt has pointed out, the IPCC’s implied best guess was that humans were responsible for around 110% of observed warming (ranging from 72% to 146%), with natural factors in isolation leading to a slight cooling over the past 50 years.
Similarly, the recent US fourth national climate assessment found that between 93% to 123% of observed 1951-2010 warming was due to human activities.
These conclusions have led to some confusion as to how more than 100% of observed warming could be attributable to human activity. A human contribution of greater than 100% is possible because natural climate change associated with volcanoes and solar activity would most likely have resulted in a slight cooling over the past 50 years, offsetting some of the warming associated with human activities.
Scientists measure the various factors that affect the amount of energy that reaches and remains in the Earth’s climate. They are known as “radiative forcings”.
These forcings include greenhouse gases, which trap outgoing heat, aerosols – both from human activities and volcanic eruptions – that reflect incoming sunlight and influence cloud formation, changes in solar output, changes in the reflectivity of the Earth’s surface associated with land use, and many other factors.
To assess the role of each different forcing in observed temperature changes, Carbon Brief adapted a simple statistical climate model developed by Dr Karsten Haustein and his colleagues at the University of Oxford and University of Leeds. This model finds the relationship between both human and natural climate forcings and temperature that best matches observed temperatures, both globally and over land areas only.
The figure below shows the estimated role of each different climate forcing in changing global surface temperatures since records began in 1850 – including greenhouse gases (red line), aerosols (dark blue), land use (light blue), ozone (pink), solar (yellow) and volcanoes (orange).
The black dots show observed temperatures from the Berkeley Earth surface temperature project, while the grey line shows the estimated warming from the combination of all the different types of forcings
Global mean surface temperatures from Berkeley Earth (black dots) and modeled influence of different radiative forcings (colored lines), as well as the combination of all forcings (grey line) for the period from 1850 to 2017. See methods at the end of the article for details. Chart by Carbon Brief using Highcharts.
The combination of all radiative forcings generally matches longer-term changes in observed temperatures quite well. There is some year-to-year variability, primarily from El Niño events, that is not driven by changes in forcings. There are also periods from 1900-1920 and 1930-1950 where some larger disagreements are evident between projected and observed warming, both in this simple model and in more complex climate models.
The chart highlights that, of all the radiative forcings analysed, only increases in greenhouse gas emissions produce the magnitude of warming experienced over the past 150 years.
If greenhouse gas emissions alone were warming the planet, we would expect to see about a third more warming than has actually occurred.
So, what roles do all the other factors play?
The extra warming from greenhouse gases is being offset by sulphur dioxide and other products of fossil fuel combustion that form atmospheric aerosols. Aerosols in the atmosphere both reflect incoming solar radiation back into space and increase the formation of high, reflective clouds, cooling the Earth.
Ozone is a short-lived greenhouse gas that traps outgoing heat and warms the Earth. Ozone is not emitted directly, but is formed when methane, carbon monoxide, nitrogen oxides and volatile organic compounds break down in the atmosphere. Increases in ozone are directly attributable to human emissions of these gases.
In the upper atmosphere, reductions in ozone associated with chlorofluorocarbons (CFCs) and other halocarbons depleting the ozone layer have had a modest cooling effect. The net effects of combined lower and upper atmospheric ozone changes have modestly warmed the Earth by a few tenths of a degree.
Changes in the way land is used alter the reflectivity of the Earth’s surface. For example, replacing a forest with a field will generally increase the amount of sunlight reflected back into space, particularly in snowy regions. The net climate effect of land-use changes since 1850 is a modest cooling.
Volcanoes have a short-term cooling effect on the climate due to their injection of sulphate aerosols high into the stratosphere, where they can remain aloft for a few years, reflecting incoming sunlight back into space. However, once the sulphates drift back down to the surface, the cooling effect of volcanoes goes away. The orange line shows the estimated impact of volcanoes on the climate, with large downward spikes in temperatures of up to 0.4C associated with major eruptions.
January 3, 2009 – Santiaguito eruption, Guatemala. Credit: Stocktrek Images, Inc. / Alamy Stock Photo.
Finally, solar activity is measured by satellites over the past few decades and estimated based on sunspot counts in the more distant past. The amount of energy reaching the Earth from the sun fluctuates modestly on a cycle of around 11 years. There has been a slight increase in overall solar activity since the 1850s, but the amount of additional solar energy reaching the Earth is small compared to other radiative forcings examined.
Over the past 50 years, solar energy reaching the Earth has actually declined slightly, while temperatures have increased dramatically.
The accuracy of this model depends on the accuracy of the radiative forcing estimates. Some types of radiative forcing like that from atmospheric CO2 concentrations can be directly measured and have relatively small uncertainties. Others, such as aerosols, are subject to much greater uncertainties due to the difficulty of accurately measuring their effects on cloud formation.
These are accounted for in the figure below, which shows combined natural forcings (blue line) and human forcings (red line) and the uncertainties that the statistical model associates with each. These shaded areas are based on 200 different estimates of radiative forcings, incorporating research attempting to estimate a range of values for each. Uncertainties in human factors increase after 1960, driven largely by increases in aerosol emissions after that point.
Global mean surface temperatures from Berkeley Earth (black dots) and modelled influence of all combined natural (blue line) and human (red line) radiative forcings with their respective uncertainties (shaded areas) for the period from 1850 to 2017. The combination of all natural and human forcings (grey line) is also shown. See methods at the end of the article for details. Chart by Carbon Brief using Highcharts.
Overall, warming associated with all human forcings agrees quite well with observed warming, showing that about 104% of the total since the start of the “modern” period in 1950 comes from human activities (and 103% since 1850), which is similar to the value reported by the IPCC. Combined natural forcings show a modest cooling, primarily driven by volcanic eruptions.
The simple statistical model used for this analysis by Carbon Brief differs from much more complex climate models generally used by scientists to assess the human fingerprint on warming. Climate models do not simply “fit” forcings to observed temperatures. Climate models also include variations in temperature over space and time, and can account for different efficacies of radiative forcings in different regions of the Earth.
However, when analysing the impact of different forcings on global temperatures, complex climate models generally find results similar to simple statistical models. The figure below, from the IPCC’s Fifth Assessment Report, shows the influence of different factors on temperature for the period from 1950 to 2010. Observed temperatures are shown in black, while the sum of human forcings is shown in orange.
Figure TS10 from the IPCC Fifth Assessment Report. Observed temperatures are from HadCRUT4. GHG is all well-mixed greenhouse gases, ANT is total human forcings, OA is human forcings apart from GHG (mostly aerosols), NAT is natural forcings (solar and volcanoes), and Internal Variability is an estimate of the potential impact of multidecadal ocean cycles and similar factors. Error bars show one-sigma uncertainties for each. Source: IPCC.
This suggests that human forcings alone would have resulted in approximately 110% of observed warming. The IPCC also included the estimated magnitude of internal variability over that period in the models, which they suggest is relatively small and comparable to that of natural forcings.
As Prof Gabi Hegerl at the University of Edinburgh tells Carbon Brief: “The IPCC report has an estimate that basically says the best guess is no contribution [from natural variability] with not that much uncertainty.”
Land temperatures have warmed considerably faster than average global temperatures over the past century, with temperatures reaching around 1.7C above pre-industrial levels in recent years. The land temperature record also goes back further in time than the global temperature record, though the period prior to 1850 is subject to much greater uncertainties.
Both human and natural radiative forcings can be matched to land temperatures using the statistical model. The magnitude of human and natural forcings will differ a bit between land and global temperatures. For example, volcanic eruptions appear to have a larger influence on land, as land temperatures are likely to respond faster to rapid changes in forcings.
The figure below shows the relative contribution of each different radiative forcing to land temperatures since 1750.
Land mean surface temperatures from Berkeley Earth (black dots) and modeled influence of different radiative forcings (colored lines), as well as the combination of all forcings (grey line) for the period from 1750 to 2017. Chart by Carbon Brief using Highcharts.
The combination of all forcings generally matches observed temperatures quite well, with short-term variability around the grey line primarily driven by El Niño and La Niña events. There is a wider variation in temperatures prior to 1850, reflecting the much larger uncertainties in the observational records that far back.
There is still a period around 1930 and 1940 where observations exceed what the model predicts, though the differences are less pronounced than in global temperatures and the 1900-1920 divergence is mostly absent in land records.
Volcanic eruptions in the late 1700s and early 1800s stand out sharply in the land record. The eruption of Mount Tambora in Indonesia in 1815 may have cooled land temperatures by a massive 1.5C, though records at the time were limited to parts of the Northern Hemisphere and it is, therefore, hard to draw a firm conclusion about global impacts. In general, volcanoes appear to cool land temperatures by nearly twice as much as global temperatures.
Carbon Brief used the same model to project future temperature changes associated with each forcing factor. The figure below shows observations up to 2017, along with future post-2017 radiative forcings from RCP6.0, a medium-to-high future warming scenario.
Global mean surface temperatures from Berkeley Earth (black dots) and modeled influence of different radiative forcings (colored lines) for the period from 1850 to 2100. Forcings post-2017 taken from RCP6.0. Chart by Carbon Brief using Highcharts.
When provided with the radiative forcings for the RCP6.0 scenario, the simple statistical model shows warming of around 3C by 2100, nearly identical to the average warming that climate models find.
Future radiative forcing from CO2 is expected to continue to increase if emissions rise. Aerosols, on the other hand, are projected to peak at today’s levels and decline significantly by 2100, driven in large part by concerns about air quality. This reduction in aerosols will enhance overall warming, bringing total warming from all radiative forcing closer to warming from greenhouse gases alone. The RCP scenarios assume no specific future volcanic eruptions, as the timing of these is unknowable, while solar output continues its 11-year cycle.
This approach can also be applied to land temperatures, as shown in the figure below. Here, land temperatures are shown between 1750 and 2100, with post-2017 forcings also from RCP6.0.
Land mean surface temperatures from Berkeley Earth (black dots) and modeled influence of different radiative forcings (colored lines) for the period from 1750 to 2100. Forcings post-2017 taken from RCP6.0. Chart by Carbon Brief using Highcharts.
The land is expected to warm about 30% faster than the globe as a whole, as the rate of warming over the oceans is buffered by ocean heat uptake. This is seen in the model results, where land warms by around 4C by 2100 compared to 3C globally in the RCP6.0 scenario.
There is a wide range of future warming possible from different RCP scenarios and different values for the sensitivity of the climate system, but all show a similar pattern of declining future aerosol emissions and a larger role for greenhouse gas forcing in future temperatures.
While natural forcings from solar and volcanoes do not seem to play much of a role in long-term warming, there is also natural variability associated with ocean cycles and variations in ocean heat uptake.
As the vast majority of energy trapped by greenhouse gases is absorbed by the oceans rather than the atmosphere, changes in the rate of ocean heat uptake can potentially have large impacts on the surface temperature. Some researchers have argued that multidecadal cycles, such as the Atlantic Multidecadal Oscillation (AMO) and Pacific Decadal Oscillation (PDO), can play a role in warming at a decadal scale.
While human factors explain all the long-term warming, there are some specific periods that appear to have warmed or cooled faster than can be explained based on our best estimates of radiative forcing. For example, the modest mismatch between the radiative forcing-based estimate and observations during the mid-1900s might be evidence of a role for natural variability during that period.
A number of researchers have examined the potential for natural variability to impact long-term warming trends. They have found that it generally plays a limited role. For example, Dr Markus Huber and Dr Reto Knutti at the Institute for Atmospheric and Climate Science (IAC) in Zurich found a maximum possible contribution of natural variability of around 26% (+/- 12%) over the past 100 years and 18% (+/- 9%) over the past 50 years.
Knutti tells Carbon Brief:
“We can never completely rule out that natural variability is larger than we currently think. But that is a weak argument: you can, of course, never rule out the unknown unknown. The question is whether there is strong, or even any evidence for it. And the answer is no, in my view.
Models get the short-term temperature variability approximately right. In many cases, they even have too much. And for the long term, we can’t be sure because the observations are limited. But the forced response pretty much explains the observations, so there is no evidence from the 20th century that we are missing something…
Even if models were found to underestimate internal variability by a factor of three, it is extremely unlikely [less than 5% chance] that internal variability could produce a trend as large as observed.”
Similarly, Dr Martin Stolpe and colleagues, also at IAC, recently analysed the role of multidecadal natural variability in both the Atlantic and Pacific oceans. They found that “less than 10% of the observed global warming during the second half of the 20th century is caused by internal variability in these two ocean basins, reinforcing the attribution of most of the observed warming to anthropogenic forcings”.
Internal variability is likely to have a much larger role in regional temperatures. For example, in producing unusually warm periods in the Arctic and the US in the 1930s. However, its role in influencing long-term changes in global surface temperatures appears to be limited.
While there are natural factors that affect the Earth’s climate, the combined influence of volcanoes and changes in solar activity would have resulted in cooling rather than warming over the past 50 years.
The global warming witnessed over the past 150 years matches nearly perfectly what is expected from greenhouse gas emissions and other human activity, both in the simple model examined here and in more complex climate models. The best estimate of the human contribution to modern warming is around 100%.
Some uncertainty remains due to the role of natural variability, but researchers suggest that ocean fluctuations and similar factors are unlikely to be the cause of more than a small fraction of modern global warming.
Methodology
The simple statistical model used in this article is adapted from the Global Warming Index published by Haustein et al (2017). In turn, it is based on the Otto et al (2015) model.
The model estimates contributions to observed climate change and removes the impact of natural year-to-year fluctuations by a multiple linear regression of observed temperatures and estimated responses to total human-induced and total natural drivers of climate change. The forcing responses are provided by the standard simple climate model given in Chapter 8 of IPCC (2013), but the size of these responses is estimated by the fit to the observations. The forcings are based on IPCC (2013) values and were updated to 2017 using data from NOAA and ECLIPSE. 200 variations of these forcings were provided by Dr. Piers Forster of the University of Leeds, reflecting the uncertainty in forcing estimates. An Excel spreadsheet containing their model is also provided.
The model was adapted by calculating forcing responses for each of the different major climate forcings rather than simply total human and natural forcings, using the Berkeley Earth record for observations. The decay time of thermal response used in converting forcings to forcing responses was adjusted to be one year rather than four years for volcanic forcings to better reflect the fast response time present in observations. The effects of El Niño and La Niña (ENSO) events was removed from the observations using an approach adapted from Foster and Rahmstorf (2011) and the Kaplan El Niño 3.4 index when calculating the volcanic temperature response, as the overlap between volcanoes and ENSO otherwise complicates empirical estimates.
The temperature response for each individual forcing was calculated by scaling their forcing responses by the total human or natural coefficients from the regression model. The regression model was also run separately for land temperatures. Temperature responses for each forcing between 2018 and 2100 were estimated using forcing data from RCP6.0, normalised to match the magnitude of observed forcings at the end of 2017.
Uncertainties in total human and total natural temperature response was estimated using a Monte Carlo analysis of 200 different forcing series, as well as the uncertainties in the estimated regression coefficients. The Python code used to run the model is archived with GitHub and available for download.
Observational data from 2017 shown in the figures is based on the average of the first 10 months of the year and is likely to be quite similar to the ultimate annual value.