Down To Earth(AUGUST 16 - 31)

CLIMATE CHANGE AND ITS IMPACT

Context: The UN’s top climate panel, IPCC, delivers its starkest warning about the world’s climate, saying human influence is unequivocally responsible for extreme disasters.

IPCC 6th Assessment Report

•     By 2040, earth will be hurtling towards a rise in the earth’s temperature by 1.5 degree celsius and 2 degree celsius by the middle of the century.

•     Science is telling us that the relative efficiency of sinks—the Earth’s natural cleaning system, the oceans, forests and soils—will go down in the coming years as emissions continue to rise.

•     Currently, oceans, land and forests together absorb some 50% of the emissions that we release into the atmosphere.

•     The US and China, put together, add up to roughly half the world’s annual emissions. On adding emissions from 1870 to 2019, then the US, EU-27, Russia, UK, Japan and China contribute 60% of the global carbon dioxide budget.

•     China will increase its share of CO₂ emissions—going from 10 Gt/CO₂ to 12 Gt/CO₂ annually in the coming decade.

•     Between 1870 and 2019, India’s share of the global CO₂ budget was some 3 per cent. While China emits some
10 Gt/CO₂ and the US 5Gt/CO₂; India emits some 2.6 Gt/CO₂ annually.

•     In the first two decades of the 21st century, the average global surface temperature was 0.99°C higher than the 1850-1900 level. But in the decade of 2011-2020, the rise was 1.09°C above the historic base period, indicating a faster warming of the planet.

•     The estimated increase in global surface temperature since AR5 (Assessment Report 5, released in 2013) is principally due to further warming since 2003–2012 (adding +0.19°C).

•     Since 2011, concentrations of greenhouse gases have continued to increase in the atmosphere, reaching annual averages of 410 ppm for CO₂, 1,866 ppb for CH₄, and 332 ppb for N₂O in 2019.

•     Climate zones have shifted poleward in both hemispheres, and the growing season has on average lengthened by up to two days per decade since the 1950s in the Northern Hemisphere extratropics.

•     The average rate of sea level rise was 1.3 mm yr–1 between 1901 and 1971, increasing to 1.9 mm yr–1 between 1971 and 2006, and further increasing to 3.7 mm yr–1 between 2006 and 2018.

 

Facts The global surface temperature in June was the fifth highest in 142 years, according to the National Oceanic and Atmospheric Administration (noaa )’s Global Climate Report June 2021. There has not been a cool month in 438 months. In 2018, IPCC’s Special Report on Global Warming of 1.5°C had estimated that two-fifths of the global population lived in regions with warming above 1.5°C. The world saw at least 227 extreme weather events between January and July 2021. The figure was 157 in 2011.

Irreversible Change Due to Changing Climate

There are nine signals that tells that the Earth System could experience an abrupt irreversible change due to changing Climate:

•     Atlantic Meridional Overturning Circulation (AMOC): West African monsoon shift Shutdown of AMOC caused by an increased influx of freshwater into the North Atlantic.

•     Greenland ice sheet: Disintegration Irreversible retreat of the ice sheet.

•     Amazon Rainforest Dieback: Deforestation and hotter, drier conditions causing dieback of the rainforest and a shift towards savannah.

•     West African Monsoon Shift: An abrupt change in Sahel rainfall, caused by a shift northwards (wetter) or southwards (drier) in the West African monsoon.

•     Permafrost loss: Abrupt increase in emissions of CO2 and methane through the thawing of frozen carbon-rich soils.

•     Boreal forest shift: A shift in boreal forests, seeing expansion into tundra to the north and dieback to the south.

•     Indian monsoon shift: A strengthening of the monsoon caused by rising CO2 emissions or a weakening as a result of high aerosol emissions.

•     Coral Reef Die-Off: Rising temperatures pushing warm water corals beyond tolerable levels of thermal stress into an alternative state dominated by macro algae.

•     West Antarctic Ice Sheet Disintegration: Collapse of the ice sheet triggered by persistent grounding-line retreat in one sector, cascading to other sectors.

 

NORTH EASTERN STATES AND NEW RAIN DISTRIBUTION TRENDS

Arunachal Pradesh

•     There is an overall trend of decreasing monsoon rains in this mountain state that has a significant forest cover of 82 per cent.

•     Only two districts, Upper Siang and Upper Subansiri, have reported an increase in rainfall but Upper Siang has reported a reduction in the number of rainy days.

•     There was a 21 percent variation or fluctuation in the amount of rainfall the state received during the monsoon season every year. The variation increases to 31 per cent in July, the wettest monsoon month in the state.

•     In 2019 and 2020, the state has largely received normal rainfall.

Assam

•     There is an overall decrease in the monsoon rains in the past decades in Assam, though the drop is not as significant as in Arunachal Pradesh.

•     Most of the districts to the north of the Brahmaputra river like Barpeta, Sonitpur, Lakhimpur and Nalbari show a trend of increase in rainfall, though the increase is not significant but these districts have seen a significant decrease in the number of  rainy days.

•     In the last two years, the overall rainfall has been normal in the state.

Nagaland

•     The hilly state, which has also recorded an overall drying trend, is witnessing an abnormal shift: monsoon rainfall is going down in the traditionally wetter districts in the north, central and the southwest parts of the state, while it is going up in the drier districts in the southern parts.

•     Monsoons, which account for 68 per cent of the annual rainfall in the state, remain highly unpredictable with an almost 25% variability in the past three decades.

•     In 2019, the overall monsoon season was normal, though six of the 11 districts experienced a deficit. In 2020, Nagaland was one of the few northeastern states to experience an overall deficit rainfall (29% lower than normal).

Sikkim

•     While the overall monsoon rainfall has only marginally increased in the past three decades, three-fourths of the state is growing drier. This has been possible because the climate in the second smallest state of India varies from place to place due to the significant variation in elevation and topography.

•     The upward trend of the monsoons is most prominent in North Sikkim, which may be causing an increase in the flooding of the Teesta river.

•     The state also received surplus rainfall during monsoon season in both 2019 (22 per cent above normal) and 2020 (61 per cent above normal).

Mizoram

•     Mizoram is the only other northeastern state where the overall monsoon rainfall has seen a minor increase between 1989 and 2018. The eight districts are equally split with four each showing minor increase and minor decrease.

•     The three wettest districts—Lunglei in the centre, Kolasib in the north and Saiha in south— have seen an increase in the overall rainfall along with a substantial drop in the number of rainy days and along with an increase in heavy rainfall days, suggesting a clear trend of heavier than usual rainfall in short spurts.

•     While Mizoram received a normal monsoon in 2019, it experienced a deficit monsoon the year later (34 per cent below rainfall) with seven districts in the red.

Meghalaya

•     Meghalaya has also recorded a downward trend in the overall monsoon rainfall. IMD data shows that deficit rainfall became a chronic problem after 2005.

•     While the three districts that are at the centre have seen minor changes in rainfall, the four districts on the outside have seen significant changes.

•     The East Khasi Hill district, which receives the most rainfall, has recorded a minor increase in the monsoon rains and a significant decrease in rainy days.

•     The state has one of the highest variations in the monsoon rainfall at almost 25 per cent. This goes up to 40 per cent in July, when it receives bulk of the monsoon rains.

•     It received normal monsoon showers in 2019 and surplus (41% excess rains) monsoon showers the year later, with five districts reporting excess or large excess rainfall.

Tripura

•     This is perhaps the only northeastern state where all the districts have seen an overall reduction in the monsoon rains over the past three decades, though the change has not been significant.

•     This is likely to have an impact on the 10 major rivers in the state that are all rain-fed and ephemeral in nature.

•     Meghalaya has also seen an overall variability in the monsoon season at 19 per cent. This, however, shoots to over 35% in June, when it receives the most rainfall.

•     The state that receives 60 per cent of its annual rainfall during the monsoon months experienced a normal monsoon in 2019 and 2020.

Manipur

•     For the hilly state of Manipur, IMD has not released the composite data for the three decades (1989-2018).

•     The state saw a significant increase in its annual rainfall between 1975 and 1989, followed by a phase of significant decrease in the rains between 1990 and 2007, says a study by the Central Agricultural University, Imphal, in 2016.

•     It adds that Manipur has seen 18 mild drought years and one moderate drought year (1979) in the three decades between 1975 and 2007.

•     The state also recorded a severe drought in 2009, when the country experienced a highly deficient monsoon.

•     In 2019, Manipur received 56 per cent lesser rains during the monsoon season, as per IMD.

•     Chandel district, located in the southeast part of the state, reported an 82 per cent deficit that year. The trend continued in 2020, when the state received a deficit rainfall of 46 per cent.

Effect of Changing Rainfall Pattern

•     The changing rainfall pattern has a cascading effect on the region’s ecological health, and this impacts the life and livelihood of the people.

•     An increase in the annual rainfall can alter the natural flow of the river.

•     A decrease in the annual rainfall dries up mountain springs. Around 200 mountain springs have already dried up in the region, suggests a 2018 report by the  NITI Aayog.

•     The riverine islands of the Brahmaputra have been identified as being the most vulnerable to diseases due to frequent floods that appear to be on the rise.

•     The increase in floods in Assam’s Golaghat district is destroying forestland inside the Kaziranga national park. This is impacting the nearby villages and hampering the natural migration routes of animals.

•     Crop failure due to high rainfall variability and increased crop water needs is identified by Manipur’s state action plan on climate change as one of the major fallouts on agriculture and its allied sectors in the state.

•     In 2005-06, Assam experienced a drought and it had an immediate impact on rice production. This can impact the region’s food security.

•     Declining vegetation cover due to drought stress also enhances soil erosion and can lead to desertification.

Conclusion

•     The June-July events this year were not just  wake up calls but a heavy jolt to acknowledge the new reality. Climate extreme events are not greater than war and biological events in number and cause more economic losses. We are at an imminent risk of hitting 1.5o in the near term. The only way to prevent exceeding this threshold is by urgently stepping up our efforts and pursuing the most ambitious path.

•     Climate scientists have for a while agreed that the change in rainfall is one of the most critical factors determining the overall impact of climate change. But As urbanisation continues, the situation is bound to get worse and it will make the monsoon rainfall even more erratic.

1.    While there are ongoing efforts to reduce greenhouse gas emissions and restrict global warming to below 2°C or even below 1.5°C, there are also efforts to help us live in a wOrld where average global temperatures are rising. Examine.

2.    Climate change is not anymore only an environmental problem, but a unique one with multi-scalar characteristics, from the global to the local. Comment, also discuss challenges in tackling the problem of climate change across the world.

1.    The frequency of urban floods due to high-intensity rainfall is increasing over the years. Discussing the reasons for urban floods, highlight the mechanisms for preparedness to reduce the risk during such events.                 (GS-3: 2016)