Global coral bleaching event expands, now the largest on record
- The mass bleaching of coral reefs around the world since February 2023 is now the most extensive on record, the National Oceanic and Atmospheric Administration (NOAA) has said.
- A staggering 77% of the world’s coral reef areas – from the Atlantic to the Pacific to the Indian oceans – have so far been subjected to bleaching-level heat stress, according to satellite data, as climate change fuels record and near-record ocean temperatures across the world.
- “This event is still increasing in spatial extent and we’ve broken the previous record by more than 11% in about half the amount of time,” said NOAA Coral Reef Watch coordinator.
- This could potentially have serious ramifications for the ultimate response of these reefs to these bleaching events.
- The NOAA coral reef authority declared the global bleaching event in April 2024, making it the fourth of its kind since 1998.
- The previous record from the 2014 to 2017 mass bleaching affected just below 66 percent of the world’s reef area.
- Triggered by heat stress in warm oceans, coral bleaching occurs when corals expel the colourful algae living in their tissues.
- Without these helpful algae, the corals become pale and are vulnerable to starvation and disease.
- A bleached coral is not dead, but ocean temperatures need to cool off for any hope of recovery.
- At least 14% of the world’s remaining corals were estimated to have died in the previous two global bleaching events.
- Though this mass bleaching is already the most widespread, affecting reefs in 74 countries and territories, NOAA has so far stopped short of calling, it the “worst” on record.
- In coming months and years scientists will conduct underwater assessments of dead corals to help tally up the severity of the damage.
- It seems likely that it is going to be record-breaking in terms of impacts.
- We’ve never had a coral bleaching event this big before.
- In just the last six weeks, bleaching has been confirmed in the waters of Palau, Guam and Israel.
- Heat stress also remains high in the Caribbean and South China Sea.
- In response to the bleaching record, scientists have called a special emergency session on coral reefs to be held at the United Nations Convention on Biological Diversity summit (COP16) in Colombia at the end of the month.
- World leaders will discuss last-ditch strategies to avert the functional extinction of corals, including further protections and financing.
- The meeting will bring together the global funding community to discuss what they are going to do about it?
- Scientists had previously projected that coral reefs would cross a tipping point at 1.5 degrees Celsius (2.7 F) of global warming, whereby up to 90% of reefs would be lost.
- The latest record bleaching adds to growing evidence that reefs have already passed a point of no return at just 1.3 C (2.3 F) of warming.
- This would have dire implications for ocean health, subsistence fisheries and tourism.
- Every year, reefs provide about $2.7 trillion in goods and services, according to a 2020 estimate by the Global Coral Reef Monitoring Network.
- The ongoing bleaching has been made worse by El Nino, a natural climate pattern that can temporarily warm some oceans, which ended in May.
- Some forecasters are projecting the world could move into a La Nina climate pattern in coming months, which typically brings cooler ocean temperatures that coral scientists hope might give corals a chance to recover.
- Yet there is concern that even with a La Nina that might not happen, with 2024 on track to be the world’s warmest year on record.
- If current ocean temperatures are the new normal, the world may be entering a period “where we’re more or less in a state of chronic global bleaching.”
Managing Chennai monsoon
Introduction:
- Over the past few years, Chennai has continued to receive unprecedented rainfall during the annual northeast monsoon.
- Sudden bursts of increased rainfall, with large volumes of water in very short spans, often result in urban floods, revealing the city’s vulnerability.
- Confronting the challenges of climate change, Chennai needs to find a solution that primarily enables its water reservoirs to absorb, store or recharge groundwater.
- The focus shifts to the imperatives of organised urban planning and the need to protect and rejuvenate Chennai’s water reservoirs – Pallikaranai marsh, Ennore creek and other large reservoirs such as Chembarambakkam lake and Red Hills lake.
- The organic and rapid growth of the city has disrupted the natural hydrological cycle with the expansion of concrete and tar-paved surfaces, indiscriminate constructions and felling of trees and vegetation.
- Environmentalists suggest that this could be some of the many reasons behind urban floods, besides augmenting the capacity of the three rivers and their reservoirs – Adyar, Cooum and Kosasthalaiyar.
- The city requires a new imagination of its relationship to the unpredictable monsoons, the sea, and its water reservoirs.
Here are five takeaways from the recent rains:
- Public awareness:
- Over the last three decades, Chennai has been at the forefront of rainwater harvesting.
- Chennai’s history indicates that well-designed rainwater harvesting systems, following safety standards, can substantially absorb excess rainwater and minimise the adverse impact of floods.
- Public awareness on waste disposal, preparedness and water conservation practices are essential to address climate-induced calamities and build resilience.
- Rainwater harvesting systems:
- In the face of heavy rains, residential complexes and institutions have begun to construct rainwater harvesting wells, as well as renew existing ones that have been defunct.
- The initiative, however, needs to be more widespread recognising its intrinsic benefits.
- It is a pragmatic indication to new apartment complexes, to be more diligent and provide for well-designed rainwater harvesting pits that collect excess rains to permeate the soil.
- The Chennai Metropolitan Board guidelines suggest that water collected from the terraces can be directed through a filtration process into storage tanks.
- While it can considerably reduce the floodwaters, it assures a long-term water security to Chennai.
- Integrating these aspects into the Third Masterplan, presently under preparation by the Chennai Metropolitan Development Authority, could strengthen the city’s capacity to address urban floods.
- It has several other ancillary benefits such as reducing urban heat, recharging groundwater, and minimising the ingress of brackish seawater.
- Apartment complexes that have recharged groundwater, through rainwater harvesting, have discovered an improvement in water quality.
- Over the past decades, innumerable studies by Chennai Metropolitan Board have indicated the effectiveness of rainwater harvesting in reducing flood water volume and stopping water logging of roads.
- Large education campuses can contribute to augmenting and recharge of groundwaters.
- However, it’s a greater challenge to address and mitigate the impacts of such cataclysmic rains.
- Permeable pavements and surfaces:
- Public awareness about designing permeable, porous pavements and surfaces can encourage and allow rainwater to infiltrate the soil and recharge groundwater naturally – urban parks and gardens, porous pavements, retention wells, and green roofs.
- Permeable pavements and surfaces have had a significant impact on reducing urban heat as well.
- While much of these details are known, their dissemination could ensure effective adoption.
- Integrated database system:
- Drawing from urban lessons of medieval Madras, these elements of rainwater harvesting can be combined with Chennai’s road network and its stormwater drain system — to assist in the natural flow of water into rivers and rejuvenate the lakes and other water reservoirs, through a natural process.
- Stormwater channels have also been equipped with filtration and recharge wells in the city today.
- A pragmatic neighbourhood approach, scientifically undertaken, ensuring surface and drain slopes and levels, requires a monitoring committee, including neighbourhood citizen groups, to coordinate the efforts.
- Digital technologies and apps, documenting citizen data of inundation, flooding, and other issues can empower a citizen-based participation and aid the planning process, providing local data.
- Low-lying areas would undoubtedly require more concerted efforts in infrastructure investments and planning.
- Protecting natural ecosystems:
- The impetus to creating urban green spaces, accessible to all, is imperative, for several reasons.
- During earlier natural calamities, the Greater Chennai Corporation had invited environmentalists and citizen groups to draw up ecological guidelines for tree-planting.
- Protecting natural ecosystems and biodiversity, regions like the Guindy deer-park and Vandalur area, and other local parks act as natural flood regulators as well.
- Rejuvenating untended parks, Open Space Reservation lands and other derelict zones would consolidate these nature-based solutions considerably.
- The flood mitigation process would require a constant monitoring and maintenance of stormwater drains.
- In the present scenario of Chennai’s growth, nature-based solutions (through the creation of new green spaces and rejuvenation of natural water reservoirs) can support a natural “stormwater management”.
- Several studies have demonstrated the contribution of such nature-based solutions (if appropriately designed) in complementing the urban drainage system.
- The need for an integrated database system with early-warning systems has to be implemented to coordinate efforts.
- Information on rescue, evacuation, helplines, relief measures, hospital support, and other relevant information have augmented such extreme predicaments.
- Areas with incomplete canals, or roads under construction have been the most affected.
- However, on a positive note, the early warning updates received by citizens provided adequate time to evacuate to safety.
- Several parts of Chennai continue to battle the receding floods, inundating low-lying areas.
- Prioritising vulnerable communities and neighbourhoods for infrastructural remedies is imperative.
- In the long-term, flood mitigation measures have often influenced the microclimate, and have the potential to make the city cooler and more liveable.
Conclusion:
- Citizen groups can participate in urban neighbourhood discussions to suggest local observations.
- Community groups monitoring stormwater canals adjacent to their homes have informally emerged in Chennai since the last decade.
- If these volunteer efforts by citizen groups can be supported in the planning process, the city can chart a resilient road map to cope with natural calamities.
What do the Atlantic Ocean hurricane forecasts foretell for India?
Introduction:
- Meteorologists had previously forecast a historic hurricane season for 2024 based on the expectation that a strong La Niña would emerge this winter.
- But while the hurricanes Helene and Milton may seem consistent with this forecast, 2024 has evolved to be a year with a summer with no major hurricanes.
- One important reason is that the strong La Niña has played truant thus far.
- In fact weather agencies are currently downgrading their La Niña forecasts.
- The 2023 hurricane season was history’s fourth-most active despite the strong El Niño that year.
- Meteorologists expect a subdued hurricane season during an El Niño and an earnest one during a La Niña.
- Now, are they to assume that the record warming during 2023-2024 has flipped the hurricane season on us or that the link between hurricanes and El Niño/La Niña has flipped? They’ll need to wait and watch.
- Forecasting seasonal cyclone activity is a challenging task but hurricane forecasts have overall become more accurate, especially in terms of narrowing the cone of uncertainty of the storms’ landfall.
- Some major challenges remain vis-à-vis forecasting the intensities, however.
- The more worrisome fact is that the forecasting community has acquired hardly any skill in terms of the aftermath of a hurricane, i.e. after it makes landfall.
- Post-landfall rain and winds wreak considerable damage to property and lead to loss of lives.
The challenge of forecasting cyclones:
- A shortcoming in any forecast automatically raises the stakes for how well people and governments can plan for hurricanes and, in India’s part of the world, cyclones.
- The climate models used to develop projections don’t explicitly resolve cyclones.
- Any projections for the future are based on other resolved metrics that indirectly indicate cyclonic activity and its potential intensity.
- Historical analyses of global cyclones suggest there hasn’t been a detectable increase in the total number of cyclones.
- However, the number of strong cyclones has increased.
- Cyclones draw the energy they need from the upper ocean, and the upper oceans are warming in all cyclone-producing regions of the planet.
- This has led to many instances of rapid intensification: when the maximum cyclone wind speed increases by 55 km/hr or more within a 24-hour period.
- Rapid intensification has proven hard to predict.
- The North Indian Ocean is also reported to be experiencing an increasing number of cyclones, especially in the Arabian Sea.
- The fact that the last few years have been unusually quiet only underscores the challenge of predicting seasonal cyclone numbers, cyclones as individual events, how they react to global warming, and of course their post-landfall effects.
Good, bad, and ugly:
- India has made impressive progress in forecasting cyclones together with a disaster management plan that has been equally effective at reducing the loss of lives.
- More good news for the North Indian Ocean is that the typical stretch of ocean where cyclones intensify is relatively small, over both the Arabian Sea and the Bay of Bengal, thus limiting the size and strength of the cyclones.
- Most cyclones over the Arabian Sea also tend to be steered northwestward, away from India.
- The bad news is that the Indian subcontinent and other countries along the rim of the Indian Ocean are highly vulnerable not only to the chronic stressors of climate change but also to the acute stressors.
- The chronic stressors refer to the warming, rising sea levels, and the increasing incidence of rainfall extremes and dry spells, all of which happen in the background.
- The acute stressors ride on top of the chronic stressors and exacerbate their effects.
- These include heavy rainfall events, flash droughts, and cyclones.
- For example, inundation from a cyclone will get worse as sea levels rise.
- Or a heatwave that co-occurs with a drought will make water scarce, wilt crops, and disrupt power supply (because power plants need water, too).
- A few days ago, parts of Tamil Nadu suffered heavy rain and flooding.
- This has become an annual event because warming in the Indian Ocean, especially the Bay of Bengal, has been extending the southwest monsoon into the northeast monsoon and delivering both excess and extreme rainfall.
- Forecasting woes are also in full display: a low-pressure system predicted to cause flooding in Chennai veered north and completely missed the city.
- Now, imagine a city has to evacuate thousands of people when a cyclone is predicted.
- Forecasts will continue to get better but our expectations will also continue to rise.
From nation to region:
- Our region needs critical advances in the quality of the predictions of rapid intensification and landfall and of the cyclones post-landfall.
- Additional efforts are also required to project the cyclone risk in the coming years at hyperlocal scales.
- India remains an economically developing country, and any increments in its ability to manage its financial and human resources will be critical for the foreseeable future.
- This is essential context for why hyperlocal risk maps can make a big difference: it will be too expensive for us to cover all regions for cyclone risk.
- India has also started to bring mitigation and adaptation actions into its mainstream fiscal policies and budgetary processes by investing in renewable energy, electric vehicles, weather and climate forecasting, early warning systems, and disaster management.
- The ugly news is that India’s dreams of sustained economic development can never materialise unless the entire subcontinent is resilient.
- India’s (and the Indian subcontinent’s) vulnerabilities to chronic and acute climate stressors aren’t only India’s socio-economic vulnerabilities: they are also India’s national security issues.
- The country’s strategies for building cooperation, trade, and stability in the region have to now include the constituent countries’ climate risks as well.
- This can start by establishing subcontinent-wide weather and climate networks and improving forecasts and projections for all parts of India’s wider neighbourhood.
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