7-Mar-2023: Climate change, glacier topography & morphology control glacial retreat
Change in debris cover plays a critical role in the glacier surface lowering, shrinkage, retreat, and mass balance, according to a recent study. Therefore, these factors need to be accounted for in future studies for a complete understanding of the observed glacier changes and responses.
Despite the importance of the Himalayan glaciation, the knowledge of the glacial dynamics and the factors that influence these dynamics is scanty. Recent studies of Himalayan glaciers indicate wide variability in retreat rate and mass balance in different sectors of the mountain range, primarily linked to the topography and climate of the region. However, variable retreat rates of glaciers and inadequate supporting field data (e.g., mass balance, ice thickness, velocity, etc.) of the Himalayan glaciers make it challenging to develop a coherent picture of climate change impact.
One of the significant characteristics of the Himalayan glaciers is that the glaciers are mainly debris-covered and have been receding since the end of the Little Ice Age. The supraglacial debris on the surface of glaciers is commonly found to have significant control over the rate of loss of mass of ice due to sun, wind, or rain (ablation). It has been observed that the thickness of supraglacial debris significantly alters the glacier response to climate forcing.
A team of scientists from Wadia Institute of Himalayan Geology (WIHG), Dehradun, Uttarakhand, India (An autonomous institute under DST, India), quantitatively evaluated the influence of the debris cover on the loss of ice mass in summer (summer ablation) and on terminus recession of glaciers.
Dr. Manish Mehta and his team studied two glaciers with different characteristics --- the Pensilungpa Glacier (PG) in Suru River and the Durung-Drung Glacier (DDG) in Doda River basins of Zanskar in the Leh district of Ladakh for a comparative study of glacier fluctuations between 1971 and 2019. While a thick debris cover characterizes the PG, the DDG has a thin debris cover, and their comparative analysis helped them trace the influence of various factors on the mass balance process.
They found that the glacier retreat rate is controlled by climate change and the topographic setting and morphology of the glacier. Their comparative study published in the journal Sustainability also confirms the possible influence of factors such as snout geometry, glacier size, elevation range, slope, aspect, debris cover, as well as the presence of supra and proglacial lakes other than the climate in the heterogeneous glacial dynamics and underlined the need to include these in glacial studies.
15-Feb-2023: WMO releases the report "Global Sea-level Rise and Implications"
According to the World Meteorological Organisation ‘s (WMO) Report “Global Sea-level Rise and Implications”, India, China, Bangladesh and the Netherlands face the highest threat of sea-level rise globally.
Several big cities on all continents are threatened by the rise in sea level including Shanghai, Dhaka, Bangkok, Jakarta, Mumbai, Maputo, Lagos, Cairo, London, Copenhagen, New York, Los Angeles, Buenos Aires and Santiago.
Highlights of the Report
Trends and Projections:
- Human influence is likely the main driver of sea-level rise increases since at least 1971.
- Global mean sea-level increased by 0.20m between 1901 and 2018.
- The rate of increase was 1.3 mm/ year between 1901 and 1971, 1.9 mm/year between 1971 and 2006, and 3.7 mm/year between 2006 and 2018.
- A temperature increase of 2 degrees could double the sea-level rise.
- Contributors to sea-level rise include thermal expansion (50%), glacier ice loss (22%), ice-sheet loss (20%), and changes in land-water storage (8%).
Impacts:
- At sustained warming levels between 2-3 degree Celsius, the Greenland and West Antarctic ice sheets will be almost completely lost over multiple millennia causing potentially multimeter sea-level rise.
- Sea-level rise will bring cascading and compounding impacts resulting in losses of coastal ecosystems and ecosystem services, groundwater salinization, flooding and damage to coastal infrastructure that cascade into risks to livelihoods, settlements, health, well-being, food, displacement and water security, and cultural values in the near to long-term.
Scenario for India:
- The sea level along the Indian coast was observed to be rising at a rate of about 1.7 mm/year during the last century (1900-2000).
- A 3 cm sea level rise could cause the sea to intrude inland by about 17 meters.
- India is most vulnerable to compounding impacts of sea-level rise.
- Half of sea-level rise in the Indian Ocean is due to the volume of water expanding since the ocean is warming up rapidly.
- India is facing compound extreme events along our coastline. Cyclones are intensifying rapidly due to more moisture and heat from ocean warming.
Recommendations:
- Address the climate crisis and broaden our understanding of the root causes of insecurity.
- Actively support grassroots resilience efforts to tackle climate change and improve Early Warning Systems.
30-Jan-2023: Kelp Forests are declining due to climate change
Highlights of the study:
- A recent study reveals that kelp forests are declining due to climate change.
- Rising temperatures are causing declines in the dominant kelp species Ecklonia radiata along the eastern Australian coastline.
- Ecklonia radiata is vulnerable to climate change, especially in regions near the equator.
- In situ protection may not be possible, but ex situ preservation in culture banks can preserve its unique genetic diversity for future restoration, hybridization, or adaptation strategies.
Kelp Forests
- are underwater ecosystems formed by the dense growth of several different species.
- are large brown algae that live in cool, relatively shallow waters close to the shore.
- attach to the seafloor and eventually grow to the water’s surface.
- require shallow, relatively clear water and sunlight to generate food and energy.
Significance:
- Serve as a food source for marine creatures and produce up to 60% of carbon found in coastal invertebrates.
- Provides underwater habitat for hundreds of species of invertebrates, fishes, and other algae.
- Provides habitat for birds to forage.
- Release carbon into the coastal ecology, increasing its productivity through primary production by kelp.