July rainfall worsened August floods in Punjab in 2023, says study

A new study found that the floods of Punjab in August 2023, that led to 50 deaths, were not caused by rainfall during the flood period, but driven by exceptionally high levels of rainfall in the month before. Mongabay reported the study by IIT-Mandi that found that lack of forecasting in operations of Pong dam resulted in the deadly flood.

Researchers compared flood events in July and August 2023 in Punjab. The August flood turned very severe despite below average levels of rainfall, inundating 11,927 villages. The Pong dam, an earth-filled storage and hydroelectric dam on the Beas River, is believed to have worsened the disaster by allowing the reservoir to fill to near maximum levels before increasing outflows too suddenly, the study found.

1.5 degree breach: Scientists propose new accountability system based on countries’  ‘carbon debt’ and carbon budget 

As the planet may overshoot 1.5°C warming over pre-industrial levels, scientists have proposed an accountability mechanism based on carbon debt that would be assessed according to each nation’s fair share of the global carbon budget already consumed, according to a study published in Nature journal. Researchers from International Institute for Applied Systems Analysis (IIASA), Laxenburg in Austria; Potsdam Institute for Climate Impact Research; Grantham Institute — Climate Change and the Environment, London among others stressed the need for accountability, in view of the International Court of Justice’s advisory opinion on “obligations of States in respect of Climate Change” delivered last year which held that the 1.5°C limit is the countries’ primary agreed target under the Paris Agreement, the report said. 

The newspaper added that this model of climate accountability especially aligns with India’s position at COP30 in Belem. India had said that developed countries need to reach net zero much earlier than projected to release the remaining carbon space in favour of developing countries, invest significantly more in negative emission technologies and fulfil their obligations under the convention, HT reported citing senior government officials. 

Scientists have proposed that such an accountability framework can be developed by taking a carbon budget that is compatible with the 1.5°C warming limit (starting from a given year, such as 1990) and assigning fair shares of the budget. Countries that have already emitted beyond this fair share are classified as ‘carbon debtors’ and each unit of subsequent emissions results in a further unit of carbon debt. Using projections of countries’ emissions, evaluations can be made regarding how much carbon debt each might accrue in future.

It can also identify potential responsibility for exceeding 1.5°C — calculated as a debtor country’s share of the sum of debt across all debtor countries. This can be projected even before the global 1.5°C remaining carbon budget is exhausted, they said in the comment.

Scientists map rare earthquakes deep within Earth’s mantle for the first time

Researchers created the first global map of rare continental mantle earthquakes which occur deep within Earth’s mantle rather than the crust, DTE reported. The study, published in Science, shows these earthquakes occur worldwide but cluster beneath the Himalayas and the Bering Strait.

The research found that while crustal earthquakes originate at depths of 10–29 km, mantle earthquakes can originate more than 80 km below the Mohorovičić discontinuity (Moho), the boundary between crust and mantle.

To identify them, the team compared Sn waves, which travel through the upper mantle, with Lg waves, which move through the crust. Analyzing over 46,000 earthquakes recorded since 1990, they identified 459 confirmed continental mantle events.The relative strength of these waves allows scientists to determine whether an earthquake originated in the crust or the mantle.