Climate Change Current Affairs

Earth’s bedrock: New source of global nitrogen discovered

According to recently published study, over quarter of nitrogen on Earth comes from weathering of planet’s bedrock. For centuries, prevailing science indicated that all of nitrogen on Earth available to plants comes from atmosphere. This study could greatly improve climate change projections.

Key Facts

The study has found that up to 26% of nitrogen in natural ecosystems is sourced from weathering of rocks, with remaining fraction from atmosphere. But input of this nitrogen source in global land system is unknown.

This study shows that nitrogen weathering is globally significant source of nutrition to soils and ecosystems worldwide. Ecosystems need nitrogen and other nutrients to absorb carbon dioxide (CO2) pollution and there is limited amount of it available from plants and soils.

Geology and carbon sequestration: Rock-derived nitrogen may fuel growth of forests and grasslands, and allow them to sequester more CO2 than previously thought. However, according to this study not just any rock can leach nitrogen. Rock nitrogen availability is determined by weathering, which can be physical, such as through tectonic movement or chemical i.e. when minerals react with rainwater.

Significance: The discovery will greatly improve climate change projections, which rely on understanding carbon cycle. It will also feed carbon cycle on land, allowing ecosystems to pull more emissions out of the atmosphere. Mapping nutrient profiles in rocks for their carbon uptake potential can help drive conservation efforts.

The work also helps solve case of the missing nitrogen. For decades, scientists had recognized that more nitrogen accumulates in soils and plants than can be explained by input from atmosphere alone, but they couldn’t pinpoint what was missing.

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India at risk of food shortage due to climate change: Study    

According to recently published global study, India is among countries which are at greatest risk of food insecurity due to weather extremes caused by climate change. The study had examined how climate change could affect vulnerability of different countries mainly 122 developing and least-developed countries (mostly in Asia, Africa and South America) to food insecurity — when people lack access to sufficient quantity of affordable, nutritious food. It examined projected changes in weather extremes and their implications for freshwater availability and vulnerability to food insecurity.

Key Findings

Climate change caused by 2 degrees Celsius global warming is expected to lead to more extremes of both heavy rainfall and drought, with different effects in different parts of world. Such weather extremes will increase vulnerability to food insecurity. The countries at greatest vulnerability to food insecurity due to climate change are Oman, India, Bangladesh, Saudi Arabia and Brazil.

Global warming is expected to lead to wetter conditions on average causing floods and putting food production at risk. But agriculture may also get harmed by more frequent and prolonged droughts in some areas caused by climate change.

Wetter conditions are expected to have biggest impact in South and East Asia, with most extreme projections suggesting flow of River Ganges could more than double at 2 degrees Celsius global warming. Some areas are projected to see increase in flood event lengths of 4 days or more, particularly India and Bangladesh, for which such increases are projected in all ensemble members to some extent.

The areas worst affected by droughts are expected to be southern Africa and South America – where flows in Amazon River are projected to decline by up to 25%. Some climatic change is already unavoidable, but if global warming is limited to 1.5 degrees Celsius, this vulnerability is projected to remain smaller approximately 76% of developing countries than at 2 degrees Celsius

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