Tipping points of global warming

Tipping points of global warming

Subject: Environment

Context-

• A new study has found that even the current level of average global temperatures — about 1.1 degree Celsius higher than preindustrial times — is enough to trigger catastrophic changes in several climatic systems.
• The research is an updated assessment of important climate tipping points or the thresholds beyond which changes in the earth’s systems become uncontrollable and irreversible.

Tipping points

• Several studies in the past 15 years have identified different tipping points such as the disintegration of the Greenland ice sheet, a spontaneous reduction in Amazon forest cover, melting of glaciers, or softening of the permanently frozen grounds in the polar regions that have large amounts of carbon trapped in them.
• Over the years, researchers have identified at least 15 tipping points, each correlated with different levels of temperature rise.
• The latest study has identified nine global and seven regional tipping points and has re-assessed their dynamics and correlation with global warming.

Tipping points at work

• Rising temperatures are causing largescale changes in these climatic systems.
• Glacial melt, thinning of Arctic ice, and rise in sea levels are all well-documented and visible changes.
• The Greenland ice sheet, which is already melting, is a good example to illustrate this process. As it melts, the height of the ice sheet gradually reduces.
• In the process, a larger part of it gets exposed to warmer air. That is because air is warmer at lower altitudes than at higher altitudes.
• Exposure to warmer air expedites the process of melting.
• Once the tipping point is crossed, this becomes a self-sustaining and cyclic system.
• The system does not reverse even if the global temperatures stop rising.
• Similar is the case with Amazon forests.
• These play a very important role in causing rain in the region.
• If deforestation continues unabated, there would be fewer and fewer trees, which would reduce rainfall, causing further stress on the trees.
• Once again, it develops into a self-perpetuating process.
• Several areas of the world remain frozen throughout the year. These are known as permafrost. Because they have remained in this state for centuries, they hold large amounts of carbon — from plants and animals that died and decomposed over the years — trapped in them.
• It is estimated that the permafrost layers hold as much as 1,700 billion tonnes of carbon, mainly in the form of carbon dioxide and methane.
• In comparison, the global emissions of carbon in a year are in the range of 40 billion tonnes.
• The softening or melting of permafrost layers is already releasing some carbon into the atmosphere. This release of carbon is adding to the warming, which in turn is expediting the process of softening permafrost layers.
• This too has a tipping point beyond which it would become a self-perpetuating cycle.

New findings-

• About two decades ago, CTP (Climate tipping points) were considered to be crossed only in warming scenarios exceeding 5 degrees Celsius.
• But more recent information, including those presented by the Intergovernmental Panel on Climate Change (IPCC), suggests that most of these tipping points would be crossed between 1 and 2 degree Celsius temperature rise.
• The latest study has presented evidence to suggest that some of these tipping points could be met even at the current levels of warming.

Policy response

• The sixth assessment report of the IPCC released earlier this year had said that global emissions of greenhouse gases needed to peak by 2025, and reduce by 43 per cent from current levels by 2030 if the 1.5 degree Celsius target was to be achieved.
• With the current level of efforts, the world is on the path to becoming more than 2 degrees warmer by the year 2100.