The planet will breach the threshold of 1.5 degrees Celsius above pre-industrial levels between 2027 and 2042 according to new research.

Ever wondered why is there so much of hue to halt the temperature rise at 1.5°C above pre-industrial levels, and why not 2°C? Read this newscard to get aware….

What does that mean?

• The world will heat up more than it can take much earlier than anticipated.
• The Intergovernmental Panel on Climate Change (IPCC) had estimated that breach to occur between now and 2052.
• But researchers have now claimed to have introduced a more precise way to project the Earth’s temperature based on historical climate data.

The fuss over 1.5°C threshold

• For decades, researchers argued the global temperature rise must be kept below 2C by the end of this century to avoid the worst impacts.
• The idea of two degrees as the safe threshold for warming evolved over a number of years from the first recorded mention by economist William Nordhaus in 1975.
• By the mid-1990s, European ministers were signing up to the two-degree limit, and by 2010 Cancun COP it was official UN policy.
• However, small island states and low-lying countries were very unhappy with this perspective, because they believed it meant their territories would be inundated with sea-level rise.
• They commissioned research which showed that preventing temperatures from rising beyond 1.5C would give them a fighting chance.

Why 1.5°C is preferred over 2°C?

• Global warming is already impacting people and ecosystems. The risks at 1.5°C and 2°C are progressively higher.
• There will be worse heatwaves, drought and flooding at 2°C compared to 1.5°C. It is characterized as “substantial differences in extremes”.
• Sea levels are expected to rise 10cm higher this century under 2°C of warming than 1.5°C.
• The collapse of ice sheets in Greenland and Antarctica could lead to rises of several metres.
• The quantity and quality of staple crops suffer under 2°C warming compared to 1.5C, as do livestock. That is bad for the availability of food in many parts of the world.

New model shows the breach in threshold

• The study according to which prediction model deployed reduced uncertainties by half compared to the approach used by the IPCC.
• The IPCC uses the General Circulation Models (GCM) to express wide ranges in overall temperature projections.
• This makes it difficult to circle outcomes in different climate mitigation scenarios.

What is the General Circulation Model (GCM)?

• GCM represents physical processes in the atmosphere, ocean, cryosphere and land surface.
• It is the most advanced tool currently available for simulating the response of the global climate system to increasing greenhouse gas concentrations.
• GCMs depict the climate using a three-dimensional grid over the globe, typically having a horizontal resolution of between 250 and 600 km.
• Many physical processes, such as those related to clouds, also occur at smaller scales and cannot be properly modelled.

Why GCM is tricky?

• Climate models are mathematical simulations of different factors that interact to affect Earth’s climate, such as the atmosphere, ocean, ice, land surface and the sun.
• The data is tricky, and predictions can more often than not be inaccurate.
• For example, an IPCC model would predict a temperature increase of a massive range — between 1.9^oC and 4.5^oC — if carbon dioxide in the atmosphere is doubled.

Back2Basics: Intergovernmental Panel on Climate Change

• The IPCC is an intergovernmental body of the United Nations that is dedicated to providing the world with an objective, scientific information relevant to understanding the scientific basis of the risk of human-induced climate change.
• It was established in 1988 by the World Meteorological Organization (WMO) and the United Nations Environment Programme (UNEP).
• Its membership is open to all members of the WMO and UN.
• The IPCC produces reports that contribute to the work of the United Nations Framework Convention on Climate Change (UNFCCC), the main international treaty on climate change.
• The IPCC’s Fifth Assessment Report was a critical scientific input into the UNFCCC’s Paris Agreement in 2015.

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