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General Studies 3 >> Enivornment & Ecology

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1. Context
There is no dearth of reports highlighting the consequences of climate change, including droughts, water scarcity, severe wildfires, rising sea levels, etc. Despite that, there are many myths and a lot of confusion around the subject. In this series of explainers, we answer some of the most fundamental questions about climate change, the science behind it, and its impact.
2.What are emission scenarios?
  • In essence, emission scenarios depict the trajectories of greenhouse gas and aerosol emissions resulting from human activities over time. These scenarios are utilized by scientists in climate models to predict future global temperatures and sea levels.
  • The most recent method for establishing emission scenarios is the Representative Concentration Pathways (RCPs).
  • According to a report from the UK’s Meteorological Office, RCPs define concentrations of greenhouse gases leading to a specified increase in total radiative forcing by 2100 compared to pre-industrial levels.
  • Total radiative forcing denotes the disparity between incoming and outgoing energy in the Earth's atmosphere.
  • The current imbalance, where more energy enters than leaves due to heightened levels of greenhouse gases and aerosols, contributes to global warming. Radiative forcing is measured in watts per square meter.
  • The four pathways are RCP8.5, RCP6, RCP4.5, and RCP2.6 (also known as RCP3PD, with 'PD' indicating Peak and Decline). These numerical values indicate the anticipated change in radiative forcing from 1750 to 2100.
  • For instance, RCP4.5 signifies a 4.5 watts per square meter increase in radiative forcing between 1750 and 2100.
  • The Intergovernmental Panel on Climate Change (IPCC) adopts 1750 as the baseline, preceding the Industrial Revolution when radiative forcing was relatively stable.
  • A higher forcing value implies increased concentrations of greenhouse gases and pollutants, resulting in more substantial global warming and a heightened impact of climate change
Source: Wikkicommons
3.What are the different RCP warming levels?

Let's begin with RCP2.6, which envisions an additional radiative forcing of only 2.6 watts per square meter by the close of the 21st Century. This represents the most optimistic outlook, characterized by a significant reduction in greenhouse gas concentrations and the implementation of rigorous mitigation measures. Also referred to as RCP3PD, this scenario sees emissions peaking around 2050 and subsequently decreasing. Consequently, the global average temperature is projected to rise by 1.6 degrees Celsius compared to pre-industrial levels.

Moving on to RCP4.5 and RCP6, these scenarios fall into intermediate ranges. In RCP4.5, the global average temperature is anticipated to increase by 2.4 degrees Celsius. For RCP6, this figure rises to 2.8 degrees Celsius above pre-industrial levels


4. Way Forward

The worst case scenario is RCP8.5, where the concentration of greenhouse gases and other pollutants will be three times more than the present. In this case, the temperature would rise to 4.3 degree Celsius by 2100


Source: Indianexpress

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