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Causes: Cooling effect of emissions 

 Image: Peggy Anke

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The cooling effect of emissions

Summary

  • Burning fossil fuels emits both long-lived greenhouse gases and short-lived aerosols such as sulfur dioxide (SO2) and nitrogen oxides (NO). Along with an increasing number of wildfires globally, these contribute to the formation of smog and acid rain, and are directly linked to the deaths of millions:

“More than 8 million people died in 2018 from fossil fuel pollution, significantly higher than previous research suggested, according to new research from Harvard University.” – Harvard School of Engineering

  • When these pollutants interact with clouds, they make them brighter and more reflective. The resulting albedo effect has led to artificial cooling that masks around 1°C of warming. A sudden reduction in emissions would, perversely, result in the abrupt rise of temperatures beyond 2°C.
  • The effects are more pronounced over the localised regions that emit the most greenhouse gases; that is, heavily industrialised areas such as China, and large fossil-fuel uses such as India. 
  • Figures used in the IPCC Sixth Assessment Report WG1 estimate the impact of pollutants is less than 1°C. Others suggest this is a dangerously conservative under-estimate (Video 1). The research supporting this under-estimate is more recent than IPCC AR6, and it has been attributed to the abrupt spike in record-breaking global temperatures in 2023 (Fig. 1 and Video 2).
  • Pollutants include hydroxyl radicals, which are present in tiny quantities and have a lifetime of less than a second. However, they remove about 85% of methane from the atmosphere. The abrupt reduction in these during Covid has been attributed to the sudden, abrupt rise of atmospheric methane 2021-2022 (Videos 1 and 3). Due to feedback effects and a possible tipping point being breached, methane continues to rise at an alarming pace.
  • Volcanoes also emit sulfates. Eruptions have masked some warming over the last few hundred years, causing global temperatures to drop slightly for short periods. 
  • See also ‘water vapour and clouds‘ and ‘ozone‘, as both influence the amount of warming or cooling depending on the type of cloud and where they are in the atmosphere.

  Causes

Other sections

Home > Climate wiki > What causes climate change? > Greenhouse gases > Emissions pollution

Summary

  • Burning fossil fuels emits both long-lived greenhouse gases and short-lived aerosols such as sulfur dioxide (SO2) and nitrogen oxides (NO). Along with an increasing number of wildfires globally, these contribute to the formation of smog and acid rain, and are directly linked to the deaths of millions:

“More than 8 million people died in 2018 from fossil fuel pollution, significantly higher than previous research suggested, according to new research from Harvard University.” – Harvard School of Engineering

  • When these pollutants interact with clouds, they make them brighter and more reflective. The resulting albedo effect has led to artificial cooling that masks around 1°C of warming. A sudden reduction in emissions would, perversely, result in the abrupt rise of temperatures beyond 2°C.
  • The effects are more pronounced over the localised regions that emit the most greenhouse gases; that is, heavily industrialised areas such as China, and large fossil-fuel uses such as India. 
  • Figures used in the IPCC Sixth Assessment Report WG1 estimate the impact of pollutants is less than 1°C. Others (Video 1) suggest this is a dangerously conservative under-estimate. The research supporting this is more recent than IPCC AR6 WGI, and attributed to the abrupt spike in record-breaking global temperatures in 2023 (Fig. 1 and Video 2).
  • Pollutants include hydroxyl radicals, which are present in tiny quantities and have a lifetime of less than a second. However, they remove about 85% of methane from the atmosphere. The abrupt reduction in these during Covid has been attributed to the sudden, abrupt rise of atmospheric methane 2021-2022 (Videos 1 and 3). Due to feedback effects and a possible tipping point being breached, methane continues to rise at an alarming pace.
  • Volcanoes also emit sulfates. Eruptions have masked some warming over the last few hundred years, causing global temperatures to drop slightly for short periods. 
  • See also ‘water vapour and clouds‘ and ‘ozone‘, as both influence the amount of warming or cooling depending on the type of cloud and where they are in the atmosphere.
Video 1: November 2022 Dr. Ye Tao explains research that critiques the IPCC 6th Assessment Report (2021) use of the lowest estimate of 0.7C, when the range is much higher. As the IPCC has consistently underestimated the speed and impacts of climate change, Tao argues that it would be prudent to prepare for a higher figure.
Video 2: January 2024, Astrophysicist Neil deGrasse Tyson & Dr. Gavin Schmidt, climate modeler and Director of the NASA Goddard Institute for Space Studies, discuss why the record breaking temperatures in 2023 was due primarily to the decline in aerosols, as predicted by Tao and Hansen (Video 1).
Video 3: Methane comes from production and transport of fossil fuels, but instead of tumbling during the global COVID lockdowns, they spiked upwards.
Fig. 1: Record breaking temperatures in 2023 & 2024 far exceeded what was predicted in the models (Video 2).
Fig. 1: Record breaking temperatures in 2023 & 2024 far exceeded what was predicted in the models (Video 2).
Fig. 2: SO2 concentrations 30 January 2024. Click on the image for an updated view and to track other data. Image: Google mapping project earth.nullschool.net.
Fig. 2: SO2 concentrations 30 January 2024. Click on the image for an updated view and to track other data. Image: Google mapping project earth.nullschool.net.

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