Anthropogenic Effects on climate change

Anthropogenic aerosols and greenhouse gases (GHGs) have altered the storage and distribution of heat in the oceans. A study led by the University of California, Riverside, discovered that anthropogenic aerosols and greenhouse gases (GHGs) had distinct roles in altering the pattern of heat intake, redistribution, and storage in the world’s seas. 

The researchers discovered that aerosol-driven alterations in ocean circulation and accompanying interbasin heat transmission are more effective than those caused by globally increasing GHGs affecting marine heat distribution. Anthropogenic aerosols and GHGs have been proposed as the primary causes of climate change. The findings of the team contribute to a better understanding of their impacts. 

Anthropogenic GHGs have gradually increased during the “historical period” from 1850 to the present. On the other hand, anthropogenic aerosols surged initially during this time before beginning to fall in the 1980s due to air quality regulations in some regions. 

The study, led by Wei Liu, an assistant professor of climate change and sustainability in the Department of Earth and Planetary Sciences, aims to develop climate mitigation strategies by gaining a better understanding of the effects of individual anthropogenic forcings on oceanic heat redistribution and its implications for regional sea level change. 

The researchers used historical coupled climate model simulations such as HIST-AER, HIST-GHG, HIST, and piControl.

1)HIST-AER — models are driven solely by human-induced aerosol changes during the historical period.

2)HIST-GHG — models are driven solely by human-induced greenhouse gas changes during the historical period.

3)HIST — models are driven by all the forcings, including human-induced aerosol and greenhouse gas changes, land use, and volcanic eruptions during the historical period.

4)piControl — all the forcings are set to preindustrial time levels.

In the aerosol-forcing scenario, interbasin heat exchange is equivalent to ocean heat uptake changes in changing stored heat, as witnessed in the Atlantic and Indo-Pacific Oceans. Interbasin heat exchange is significantly less important than changes in ocean heat intake under the greenhouse-gas-forcing scenario because temperature variations strongly negate ocean circulation impacts.

He said, “Since the past century, rapid sea level rise has been one of the most serious threats and will continue for at least another century. Sea level rise is not globally uniform but regional in distribution. Regional and coastal sea level changes and extremes along coastlines may raise societal concerns, such as relocating coastal communities and potentially harming natural resources and infrastructure along the coast.”

The study discovered that changes in ocean circulations and related interbasin heat transports caused by aerosols could modify oceanic heat distribution more efficiently than changes caused by globally increasing GHGs. This may be attributed to the difference in aerosol and GHG distributions, as increases in well-mixed GHGs are global, whereas changes in aerosols increase in the Northern Hemisphere due to more human activities and industries.

Liu said, “We found the oceanic warming from model simulations closely matched observations.”

The researchers also compared their model results to observations, discovering that the oceanic warming from model simulations closely matched observations. 

The National Science Foundation funded the research.

Journal Reference:

1. Li, S., Liu, W., Allen, R.J. et al. Ocean heat uptake and interbasin redistribution driven by anthropogenic aerosols and greenhouse gases. Nature Geoscience. DOI: 10.1038/s41561-023-01219-x