Since the industrial era, anthropogenic aerosols and greenhouse gases, or greenhouse gases, have played a role in regulating the storage and dissipation of heat in the oceans. A team led by the University of California, Riverside found that anthropogenic aerosols and greenhouse gases play different roles in shaping the pattern of heat uptake, redistribution and storage in the world’s oceans.
This was done by isolating and quantifying the effects of both forcing elements using coupled climate model simulations.
The researchers found that aerosol-driven changes in ocean circulation and the associated heat transfer between basins are more effective in altering the distribution of ocean heat than those driven by globally increasing greenhouse gases.
“A better understanding of the effects of individual anthropogenic forcings on the redistribution of ocean heat and its implications for regional sea level change will help develop climate mitigation strategies,” said Wei Liu, assistant professor of climate change and sustainability in the Department of Earth and Planets. Sciences, who led the study published yesterday in Nature Geoscience.
Anthropogenic aerosols and greenhouse gases have been proposed as the main drivers of climate change. The team’s results accelerate understanding of their effects.
Anthropogenic greenhouse gases have increased steadily during the “historical period” from 1850 to almost the present. On the other hand, anthropogenic aerosols first increased during this period, but then began to decrease from the 1980s due to air quality legislation in some parts of the world.
The researchers primarily used the following coupled climate model simulations that were run over the historical period:
HIST-AER — models are driven solely by human-induced aerosol changes over the historical period.
HIST-GHG — models are driven solely by human-induced changes in greenhouse gases over the historical period.
HIST – models are driven by all influences, including human-induced aerosol and greenhouse gas changes, land use, and volcanic eruptions over the historical period.
“In the aerosol generation scenario, heat exchange between basins — heat exchange between ocean basins — is comparable to changes in heat uptake by the ocean as heat storage is modified,” Liu said. “This is seen especially in the Atlantic and Indo-Pacific.” Under the GHG forcing scenario, heat exchange between basins is much less important than changes in ocean heat uptake. This may be due to the fact that in this scenario the effects of ocean circulation are strongly offset by temperature drifts.
Liu explained that heat exchange between basins is important for the redistribution of heat between basins, which can affect regional climate change such as sea level rise.
“Since the last century, rapid sea level rise has been one of the most serious threats and will continue to be so for at least another century,” he said. “Sea level rise is not globally uniform but regional in distribution. Regional and coastal changes in sea level, as well as changes in extremes along the coast, can raise societal concerns such as displacement of coastal communities and potential damage to natural resources and infrastructure along the coast.
Shouwei Li, first author of the paper and a graduate student in Liu’s lab, explained why the study found that the distribution of heat in the ocean can be altered more effectively by changes in aerosol-driven ocean circulation and associated inter-basin heat transfers than by changes caused globally. increase in greenhouse gases.
“This may be related to the difference between the distribution of aerosols and greenhouse gases,” he said. “The increase in well-mixed greenhouse gases is global, while changes in aerosols are mostly amplified in the Northern Hemisphere due to more human activities and industries.”
The research team also used observations to compare with their model results. “We found that ocean warming from model simulations closely matches observations,” Liu said.
Liu and Li were joined on the research by Robert J. Allen of UCR, Jia-Rui Shi of Woods Hole Oceanographic Institution, and Laifang Li of Pennsylvania State University.
