Newswise — RIVERSIDE, Calif. --The University of California, Riverside-led team has discovered that anthropogenic aerosols, which are aerosols originating from human activity, and greenhouse gases (GHGs) have influenced the storage and distribution of heat in the world's oceans since the industrial age. Through the use of coupled climate model simulations, the researchers were able to quantify and isolate the effects of both factors, revealing their distinct roles in shaping the pattern of heat uptake, redistribution, and storage in the oceans.
The study indicates that changes in ocean circulation and interbasin heat transport driven by anthropogenic aerosols have a greater impact on altering the distribution of oceanic heat compared to the effects of globally increasing GHGs. These findings are crucial for developing effective climate mitigation strategies and understanding the implications of individual anthropogenic forcings on regional sea level change.
Wei Liu, an assistant professor of climate change and sustainability in the Department of Earth and Planetary Sciences at the University of California, Riverside, who led the study, emphasized the importance of comprehending the effects of specific anthropogenic forcings on oceanic heat redistribution. This understanding will contribute to the development of strategies to mitigate climate change.
The study's results significantly enhance our understanding of the effects of anthropogenic aerosols and GHGs, which have been identified as key drivers of climate change. Throughout the "historical period" from around 1850 to the present, anthropogenic GHG emissions have steadily increased. Conversely, anthropogenic aerosols initially experienced an increase during this period but have since declined since the 1980s due to air quality legislation implemented in certain regions of the world.
The researchers conducted their study using several coupled climate model simulations focused on the historical period. These simulations included:
- 1.HIST-AER: This scenario specifically examined the impact of human-induced aerosol changes during the historical period.
- 2. HIST-GHG: This scenario focused on the effects of human-induced greenhouse gas changes during the historical period.
- 3. HIST: This scenario encompassed all forcings, including human-induced aerosol and greenhouse gas changes, land use modifications, and volcanic eruptions during the historical period.
- 4. piControl: This scenario set all forcings to preindustrial levels.
According to Wei Liu, the lead researcher, in the aerosol-forcing scenario, interbasin heat exchange (the exchange of heat between ocean basins) played a significant role in modifying stored heat. This effect was particularly noticeable in the Atlantic and Indo-Pacific Oceans. Conversely, in the greenhouse-gas-forcing scenario, interbasin heat exchange had a lesser impact compared to changes in ocean heat uptake. Liu suggested that this discrepancy may be attributed to the fact that temperature shifts strongly counterbalance the effects of ocean circulation in the greenhouse-gas-forcing scenario.
Liu further emphasized the importance of interbasin heat exchange in redistributing heat among basins, as it can influence regional climate changes such as sea level rise. Sea level rise has been a significant concern in the past century and is expected to continue for at least another century. Regional and coastal variations in sea level, along with changes in extreme events along coastlines, raise societal issues such as the potential relocation of coastal communities and the vulnerability of natural resources and coastal infrastructure.
Shouwei Li, the first author of the study and a graduate student in Liu's lab, explained why the research highlighted the effectiveness of aerosol-driven changes in ocean circulation and interbasin heat transport in altering oceanic heat distribution compared to the impact of increasing greenhouse gases on this distribution.
According to Shouwei Li, the difference in the distributions of aerosols and greenhouse gases (GHGs) may explain why aerosol-driven changes in ocean circulation and interbasin heat transport have a greater impact on oceanic heat distribution. Li pointed out that well-mixed GHGs experience global increases, whereas aerosol changes are predominantly concentrated in the Northern Hemisphere due to higher levels of human activities and industrialization.
To validate their findings, the research team also compared their model simulations with observational data. Wei Liu noted that the oceanic warming observed aligned closely with the warming patterns predicted by their model simulations.
Wei Liu collaborated with Robert J. Allen from the University of California, Riverside, Jia-Rui Shi from the Woods Hole Oceanographic Institution, and Laifang Li from Pennsylvania State University in conducting this research.
The study was funded by the National Science Foundation.
The research paper is titled “Ocean heat uptake and interbasin redistribution driven by anthropogenic aerosols and greenhouse gases.”
The University of California, Riverside is a doctoral research university, a living laboratory for groundbreaking exploration of issues critical to Inland Southern California, the state and communities around the world. Reflecting California's diverse culture, UCR's enrollment is more than 26,000 students. The campus opened a medical school in 2013 and has reached the heart of the Coachella Valley by way of the UCR Palm Desert Center. The campus has an annual impact of more than $2.7 billion on the U.S. economy. To learn more, visit www.ucr.edu.
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