Climate change predictions may be underestimated

Climate change is one of the most pressing environmental issues of our time, contributing to extreme weather events such as droughts, wildfires and floods. The main cause of climate change is the emission of greenhouse gases from human activities, which trap heat and increase the Earth’s temperature. Aerosols such as particulate matter (PM2.5) also affect not only public health but also the Earth’s climate by absorbing and scattering sunlight and changing cloud properties.

Although there are predictions about climate change in the future, the effects of climate change may be more severe than expected. Therefore, climate changes need to be detected accurately and as early as possible.

Building on these findings, a research team from Japan, led by Professor Hitoshi Irie of the Environmental Remote Sensing Center of Chiba University, used long-term observational data to study the impact of climate change on cross-border air pollution in the downwind region of China using aerosols. They took a completely unique look at how aerosols affect climate and developed a new metric to measure climate change using aerosols as indicators.

Observational data and team input

“The significance of this study is that most of its results are based on observational data. In Earth-focused natural sciences, the ultimate goal is to combine high-precision observational data to quantitatively understand Earth’s processes and to search for unchanging realities. Therefore, the more observational data we have, the better. With continued Earth observations by Japan’s major Earth observation satellites (such as the GCOM series, GOSAT series, Himawari series and ALOS series), we aim to complement these efforts with numerical modelling and data science methodologies to achieve a secure global environment that also mitigates the consequences of the climate crisis,” explains Professor Airey.

The research team included Ms. Ying Tsai from the Graduate School of Science and Engineering, Chiba University; Dr. Alessandro Damiani from the Center for Climate Change Adaptation, Dr. Shuichi Itahashi from the National Institute of Environmental Research; Professor Toshihiko Takemura from the Department of Applied Mechanics, Kyushu University; and Dr. Pradeep Khatri from the School of Science and Engineering, Soka University. Their work was made available online on May 23, 2024, and published at: Total Environmental Science August 20, 2024.

China is the main source of air pollution in East Asia. The Leeward Region of China analyzed in this study is a unique open ocean area with minimal human disturbance, but is a major area of ​​transboundary air pollution pathways, making it an ideal location to study meteorological fluctuations resulting from climate change.

In their study, the researchers analyzed satellite-derived aerosol optical depth (AOD) datasets, reanalysis datasets, and numerical simulations focused on the Pacific Ocean downwind of China for 19 years from 2003 to 2021. AOD, a measure of the amount of sunlight blocked by aerosols, is a key factor in analyzing aerosols and their impact on climate change.

The results and implications of R_AOD

Researchers have developed a new metric called R _AOD used the potential of aerosols as indicators to assess the impact of climate change on transboundary air pollution pathways. Using R_AOD, The researchers were able to measure significant temporal changes in aerosol transport. They found that there were long-term changes in R._AOD Due to climate change, the meteorological field has been dominated by larger year-to-year changes. In addition, seasonal trends showed that aerosols moved from west to east in spring and winter and northward in summer. They concluded that the probability of aerosol transport from China to the Far East is low, highlighting the change in transboundary pollution pathways due to global warming. In this study, the authors successfully detected climate change using long-term satellite observations, unlike most existing studies that monitor transboundary air pollution using model simulations.

“These results show that R_AOD “These results are a valuable indicator for measuring long-term changes in transboundary air pollution pathways due to climate change. These results are particularly important because most of them are based on observational data,” says Professor Airey, emphasising the importance of the study. Sharing the future results of his research, he concludes: “The impacts of climate change may be more severe than currently estimated. This research will help test climate change predictions from an unconventional ‘aerosol observation’ perspective, allowing for a more accurate understanding of the progression of climate change and the implementation of rational countermeasures.”

This study therefore demonstrates the innovative use of aerosols as indicators of climate change and marks a significant step forward in global efforts to address the urgent problem of climate change.