Climate records kept worldwide clearly show that ongoing changes are happening in our eco-systems. Such climate changes include temperature, precipitation, or sea level, all of which are expected to keep changing well into the future, thereby affecting human health, the environment, and the economy. The natural causes by themselves are not able to describe these changes, so to understand these, scientists are using a combination of state-of-the-science measurements and models. Human activities are a major contributor due to the release of different air contaminants through various activities. Air pollution is one case-in-point, a human-made factor that contributes to climate change by affecting the amount of incoming sunlight that is either reflected or absorbed by the atmosphere. An overview of modeling techniques used to relate air quality and climate change is presented. The discussion includes the role of air pollution levels affecting the climate. Emerging topics such as black carbon (BC), fine particulate matters (PMs), role of cook stove, and risk assessment are also covered.
TopIntroduction
It is important to understand climate in order to study climate change, which includes the harm caused by air pollutants. These can occur through natural processes or through human activities, which in turn affect human health and the ecosystem, resulting in millions of annual premature deaths, and hospitalizations (Schreiner et al., 2006; Shandilya and Khare, 2012). Further, climate change highly impacts on agriculture and fisheries (farmers and ranchers). Increases in temperature and CO2 level in the atmosphere can change in the frequency and severity of droughts and floods, which can threat food safety. In addition, warmer water temperatures are likely to cause the habitat ranges of many fish and shellfish species to shift, which could disrupt ecosystems (USEPA, 2018a).
Climate change is able to alter how primary pollutants are dispersed and to intensify secondary pollutant formation. Therefore, it is helpful to review the impact of climate change. In particular, it is necessary to note that there is a relation between weather and climate. Weather is defined as the state of the atmosphere at any given time and place, while climate is the long-term average (e.g., decades) of the weather in any place (Rosenzweig et al., 2001). Figure 1 shows the relationship between the weather variability and climate change (Solomon et al., 2007).
Figure 1. Schematic view of the major components of the climate system, main processes and key interactions
As shown in Figure 1, the climate system is comprised of five natural components, (1) the atmosphere, (2) the hydrosphere, (3) the cryosphere, (4) the land surface, and (5) the biosphere.
The atmosphere includes gases that surrounds Earth, including the naturally occurring greenhouse gases or GHGs that warm the planet’s surface. The hydrosphere includes all of Earth’s liquid and gaseous water (water vapor), while the cryosphere includes all frozen water (ice). The land surface only consists of all vegetated and non-vegetated surfaces. The biosphere is the global ecological system integrating all living beings and their relationships.
Several external forces influence the five climate system components, with radiation from the Sun being most important. The Sun is the primary energy source for Earth’s climate. Some incoming sunlight is reflected into space (via bright surfaces like ice and clouds), while the rest is absorbed by the surface and the atmosphere. A considerable amount of this absorbed solar energy is re-emitted as heat through long-wave or infrared radiation, but some heat escapes when the atmosphere absorbs and re-radiates heat. Disturbing this balance (incoming and outgoing energy) results in climate change (Wittneben and Kiyar, 2009). Additionally, climate scientists consider the impact of human activities on the climate system as another example of external forcing.
The instability of the atmosphere within the climate system is evident in how it is composed of nitrogen, oxygen, and argon with 78.1, 20.9, and 0.93% vol. mixing ratio, respectively. In the atmosphere, these three elements have limited interaction with the solar radiation and do not interact with long-wave or infrared radiation. Also, GHGs (e.g. water vapor, CO2, CH4, O3, and N2O (<0.1% by volume)), can absorb and emit these radiations keeping Earth’s surface and lower atmosphere warm. Likewise, solid and liquid particles (aerosols) interact with radiation in a complex and spatial manner (Shandilya et al., 2009).