Land cover change in low-warming scenarios may enhance the climate role of secondary organic aerosols

Abstract. The effects of future land use and land cover change on the chemical composition of the atmosphere and air quality are largely unknown. To investigate the potential effects associated with future changes in vegetation driven by atmospheric CO2 concentrations, climate, and anthropogenic land use over the 21st century, we performed a series of model experiments combining a general circulation model with a dynamic global vegetation model and an atmospheric chemical-transport model. Our results indicate that climate- and CO2-induced changes in vegetation composition and density could lead to decreases in summer afternoon surface ozone of up to 10 ppb over large areas of the northern mid-latitudes. This is largely driven by the substantial increases in ozone dry deposition associated with changes in the composition of temperate and boreal forests where conifer forests are replaced by those dominated by broadleaf tree types, as well as a CO2-driven increase in vegetation density. Climate-driven vegetation changes over the period 2000–2100 lead to general increases in isoprene emissions, globally by 15 % in 2050 and 36 % in 2100. These increases in isoprene emissions result in decreases in surface ozone concentrations where the NOx levels are low, such as in remote tropical rainforests. However, over polluted regions, such as the northeastern United States, ozone concentrations are calculated to increase with higher isoprene emissions in the future. Increases in biogenic emissions also lead to higher concentrations of secondary organic aerosols, which increase globally by 10 % in 2050 and 20 % in 2100. Surface concentrations of secondary organic aerosols are calculated to increase by up to 1 μg m−3 for large areas in Eurasia. When we use a scenario of future anthropogenic land use change, we find less increase in global isoprene emissions due to replacement of higher-emitting forests by lower-emitting cropland. The global atmospheric burden of secondary organic aerosols changes little by 2100 when we account for future land use change, but both secondary organic aerosols and ozone show large regional changes at the surface.

Download Full-text

The role of landscape pattern analysis in understanding concepts of land cover change

Journal of Geographical Sciences ◽

10.1007/bf02873085 ◽

2004 ◽

Vol 14 (S1) ◽

pp. 3-17 ◽

Cited By ~ 6

Author(s):

Jerry A Griffith

Keyword(s):

Land Cover ◽

Land Cover Change ◽

Landscape Pattern ◽

Pattern Analysis ◽

Landscape Pattern Analysis

Download Full-text

Accelerating land cover change in West Africa over four decades as population pressure increased

Communications Earth & Environment ◽

10.1038/s43247-020-00053-y ◽

2020 ◽

Vol 1 (1) ◽

Author(s):

Stefanie M. Herrmann ◽

Martin Brandt ◽

Kjeld Rasmussen ◽

Rasmus Fensholt

Keyword(s):

Land Cover ◽

West Africa ◽

Land Cover Change ◽

Regional Scale ◽

Population Pressure ◽

Human Footprint ◽

Long Time ◽

Quantitative Analyses ◽

Change Intensity

AbstractRapid population growth in West Africa has exerted increasing pressures on land resources, leading to observable changes in the land cover and land use. However, spatially explicit and thematically detailed quantitative analyses of land cover change over long time periods and at regional scale have been lacking. Here we present a change intensity analysis of a Landsat-based, visually interpreted, multi-date (1975, 2000, 2013) land cover dataset of West Africa, stratified into five bioclimatic sub-regions. Change intensities accelerated over time and increased from the arid to the sub-humid sub-regions, as did population densities. The area occupied by human-dominated land cover categories more than doubled from 493,000 km2 in 1975 to 1,121,000 km2 in 2013. Land cover change intensities within 10 km of new settlement locations exceeded the region-wide average by up to a factor of three, substantiating the significant role of population pressure as a force of change. The spatial patterns of the human footprint in West Africa, however, suggest that not only population pressure but also changing socioeconomic conditions and policies shape the complexity of land cover outcomes.

Download Full-text