Which human activity can negatively impact the effectiveness of carbon sinks?

Deforestation and land use changes significantly reduce the effectiveness of carbon sinks because these activities lead to the direct removal or alteration of forests and natural landscapes that are essential for capturing and storing carbon dioxide from the atmosphere. Trees and vegetation absorb carbon dioxide during photosynthesis, effectively acting as a natural buffer against climate change. When forests are cut down or converted to agricultural land or urban environments, not only is the capacity to store carbon lost, but the release of stored carbon from soil and biomass can also occur, further exacerbating greenhouse gas concentrations.

In contrast, the other options involve practices that either enhance carbon sequestration, like planting trees in urban areas, or contribute to sustainability and reduced carbon footprints, such as recycling and investing in renewable energy sources. Each of these activities, rather than harming carbon sinks, supports the reduction of carbon emissions or promotes the growth of new carbon-absorbing resources. Thus, while implementing measures that protect and enhance carbon sinks is essential, practices like deforestation undermine their role in climate regulation.