Conservation is a major issue around the world with the impacts that humans have on natural ecosystems through activities from mining, building new cities and global warming. There are many conservation groups and efforts that lobby for the conservation of particular species (for example, the polar bear) or groups of animals (for example, tigers), while others are aimed at entire habitats, such as the Amazon rainforest. Conservation efforts can also aim to protect natural resources. Some conservation is done by setting aside national parks and wildlife preserves, while other conservation works targets specific threats to particular species. Read about various conservation efforts and issues below.