Other aspects of global warming's broad footprint on the world's ecosystems include changes in the abundance of more than 80 percent of the thousands of species included in
population studies; major poleward shifts in living ranges as warm regions become hot, and cold regions become warmer; major increases (in the south) and
decreases (in the north) of the abundance of
plankton, which forms the critical base of the ocean's food chain; the transformation of previously innocuous insect species like the Aspen leaf miner into pests that have damaged millions of acres of forest; and an increase in the range and abundance of human pathogens like the cholera - causing bacteria Vibrio, the mosquito - borne dengue virus, and the ticks that carry Lyme disease - causing bacteria.