A key premise of the report was that an ecological threshold is the point at which there is an abrupt change in an ecosystem that produces large, persistent and potentially irreversible changes. The report concluded that slight changes in climate may trigger major abrupt ecosystem responses that are not easily reversible. Some of these responses, including insect outbreaks, wildfire, and forest dieback, may adversely affect people as well as ecosystems and their plants and animals. One of the greatest concerns is that once an ecological threshold is crossed, the ecosystem in question will most likely not return to its previous state. The report also emphasized that human actions may increase an ecosystem's potential for crossing ecological thresholds. For example, additional human use of water in a watershed experiencing drought could trigger basic changes in aquatic life that may not be reversible. Ecosystems that already face stressors other than climate change, will almost certainly reach their threshold for abrupt change sooner.