Vulnerable countries, communities, and ecosystems are already feeling the effects of climate change, as sea levels and temperature rise, rainfall patterns change, and extreme weather events, such as droughts, floods, storms, and other natural disasters, occur more frequently and intensively. These events not only adversely affect core development needs, such as access to drinking water, food security, irrigation, and health, but also entire ecosystems on which all life forms depend— and they exact the heaviest toll on poor people.