Due in large part to this enhanced greenhouse effect, the world today is nearly 1˚C (1.8˚F) warmer than it was before the Industrial Revolution. While 1˚C may seem hardly noticeable on a sunny day, countries are already seeing the severe effects of planet-wide warming at this level. Heat waves are lasting longer, crop yields are shrinking, and rising sea levels are threatening coastal areas.
Scientists warn that human activity will likely raise global temperatures to 1.5˚C (2.7˚F) above nineteenth-century averages by 2050, and, without a significant reduction in greenhouse gas emissions, global temperatures could reach 2˚C (3.6˚F). Should this happen, the results would be catastrophic. And, in some cases—such as species going extinct, coral reefs dying, and sea levels rising—the effects would be irreversible.