Causes

The overall consensus among climate scientists worldwide is that the Earth’s climate has changed substantially over the last century and will continue to change in the coming decades as a result of increasing greenhouse gas emissions from human activities. The impacts of a changing climate are being observed throughout the world: global temperatures are increasing, mountain snowpack is declining, habitats and species ranges are shifting, and sea level is rising. Locally, average annual temperature at Sedro Woolley increased 1.6°F (from 1895 to 2010)  Source: Office of the Washington State Climatologist, mean sea level at Friday Harbor increased by 4 inches (from 1934 to 2006)  Source: NOAA, and the nearly 400 active glaciers in the North Cascades have lost an estimated 50% of glacial mass since the start of the 20th century.

The following webpages provide some basic background information on climate for those seeking to understand what may be happening and the implications of those changes on things they care about. They cover climate change and variability as well as information on scientific certainty and climate models.