8.6 Evidence for Climate Change

Notes

Several independent lines of evidence show Earth has warmed since the late 1800s (about 1.1-1.2°C).

• Thermometer records and satellite data; the last decade was the warmest on record.
• Ice cores trap ancient air bubbles showing CO₂ and temperature for 800,000 years. Glaciers and sea ice are shrinking.
• Sea level is rising from melting ice and thermal expansion of warming water, about 3-4 mm per year recently.
• Tree rings, coral and sediments give older records (proxies).
• The scientific consensus is that human greenhouse gas emissions are the main cause of recent warming.