e. Based on evidence from tree rings, other natural records, and scientific observations made around the world, Earth's average temperature is now warmer than it has been for at least the past 1,300 years. Average temperatures have increased markedly in the past 50 years, especially in the North Polar Region.

This color-coded map displays a progression of changing five-year average global surface temperatures anomalies from 1880 through 2010. The final frame represents global temperature anomalies averaged from 2006 to 2010. The temperature anomalies are computed relative to the base period 1951-1980.

This short video describes how the compression of Antarctic snow into ice captures air from past atmospheres. It shows how ice cores are drilled from the Antarctic ice and prepared for shipment and subsequent analysis.

This is an interactive graph that involves records of ice cover in two Wisconsin lakes - Lake Mendota and Lake Monona - from 1855-2010.

This video is part two of a seven-part National Academies series, Climate Change: Lines of Evidence. The video outlines, with the use of recent research and historical data, how we know that the Earth is warming.

This video, from ClimateCentral, features a team of scientists from the Northern Greenland Eemian Ice Drilling Project (NEEM), who study atmospheric air bubbles trapped in an ice core from a period in Greenland's ice sheet which began about 130,000 years ago and lasted about 10,000 years; a period known as the Eemian. The air bubbles from the ancient atmosphere - all aligned on the same time scale - reveal what happened with climate change over that period of time.

In this TED talk, Wall Street Journal science columnist Lee Hotz describes the research of the Western Antarctic Ice Sheet Divide project, in which scientists examine ice core records of climate change in the past to help us understand climate change in the future.

This teaching activity is an introduction to how ice cores from the cryosphere are used as indicators and record-keepers of climate change as well as how climate change will affect the cryosphere.

This interactive visualization describes how climatologists obtain and interpret evidence from the Greenland Ice Sheet in an effort to piece together a picture of Earth's distant climate history. Resource describes how glaciers form and how they can be used to collect ancient atmospheric data. The issues analyzed in the data collection are particularly good in showing how science is done in the field.

This is a classroom activity about the forcing mechanisms for the most recent cold period: the Little Ice Age (1350-1850). Students receive data about tree ring records, solar activity, and volcanic eruptions during this time period. By comparing and contrasting time intervals when tree growth was at a minimum, solar activity was low, and major volcanic eruptions occurred, they draw conclusions about possible natural causes of climate change and identify factors that may indicate climate change.

In this activity, students chart temperature changes over time in Antarctica's paleoclimate history by reading rock cores. Students use their data to create an interactive display illustrating how Antarctica's climate timeline can be interpreted from ANDRILL rock cores.