In this short video from ClimateCentral, host Jessica Harrop explains what evidence scientists have for claiming that recent global warming is caused by humans and is not just part of a natural cycle.

This is a sequence of 5 classroom activities focusing on the El NiÃo climate variability. The activities increase in complexity and student-directedness. The focus of the activities is on accessing and manipulating real data to help students understand El NiÃo as an interaction of Earth systems.

In this lesson, students examine and interpret varied observational datasets and are asked to determine whether the data supports or does not support the statement: climate change is occurring in Colorado.

This video features research conducted at University of Colorado's Institute of Arctic and Alpine Research, which studies isotopes of hydrogen trapped in ice cores to understand climate changes in the past.

In this activity, students reconstruct past climates using lake varves as a proxy to interpret long-term climate patterns. Students use data from sediment cores to understand annual sediment deposition and how it relates to weather and climate patterns.

This animation shows the Arctic sea ice September (minimum) extents from 1979-2014.

These graphs show carbon dioxide measurements at the Mauna Loa Observatory, Hawaii. The graphs display recent measurements as well as historical long term measurements. The related website summarizes in graphs the recent monthly CO2, the full CO2 Record, the annual Mean CO2 Growth Rate, and gives links to detailed CO2 data for this location, which is one of the most important CO2 tracking sites in the world.

This interactive graphic shows the different components of the ocean biological pump, i.e., how carbon in the form of either plankton or particles moves into the ocean's depths. The diagram illustrates the processes at the surface, 0-100 meters, 100-500 meters, and below 500 meters.

In this activity, students are introduced to tree rings by examining a cross section of a tree, also known as a 'tree cookie.' They discover how tree age can be determined by studying the rings and how ring thickness can be used to deduce times of optimal growing conditions. Next, they investigate simulated tree rings applying the scientific method to explore how climatic conditions varied over time.

This beautifully filmed and produced video describes the changes that global warming is already bringing to Northern Canada and Greenland. Local people describe changes to ecosystems, impacts on culture and life styles, and the challenges of melting permafrost. Ship captains describe changes in navigational channels and fjords. Scientists describe changes in albedo and permafrost, as well as increased pollution transported from outside the Arctic (the Grasshopper effect).