2C. Long-term Trends in Carbon Dioxide and Surface Temperature
As can been seen in this figure, throughout the millennia, there has been a clear correlation between carbon dioxide levels and average global surface temperatures. Looking back even further than the past 150 years (see figure 2B) gives further evidence of the human role in the enhanced greenhouse effect.
Scientists say the world is entering largely uncharted territory as atmospheric levels of greenhouse gases continue to rise. Today’s carbon dioxide levels are substantially higher than anything that has occurred for more than 400,000 years. To understand the role of humans in increased surface temperature, go to figure 2D.
