32. What do we know about global climate change? What does the ice tell us?
That’s a big question, Ali. I’ll do my best to keep my answer short.
The global climate is warming due to human greenhouse gas emissions, particularly carbon dioxide. Humans emit carbon dioxide when we burn fossil fuels – activities like driving a car or generating electricity. The concentration of carbon dioxide has been increasing due to these human emissions, and measurements of temperature show the globe is getting hotter.
Ice cores give us a window into the past – to before we were able to make measurements. The ice and the gas it traps show us what the temperature and carbon dioxide concentration were in the past. From ice core records, we’ve learned three really important things:
1) Today’s carbon dioxide concentration is higher than any time in the past 750,000 years.
2) The temperature of the earth has changed through time (ice-age cycles). Sometimes, the temperature change is rapid – up to a few degrees in a decade in Greenland.
3) Temperature and carbon dioxide vary together. When carbon dioxide concentrations are high, the temperature is high. When carbon dioxide concentrations are low, the temperature is low.
Ice cores tell us that the earth will warm to a point not experienced in the past 750,000 years and that the warming could occur rapidly. They also provide many clues to how the earth’s climate works. I’ll stop writing there, but am happy to answer follow up questions.