25 days earlier: global warming makes birds nest sooner

In 10 seconds? A century-old collection of birds’ eggs has helped scientists determine that birds are nesting earlier than they used to a hundred years ago. The reason? Climate change.

What’s the breakthrough? Researchers have found that a third of the bird species found in Chicago are nesting and laying their eggs a month earlier than they were a hundred years ago. The scientists compared recent observations with eggs from museum collections and determined that birds are laying their eggs 25 days earlier on average. The researchers then examined carbon dioxide records to estimate changes in temperatures in the region over the last century and found that the estimated increases in carbon dioxide, and hence temperature, correlated with the earlier egg-laying, suggesting climate change is the cause.