This graph, based on the comparison of atmospheric samples contained in ice cores and more recent direct measurements, provides evidence that atmospheric CO2 has increased since the Industrial Revolution. (Credit: Luthi, D., et al.. 2008; Etheridge, D.M., et al. 2010; Vostok ice core data/J.R. Petit et al.; NOAA Mauna Loa CO2 record.) Find out more about ice cores (external site). Source: Climate.Nasa.gov
A lot of information on threatened and endangered species is collected by government agencies as well as nonprofits focused on conservation. While the data they collect can usually be considered credible, it is also important to be aware of the sources behind that data, whether government agency or nonprofit, just as it is important to consider the credibility of all information you may come across.
Image: "Spectacled eider (Somateria fischeri)" by Laura L. Whitehouse, USFWS (public domain, via the U.S. Fish & Wildlife Service)