I am linking three potential articles for you to use, all published by credible sources. The publication information you'll need is generally at the very bottom of the home page of each site. You can also use tools such as easybib.com, which helps pull the needed information off those pages for you. You should, of course, verify that the citation matches the format your instructor has provided. I'll try to provide a bit of guidance for each of the sources I linked below.

EPA Source:

• By analyzing scientific observations and data, there is a 95% chance that humans have created global warming.
• Burning fossil fuels has changed our climate more than anything else humans have done.
• Investigating natural causes, such as solar activity volcanic eruptions, does not explain the increases in global temperatures.
• The impacts pose health risks to the elderly and children. Rising sea levels also threaten ecosystems.

NASA Source:

• The "greenhouse effect" is created by warming that occurs when the atmosphere traps heat close to the Earth's surface.
• Some gases make it more difficult for heat to escape the atmosphere because they do not respond to changes in temperature: carbon dioxide, methane, and nitrous oxide. The article also provides information about how humans contribute to an abundance of these gases, which should be part of your information.
• As the Earth continues to warm, some regions will become warmer than others.
• The way climate extremes can impact crop yields is explained in this article. An important note here is that these temperature fluctuations can threaten food security worldwide, particularly as weeds and pests find more favorable conditions in warmer temperatures.

WWF Source:

• This article discusses the impact of global warming on various species, including tigers, snow leopards, and arctic animals.
• The impact on marine life includes increasing the acidity level of oceans.
• Oceans have seen an approximately 1 degree Celsius increase in temperature; if they warm by another degree, virtually all coral reefs will be lost. This also impacts fishing environments which rely on reefs as part of animals' natural habitats.
• There are helpful links at the bottom where you can measure your own footprint and find ways to reduce your own impact on global warming.