Global challenges

Tackling the many issues of climate change is a monumental task for scientists, policymakers, and the public alike. There is no doubt that Earth’s climate has naturally fluctuated throughout time—mostly due to changes in solar activity, changes in the Earth’s orbit around the sun, and other natural changes within the climate system, such as changes to ocean circulation patterns and volcanic activity. But today many people still ask the question, “Have humans actually caused recent global warming?” Although a few remaining skeptics would argue that there is insufficient evidence to draw a definitive causal link between human activity and climate change, the most recent report by the Intergovernmental Panel on Climate Change (IPCC) puts this debate to rest. Three main points are clear:

• Warming of the Earth’s climate is unequivocal;
• Human activity (e.g. the burning of fossil fuels) has dramatically increased atmospheric carbon dioxide and other greenhouse gas emissions since the Industrial Revolution;
• Human activity has very likely (greater than a 90% chance) contributed to recent global warming—and this trend will continue over the coming decades, if not centuries.

Climate change will continue to increase global sea surface temperatures, resulting in sea level rise, coral bleaching, and more intense tropical storms and hurricanes. Image: NASA Goddard Space Flight Center