On Tuesday, Nov. 4, Dr. Jennifer Francis gave a lecture titled “Truth and Fact: Global Climate and Temperature” at Bowers Writers House. During her lecture, Francis discussed change in the arctic and its relation to the jet stream, which affects extreme weather patterns. After specializing in the arctic weather patterns, Francis switched concentrations to research why the arctic is melting and how it affects the weather. Global climate change is a popular topic among the science community because extreme weather and climate is on the rise. However, these are gradual trends that have risen since the 1980s, and there is a correlation between extreme weather trends and climate.
Extreme weather includes nor’easters, floods and heavy rainfall in unnaturally rainy places. Additionally, cold weather began occurring in normally hot places like the Mediterranean and heatwaves and droughts in places like Texas, Eurasia and California. This is due to weather patterns that normally pass quickly, but are persisting in the same location longer than usual.
Francis used a graph to demonstrate how the increase in extreme weather patterns caused by humans. She showed a graph of Earth’s temperature for the past 1,000 years. The graph charts a trend of the temperature cooling, which is a part of Earth’s natural cycle; however, in the last 100 years, a large red spike protrudes from graph that symbolizes the extra carbon dioxide people added to the atmosphere. The carbon dioxide levels are at the highest they been in at least 800,000 years.
The Earth’s temperature has not been changing evenly; the arctic is warming faster. The last 335 months have had a temperature warmer than the average. Over the last 30 years, the arctic sea ice has shrunk by half its size and 75 percent of its volume. Ice quality has decreased, and the old thick ice, is now slushy, fragile and broken.
Francis showed an animation that reconstructed the arctic sea ice over the last 1,450 years. The last 100 years showed a drop off in arctic sea ice. It showed the trend of old, thick ice and the cycle of ice movement, how the ice grows, shrinks and melts into the North Atlantic. However, the animation over time showed a gradual decrease of old, thick ice to its current state. The arctic sea ice being incredibly sensitive to temperature change causes the issue.
Francis showed another graph of near-surface air temperature in the 1990s. It shows a trend of arctic amplification, which refers to the temperature spike in the arctic.
The layer of air expanding in the arctic is thinner than it is near the equator. Air flows down from the arctic and makes its way toward the east as the Earth spins, creating a jet stream.
However, as the arctic warms faster, the air flow from the arctic weakens and slows the jet stream. As these weak jet streams shift eastward, they do so in a path that is slower and wider. Jet streams control weather patterns, meaning that the weakened jet streams have been causing the extreme weather patterns.
Francis’ hypothesis attempted to link arctic heating, poleward temperature gradient weakening and upper-level westerly winds. The decrease of these winds leads to upper-level flow becoming more wary and amplifies weather patterns more frequently. Francis also studied larger waves progressing eastward more slowly together.
Francis summarized the lecture by stating that essentially the Earth’s summers are becoming hotter and the winters are becoming colder. The arctic is warming, causing west winds to weaken. This causes a slower, wider jet stream path. A slow jet stream causes extreme weather patterns to persist in areas for long times, causing the population to suffer the affects of the extreme weather. Therefore, extreme weather is due to climate change.
