Decades of climate research has established that the Earth is warming and that humans are a significant factor. Largely due to humans adding greenhouses gases to the atmosphere — through burning of fossil fuels, deforestation, and many other agricultural, industrial and human activities — the rise in temperatures over the past century has been unprecedented.
According to researchers at NASA and the National Oceanic and Atmospheric Administration (NOAA), 2016 was the warmest year in documented history. In fact, 16 of the 17 warmest years on record have occurred since 2001. By 2050, annual average temperatures are expected to rise in the United States by approximately 2.5 degrees Fahrenheit under even the most optimistic projections.
The rise in temperatures fuels many extreme weather events. Increased surface temperatures can cause extreme storms when combined with excess moisture and result in heavy precipitation, while causing drought-inducing heat waves in other parts of the world. Scientific advances, including better observational data, improved climate models, and more sophisticated detection methods have made it possible to attribute extreme weather events to rising global temperatures.
It is important to note that attributing individual extreme weather events to long-term climate trends, and accurately predicting future climate events, are still remarkably difficult endeavors.
Commenting on the global frequency of tropical cyclones, Michael Bell, associate professor of atmospheric science at Colorado State University wrote in an email to 24/7 Wall St, “While we do have strong evidence that extreme weather events are getting worse, it is still an active area of research to improve our confidence in attribution and projections of climate change impacts.”
Also commenting on the difficulty of making accurate predictions, meteorologist Stanley Goldenberg at the hurricane research division of NOAA wrote, “[W]e have a hard time reliably predicting an El Niño or La Niña event even 3-4 months in advance — and these are very robust climate phenomenon.”
Is global warming causing the worsening of the Earth’s weather? It is very likely that extreme weather events will occur more frequently and with greater intensity as the Earth continues to heat up. However, to avoid overstating the causal connections between such complex phenomenon, the appropriate framing for the question is whether global warming has altered the odds of extreme weather occurrences.
24/7 Wall St. reviewed regions in the United States where there is evidence of an association between climate change and exceptional weather events recorded recently in these regions.
The significant increased wildfire activity in Alaska in recent decades is associated with manmade and natural factors. A Climate Science Special Report estimates the risk of devastating wildfires in the state has likely risen by 33%–50% and is projected to increase fourfold by the end of 21st century. The 2015 fire season in Alaska burned the second-largest number of acres since 1940, when record keeping began.
2. Arctic Ocean: Alaska
The amount of sea ice in the Bering and Chukchi seas that separate Alaska from Asia fell to 135,000 square miles last November, the lowest level for that time of year in 40 years.
3. Arizona: Phoenix
In late June 2017, Phoenix, Arizona — always among the hottest cities in the nation — recorded a high temperature of at least 112 degrees for nine straight days, tying a previous city record set in 1990, according to the National Weather Service.
4. Central Pacific: Near Hawaii
The central Pacific Ocean near Hawaii typically has cooler ocean temperatures and stronger vertical wind shear patterns, conditions not favorable to hurricanes. However, according to CSSR findings, the greater tropical storm activity in 2014 and 2015 was associated with warmer oceans and weaker vertical wind shear that was linked to the effects of El Niño and human-caused climate change.
5. Central United States: Oklahoma
A drier-than-average winter, worsening drought conditions, and strong winds in the spring — some gusting over 40 mph — led to wildfires in April in Oklahoma and the central United States.
Scientists warn that man-caused global warming will likely increase the potential for wildfires. Weather conducive to fires is expected to become both more extreme and span longer times as a result of climate change.