News coverage across the United States this week has focused on the intense winter storm or “bomb cyclone” that brought snow, ice, hurricane force winds and bitter arctic air to the U.S. east coast. The storm’s blast of frigid air reached as far south as Florida, cold-stunning iguanas that reportedly dropped unconscious from trees. Prior to the storm, the record-breaking cold air that gripped much of the United States, impacted other cold-blooded animals, with frozen sharks, or “sharksicles” washing up on Cape Cod beaches. And beyond the United States, other winter storms are also raging, such as the major storm hitting western Europe that left hundreds of thousands without power. As a result of this severe winter weather, a few pundits and politicians on both traditional and social media have weighed in with the question, “if global warming is really a critical threat to our communities, why are so many regions seeing nearly record cold temperatures?”
That line may make for a good sound bite, but it doesn’t make for a scientifically sound argument at all. Just because certain cities or countries are experiencing their coldest week of the year, or in a decade or longer, 2017 will still end as one of the three warmest years on record, if not the warmest ever, when the National Aeronautics and Space Administration (NASA) releases its final analysis later this month. NASA also tells us that the 10 warmest years on record have occurred since 1997. And the National Oceanic and Atmospheric Administration (NOAA) reports that recent decades have been the warmest since at least around 1000 AD, and that the warming we’ve seen since the late 19th century is unprecedented over the last 1,000 years.
This is the crucial distinction between weather and climate. Weather patterns are volatile, local and often unpredictable. The planet is large and complex, and an enormous number of factors, not all of which can even be anticipated, impact weather fluctuations. Climate, on the other hand, refers to long-term, gradual and much more predictable changes. Dr. J. Marshall Shepherd, past President of the American Meteorological Society, described the difference between weather and climate using a succinct analogy: “weather is your mood and climate is your personality.” He also highlights the need to correct the misperception that cold snaps disprove climate change, comparing it to the rationale: “because its night time, the sun went away.”
NOAA, in fact, makes this distinction even more clear, as their definition for “climate” is “the average of weather over at least a 30-year period.” The “weather” mentioned in that definition is simply the temperature and data seen on any given day in one specific place. Therefore, any temporary aberrations—like the major winter storms ravaging the east coast and Europe—do not call the science of global warming into question. The evidence for global warming, and the links to human emissions, are becoming increasingly irrefutable.
Obviously, this discussion triggers the question about whether we can trace any specific one of these storms to climate change, and humanity’s direct impact to our planet. While no single event, including this week’s most recent storms or the catastrophic hurricanes of the 2017 summer months can be attributed solely to climate change, scientists are increasingly certain that through sea-level rise, climate change definitely increases the destructive impact of storm surges, and through warmer seas and warmer air, climate change increases the probability of extreme precipitation events and contributes to rainfall amounts in tropical cyclones and other storms. In fact, quantifying links between climate change and extreme weather events is one of the most rapidly expanding areas of climate science. There is even a team of scientists who assess these links for particularly devastating events, soon after they occur.
Additionally, recent studies have also suggested that warmer air temperatures could lead to increased snowfall in some regions, due to escalating amounts of evaporating water from oceans, rivers, and lakes. As scientists continue to gather information about human-caused climate change and the impacts to ecosystems, it should become increasingly clear that issues like the loss of Arctic sea ice will change our planet’s weather in ways we can’t yet forecast.
That loss of ice is creating a smaller Arctic air pool, which means, in the long term, there is less cold air to go around. So, despite the freezing temperatures in the eastern U.S. right now, the northern hemisphere as whole is 0.9℃ warmer than normal, while the Arctic is 3.2℃ hotter. Some scientists suggest there is a link between Arctic warming and the extreme weather we’ve been experiencing in the United States, including the recent blast of cold air. As the Arctic warms, the jet stream becomes more wavy and elongated, intensifying both ridges and troughs and leading extreme weather to get stuck in place for longer.
Clearly, the storms hitting the United States and Europe this week are significant and should be treated with the respect and caution they deserve. Communities will spend days digging out and tracking the human and financial costs of this weather. But, next time there’s a “tweetstorm” about how cold temperatures and frozen sharks mean climate change isn’t real, it’s important to remember just how many other areas are suffering from unprecedented heat and drought, and that while the weather may change day-to-day, the climate has not.
Dr. Nicholas Wolff is a Climate Change Scientist at The Nature Conservancy with more than 30 publications on topics such as climate change vulnerability, climate change inequity, climate change adaptation, coral reef resilience, conservation planning, connectivity, ecosystem services, biodiversity, tropical cyclones and oceanography. Dr. Wolff holds a Ph.D from University of Queensland, School of Biological Sciences, and is based in our Maine Field Office.