THIS WEEK, THE topic of extreme weather was brought to everyone’s attention as the US braced itself for what meteorologists said could be the worst winter storm ever recorded on the east coast. While New York managed to escape the worst of it, Connecticut, Maine, Massachusetts and New Hampshire were subjected to about three feet of snow, and power cuts as temperatures dipped to -12C.
This kind of ‘freak weather’ is referred to as extreme due to its typically infrequent occurrence, and storms of the magnitude of Storm Juno are generally only observed once per century. However, a growing body of scientific research is finding that the frequency of such weather may increase as a direct result of global warming.
It may seem counterintuitive, but global warming could result in more intense snowfall
Despite the fact that temperatures on average are on the increase, each hemisphere still spends half of the year tilted away from the sun with shorter days and colder temperatures. The storm set to hit parts of North America this week is what is known as a “nor’easter”, a storm that draws its energy when freezing Arctic air meets warmer Gulf Stream water.
While it may seem counterintuitive that global warming could result in more intense snowfall, it is actually quite a logical conclusion: warmer ocean temperatures as a consequence of a warming planet provide more moisture in the air for a winter storm to feed off, thus producing huge levels of snowfall inland. This phenomenon has become all too apparent in the Northeast United States, with notable recent events including the blizzard of November 2014, in which Buffalo, NY saw six feet of snow drop in 24 hours, and now this week’s extraordinary blizzard.
While it may have come as a shock to most of us, climate scientists argue that weather like this is completely predictable for a warming climate. In fact, such heavy storms have increased by more than 70% in the past six decades in the Northeast, according to the 2014 National Climate Assessment report.
Paul Baxter digs his cars out of drifted snow after a winter storm, Tuesday, Jan. 27, 2015, in Marlborough, Mass. A storm packing blizzard conditions spun up the East Coast early Tuesday, pounding parts of coastal New Jersey northward through Maine with high winds and heavy snow. (AP Photo/Bill Sikes)
Switching between extremes of wet and dry
It cannot be said that climate change is responsible for individual weather events like this one; however, certain aspects of the storm are most likely intensified as a result of climate change.
El Niño–Southern Oscillation (ENSO) is a naturally occurring climate pattern made up of El Niño (warm phase) and La Niña (cold phase) which are both huge drivers of extreme weather. Climate scientists project that the frequency of these events may double as a result of global warming; meaning extreme weather like North America’s current ‘Snowmaggedon’ may be something we should learn to expect.
A study in leading scientific journal Nature Climate Change found that the La Niña extreme weather – which happens about once every 23 years – will occur every 13 years by the end of this century, based on an analysis of 21 climate models. It is thought that around 70% of those increased La Niña events will follow extreme El Niño events, thus projecting that parts of the world could experience weather patterns that switch between extremes of wet and dry.
Cots line a hallway where stranded travelers slept at LaGuardia Airport in New York. (AP Photo/Seth Wenig)
Last year was the warmest since records began
Official reports released in the last few weeks by the NASA and the National Oceanic and Atmospheric Administration (NOAA) confirmed that 2014 was the warmest year since records began in 1880, and we were once again reminded of the detrimental effect that humans are imposing on the earth; the burning of fossil fuels and deforestation are among the leading causes of increased CO2 emissions.
However, one of the most worrying facts regarding the temperature record of 2014 is that it happened in the absence of an El Niño. In the same way that La Niña events are responsible for driving extreme cold weather, El Niño events cause spikes in temperatures, and all of the warmest years since 1998 have coincided with one. But despite 2014 setting a new temperature record, the last El Niño occurred during 2009/10. Gavin A Schmidt, head of NASA’s Goddard Institute for Space Studies in Manhattan, told the New York Times earlier this month that the next strong El Niño would probably rout all temperature records.
Carbon emissions are driving the global temperature average up, which intensifies aspects of otherwise conventional weather like what we are seeing across the Atlantic this week. This in itself is requiring us to reassess our definition of ‘expected’ annual weather. But combine this with projected increases in El Niño and La Niño events resulting from global warming, and we may be looking at a very different world in terms of weather events by the end of the 21st century.
Leah Gainey is the Senior Environmental Analyst & REDD+ Advisor for Irish Eco-business Celestial Green Ventures. To see more from Celestial Green Ventures, please visit their reports page.
To embed this post, copy the code below on your site
have your say