Meteorologist Jeff Masters: ‘The climate has shifted to a new state capable of delivering rare and unprecedented weather events’

By Christine Shearer
6 February 2012 If you are interested in weather, chances are you have visited Weather Underground and read the posts of its director of meteorology, Dr. Jeff Masters. The consistently reliable Masters has been a rare voice in helping make sense of, rather than cloud (zing!), the increasingly strange weather events hitting the planet. […]

Masters shared some of his thoughts on meteorology, the effect of increasing greenhouse gases on weather and weather cycles, and the future of the earth’s climate. Christine Shearer: As far as I can tell, you are one of the few meteorologists that puts daily weather events in a historic context, and therefore really looks at averages and deviations from the average. Would that be a fair assessment of what you do? Jeff Masters: I focus on current weather events that have a high impact on people or society, and put them in a historical context. If there is current research which is relevant, I will mention that, particularly if the weather event in question is unusual and fits in with the general predictions of climate change. […] Christine Shearer: How do you think about the relationship between climate, climate change, and daily weather? Jeff Masters: Climate is what you expect; weather is what you get. I like to think of the weather as a game of dice. Mother Nature rolls the dice each day to determine the weather, and the rolls fall within the boundaries of what the climate will allow. The extreme events that happen at the boundaries of what are possible are what people tend to notice the most. When the climate changes, those boundaries change. Thus, the main way people will tend to notice climate change is through a change in the extreme events that occur at the boundaries of what is possible. If you want a longer explanation, think of the weather as a game of dice like craps or backgammon, where Mother Nature rolls two six-sided dice to decide the day’s weather. There are 36 possible combinations of the two dice, and rolls can range from two to twelve. Most often, an ordinary roll like six, seven, or eight comes up; seven is the most common, with a 6 in 36 probability. Rolls of six and eight are only slightly less common, coming up with a 5 in 36 probability. These rolls of the “weather dice” correspond to typical summer weather–high temperatures in the mid- to upper 70s on a nice summer day in New York City, for instance. It is much harder to roll an extreme event–snake eyes (corresponding to a record cold day, with a high near 65), or double sixes (a record warm day, with a high near 100.) These rolls only have a 1 in 36 chance of occurring–about 3%. Now think about what happens if we take one of the six-sided “weather dice” and paint an extra spot on each side. The old die still rolls a one through six, but the new die now rolls a two through seven. The most likely roll increases to an eight, so we’ve shifted to a warmer climate, getting a typical summertime high of 78 degrees instead of 76. However, the increase in 78 degree days isn’t that noticeable, since we’ve only increased the likelihood of getting an eight on our “weather dice” from 5 in 36 to 6 in 36. But now look at what has happened to extreme events as a result of loading our “weather dice” in favor of higher rolls. Whereas before we had only a 3% chance of rolling an twelve on our “weather dice”–an extreme heat day of 100 degrees in New York City–we’ve now tripled these chances to almost 9%, since there are three possible combinations of the dice that total twelve or higher. Moreover, it is no longer possible to roll snake eyes, corresponding to a record cold day, but it is now possible to roll a 13–a previously unprecedented weather event. Temperatures higher than 106, New York City’s previous all-time high temperature, can now occur. […] Christine Shearer: A recent popular science magazine had an article stating that many experts so far attribute this year’s warm weather in the continental U.S. to La Niña and the effect of the Arctic and North Atlantic Oscillations on the jet stream, “not global warming.” But is there a case to be made that increasing greenhouse gases and their effects could be affecting pressure systems? What is your take on this year’s U.S. winter and what you have said is the most “unusual configuration” of the jet stream ever recorded? Jeff Masters: The natural weather rhythms I’ve grown used to during my 30 years as a meteorologist have become disrupted over the past few years. Many of Earth’s major atmospheric circulation patterns have seen significant shifts and unprecedented behavior; new patterns that were unknown have emerged; extreme weather events were incredibly intense and numerous during 2010 – 2011. The laws of physics demand that the huge amount of heat-trapping gases humans are pumping into the atmosphere must be significantly altering the fundamental large-scale circulation pattern of the atmosphere. Unprecedented behavior like we’ve witnessed in the configuration of the winter jet stream over North America–with the four most extreme years since 1865 occurring since 2006–could very well be due to human-caused climate change. Something is definitely up with the weather, and it is clear to me that over the past two years, the climate has shifted to a new state capable of delivering rare and unprecedented weather events. Human emissions of heat-trapping gases like carbon dioxide are the most likely cause of such a shift in the climate. Christine Shearer: Having really looked closely at the weather for a while now, is there something that stands out to you most? Jeff Masters: The atmosphere I grew up with no longer exists. My new motto with regards to the weather is, “expect the unprecedented.” Christine Shearer: Anything you would like to say? Jeff Masters: Stronger hurricanes, bigger floods, more intense heat waves, and sea level rise have been getting many of the headlines with regards to potential climate change impacts, but drought should be our main concern. Drought is capable of crashing a civilization. To illustrate, drought has been implicated in the demise of the Mayan civilization in Mexico, the Anasazis of the Southwest U.S., and the Akkadians of Syria in 2200 B.C. The Russian heat wave and drought of 2010 led to a spike in global food prices that helped cause unrest in Africa and the Middle East that led to the overthrow of several governments. It’s likely that global-warming intensified droughts will cause far more serious impacts in the coming decades, and drought is capable of crashing our global civilization in a worst-case scenario, particularly if we do nothing to slow down emissions of carbon dioxide. Extreme weather years like 2010 and 2011 are very likely to increase in frequency, since there is a delay of several decades between when we put heat-trapping gases into the atmosphere and when the climate fully responds. This is because Earth’s oceans take so long to heat up when extra heat is added to the atmosphere (think about how long it takes it takes for a lake to heat up during summer.) Due to this lag, we are just now experiencing the full effect of CO2 emitted by the late 1980s; since CO2 has been increasing by 1 – 3% per year since then, there is a lot more climate change “in the pipeline” we cannot avoid. We’ve set in motion a dangerous boulder of climate change that is rolling downhill, and it is too late to avoid major damage when it hits full-force several decades from now. However, we can reduce the ultimate severity of the damage with strong and rapid action. A boulder rolling downhill can be deflected in its path more readily early in its course, before it gains too much momentum in its downward rush. For example, the International Energy Agency estimates that every dollar we invest in alternative energy before 2020 will save $4.30 later. There are many talented and dedicated people working very hard to deflect the downhill-rolling boulder of climate change–but they need a lot more help very soon.