The final data is in for the unprecedented March heat wave that was “unmatched in recorded history” for the U.S. (and Canada). New heat records swamped cold records by the stunning ratio of 35.3 to 1.
This ratio is almost off the charts, even with the brutally warm August we had, as this chart from Capital Climate shows.
For the year to date, new heat records are beating cold records by 22 to 1, which trumps the pace of the last decade by more than a factor of 10!
I like the statistical aggregation across the country, since it gets us beyond the oft-repeated point that you can’t pin any one record temperature on global warming. A 2009 analysis shows that the average ratio for the 2000s was 2.04-to-1, a sharp increase from previous decades. Lead author Dr. Gerald Meehl explained, “If temperatures were not warming, the number of record daily highs and lows being set each year would be approximately even.”
Meteorologist Jason Samenow points out just how extreme the heat wave was: “More than 7,700 daily record high temperatures were set (or tied, compared to just 287 record lows), in some cases by mind blowing margins and over multiple days. In several instances in the Great Lakes and Upper Midwest region, morning lows even bested record highs and high temperatures soared above mid-summer norms.”
Many of the country’s leading climatologists and meteorologists have looked at the data and concluded that like a baseball player on steroids, our climate system is breaking records at an unnatural pace.
Weather Channel meteorologist Stu Ostro calls the current heat wave “surreal” and explained that “While natural factors are contributing to this warm spell, given the nature of it and its context with other extreme weather events and patterns in recent years there is a high probability that global warming is having an influence upon its extremity.”
Meteorologist Dr. Jeff Masters has said, “this is not the atmosphere I grew up with.” He published a detailed statistical analysis concluding, “It is highly unlikely the warmth of the current ‘Summer in March’ heat wave could have occurred unless the climate was warming.”
Climate Central pointed out that given the intensity, duration, and geographical breadth of the heat wave, “this may be an unprecedented event since modern U.S. weather records began in the late 19th century.” They interviewed several top scientists who explained global warming’s likely role in helping to make this extreme event so unique.
Welcome to the new climate in which heat waves are pushing farther outside the envelope of what has been observed previously during the historical record. To quote Hansen et al. (2011), “Today’s extreme anomalies occur because of simultaneous contributions of specific weather patterns and global warming.” I’m usually very cautious about linking weather events to global warming as there is considerable natural variability in the system, but these are jaw-dropping records and such events are more likely today than 60 years ago.
NBC News has a very good story about the cause of the extreme weather. Their chief environmental correspondent Ann Thompson interviews NOAA scientist, Dr. David Easterling:
Thompson: But scientists say ping-ponging between weather extremes may be an indicator of a much bigger problem: the heat trapping gases of climate change
Easterling: The warming that we’ve seen actually increases the chances, kind of loads the dice that were going to see these kinds of events more often.
Thompson: Dr. David Easterling of the National Oceanic and Atmospheric Administration is a co-author of United Nations report out this week that points to climate change as leading to extreme weather events since 1950.
Easterling: The unusual warm days and nights, and to some extent heat waves, you can actually begin making that link between climate change and those events.
Since the science of attributing extreme events to global warming is still emerging, scientists still disagree to what extent a specific event like this heat wave is driven by global warming. But two of the leading experts explain at RealClimate why even small shifts in average temperature mean “the probability for ‘outlandish’ heat records increases greatly due to global warming.” Furthermore, “the more outlandish a record is, the more would we suspect that non-linear feedbacks are at play – which could increase their likelihood even more.”
The really worrisome part is that we’ve only warmed about a degree and a half Fahrenheit in the past century. We are on track to warm five times times that or more this century.
In short, we ain’t seen nothing yet!