News broke over the weekend that NASA’s preliminary data indicated that February 2016 set yet another record as the warmest month globally since record-keeping began in the late 1800s. According to the data, February was a whopping 1.35⁰C warmer than the average temperature for the month between 1951-1980, and 0.02⁰C warmer than the previous NASA record, set in January 2016, which was 1.15⁰C above the long-term average for that month.
“Yet another” is an important component of this, because this new record comes directly on the heels of the previous month’s record, January 2016, and of the warmest year, 2015. The other important component of this is “1.35⁰C,” which means February was warmer than January by 0.2⁰C.
Today NOAA (which measures temperatures against a different baseline) officially released their numbers confirming the warming trend—February checked in at 1.21⁰C above the global average for the 20th century, exceeding the previous NOAA record of December 2015, which was 1.11⁰C warmer than the average.
No matter how you measure it, February shattered previous records. As Gavin Schmidt of NASA put it on Twitter: WOW.
Here I pause to remind you of the commitment made by 190+ nations in December 2015 (the Paris Agreement) to try to limit annual global average global warming to 2⁰C from pre-industrial levels—preferably to 1.5⁰C—to prevent Earth as we know it from turning into an Earth we don’t know at all. We don’t want to surpass 2⁰C increase in annual average, we would prefer to stay below 1.5⁰C, and here is February, with a monthly record getting dangerously close to 1.5⁰C, trying to derail our efforts so early on!
Current extremes provide glimpses into a warmer future
But what types of changes would warming above 2⁰C bring? We are already having glimpses into the future. In addition to early spring onset, animal and plant species changing their distribution and life cycle traits (such as butterflies expanding northward or flying earlier), there have been noticeable differences in weather patterns and frequency of extreme events all around the globe.
Examples include the deadly 2010 heat wave in Russia, superstorm Sandy, the 4-year-long record drought in California, a 1,000-year flooding event in South Carolina. Extreme events are particularly concerning, because they often leave loss to property—and sometimes life—in their wake, with impacts on economies and livelihoods, even when they don’t appear threatening, such as a December heat wave in the Northeastern U.S. that had people in shorts at Christmas time but affected retail and tourism businesses, which depend on cold weather.
Have these events been made more intense or more likely by climate change?
One wonders how climate may have affected the intensity or likelihood of such events. And is there a way we can plan for them so as to reduce the risks and the devastation?
A new report released on March 11 by the National Academies of Sciences, Engineering, and Medicine seeks to answer those questions through the science of extreme event attribution. Attribution evaluates the contributions of multiple causal factors to an event.
To paraphrase report committee chair David Titley, a retired Navy rear admiral and professor of meteorology at Pennsylvania State University, each extreme event is a consequence of multiple factors under a set of conditions—much like a cookie is the product of various ingredients and conditions. You tweak one ingredient or condition and the result will be slightly different, while still remaining a cookie—or in our case, an extreme event. Finding out what and how ingredients and conditions lead to an individual event is the key to attribution.
Through the evaluation of a number of attribution studies, the report committee found that events are easier to attribute when there is consistent quality and length of past observational records of similar events, there is good understanding of the physical mechanisms leading to changes in those types of events, and models can replicate the events.
Events related to an aspect of temperature (such as warming) are easier to attribute than events that have a variety of other influences. For example, the report found that there is high confidence on the capability of attribution and high understanding of the effects of climate change on heat waves and cold waves, but not hurricanes or droughts, which involve a lot more complex interactions both physical and human-induced.
The report cites the example of Russia, where an unusually persistent atmospheric high pressure in 2010 might have caused heat waves anyway, but models showed that the high temperatures observed were significantly more likely to occur with human-caused warming than without, i.e., climate change influenced the likelihood of it happening. It should be noted that this is not to say that every heat (or cold) wave is attributable to climate change: each case is unique and depends on its “ingredients” and conditions.
Scientists can evaluate the effect of climate change on a single extreme event
This report is a really big deal, and its novelty lies in the fact that attribution of a single event can now be estimated. If one is able find out whether an event had climate change as a major component, then one can estimate if similar events will be more likely in the future, and plan for risk reduction and adaptation strategies.
The report states that ultimately the goal would be to provide predictive forecasts of extreme events at longer lead times, which would be invaluable for federal disaster risk management efforts, land use and development policies, emergency responders, decision makers and city planners, to name a few.
Understanding the linkage between extreme events and climate change is but one piece of the climate puzzle, one we must deal with because of our past actions. However, while we know that climate is changing and humans are responsible, we also know that there are things that can be done to slow down global warming and reduce the likelihood and intensity of those events made more likely or more extreme by climate change.
Reduction of emissions from burning coal, oil, and natural gas and more investment in renewable and low-carbon energy are at the forefront of actions that should be taken to slow the rate of global warming. The 190+ countries who pledged emissions reductions in the Paris Agreement know that, and their concerted actions will make a big difference in keeping Earth as we know it.
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