Since today marks the astronomical start of summer, I thought this would be a good day to share some climate change projections about our summer heat.
And I repeat my promise: I will NEVER report on anything that comes from advocacy groups. It doesn’t matter if it is a conservative or liberal organization: if information comes to me from one, I throw it in the trash. I ONLY report scientific facts that come from climate scientists.
First and foremost, one of the most difficult concepts for people to grasp is what an increase in average temperature really does to our weather. Here in Detroit, our average summer temperature has increased by 3.1 degrees since 1970. That sure doesn’t sound like much. In fact, if you stepped outside on a summer day and I increased or decreased the temperature by that amount, you would barely notice the difference. But a summer’s average temperature is the average over the three month summer period, and that’s the key: a longer term average smooths out individual, daily extremes. What you don’t “see” with a change in a summer’s average temperature statistic is the change in the associated temperature extremes that occur. Take a look at the animation below:
The blues and oranges on the left and right side of this bell curve represent record cold and record heat, respectively. Everything in-between is closer to average. If a planet’s climate isn’t changing, then there will be a roughly equal amount of record heat and cold, which is the beginning of the animation. However, in the case of our warming climate, we see a marked increase in record heat events, and a corresponding decrease in record cold events, which is the end of the animation. Understand that this doesn’t mean that record cold CAN’T happen. It just means that it’s less frequent. I’ve researched this for southeast Michigan, and here are the stats for the past three decades:
1990s: 3-to-1 ratio of record heat to record cold
2000s: 6-to-1 ratio of record heat to record cold
2010s: 4-to-1 ratio of record heat to record cold (and remember that, even with the bitter cold winters of 2013-14 and 2014-15, we are still significantly skewed toward more overall record heat for this decade)
As I mentioned above, our summers here in Detroit have seen a marked increase in average temperature since 1970. As you can see on the graph below, there are indeed ups and downs from year to year…that results from natural variation. However, if you look closely, you’ll see that not only are the hot summers getting warmer, the colder summers are, too.
So, if this warming in our average summer temperature continues, what does this mean for our future? Several years ago, a climate scientist who specializes in regional climate change told me in an interview that, in seventy-five years, a southeast Michigan summer will feel like a southwest Missouri summer does today…and that forecast was using conservative greenhouse gas emission projections. Here’s a more tangible way to look at this: the animation below shows you another climate scientist’s projection of the increase in the number of 100 degree days we’ll see between now and the year 2100.
The increase in extreme heat has repercussions for health, farming, and the energy grid that we rely on to stay cool in the summer. More extreme heat raises the risk of heat-related illnesses, like heat exhaustion, and allows insects to move into new areas, potentially increasing the spread of vector-borne diseases. It stresses crops accustomed to a milder climate, and can worsen drought. Extreme heat is also associated with air stagnation, which traps pollutants and can worsen respiratory illnesses like asthma. The additional heat raises the demand for air conditioning, increasing cooling costs and straining the electric grid. There are many repercussions that result from a warming climate, and many of them will impact us here in southeast Michigan.