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It was a scorching June, and it’s been a wet July so far. Is this more evidence of climate change?

A man walked past a Beyond Walls collaborative mural by artists Yu-baba and Key Detail called “Under the water”.Jessica Rinaldi/Globe Staff

This has been a pretty wild meteorological summer so far, with the hottest June on record and now one of the wettest Julys.

There’s been at least a trace of rain every day this month, with over 8.89 inches total in Boston. In addition to the rain, it’s been very muggy, and there’s a lot more humidity on the way this week. Although I don’t see any heat waves in the foreseeable future, the higher humidity is going to dominate.

This much rain in the first half of July has been unprecedented in our record-keeping since 1872. With over two weeks left in July, even if it never rained again this month we would still end up as the third-wettest July on record.


It was a little dry this spring compared to the average, but we have more than made up for any deficit. The ground is so saturated that it won’t dry out until we have an extended amount of low humidity days without any rain. The massive foliage growth alone is preventing a lot of evaporation, plus there’s been little sunshine. Mold, mildew, and other fungus are definitely going to start to be a problem if it isn’t already, and we may have the added challenge of mosquito explosions as we head into Eastern Equine Encephalitis season.

So what’s going on? Is this more evidence of a changing climate?

It seems the term “climate change” gets thrown around a lot and is applied to all sorts of seemingly weird weather, but abnormal weather has occurred for millennia. So what should we think?

One of the factors is that humans want to categorize everything and somehow make meaning in it. It’s more comfortable if we understand the reason behind something unusual happening. Some people want to use abnormal heat as proof of climate change while others say that very hot weather has been occurring for years, so there isn’t any climate change in the first place. Both of those trains of thought still use deductive reasoning, even if not accurate.


I like to look at the data as well as the global climate models to observe how what’s happening now fits into the bigger picture. The weather this summer is due to the jet stream, but it’s all happening with climate change in the background. In other words, weather can slowly shift along with the climate. First, it is indisputable that humans are adding carbon dioxide to the atmosphere at a very rapid rate.

The amount of overall CO2 in the atmosphere has been steadily climbing for decades, a result of the anthropogenic contribution of fossil fuel consumption.NOAA

We also know global temperatures are warming. Even in a warming atmosphere there can be cold months or a cold year, but they don’t negate the trend. It’s no different than the fact that the stock market or value of a home will go up over time, but no one expects those values to not go down occasionally. It’s the slope of the curve that’s important, not the shorter term fluctuations.

Warmer air moves faster and has more space between molecules. It is in this space that water vapor can fit. The hotter the air, the more room for moisture. Moist air holds the heat of the day and can’t cool off as fast, which is why our nights are getting warm so quickly, too.

The curve of typical low temperatures during the year has shifted warmer since the turn of the 21st century by about 2 degrees.NOAA Data

Let’s connect our recent rain with climate change. Computer models of the future atmosphere all point towards it becoming warmer and wetter in this part of the world. There are still questions about how much warmer and wetter it will become in the future, but when you look at all the information and trends, the direction we are headed is clear.


According to the State Hazard Mitigation and Climate Adaptation Plan prepared for the Massachusetts Emergency Management Agency, there will be more heavy precipitation events.Resilient MA
The report predicts there will be more overall precipitation in the coming decades.Resilient MA

The recent rains themselves are not climate change, but most models point to a higher probability of wet events in future decades. Perhaps without humans’ super-charging climate variability this month’s rain would be somewhat less, the humidity not quite as intense, or the June heat not so prolonged.

Those who might still be skeptical and point out that the climate has been changing for millennia or it was really cold in a particular month should realize that type of reasoning isn’t scientific. Humans have been getting taller for decades, but we don’t point to someone who is below-average height as evidence that it’s not happening.

Lastly, just ask yourself a simple question: Why would anyone think that spewing billions of metric tons of carbon dioxide for decades into the atmosphere wouldn’t be doing something? And that something can’t be good.

Global temperatures continue to steadily rise as a result of human induced CO2 putting additional pressure on natural variability.NOAA