The recent heat wave and subsequent fires have provided a opportunity to remind climate change deniers that it’s real.
The incineration of Lytton has captured global attention. And rightly so: the event was of biblical proportions. Record high temperatures were recorded day after day until the village exploded like a matchstick.
Lytton provided an opportunity for climate change activists to say: “see, I told you so.” Swedish climate activist Greta Thunberg made her point:
“Heat records are usually broken by tenths of a degree, not 4.6 C,” said Thunberg in reference to Lytton. “We’re in a climate emergency that has never once been treated as an emergency.”
Don’t get me wrong. There is no mistaking that climate change is real. Extreme weather is real. And evidence of the connection between them is growing. But in scientific terms it’s just an association not yet a proven fact.
Scientists are a skeptical bunch and are careful to establish cause and effect.
The acknowledged authority on the study of climate change is the Intergovernmental Panel on Climate Change (IPCC). It was established by the United Nations body for assessing the science related to climate change.
The IPCC explains the difficulty in establishing causality:
“An integral feature of IPCC reports is the communication of the strength of and uncertainties in scientific understanding underlying assessment findings. Uncertainty can result from a wide range of sources. Uncertainties in the past and present are the result of limitations of available measurements, especially for rare events, and the challenges of evaluating causation in complex or multi-component processes that can span physical, biological and human systems.”
A key finding of the last report from the IPCC is: “Human influence on the climate system is clear, and recent anthropogenic emissions of greenhouse gases are the highest in history. Recent climate changes have had widespread impacts on human and natural systems.”
IPCC concludes that it’s “extremely likely” that humans have caused global warming.
What’s less certain is whether the blocking pattern that held the “heat dome” in place over Western Canada is caused by climate change. It probably it is.
The blocking pattern is a feature of a stationary jet stream; that’s the dividing line between cooler temperatures to the north and warmer temperatures to the south. When the jet stream gets stuck, so do weather patterns and weather changes get blocked.
The likely reason that the jet stream gets stuck is because temperatures on the north side, in the arctic, are warming faster than the south. The difference in temperature is what drives changes in the jet stream.
In the winter of 2014, the same blocking patterns resulted in a “Polar Vortex” that led to one of the coldest winters on record for most of eastern North America.
Yet, even though both the heat dome of Western Canada and the Polar Vortex of Eastern Canada were caused by the same blocking patterns, no one blamed climate change then.
It seems like the cries of “climate change” are selective and depend on the weather.