Picking cherries on climate change

Art Betke's letter in last Friday's Citizen is a classic example of cherry-picking - selecting examples that fit your pre-conceived bias, in his case an anti-climate change bias.

For example, the cold temperatures in Irkutsk, Siberia this winter was used to argue that climate change isn't happening. Siberia is very cold with temperatures often falling past -60 C, so rather than residents being "totally unprepared," the cold temperatures of 2018 were not much out of the ordinary for them. The bigger story is that the Arctic had one of the warmest winters on record with temperatures up to 30 C above normal and with sea ice approaching record lows.

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If you look at temperature records across the planet, the ratio of record highs to record lows since 2000 is nearing 2:1 according to the website www.climatecentral.org. - there are nearly twice as many record highs as record lows. If climate change wasn't happening you would expect about the same number of record lows as record highs. Conclusion: if you don't cherry pick examples, it is clear that the planet is warming overall.

What about "for two years, ocean temperatures have been falling all over the globe?" Short term variations are often exploited by climate change deniers and conspiracy theorists on blogging websites. It's not unusual for temperatures to drop over the short term as the Earth transitions from El Nino to La Nina events. But scientific studies over the long term show that ocean temperatures overall are rising. An April 2018 paper in the scientific journal Climate Dynamics compared three different ocean temperature measurements made by three different research groups and found that all consistently showed an increase in ocean temperature since 1970, despite short-term rises and falls due to El Nino and La Nina events. So, over the long term, ocean temperatures are rising, not falling.

What about fire frequency as an indicator of climate change? This one is trickier because in the past there was no large-scale fire suppression. A study by Zachary Steel and others in 2015 in the scientific journal Ecosphere looked at the fire frequency-severity relationship in California. Their findings: fires are less frequent and higher intensity now than in the past. So Betke is correct that California burned more before Europeans came, but that's not an argument against climate change it's the result of Europeans suppressing fire (to quote Smokey the Bear "Only you can prevent forest fires"). Reputable sources, including NASA, show that wildfires are increasing worldwide due to longer fire seasons caused by earlier snowmelt and more lightning due to hotter summer temperatures.

Mr. Betke states that hurricane frequency and intensity has been declining for decades and tornados are at record lows. I don't know where he got his information, but a credible analysis by the NOAA (https://www.gfdl.noaa.gov/global-warming-and-hurricanes/) shows no decrease in Atlantic hurricanes or their Pacific equivalent, tropical cyclones. Rather it concludes that tropical cyclone intensities and rainfall rates will likely increase due to climate warming, although whether Atlantic hurricanes will do the same is unclear.

As for tornados, low activity is a result of the same phenomenon that gives us Arctic outbreaks in winter. As the Arctic warms, the jet stream weakens, causing Arctic outbreaks as cold extends further south than usual - hence snow in Rome (another example used by Mr. Betke). When the jet stream loops further south in the summer it blocks moisture from moving north, which reduces tornado activity. But the erratic behaviour of the jet stream is itself a result of Arctic warming because it is stabilized by the temperature difference between the Arctic and temperate regions, so low tornado activity is more of an argument for climate change than against it.

Where I don't disagree with Mr. Betke is that altering the course of climate change will be hard and it's unclear if there is the political will to do it. But change to a low carbon economy will happen if people see through the tactics of the climate change deniers and trust the scientists who have devoted their careers to objectively studying this issue.

Do you put more trust in scientists who incorporate all examples and try to decipher the long term trends or bloggers and conspiracy theorists who cherry pick examples and confuse short term variations with long term trends?

No question for me - I'll stand with the hundreds of scientists who produced the IPCC report based upon thousands of published scientific studies. Among scientists there's only a tiny rump of skeptics remaining - the consensus is that climate change is real, it's caused by human activity, and it's happening now.

-- Prof. Keith Egger teaches, supervises graduate students and conducts research in the ecosystem science and management department at UNBC.

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