Thursday, January 11, 2024

The Hills Are A-Changin’: Tracking our Hotter and Wetter Weather

Here's a two-part series that I wrote for the Low Down newspaper - my local community paper in the Gatineau Hills. Republished here with supporting visuals:

The Hills Are A-Changin’: Tracking our Hotter and Wetter Weather (Part 1)

By Ryan Katz-Rosene, October 23rd, 2023

September 2023 was a stunner for climate change scientists. The average global temperature that month was 1.8°C warmer than the typical September of the pre-industrial era, completely shattering the record which had only been set earlier this summer, in July. 1.8°C may not sound like a lot, but consider that the Earth’s average temperature during the last ice age – when most of North America was covered in a sheet of ice – was only about 5°C cooler than the pre-industrial era.

Unsurprisingly, September was warm here in the Hills too, with the average monthly temperature clocking in at 2.59°C warmer than the typical September from the mid-Twentieth Century (using a 1951-1980 baseline). But it wasn’t our warmest September ever. Remarkably, September 1961 holds the record for that month here in La Pêche (at least going back to 1940, at 3.68°C warmer than the 1951-1980 baseline). 

You’ll note two important things from the above: First, localized temperature patterns are far more variable than global temperature trends. As Dr. Saravanan, Professor of Atmospheric Sciences at Texas A&M University, told me, one does need to be “very cautious in interpreting local trends, which include both human-induced warming and natural variability,” with the latter being “much stronger locally”. Second, warming here has actually been much greater on average than the global mean warming. Globally, the world has warmed on average about 1.3°C (even though this year specifically will likely surpass 1.5°C) since the pre-industrial era, but much of Canada has already warmed by 2-3°C on average (this is because land and extreme latitudes have warmed at a greater pace than the vast oceans covering Earth).

If we chart the annual average temperature change observed here in the Gatineau Hills (specifically here in La Pêche), we can see a clear trend of warming since the 1940s. The early 1950s were surprisingly warm here, and the region saw cooler temperatures through much of the 1960s and 1970s. We then saw some rather large temperature swings, with hot years bringing up the running 10-year average up by about +0.8°C relative to the 1951-1980 baseline. While in global terms 2023 is on track to be the warmest year on record, the jury is still out on whether that will also be the case locally – but the current record warm 1998 (a super El Niño year which was 2.25°C warmer than baseline locally) will be hard to beat.

The temperature changes are more pronounced when you break them up by season. Here in the hills our winters have seen greater warming than other seasons. The typical winter of the last decade was about 1.4°C warmer than the typical winter of the 1951-1980 baseline. A few anomalously warm summers in the 1940s and 50s, and warm autumns in the 1940s drove up the decadal averages earlier in this series for those seasons, but make no mistake – the clear trend is one of warming since 1940 (even though the linear trend for fall is mostly flat over the last 80 years).

What kind of warming is coming down the pike? That’s for another piece. But it is interesting to note that the world is currently transitioning from a ‘triple dip la Niña’ to at least a moderate-strength el Niño, and the last few times that’s happened have tended to be record warm in global terms. What happens here in the Hills may differ: The Weather Network is reporting that this could become a “Modoki El Niño” which starts off warm across the country but then could see bursts of intense cold here in the Eastern half of the country over the winter. Only time will tell!

Tracking our Hotter and Wetter Weather (Part 2)

By Ryan Katz-Rosene, November 24, 2023

One of the most reassuring – yet simultaneously daunting – things about climate change is this: Global warming will stop when human activities stop emitting Carbon Dioxide (CO2). There are of course a few caveats, the most important of which is that anthropogenic emissions of other greenhouse gases (like Methane and Nitrous Oxide) will also need to be reduced significantly (though not to zero, as CO2 needs to). It won’t stop overnight, but as world-renowned climate scientist Zeke Hausfather from UC Berkeley has written “warming is likely to more or less stop once CO2 emissions reach zero”.
This factoid is partly reassuring because it tells us that we humans are largely the authors of our own fate when it comes to climate change. The best available science tells us there is no significant additional warming “baked in” once we reach that zero emissions target. The daunting part is that the objective of zero CO2 emissions still seems very far away. It is not even clear that global CO2 emissions have peaked yet. What’s more, any additional CO2 we emit between now and reaching ‘Net Zero’ will only continue to drive up Earth’s average temperature. 

Our future climate here in the Hills, in turn, is closely tied to how successful the world at large is in reducing GHG emissions. To help model the potential futures that await us, the Intergovernmental Panel on Climate Change has created five core ‘scenarios’ for future global warming – called ‘Shared Socioeconomic Pathways’ (SSPs1 through SSP5). These scenarios – based on a range of different assumptions about social, political, and economic progress are then cross-referenced with a range of different End-of-Century scenarios for how much additional energy there could be in the Earth System. These latter energy balance scenarios are called ‘Representative Concentration Pathways’ (RCPs). 
Generally-speaking, the lower the SSP and RCP numbers, the more favourable our future is. For instance, “SSP1-1.9” (i.e. a socio-economic scenario 1, featuring high levels of cooperation and socio-economic development, combined with a lower future energy balance of 1.9 Watts per square meter) is one of the ‘best-case scenarios’, wherein we would limit global warming to about +1.4°C by 2100 (relative to an 1850-1900 baseline). In contrast, the dreaded ‘SSP5-8.5’ is a ‘worst-case scenario’, in which the world warms by +4.4°C by end of the Century on average. Unfortunately, the ‘best-case scenario’ is almost impossible to achieve now – in fact, many climate scientists now say it’s too late to limit global warming to +1.5°C. And luckily, the worst-case scenario is also considered to be rather unlikely by climate scientists. At present, the world is on track for about +2.8°C of warming by end of Century when policies in place are modelled. If we factor in additional pledges, it gets down to +2°C of warming. We can technically limit global warming to +2°C or even below, but major political breakthroughs would be required, and we are in a race against time.

As Part 1 of this series hinted, warming here in the hills is largely determined by the extent of warming globally. The average annual temperature here (in the Wakefield area) over the last 30 years is about 6.1°C. This already represents a warmer climate than mid-Century (1940-1970), when the average annual temperature here was 5.5°C (i.e. we’ve seen +0.6°C over the last 7 decades). If we model different climate scenarios into the future, we can see just how much our climate is expected to warm further. Under a more favourable global scenario – say, SSP1-2.6 – then here in the Hills we can expect the average annual temperature to be around 7.7°C by late Century (2070-2100). However, in a worst-case scenario (SSP5-8.5) it would be 10.9°C. Yikes indeed! If I were a betting man, I’d say we will likely end up somewhere between the two, perhaps tracking closer to SSP2-4.5, in which case the average annual temperature here by end of Century would be 8.9°C. But boy oh boy do I hope I’m wrong! That would mean our regional climate is +3.4°C warmer on average than our mid-20th Century climate. As I’ll explain in my next post, the impacts associated with that level of warming could significantly change life as we know it here in the hills.

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