The WMO's statistical temperature gamble

We are going to be fed a regular diet of global temperature reports in the run-up to the COP26 climate talks later this year. They’re all going to be based on model projections of what’s likely to happen in coming years. The Paris Agreement's 1.5 °C climate target is in focus, but whether it be exceeded and when remains uncertain.

2021 so far is comparatively cool, roughly the same as in 2014. Source Clive Best blog

The latest report from the World Meteorological Organisation says that over the next five years at least one of them will exceed that limit with a 90% certainty dislodging 2016 as the world’s warmest year, “these are more than statistics,” says WMO Secretary-General Prof. Petteri Taalas. “Increasing temperatures mean more melting ice, higher sea levels, more heatwaves and other extreme weather, and greater impacts on food security, health, the environment and sustainable development,” he says. His claims are the habitual alarmist mantra in contrast to empirical observations.

Taalas adds that 2020 was among the top three warmest years despite being influenced by the cooling La Nina effect. It’s a pity he didn’t also mention that the warmest year on record, 2016, attained its position because of a very intense El Nino warming effect. It is noteworthy that any annual rise in global temperature is blamed on climate change while any fall in temperature is regarded as natural variability.

The report is part of the “Annual to Decade Climate Update.” This is an interesting period since the definition of 'climate' is taken to be a 30-year average, but then an “Annual to Decade Weather forecast,” wouldn’t convey the same urgency.

So far 2021 is a very cool year with global temperatures similar to those seen fifteen years ago when they were meandering nowhere - until influenced by the 2007 and 2015 El Ninos. I suspect that if 2021 continues to be a comparatively cool year it will be rarely mentioned in the run up to COP26. But if the WMO’s models are right then we can expect a large increase in global temperature after the current La Nina conditions even if there is not an El Nino.

The obvious conclusion to be drawn is that annual temperature changes are, to the first order, modified by the lead up to and the aftermath of El Ninos and La Ninas which dominate the long-term trend of greenhouse gas forcing. We have been waiting for years for the warming trend to overwhelm these ocean cycles. Having one year reaching 1.5 °C doesn’t do that.

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