Somewhere on a Hollywood movie set for Groundhog Day, Part Two: Bill Murray wakes up to find he’s just lived through the hottest decade on record, just as he did in the 2000s, just as he did in the 1990s, just as he did in the 1980s. And he keeps waking up in the hottest decade on record, until he gains the kind of maturity and wisdom that can only come from doing the same thing over and over and over again with no change in the result. Ah, if only life were like a movie.
Here is global mean surface temperature — by decade:
Of course, this decade is far from over, and the decadal average temperature is all but certain to be much higher than the average of the years 2010 through 2015 — which is to say, much closer to the dashed line representing the record-smashing 2015.
After all, 2016 is already expected to be at least as warm as 2015 — and very possibly warmer. Indeed, the UK’s Met Office released a detailed projection last month that concluded, “During the five-year period 2016-2020, global average temperature is expected to remain high.” Their likeliest projection is for the average temperature of those five years to exceed the 2015 record!
This speed up in warming has been expected. A 2015 Pacific Northwest National Laboratory (PNNL) study, “Near-term acceleration in the rate of temperature change,” predicted that the rate of climate change will soar by the 2020s, and human-caused warming will move the Earth’s climate system “into a regime in terms of multi-decadal rates of change that are unprecedented for at least the past 1,000 years.”
In PNNL’s best-case scenario, CO2 concentrations in the air stabilize at about 525 parts per million — the RCP4.5 scenario, which requires humanity to go far beyond the climate pledges made in Paris. In this scenario, the four-decade warming trend hits 0.45°F (0.25°C) per decade. That means over a four-decade period, the Earth would warm 1.8°F (4 x 0.45) or 1°C (4 x 0.25). This is a faster multi-decadal rate than the Earth has seen in at least a millennium.
Because of Arctic amplification, the most northern latitudes warm two times faster (or more) than the globe as a whole does. PNNL projects that, in this best-case scenario, the rate of Arctic warming would quickly exceed 1.0°F (0.55°C) per decade, which would worsen:
- Greenland ice sheet loss and sea level rise
- Arctic sea ice loss and extreme weather
- Permafrost melt and amplified greenhouse gas emissions (which could add up to 1.5°F to total global warming by 2100).
Somewhere in Pennsylvania: Punxsutawney Phil saw the shadow of unrestricted fossil-fuel pollution from Homo “sapiens” today. That means global warming for another six thousand weeks — and then some (see NOAA: Climate change “largely irreversible for 1000 years”).
If the world keeps listening to the siren song of delay from the anti-science, pro-pollution crowd and their enablers, then eventually people aren’t going to go through this elaborate charade of wondering whether some large rodent in Pennsylvania can predict the weather. The forecast will always be the same: “bloody hot.” In PNNL’s worst-case scenario — where we keep taking little action to reduce carbon pollution (the RCP8.5 scenario) — the rate of warming post-2050 becomes so fast that it is likely to be beyond adaptation for most species, including marmota monax and homo “sapiens” in large parts of the world. The mean global warming rate in this scenario hits a stunning 1°F per decade, and Arctic warming would presumably be at least 2°F per decade. And this goes on for decades.
If we get anywhere near that outcome, I seriously doubt anybody is going to care about what Punxsutawney Phil thinks about whether it’s going to be an early spring or not.