Real Global Temperature Trend, p24 – Paleoclimate tells we may have 3 degrees additional warming in pipeline at current CO2 concentration!

Either the entire world is set to experience dramatic additional warming once we stabilise at the current (400+ ppm) CO2 concentration – or we are still dramatically underestimating the local climate sensitivity of the Arctic – a region that might in that case not warm 2 or 3 times as fast as the global average, but rather about 6 to 8 times. (Perhaps most likely it’s something in between.)

In any case, it’s bad news that’s being dredged up from the bottom of Lake El’gygytgyn.

Pliocene Arctic climate - 400ppm CO2 - yet 8 degrees warmer!
Continue reading

Real Global Temperature Trend, p23 – Climate sensitivity has large geographical spread: 2-3 degrees global average equals 6+ in the Arctic

Why climate change is such a killer? Because disruption is never a linear process. We see that with ecosystem disintegration – where beyond a certain threshold cascading damage sets in – leading to shifts and collapse scenarios that are easy to succumb to, yet almost impossible to predict.

We also see this with weather extremes. A seemingly innocent shift in the climatic average (precipitation, or temperature – likely both) leads to an ‘unexpectedly’ [unless of course your name is Thomas Bayes or Carl Friedrich Gauss – then this would be intuitive we guess] large increase in the incidence of the old category of weather extremes – and a submerging new category of equally rare but now far extremer weather extremes. These extremes of course are responsible for a lot of the (ecological, agricultural, economical) damage of the (average) change.

Average climate change leads to rapid increase of weather extremes
Continue reading

Real Global Temperature Trend, p22 – World still on course for dramatic 3 degrees warming, need to more than double reduction speed

Let’s keep this one short, because in essence there’s nothing new. Before the start of the Paris climate summit we saw that if you combine all the world’s nations’ 2025 & 2030 emission reduction targets you get to a pathway of around a 860 ppm CO2 equivalent greenhouse gas concentration. By the year 2030 that’s already a 19 gigatonne emissions gap compared to the 2 degrees climate target – and a 25 gigatonne emissions gap compared to the newly adopted 1.5 degrees target.

That is if countries actually deliver on their reduction pledges. During the climate conference there were no increases in national targets – although the world did agree on a higher ambition for the whole: “holding global warming to well below 2 degrees Celsius and to “pursue efforts” to limit it to 1.5 degrees Celsius.”

Well – the below graph sums up where exactly we’re standing:

3 degrees warming
Continue reading

Real Global Temperature Trend, p21 – Science is ruthless. We have ‘about zero’ years of emissions to stay below 1.5 degrees

That is if you correct for one important piece of scientific criticism to the below graph. But even if you prefer to ignore what may seem the nitty gritty of climatology and accept a maximum global carbon budget of 8.9 years one conclusion should resound across our planet: The time of coal is over.* Yesterday. We cannot build any new coal lock-in infrastructure – and we have to shut down all the existing coal plants, and stop all the existing coal transport – both exports and imports.

Continue reading

Real Global Temperature Trend, p20 – Combining thermal inertia & carbon cycle inertia: 1 decade extra warming after emissions stop

Apart of course from the amount of greenhouse gases we keep pumping into the atmosphere, there are mainly three factors that determine the amount of warming we will experience in the near future: CO2 climate sensitivity, ocean thermal inertia, and carbon cycle inertia. Here we try to make better sense of their combination.

Climate inertia atmospheric warming
Continue reading

Real Global Temperature Trend, p19 – There is hot, hotter, hottest – and 2016: dangerously close to pre-industrial +1.5 degrees…

The 19th edition of our global temperature trend series is ‘just a graph’. That is because we are still overwhelmed by Break Free 2016. And because some graphs simply speak for themselves.

The progression of the 2016 hottest year global temperature record does that like no other. It shouts:

2016 hottest year on record - graph
Comparing hottest years. 2014 broke 2010. Then 2015 broke 2014. Then suddenly in early 2016 we almost crossed a line we’re not supposed to cross for the rest of the century.

Continue reading

Real Global Temperature Trend, p18 – Now how high is climate sensitivity? Here’s the answer of the world’s 16 leading climate experts!

If you have any affinity with climate science, this should interest you – probably a lot:

Piers Forster, James Hansen, Gavin Schmidt, Alan Robock, Michael Mann, Ken Caldeira, Stefan Rahmstorf, Chris Forest, Gabriele Hegerl, Hans Joachim Schellnhuber, Jonathan Gregory, Drew Shindell and Andrei Sokolov share their thoughts, and gut feelings, on climate sensitivity.

[Update! Shortly after publishing this piece we've received the answer of three other leading climate sensitivity experts, Mark Zelinka, Trude Storelvmo and Knutti Reto. You can find their thoughts on ECS value in the update at the bottom of this article.]

climate sensitivity estimates
Continue reading

Real Global Temperature Trend, p17 – Climate System Thermal Inertia is lower when you don’t assume CO2 flatline

Oceans, oceans, oceans. You thought the atmosphere was complex? Well, just take a look at the oceans. Oddly shaped features with disturbing cycles and conveyor belt currents. Home of the octopus, the blue whale and a Mariana Trench full of complicated science.

ocean CO2 climate inertia & ocean thermal climate inertia
Continue reading