Where to start? No, the rate of global sea-level rise 70 years ago was not "as large as what we observe today", at least in 4 out of 5 available reconstructions: carbonbrief.org/explainer-how-…
Yes, the the number of significant tornadoes hasn’t changed much at all, but scientists never claimed that they would (and our models generally can't resolve small-scale events like tornadoes): carbonbrief.org/tornadoes-and-…
Yes, the hottest summer temperatures in the US likely occurred in the 1930s/1940s. But there is a lot more variability in 2% of the planet in one season (Summer) than for global average temps. And what was a localized event then is a global event now:
No, scientists in fact can "untangle" natural phenomena from human influence. There are not large "deficiencies of climate data". The data suggests that effectively all the warming we have experienced is due to human activity:
No, the idea that we could stop climate change is not "delusional". Despite the fact that CO2 lasts in the atmosphere for centuries, once we reach net-zero warming will stop: carbonbrief.org/explainer-will…
Yes, people in poor countries need more energy, and some will come from fossil fuels (though ideally not coal) in the short-term. But thats not a meaningful contributor to climate change, relative to the emissions of middle income and rich countries: nature.com/articles/d4158…
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I missed quite the climate twitter drama, being offline over the weekend.
I'll just say that while I disagree that ~ half of emissions reductions need to come from tech that we don’t yet have, theres a case to be made that > 50% needs to come from tech that is not mature today.
Debates around mitigation are often framed as a choice between mature technologies today and future innovations. In reality we need to do both; to deploy what is cost-effective today, and to invest in range of solutions needed to tackle hard-to-decarbonize parts of economy.
I suppose a lot of the debate about Kerry's statement comes down to how you interpret "technologies that we don’t yet have". It doesn't help that the Guardian changed that to "technologies that have not yet been invented"...
There is some truth to criticism of Smil's pessimism around energy transitions. The past is an important guide, but at the same time we have not previously had exogenous pressures like climate to force transitions. Where I disagree with @mbarnardca's take is on Gate's investments
Solar and wind are huge success stories today, and will be the largest drivers of decarbonization for the next few decades. But theres a growing view among energy models that 100% WWS systems – as Jacobson proposes – are much more costly than mixed ones. thebreakthrough.org/issues/energy/…
We should be ecumenical about future energy tech, and on any particular technology to fill in the remaining gaps. For that reason I think its great if billionaires throw lots of money at speculative technologies that might not pan out, vs say improving solar efficiency by 2%.
First, there are a lot of places where Tim and I agree. We agree on the need to replace fossil fuels with clean energy, and to get emissions down to zero. We agree GDP is a poor proxy for human wellbeing, and that modern economies have huge problems with inequality. 2/
Where we differ is on whether technology allows us to "decouple" economic activity from its environmental impact. 3/
Skepticism is the heart of science, but needs to be informed skepticism. We shouldn't blindly follow experts, but should acknowledge our own biases and preconceptions when encountering new evidence.
This video by @neilhalloran strikes a perfect balance:
Also the data visualization is simply gorgeous. I'm more than a little professionally jealous!
I will make one criticism: the warming scenario he labels "current course that assumes we make no new efforts to reduce emissions" is not, in fact that. It was designed as the 90th percentile of possible outcomes in a world with no new policies after 2005. nature.com/articles/d4158…
Much of the confusion around committed warming comes from a conflation of two different scenarios: one where atmospheric CO2 is held at constant levels (say, ~414 ppm today), and one where all our emissions go to zero. 2/
Until the mid-2000s, many climate models were unable to test the impact of emissions reaching zero. This is because they did not include biogeochemical cycles – such as the carbon cycle – and could not effectively translate emissions of CO2 into atmospheric CO2 concentrations. 3/
Last week the folks at @SwissRe released a report suggesting global losses of up to 14% of global GDP by 2050 due to warming expected in a current policy world.
First, credit where credit is due. The report focused on the RCP4.5 scenario in line with current policy projections from folks like @climateactiontr rather than the increasingly implausible RCP8.5 pathway: 2/
However, they then suggest that 2050 temperature outcomes under RCP4.5 would likely be 2C (50th percentile) to 2.6C (95th percentile) based on climate models used in the IPCC 5th Assessment Report. Its here that the problem arises. 3/