🎉To celebrate that we just released SpeedyWeather.jl v0.4, a 🧵about global grids 🌐 that are used in spectral models, Gaussian grids, octahedral grids etc: If you wonder how we deal with the pole problem, or what we could adopt from astronomy read on ... github.com/milankl/Speedy… Last thing first, SpeedyWeather.jl now support HEALPix grids, which have been invented for astronomy, are true equal-area, tesselate the sphere into N squares which allow nesting and arer easily Fourier and Legendre-transformable. What that all means? Let's start at the beginning

Flying✈️contributed 4% to #globalwarming, and back-to-normal after COVID means 6-17% in 2050. Why aviation's CO₂ footprint is only ½ the story, COVID's impact, and how to fly net zero. We quantify aviation's contribution, preprint doi.org/10.1002/essoar… summary thread🧵here 1/n Okay, how do all the aircraft emissions impact the climate? Burning 1bn litres of jet fuel/day emits CO₂, but also water vapour H₂O, nitrogen oxides NOₓ & soot, which interact with methane and ozone in the atmosphere and forms contrails☁️🛫 In total there's a net warming: 2/n

Right now 28,000 scientists are at the #AGU19 conference in San Francisco:How far do they fly to SF&back? 285million km=1.9x Earth-Sun=🌎🛫🌞🛬🌎.That's a big carbon footprint.Why we can't decarbonise @theAGU without virtual participation?White paper: github.com/milankl/Carbon… 1/5 How big is big? The travel carbon footprint of 24,000 presenters at #AGU19 is 69,300tCO2e, 2.9tCO2e per scientist. Why? Despite 63% of attendees are from North America, intercontinental flights are 75% of total emissions: Scientists commuting between NA, East Asia and Europe. 2/5