It's #FigureFriday, so let's chat about my favorite subject: color palettes 🎨 for climate science visualization! (1/12)

THOUGHT EXPERIMENT: Some 70% of people, depends how you ask, accept the global emergency. Climate system destabilisation is one aspect, declining biodiversity and increasing pollution is another. I ask: what would actually *break* if humanity responded decisively? 1/

Climate: a decisive response = cap on fossil fuel extraction and planned phase out. Fewer private car journeys, less electricity. Nothing would *break*. We still live and eat. There are alternatives and we can all cut back and share more. So what are we afraid of breaking? 2/

Pollution: reducing the above helps all that, cracking down on pollution and biodiversity loss will reduce materials consumption but changing and sharing we can still live on the planet. What would break? 3/

Most pollution and resource consumption is done by rich people. Billions of poor people live and thrive so the rich can too. Nothing will *break* there? 4/

Of course, a rapid reduction in resource consumption, less of most things and enough of the essentials for everyone will *break*something. Economic growth for one thing. But if that broke, what would *break*with it? 5/

Earth has a fever in more ways than one. Some places averaged + 5-7 °C warmer than normal for the ENTIRE YEAR of 2020.

An enormous area of anomalous warmth plagued Arctic Siberia effectively all year but it was not just the Arctic where we saw record shattering warmth.

THREAD

Another way of looking at it... Very few cold blobs left. La Niña developed and shows up in the Pacific.

The climate is not changing uniformly, the Arctic is warming much faster than the rest of the world.

Data: @CopernicusEU and compares to 1981-2010 average.

JANUARY was joint hottest January globally on record according to NASA GISTEMP v4 (joint record with 2016).

Profound winter warmth for North America plus Europe and Asia.

FEBRUARY was second hottest on record (1st place is still held in 2016).

The winter 'warmth' in Europe and Asia was just insane.

MARCH: A cold Canada, Greenland and Svalbard... but obvious warmth still striking across the continents, particularly northern/central Asia.

This was the second hottest March on record (2016 still holds the record).

Thread on very strong inbound CA storm. A cold & clear morning will quickly give way to increasing clouds, NorCal valley rain & snow down to 1,500-2,000 ft (locally lower) later this PM. Current satellite imagery shows this strengthening system off the coast. (1/10) #CAwx

Tonight, a rapidly intensifying cold front will sweep across NorCal. This front will be unusually well defined, for a CA winter storm, and will replace an already cold airmass with...another cold airmass! (2/10) #CAwx

The cold frontal passage is expected to be quite dramatic across NorCal in the overnight hours. A convective "narrow cold frontal rainband" (NCFR) will likely develop, which could bring a period of torrential rain or snow to many areas, as well as possible lightning. (3/10) #CAwx

Extremely heavy precipitation is possible for a 30-60+ minute period when this NCFR feature moves ashore. Over an inch of rain could fall per hour in some spots. This portion of the event poses a high threat of debris flows in/near recently burned areas. (4/10) #CAwx

In addition to torrential rainfall, the cold front/NCFR will be accompanied by very strong wind gusts across much of NorCal. In fact, high-res models are suggesting potential for gusts of 60-70 mph even in lower elevation places. Widespread power outages possible. (5/10) #CAwx

Thread on snow ratios. The snow ratio, or snow-to-liquid ratio states how many inches of snow, when melted, yields one inch of liquid water. Ratios are usually around 10:1 or 12:1, but can vary from as little as 6:1 or as high as 30:1, or sometimes more. 1/

There's a common misunderstanding that the colder the surface temp is, the higher the snow ratio will be (fluffier snow). This is incorrect. As long is the surface temp is not close to freezing, it really doesn't matter all that much. 2/

As the surface temp gets close to or exceeds freezing, more snow is lost to melting, yielding lower ratios and heavy, wet snow. The same reasoning also applies to temps above the ground; if they exceed freezing, sleet or rain can mix with the snow, dramatically lowering ratios 3/

Much more important is the dendritic growth zone (DGZ), the layer of the atmosphere with temperatures between -12 and -18C. In this layer, snowflakes grow as dendrites, which can easily clump together into aggregates, which contain a lot of air, increasing the ratio 4/

At warmer or colder temps, the flakes grow as plates, columns, or needles, which don't clump together as well and contain less air, lowering the ratio. To make this even more complicated, there's also a dependence on atmospheric humidity. 5/