We’ve learned the saw-toothed pattern of carbon dioxide levels over the past 1 million years. It has shot swiftly up during climbs to past warm intervals like the climate of today and ramped slowly down into the long ice ages in between. We can also see the sharp recent increase in carbon dioxide that humans have caused, mainly by burning fossil fuels for energy. The graph used to show this jump is arguably the most iconic figure in climate science.   To me, it’s long been the most powerful illustration of climate change’s danger. At a glance, it shows how huge a departure we’ve made from normal.  - Washington Post 

The climate crisis continued unabated in 2020, with the joint highest global temperatures on record, alarming heat and record wildfires in the Arctic, and a record 29 tropical storms in the Atlantic. Despite a 7% fall in fossil fuel burning due to coronavirus lockdowns, heat-trapping carbon dioxide continued to build up in the atmosphere, also setting a new record. The average surface temperature across the planet in 2020 was 1.25C higher than in the pre-industrial period of 1850-1900, dangerously close to the 1.5C target set by the world’s nations to avoid the worst impacts. - Guardian

Forty years of satellite data show that 2020 was just the latest in a decades-long decline of Arctic sea ice. In a review of scientific literature, polar scientists Julienne Stroeve and Dirk Notz outlined some of these changes: In addition to shrinking ice cover, melting seasons are getting longer and sea ice is losing its longevity.  The longer melting seasons are the result of increasingly earlier starts to spring melting and ever-later starts to freeze-up in autumn. The map above shows trends in the onset of freeze-up from 1979 through 2019. Averaged across the entire Arctic Ocean, freeze-up is happening about a week later per decade. That equates to nearly one month later since the start of the satellite record in 1979. - Earth Observatory / NASA