The year 2021 in Science
The year 2021 (and mostly 2020) was dominated by Covid-19 and climate change. Here is a compilation of some of the highlights in science of 2021.

Jan 2021:
. Chinese scientists have established the world's first integrated quantum communication network. It connects two ground-to-satellite links to 4,600 kilometers of optical fibres.
. Global ice loss is found to be accelerating at a record rate in a scientific review, matching the worst-case scenarios of the IPCC.

Feb 2021: 
. COVID-19 pandemic: Russia's Sputnik V vaccine is shown to be 92% effective against COVID-19.
. The Chinese Tianwen-1 spacecraft successfully enters orbit around Mars. Its lander Zhurong (seen with its platform) landed on Mars in May.

March
. The Event Horizon Telescope presents the first polarized-based image of a massive black hole, at the center of Messier 87, revealing the forces giving rise to quasars.

April 
. NASA's Mars 2020 mission (containing the Perseverance rover and Ingenuity helicopter drone) lands on Mars at Jezero Crater in March. Ingenuity performs the first powered aircraft flight on another planet in history.
. A malaria vaccine with 77% efficacy after 1 year – and first to meet the WHO's goal of 75% efficacy – is reported by the University of Oxford.

May 
. Google demonstrates a research project called LaMDA, an automatic language generation system designed to sustain a conversation with a person on any topic.
. Google and Harvard University made an amazing colour-coded 3D map of nearly 4,000 incoming axons connecting to a single neuron in the human brain. The 1 mm³ sized map is the most detailed map ever of the brain.

June
. Toshiba achieves quantum communications over optical fibres exceeding 600 km in length, a new world record distance.

. Researchers report the development of a plant proteins-based biodegradable packaging material. It can be an alternative to plastic but it can be as strong as high-strength spider silk.

July
. The SARS-CoV-2 Delta variant, first discovered in India in late 2020, is found to cause a ~108 % increased – or more than twice as large – risk for hospitalization, a ~234 % increase for ICU admission and 132% for death compared to other variants of Covid-19. It triggers several waves of the pandemic across the world, including in India.
. The first direct observation of light from behind a black hole is reported, further confirming Einstein's theory of general relativity.

August
. The Intergovernmental Panel on Climate Change (IPCC) reports (in its Sixth Assessment Report) that effects of human-caused climate change are now "widespread, rapid, and intensifying".

. Probiotics can help coral reefs mitigate heat stress. It could help them overcome coral bleaching due to climate change.
. Nationwide data of Israel's vaccination programme finds that immunity from the Pfizer-BioNTech COVID-19 vaccine decrease significantly after 6 months. So the protection from vaccines is not long-lasting.

September
. In Japan the first CRISPR-edited (genetically edited) food has gone on public sale. Tomatoes were genetically modified so they contain about five times the normal amount of possibly GABA, a neurotransmitter that calms you down.

October
. 98% of DNA does not code for proteins and is considered "junk". Scientists show experimentally that differences between humans and chimpanzees are also substantially caused by this so-called "junk" DNA.
. A study shows for the first time how immunity is inherited, via epigenetic (via behaviour and environment) changes, in mammals

November
. A study reports the second case of a person whose immune system apparently cleared HIV (virus that causes AIDS) on its own without treatment.
. The World Health Organisation (WHO) announces the classification of the Omicron variant as a SARS-CoV-2 variant of concern (schematic shows how different it is from other variants).

December
. Scientists studying the huge Thwaites Glacier in West Antarctica report evidence that it could "shatter like a car windscreen" within five to ten years. This would add about 65 cm to global sea levels.