Greenhouse gases (GHGs) include carbon dioxide, methane, nitrous oxide and synthetic fluorinated gases. When released into the atmosphere, these gases absorb heat energy, which keeps Earth’s surface and lower atmosphere warm, a phenomenon known as the “greenhouse effect.” As the concentration of these greenhouse gases in the atmosphere increases, more heat radiated from the Earth’s surface is trapped, and the warming effect is enhanced. There is strong scientific evidence that human-induced greenhouse gas emissions are the main cause of climate change. Through atmospheric and ocean warming, these emissions worsen extreme weather events, cause rising sea levels and other environmental changes which threaten people and nature around the world.
In summer 2021, air temperatures in Canada broke records multiple days in a row as a powerful heatwave spread over the Pacific Northwest, registering over 600 heat-related deaths and setting an all-time high-temperature record for the country at 49.6°C (121.3°F).
On 1 September 2021, remnants of Hurricane Ida, the costliest disaster of 2021, brought historic rainfall to New York City, triggering the city’s first-ever flash flood alerts as water flooded streets, subway stations and apartments.
Lagos faces increasingly severe annual flooding, exacerbated by sea level rise and subsidence. In 2021, floods again submerged vehicles and houses, displacing thousands from their homes.
In summer 2021, drought and low humidity combined with record-breaking heat of up to 48.8°C (119.8°F) led to fire outbreaks across the Mediterranean countries, killing more than 100 people and burning more than 620,000 ha of land in July and August
Southern Madagascar’s worst drought in 40 years led to severe stress on vegetation, triggering a drastic decline in rice, maize and cassava production. By December 2021, more than 1.6 million people were estimated to have been suffering high levels of food insecurity.
During the 2020-2021 typhoon season, for the first time in 56 years, no typhoon made landfall on Taiwan, leading to one of the worst droughts in the island’s history. As reservoirs fell below 5% capacity, more than one million households and businesses had to ration water.
From March 2020 to September 2021, a herd of approximately 15 Asian elephants left their home in Xishuangbanna National Nature Reserve. Along their journey, the herd broke into homes, damaged buildings and infrastructure, and destroyed crops, totaling estimated damage of over $1 million.
In 2020 alone, an area of the Amazon forest burnt down that was larger than Fiji. While fire is often a natural process to manage vegetation, 9 out of 10 of the Amazon fires in 2020 were intentionally set to convert tropical rainforest into commercially used land.
In 2020, the Arctic had the second-highest air temperatures and second-lowest area of sea ice coverage on record. Temperatures reached 38.0°C in Verkhoyansk, provisionally the highest known temperature anywhere north of the Arctic Circle.
From October to November 2020, 9 storms in 7 weeks caused widespread flooding in central Viet Nam. As a result, a total of 7.7 million people were affected by the disruption to basic services and 291 people lost their lives.
On 20 May 2020, Super Cyclone Amphan hit the Sundarbans region bordering India and Bangladesh as a Category 5 storm, with wind speeds over 260 km/h, killing over 100 people and displacing over 4.9 million.
Between 2019 and 2021, swarms of desert locusts formed and spread across 23 countries on multiple continents, including Djibouti, Eritrea, Ethiopia and Kenya. They devoured their weight in vegetation every day. One mega-swarm alone, measured in Kenya in 2020, was the size of the country of Luxembourg.
During summer 2020, around 2,300 km of the Great Barrier Reef in Australia was affected by a record mass bleaching event where corals expel their algae and turn white. Over 25% of the Great Barrier Reef suffered severe bleaching, seriously threatening them with extinction.
From 11 to 20 February 2021, a powerful cold wave swept across North America. In Texas, the freezing temperatures killed at least 210 people and caused the power grid to fail, leaving 3.5 million people without electricity and heat.