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Why was 2023 the warmest year on record globally?

The Copernicus Climate Change Service confirms 2023 as the hottest year globally, overtaking 2016 – the previous warmest year – by a large margin. 

Last year there were 7 months that all had new global temperature records set. June through to December were warmer than the corresponding months in any previous year, in records going back to 1850. 

The Met Office also confirms 2023 to be the second-hottest year on record for the UK. 2022 holds the current record, and only by 0.06°C. 

A new stripe for 2023 has also been added to the Warming Stripes, the colourful graphic that represents a visual timeline of our changing climate – designed by Professor Ed Hawkins. 

Professor Hawkins, who is a climate scientist at the National Centre for Atmospheric Science and University of Reading, explains how 2023 was “off the end of the scale”: 

“This was always going to happen at some point, given the continued increase in global greenhouse gases, and is in line with what scientists have been predicting for decades. But the margin of record-breaking in 2023 has still been a surprise. The stripes are all about starting conversations about climate change, and 2024 has to be the year we turn conversations into faster action.”

How are greenhouse gas emissions and El Niño causing increased global warming?

The temperature records set in 2023 are thought to be driven primarily by human-caused climate change

The dramatic rise in global temperatures is driven by human emissions of greenhouse gases into the atmosphere, due to ongoing fossil fuel burning that began in the 1800s during the Industrial Revolution.

In 2023, atmospheric concentrations of the greenhouse gases carbon dioxide and methane continued to increase. Carbon dioxide and methane reached record levels in 2023, at 419 ppm and 1902 ppb respectively. Carbon dioxide concentrations in 2023 were 2.4 ppm higher than in 2022, and methane concentrations increased by 11 ppb.

Scientists are also investigating the role of regional climate and weather, ocean circulation, and El Niño.

El Niño is an irregular climate pattern occurring every 2-7 years, which causes warming of surface and subsurface waters in the eastern and central tropical Pacific Ocean. In turn this warming affects atmospheric circulation and influences global climate, meaning El Niño can warm the planet significantly (up to about 0.2°C averaged over a given year). 

Based on the latest National Oceanic and Atmospheric Administration forecasts, there is now a 54% chance of a “historically strong” El Niño during the November to January season – which could bring it into the top 5 El Niño events since 1950. Stronger El Niño events can increase the likelihood of El Niño-related warming of the planet. 

Climate change causes the background temperature of the planet to be warmer, meaning periods of hot weather are likely to be more frequent and more intense. Alongside a strong El Niño, climate change is leading to unparalleled temperatures being recorded. 

Does the 2023 warmest year record mean the Paris Agreement threshold is close?

The Paris Agreement has set a goal of holding the increase in global average temperature to well below 2°C above pre-industrial levels – and to aim for 1.5°C. 

According to the Copernicus Climate Change Service, from January to November the global mean temperature for 2023 is the highest on record at 1.46°C above the 1850-1900 pre-industrial average.

This starkly illustrates the global temperature extremes in 2023, but should not be misinterpreted to mean the Paris Agreement has been breached. 

Breaking the 1.5°C – 2°C global warming threshold refers to long-term annual average global surface temperatures, not individual months.

Assuming that no drastic greenhouse gas emission reductions are implemented in the coming years, the planet is expected to overshoot 1.5°C global warming in the mid-2030s – in around 12 years from now. 

It is widely anticipated by climate scientists and the United Nations’ Intergovernmental Panel on Climate Change that breaching the 1.5°C threshold will mean much more severe climate and weather extremes and large-scale damaging impacts. 

What do rising temperatures mean for our planet?

Rising temperatures are causing serious changes to our climate, with consequences for food security, water resources, health and biodiversity.

Extreme weather is also becoming more frequent and is a major threat to lives, livelihoods and infrastructure. 

Floods, droughts, and forest fires have become more common over the last few decades. 

2023 saw wildfires across Europe, Canada and Hawaii, typhoons and floods in East Asia, and droughts in Spain.

Will 2024 see new temperature records set? 

It is anticipated that 2024 will see more global temperature records broken, especially as El Niño is expected to continue through the first few months of the year.  

The World Meteorological Organization advises that the ongoing El Niño could influence weather patterns, contribute to a further spike in temperatures both on land and in the ocean, and exacerbate extreme weather events like heatwaves, floods, and droughts. 

The Copernicus Climate Change Service has also stated that the 12-month period ending in January or February 2024 is likely to exceed 1.5°C above the pre-industrial level.