The year 2023 was one of the hottest and most extreme in human history. It witnessed record-breaking heat waves, devastating storms and floods, deepening droughts and raging wildfires across the globe. These events showed how climate change is affecting the global water cycle and our livelihoods.
Our international team of researchers today released a report, the Global Water Monitor, documenting the impact of the record heat in 2023 on the water cycle. We used data from thousands of ground stations and satellites to provide real-time information on various environmental parameters. The report summarises conditions and events in 2023 and long-term trends.
Heat is drying out the world
The most obvious sign of the climate crisis is the unprecedented heat waves that swept the globe in 2023. Earth’s hottest year on record gave us a glimpse of what a typical year with 1.5 C of warming may look like.
Global warming consistently more than 1.5 C above pre-industrial levels is expected to have extreme and irreversible impacts on the Earth system.
Some 77 countries experienced their highest average annual temperature in at least 45 years. Temperature records were shattered from Canada to Brazil, Spain to Thailand.
The high temperatures were often accompanied by very low air humidity. The relative air humidity of the global land surface was the second-driest on record in 2023.
Rapid drying of farms and forests caused crops to fail and forests to burn. Lack of rain and soaring temperatures intensified multi-year droughts in vulnerable regions such as South America, the Horn of Africa and the Mediterranean.
The past two decades have significantly increased air temperatures and reduced air humidity. This continuing trend toward drier conditions is threatening agriculture, biodiversity and overall water security. These conditions heighten heat stress and increase the water needs of people, crops and ecosystems.
Scorching conditions inflicted extensive damage on the world’s largest forests. Massive wildfires ravaged Canada during the northern summer. Later in the year, the Amazon rainforest and rivers descended into severe drought.
The world’s forests have been soaking up a lot of our fossil fuel emissions. That’s because plant photosynthesis absorbs carbon dioxide from the atmosphere. Large disturbances like fire and drought reduce or even reverse that function.
Water cycle changes fuel intense storms
A change in circulation and sea temperatures in the Pacific Ocean to El Niño conditions influenced the global water cycle in 2023.
El Niño events occur when warm water shifts eastward along the equator, affecting weather patterns around the world. They can cause more rainfall in some areas, but also more droughts elsewhere.
In 2023, El Niño reached its strongest level since records began in 1950. This resulted in more frequent and intense storms across Asia, Australia, North America and Europe.
Some regions experienced heavy downpours that caused floods or landslides. Others faced severe droughts that affected water availability for human consumption or irrigation.
The storms also disrupted power grids, transportation networks, communication systems and infrastructure projects around many countries. They damaged crops, livestock, buildings and homes.
The impacts of El Niño varied depending on local factors such as topography, vegetation cover, urbanisation and climate adaptation measures. However, they all highlighted how vulnerable we are to extreme weather events driven by climate change.
The Global Water Monitor report shows that climate change has altered many aspects of our planet’s water cycle. It has increased temperatures, reduced humidity, altered precipitation patterns, intensified storms and floods or droughts depending on location.
These changes have serious consequences for human health, food security, biodiversity conservation and economic development. They also pose challenges for disaster management planning and response.
We need urgent action to reduce greenhouse gas emissions that cause global warming. We also need to adapt to these changes by improving our resilience to natural hazards.
We hope that this report will raise awareness about these issues among policymakers, researchers, media outlets and citizens around the world.