"More than ever, we need information on the current state of the water cycle"

How did the idea of producing the Global Water Monitor emerge, and how is it intended to be used? Are there plans to make the report a regular publication?

Our global water resources are under pressure. The growing world population needs more and more water for agriculture, industry and households, while global warming is changing both rainfall patterns and the water requirements of plants, people and ecosystems. More than ever, we need information on the current state of the water cycle. Unfortunately, the global measurement network is in decline, and much of the remaining observations are not publicly available. Earth-observing satellites help fill gaps in our knowledge by measuring the atmosphere and the Earth’s surface. 

The Global Water Monitor Consortium brings together several public and private research and development organisations that share a goal of providing free, rapid and global information on climate and water resources. 

Over the years, the partners have developed methods to combine and interpret water measurements made at thousands of ground stations and several tens of satellites orbiting the Earth. They use these to produce up-to-date information on different components of the water cycle. Recently, they teamed up to provide comprehensive climate and water information via the Global Water Monitor (www.globalwater.online), an online data explorer that unlocks an extraordinary trove of climate and water data to anyone interested, free of charge. 

Normally, it takes many months for this kind of data to be collected, collated, analysed and interpreted. Our team combines water measurements made at thousands of ground stations and by satellites to produce up-to-date information on rainfall, air temperature and humidity, soil water, river flows and the volume of water in natural and artificial lakes. By making the best possible use of satellite instruments orbiting the Earth and by automating the whole data analysis and interpretation process, our team has been able to reduce that time to a few days.

The report will be produced annually. We produced this first annual report to use and demonstrate that capacity. The first report included information on precipitation, air temperature and humidity, soil water availability, river flows and water volumes in natural and artificial lakes. It summarised the state and any trends in the global water cycle in 2022 and examined some of the most important hydrological events of the year. Next year, we expect to also include data on groundwater and vegetation (e.g., grazing, cropping) conditions.

What are the challenges related to data availability and how can they be addressed?

The world is changing fast, and it's important to have more immediate access to what is going on with climate and water

A lot of climate and water data that is collected at on-ground stations goes through a curation process and takes months, if not years, to become publicly available – if ever. But the world is changing fast, and it's important to have more immediate access to what is going on with climate and water.

Combining data from more than 40 satellites and thousands of ground-based stations to get a global picture of water resources, the Global Water Monitor has been up and running for about a year now. It is not intended as an alternative to the water information that national agencies like national water data agencies such as the USGS, meteorological services or similar agencies. We are also not the only group monitoring how the global water cycle is changing. For example, the Intergovernmental Panel on Climate Change has been looking at the global water cycle for a few years now. However, they keep finding that there is not enough data available, in many cases, to do a full global assessment, and their reporting process is very slow. That’s the gap we address.

The Global Water Monitor report explores trends and focuses on specific regions. Which findings would you highlight, and did any of them surprise you?

Some of the trends identified in the report confirm climate shifts that are already well known. An obvious example is the rising temperatures. But some of the trends may be less known. For instance, the effect that increasing temperatures and reducing humidity are having on the occurrence of flash droughts. Worldwide the underlying trend of warming has consequences that are starting to be felt as drought and flood records continue to be broken.

What used to be a cool year, a La Niña year is no longer a cool year. If anything, it’s an average year, compared to data from the past. Rather than being wet and cool, it’s now wet and warm. Whereas El Niño years are likely to be hotter than usual and to be drier. This all has consequences for how fast drought impacts develop. Flash droughts increase the risk of water shortage, crop losses and severe bushfires, and we see more and more of them.

To what extent is it possible to predict the outlook for the following year (and beyond) based on the conditions in a particular year?

There is a well-known gap in our ability to predict what falls between weather, which we can predict reasonably well over up to about 10 or 15 days, and climate, which we can predict over the long term, especially when it comes to slow trends such as average temperatures.

For water availability next year, we can make some predictions on the current ocean circulation patterns, especially the El Nino Southern Oscillation, and combine those with the current storage of water in the soil, groundwater and water bodies. That can especially help predict the likelihood of droughts developing, intensifying or waning. This is true to a lesser extent for floods, as the change from drought to flood conditions can happen more rapidly following intense rainfall.

There is rising awareness of the need to manage water and climate considering their interdependencies. What are your thoughts and expectations in this regard?

For water availability next year, we make predictions on the current ocean circulation patterns, combined with the current water storage

The two are tightly linked, as our and many other reports show. The dependency of water resources on rain and snowfall is intuitive, but it is now very clear that rising temperatures are also having quite a strong impact on the rate at which soils dry out, bushfires start, glaciers melt, and so on. In turn, the climate is sensitive to landscape wetness, and some regions are heavily dependent on the recycling of evaporation from the landscape as rainfall, such as for example the Amazon forests. So those interdependencies are quite strong and obviously, they cannot be measured in separation, just like water management can't be seen separate from economic development, population growth, energy use and natural ecosystems, for example. Water resources management is, first and foremost, the skill of understanding and managing those connections.

How can initiatives like the Global Water Monitor help us prepare for a challenging future ahead? What else is needed?

Our main purpose is to provide an up-to-date picture of the global water cycle and water resources, so that we can identify threats as and when they emerge.

Most urgently, we will have to prepare for the changes in climate that we can already no longer prevent, find ways to slow and then reverse the increase of greenhouse gases in the atmosphere so we don't make a bad situation worse, and roll out existing solutions for water threats and water scarcity as well as develop new ones. For example, you can think of new ways to what likely will become an abundance of cheap renewable energy in future to increase water resources availability where necessary.