World Water Day 2020: Water and Climate Change... and Isotopes

Agriculture consumes, on average, 70% of the total freshwater used around the world, mainly through irrigation for food production. However, less than half of this water is being used efficiently; the rest is wasted through evaporation and deep drainage and runoff. This water – whether from rainfall or irrigation ­– carries nutrients, pesticides and chemicals to ground and surface water resources, harming water quality and habitat, said Heng.

Isotopic and nuclear techniques are contributing to better soil and irrigation management by improving water use practices and efficiency. These techniques are becoming an integral part of agricultural water management, as isotopes (oxygen-18 and deuterium) can help determine the origin and movement of water in plants and soils (see The Science box). For instance, scientists can measure with isotopes how much water is used and “transpired” by a plant or is evaporated from the soil.

With such information, strategies can be developed to improve crop production, reduce water losses and prevent land, water and ecosystem degradation.

In Africa, which suffers from severe drought in some areas, the IAEA has run several technical cooperation projects on adaptation to climate change using drip irrigation. In Sudan for example, scientists were successfully trained to use the minimal amount of water and fertilizer crops need to flourish, and in turn they supported 1050 small scale women farmers – among them many refugees from neighbouring countries – improve subsistence agriculture production. They succeeded turning dry lands into vegetable fields that feed families and entire villages, contributing to poverty alleviation and local food security enhancement in rural areas.

In Mauritania, 400 rural women, family farmers, living in a hostile desertic environment – with water scarcity, high temperatures and sandy soils – have benefited from the support of scientists trained by the IAEA. They increased yield and varieties of vegetables grown in the desert and grew their income for improving education and health.

To help predict future impacts of climate change, scientists must explore and understand how complex Earth systems work and can evolve.  For that, some choose climate models, systems using mathematical equations to characterize how energy and matter interact in different parts of the ocean, atmosphere and land. It is a complex process that necessitates powerful supercomputers and, among others, accurate data on water.

The IAEA offers a unique resource to climate modelers around the world: the Global Network of Isotopes in Precipitation (GNIP). Created in 1960 by the IAEA together with the World Meteorological Organization to collect hydrogen and oxygen isotope data on precipitation worldwide.  These isotopes are highly sensitive indicators of climatic processes. The GNIP helps scientists to study the global water cycle and the origin, movement and history of water, and to validate climate model predictions. In over 90 countries, hundreds of monitoring sites have generated more than 130,000 isotope records worldwide.

An IAEA coordinated research project has just been launched to assess climate change impacts with hydrological modelling, said Leonard Wassenaar, Head of the IAEA’s Isotope Hydrology Laboratory.  “We aim to improve the expertise among countries in the use of environment isotopes for an in-depth assessment of different types of precipitation,” he said. “This will help to better understand the possible range of climatic changes induced impacts to the rainfall characteristics, such as frequency, amount, duration and intensity.”