Nav: Home

Water availability has changed, and humans are to blame

August 24, 2020

Changes in the water cycle have important impacts on ecosystems and human activities. In the context of the current and expected temperature rise due to global warming, it is extremely important to understand the origin and extent of these changes.

A recent study published in the journal Nature Geosciences analyses the changes in global average water availability on land - defined by the difference between precipitation and evapotranspiration - eliminating any remaining uncertainties about human responsibility for variations in the hydrological cycle observed during the dry-season throughout the last century.

The research, realized with the contribution of the CMCC Foundation - Euro-Mediterranean Center on Climate Change, is entitled "Observed changes in dry-season water availability attributed to human-induced climate change" and is made up of two phases.

First, authors used land surface models and statistical models guided by observations to produce and compare global maps of water availability from 1902 to 2014, a period during which our planet experienced a global warming effect of approximately 1°C. The analysis focused on the difference in average water availability of the driest month between the 1902-1950 and the 1985-2014 period.

Results show a reduction in average water availability at a global level during the last century, with some regions experiencing increased and some decreased water availability. 57-59% of land areas, predominantly in extratropical latitudes, experienced a decrease in dry-season water availability. These areas include Europe, western North America, northern Asia, southern South America, Australia, northern Andes and eastern Africa. On the other hand, humidity during the dry season has increased in 41-43% of land areas, including inland China, southeastern Asia and the Sahel.

Moreover, the study shows that the intensification of the dry season is generally a consequence of increasing evapotranspiration rather than decreasing precipitation.

The second step was to understand the causes of this change, in order to understand if and in what terms these effects are connected to human-induced climate change rather than natural variability.

"Through a multi-model analysis, we have compared in different sets of experiments the spatial distribution of water availability in three different configurations: the world in 1850 (pre-industrial), the world as we observe it today (which is influenced by both natural and human-induced variability) and the world we would observe today if the climate had been influenced only by natural variability", explains Daniele Peano, researcher within the Climate Simulations and Predictions division at the CMCC Foundation, and co-author of the study. "With or without considering human activity, simulations bring us into a completely different early twenty-first-century world. Instead, the pre-industrial world is not so different from what we would have had today without anthropogenic influence on the climate system. Thus, we excluded the impact of natural variability, establishing human influence as the only explanation for the changes in water availability on land from the pre-industrial era to date."

This is the first time a scientific study demonstrates a correlation between human-induced climate change and changes in the water availability during the dry seasons: in previous assessments, a high level of uncertainty remained, due to the inability to exclude the influence of natural climate variability.
-end-
For more information:

Padrón, R.S., Gudmundsson, L., Decharme, B. et al. Observed changes in dry-season water availability attributed to human-induced climate change. Nat. Geosci. 13, 477-481 (2020). https://www.nature.com/articles/s41561-020-0594-1

CMCC Foundation - Euro-Mediterranean Center on Climate Change

Related Climate Change Articles:

Mysterious climate change
New research findings underline the crucial role that sea ice throughout the Southern Ocean played for atmospheric CO2 in times of rapid climate change in the past.
Mapping the path of climate change
Predicting a major transition, such as climate change, is extremely difficult, but the probabilistic framework developed by the authors is the first step in identifying the path between a shift in two environmental states.
Small change for climate change: Time to increase research funding to save the world
A new study shows that there is a huge disproportion in the level of funding for social science research into the greatest challenge in combating global warming -- how to get individuals and societies to overcome ingrained human habits to make the changes necessary to mitigate climate change.
Sub-national 'climate clubs' could offer key to combating climate change
'Climate clubs' offering membership for sub-national states, in addition to just countries, could speed up progress towards a globally harmonized climate change policy, which in turn offers a way to achieve stronger climate policies in all countries.
Review of Chinese atmospheric science research over the past 70 years: Climate and climate change
Over the past 70 years since the foundation of the People's Republic of China, Chinese scientists have made great contributions to various fields in the research of atmospheric sciences, which attracted worldwide attention.
A CERN for climate change
In a Perspective article appearing in this week's Proceedings of the National Academy of Sciences, Tim Palmer (Oxford University), and Bjorn Stevens (Max Planck Society), critically reflect on the present state of Earth system modelling.
Fairy-wrens change breeding habits to cope with climate change
Warmer temperatures linked to climate change are having a big impact on the breeding habits of one of Australia's most recognisable bird species, according to researchers at The Australian National University (ANU).
Believing in climate change doesn't mean you are preparing for climate change, study finds
Notre Dame researchers found that although coastal homeowners may perceive a worsening of climate change-related hazards, these attitudes are largely unrelated to a homeowner's expectations of actual home damage.
Older forests resist change -- climate change, that is
Older forests in eastern North America are less vulnerable to climate change than younger forests, particularly for carbon storage, timber production, and biodiversity, new research finds.
Could climate change cause infertility?
A number of plant and animal species could find it increasingly difficult to reproduce if climate change worsens and global temperatures become more extreme -- a stark warning highlighted by new scientific research.
More Climate Change News and Climate Change Current Events

Trending Science News

Current Coronavirus (COVID-19) News

Top Science Podcasts

We have hand picked the top science podcasts of 2020.
Now Playing: TED Radio Hour

Listen Again: The Power Of Spaces
How do spaces shape the human experience? In what ways do our rooms, homes, and buildings give us meaning and purpose? This hour, TED speakers explore the power of the spaces we make and inhabit. Guests include architect Michael Murphy, musician David Byrne, artist Es Devlin, and architect Siamak Hariri.
Now Playing: Science for the People

#576 Science Communication in Creative Places
When you think of science communication, you might think of TED talks or museum talks or video talks, or... people giving lectures. It's a lot of people talking. But there's more to sci comm than that. This week host Bethany Brookshire talks to three people who have looked at science communication in places you might not expect it. We'll speak with Mauna Dasari, a graduate student at Notre Dame, about making mammals into a March Madness match. We'll talk with Sarah Garner, director of the Pathologists Assistant Program at Tulane University School of Medicine, who takes pathology instruction out of...
Now Playing: Radiolab

What If?
There's plenty of speculation about what Donald Trump might do in the wake of the election. Would he dispute the results if he loses? Would he simply refuse to leave office, or even try to use the military to maintain control? Last summer, Rosa Brooks got together a team of experts and political operatives from both sides of the aisle to ask a slightly different question. Rather than arguing about whether he'd do those things, they dug into what exactly would happen if he did. Part war game part choose your own adventure, Rosa's Transition Integrity Project doesn't give us any predictions, and it isn't a referendum on Trump. Instead, it's a deeply illuminating stress test on our laws, our institutions, and on the commitment to democracy written into the constitution. This episode was reported by Bethel Habte, with help from Tracie Hunte, and produced by Bethel Habte. Jeremy Bloom provided original music. Support Radiolab by becoming a member today at Radiolab.org/donate.     You can read The Transition Integrity Project's report here.