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A report warns that the atmosphere above the Amazon rainforest has become increasingly dry over the past two decades due to human activities and is at risk of drying out completely. This could increase the rainforest’s demand for water and make it more vulnerable to droughts and fires. 

The study, published in the journal, Science, observed an increasing trend in a measure called Vapour Pressure Deficit (VPD) over tropical South America in dry season months. VPD is a combined function of air temperature and relative humidity and is a critical variable in determining plant photosynthesis. Higher VPD values indicate a decline in atmospheric moisture. This implies that the Amazon is likely to increasingly struggle to sustain its water demands, triggering more widespread and severe droughts. As a result, wildfire risk and tree mortality will increase, causing a significant loss of carbon over the Amazon basin

This has already been seen with previous droughts. After the 2005 megadrought, where more than 70 million hectares of pristine forests in southwestern Amazonia were affected, the most negative annual carbon balance ever was recorded in the region. This decrease can be attributed to extensive and severe damage to the forest canopy that was detectable by satellite. The older, larger, more vulnerable canopy trees were especially susceptible to dieback and tree falls. Even when rainfall levels recovered in the following years, about half of the forest affected by the 2005 megadrought – an area the size of California – did not recover by the time the next major drought began in 2010.

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Furthermore, during the 2015 Amazonia drought, the highest VPD since 1979 was recorded. Similar values that are well beyond the scope of natural variability have been observed across the last decades, insinuating a human influence. The researchers suggest that elevated levels of greenhouse gases account for approximately half of the increase in atmospheric dryness. Other influencing factors are unclear, but burning of rainforest biomass for agriculture that causes widespread land-cover change, is thought to be another predominant cause. Satellite data taken in 2018 revealed that an area of Amazon rainforest roughly the size of a football pitch is now being cleared every single minute. 

Dr Armineh Barkhordarian from the University of California and lead author of the study said, “We observed that in the last two decades, there has been a significant increase in dryness in the atmosphere as well as in the atmospheric demand for water above the rainforest. In comparing this trend to data from models that estimate climate variability over thousands of years, we determined that the change in atmospheric aridity is well beyond what would be expected from natural climate variability.”

Higher VPD levels are concerning as the Amazon rainforest- commonly coined ‘the lungs of the Earth’- is critical in regulating the global climate. The multitude of flora found in tropical forests enable them to extract half of the atmospheric carbon dioxide via photosynthesis – thus helping to reduce levels of this greenhouse gas and help mitigate global warming. 

In addition, the Amazon basin plays an important role by regulating rainfall in the region. It cycles water between the forest and the atmosphere via rainfall and transpiration of leaves, leading to a freshwater ocean in South America – the rivers and groundwater – that maintains rainfall in the southern agricultural regions of the continent. However, the Amazon rainforest is extremely vulnerable to increases in atmospheric drying and warming, as they are thought to produce up to 80% of their own rainfall. A decrease in atmospheric moisture, combined with an increase in global temperatures, decreases the ability of the Amazon to regulate its rainfall, thus increasing the vulnerability of major Brazilian cities to water shortages

Will the Amazon rainforest survive?

The dire potential situation has highlighted the need for a greater focus on halting deforestation in the Amazon basin, in conjunction with decreasing emissions of greenhouse gases. Both will help decrease VPD and hence reduce the potential risk of droughts and the associated threat of wildfires and tree mortality. It has never been more critical to address this drying out issue because if the Amazon forest is lost, the crucial ecosystem services it provides will also be lost.

Featured image by: Anna & Michal

A megadrought is an extreme and prolonged drought that lasts for 20 years or longer. Human activities, such as burning fossil fuels and deforestation, trap more energy from the sun in the atmosphere and are playing a critical role in exacerbating the drought, consequently drying the Southwest areas of the US.

What causes a megadrought?

Radiative forcing is one of the causes of a megadrought, which occurs when the Earth’s atmosphere captures more energy from the sun. The more energy retained in the atmosphere, the higher the rate of water evaporation. 

Physical Risk

Droughts are one of the most expensive natural disasters, and it is estimated that the average annual loss in the US in 2018 was between USD$10 billion and $14 billion. There are few studies that have estimated the monetary losses to the agricultural sector caused by drought. Among these studies, one suggested that the megadrought in the US from 1988 to 1989 had caused the loss of crops worth $15 billion. Analysts at the University of California evaluated the economic impact of the California drought on the US’s agricultural sector from 2014 to 2016 (the most recent megadrought). They disclosed significant losses in crops, dairy products and livestock, as well as additional groundwater pumping costs, with a combined loss of approximately $3.85 billion. At the same time, some researchers have disclosed that the reduction in crop yields has led to higher crop prices to try and offset the loss from this drought on agricultural revenue.

Efforts to Mitigate Physical Risk

International Water Management Institute (IWMI)’s efforts to support nations and regions preparing for climate shocks (such as a megadrought) involve enhancing farmers’ resilience. In recent years, the Institute developed an index-based flood insurance (IBFI) product to compensate farmers whose crops have been ruined as a result of floods.

The technology uses satellite data and modelling tools to estimate when the depth and duration of flooding exceeds predefined limits, triggering automatic payouts. Between 2017 and 2019, the IBFI scheme supported insurance payouts in India ($22 000) and Bangladesh ($31 500) to 1 306 out of 2 300 eligible farming households, increasing their resilience to floods and minimising their vulnerability to natural hazards.  A new trial seeks to build on the success of IBFI by bundling SMS-based weather information, advice on crop and water management methods, and fertilisers together with the insurance product. The trial covered 1 000 households, of which 450 benefited from an insurance payout of $12 500 each.

How Unilever is Mitigating its Water Risks 

Unilever is one of the largest fast-moving consumer brand companies in the world with over 400 different brands in almost 200 countries. Unilever is currently focused on creating ‘sustainable products’ for their consumers, and their vision is ‘to make sustainable living commonplace’. They created the Unilever Sustainable Living Plan to realise this vision. Unilever identified key issues and topics on a materiality matrix, and prioritised them based on current stakeholder importance and short-term business impact.

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megadrought
Unilever’s materiality matrix, ranking their priorities based on current stakeholder importance and short-term business impact (Source: Unilever Materiality Matrix 2019/2020.

Unilever set three general goals: Improving health and well-being for more than 1 billion, Reducing environmental impact by half and enhancing livelihoods for millions. To improve its water usage, Unilever has pledged to halve the water associated with the consumer use of its products by 2020 and maintain the water abstraction levels for production at or below 2008 levels by 2020. In 2019, they exceeded their second goal, where the water abstraction levels are 47% lower compared to 2008. However, they failed to meet the first goal to halve consumer water consumption- water consumption is actually 1% greater in 2019 than in 2010.                       

Unilever’s manufacturing department does an exemplary job of meeting these goals. However, their products department greatly lags behind to meet these goals. Even though the manufacturing department does not pledge to halve manufacturing emissions, water consumption or waste, it does so for all three areas. The explicit goals for the products department to halve product emissions, water consumption and waste are more difficult to achieve. However, the product department fails to even maintain the level of emissions and water impact at 2010 levels. Unilever needs to address these product department weaknesses to better align with their vision to make sustainable living commonplace.

What Governments Are Doing to Mitigate Water Risk

In 2017, the US government developed a Global Water Strategy to aid the global water crisis. The strategy contains four main strategic objectives revolving around conserving and providing clean water sources to countries with high water risk.

The first objective is to promote sustainable access to safe drinking water and sanitation services, and to adopt key hygiene behaviours. The US aims to increase the amount of sources for safe drinking water and sanitation, while decreasing the mortality rate related to unsafe drinking water and unhygienic living standards.

The second objective is to encourage the sound management and protection of freshwater resources. This strategy primarily addresses physical water risk, in particular, flooding and groundwater deficiency. The US aims to support access to water supplies and protect ecosystems that provide these water supplies. It also focuses on improving preparedness for water-related disasters such as floods and megadroughts. 

The third objective is to reduce conflict by promoting cooperation on shared waters. This strategy aims to resolve the issues of river basins and aquifers shared between multiple countries without formal agreements. This is done by increasing mediation activities between such countries through the creation of  designated institutions to address these issues.

The last objective is to strengthen water sector governance, financing and institutions. This is done by improving upon environmental policies, building partnerships with other international organisations to support the development of water resources and increasing the amount of private and public resources mitigating water issues.

The US government has set various approaches to fulfil these four strategies. Most notably, it plans to use its scientific and technical expertise to assist countries that require the most assistance for countering water risk. It also plans to mediate with governments and organisations to better understand the needs of the community while raising funds necessary for  supporting the development of water and sanitation infrastructures. 

The strategy lists 13 ‘High Priority Countries’ that have high levels of water risk and assistance needs. Such countries include Afghanistan, Haiti, Indonesia and Uganda. The US will focus their attention on these countries, and have deliberated country-specific plans to better help these countries.

However, there are potential difficulties and risks that should be addressed. This is especially apparent for the third objective, where the US aims to reduce conflict by promoting cooperation on shared waters. It is extremely difficult for countries to agree and share water resources, especially in high-risk countries. Even if the US government is able to bring the conflicting parties together to discuss, it is unlikely that a formal consensus can be made immediately. In fact, greater conflict may arise when the two parties discuss formal conditions for cooperation. 

Drought and Climate Change

China suffers from both too much as well as too little water due to climate change. Southern parts of China and coastal cities are often flooded from typhoons, storm surges or river/pluvial floods while certain areas experience extreme drought; for example, the middle and the lower reaches of the Yangtze River is characterised by alternating periods of drought followed by floods.

Over-extraction of groundwater and falling water tables are significant problems in China- there is an average annual groundwater depletion rate of more than 10 billion cubic metres and water resource usage is set to peak in 2030 when the population also peaks. Groundwater extraction can lead to land subsidence- 60 000 sq kms of the ground surface in the country has sunk, with more than 50 cities suffering from severe land subsidence. Further, Asia’s ten largest rivers, including the Yangtze, Yellow, Mekong and Ganges, are fed by seasonal melting, which is being affected by the climate crisis.

Existing drought models are very simplistic and therefore lead to wrong predictions. Moreover, rainfall data is not collected in most regions in Asia. It is therefore very difficult to make any drought analysis on a meaningful grid case. Intensel Limited, an Asia startup focusing on physical climate risk assessment and predictions, models drought using a combination of several factors including snowmelt and other climate variables. In addition, Intensel’s dynamic climate models and AI technology is able to generate missing historical data, for example, granular rainfall data. Organisations such as these are vital, as the climate crisis is making these predictions even more difficult with changing trends, increasing variation of weather. 

This post was written in collaboration with Entela Benz, Adjunct Associate Professor at HKUST and CEO of Intensel.

New research shows that warming temperatures in the Indian Ocean could lead to the return of an ancient El Niño- style system not seen since the Ice Age that may increase storms, floods and droughts that occur around the Indian Ocean, impacting vulnerable regions already threatened by the climate crisis.

The study, published in Science Advances, shows that small surface temperature increases in the Indian Ocean could see its associated weather patterns start to match the El Niño patterns currently seen over the Pacific Ocean, as soon as 2050. This matches up with how winds and rainfall used to affect the region during the last ice age, at least 21 000 years ago. This threatens some of the people that are already at extreme risk from the climate crisis, across Africa, Asia and Australia. 

Pedro DiNezio, one of the lead authors of the study, says, “Our research shows that raising or lowering the average global temperature just a few degrees triggers the Indian Ocean to operate exactly the same as the other tropical oceans, with less uniform surface temperatures across the equator, more variable climate, and with its own El Niño.”

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The Indian Ocean Dipole and the Australia Fires

El Niño is a weather system characterised by unusually warm water in the Pacific Ocean off the coast of Peru and Ecuador. It is linked to droughts in Australia and heavy rains in South America and is exacerbated by the climate crisis.

The researchers analysed 36 different climate models, picking out the ones that matched current weather conditions most accurately. These models were then used to examine how further warming might change the meteorological conditions around the Indian Ocean.

Currently, the Indian Ocean sees little change in temperature year-on-year; the west-to-east winds tend to keep conditions stable. However, the models show that the climate crisis may reverse these winds, completely altering weather patterns in the region. The study shows that the rising temperatures of today are affecting the Indian Ocean in a similar way as the glaciers did tens of thousands of years ago.

This could lead to increased flooding in some areas to longer dry spells in others, affecting massive parts of the world already feeling the effects of the crisis, as seen recently with the bushfires in Australia. 

These studies are valuable in showing the future impacts of human activity on the planet, and allow countries to plan to a certain extent, however in many countries, there simply are not enough resources to plan for the climate crisis in a meaningful way. 

DiNezio says, “We are certain that the risks of these extreme events are becoming larger and larger as we pump more CO2 into the atmosphere, and certainly going to have an unequal impact on countries in the tropics.”

Featured image by: Jon Sullivan

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