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Determining whether extreme weather events are caused by climate change

is crucial in planning for risks. Else, we will reach a situation in which

corrective action may not be enough to protect us

Over the past several years, headlines on weather-related extreme eventshave included heavy downpours followed by floods, droughts, storms, heat

and cold waves, and wild fires. Such events typically destroy lives, property

and ecosystems while stretching the capacities of disaster management

departments and coffers for emergency funds in various parts of the world.

Protecting people before and after major floods, storms, and extreme

events is a core part of our business, said Karsten Lffler, Managing Director

of Allianz Climate Solutions.

Since one of the main impacts anticipated from climate change is an increase

in the intensity, frequency or duration of extreme events, there is usually a

lot of interest from the media and the public after an extreme event to learnif it was due to global warming. The challenge that scientists and insurers

face in responding to such questions is that of attribution that is, to

what extent can one consider climate change to be the cause of an extreme

event?

Most such events have one or more components that are not related to

climate change. For example, incompetent forest management practices

contribute to fires. Poor land use planning contributed to heavy downpours

and floods in Chennai last year. Consequently, what experts are trying to do

to understand attribution is to separate the climate signal from everything

else. There are generally nine kinds of extreme events that are considered:

heat and cold waves, droughts, wildfires, extreme rainfall, tropical and other

cyclones, extreme snow and ice events, and severe convective storms.

Scientific studies of extreme weather events and their attribution to global

warming may help various groups such as planners, emergency responders,

policymakers and insurance companies. Better knowledge of the risk

contributes to how communities, governments, investors and others prepare

for the future, with regard to planning cities, proposed infrastructure, natural

resources or food security.

Determining attribution

Can scientists tell if an event is caused by climate change?

In order to determine attribution, scientists run climate models to simulate

an event or they rely on the observational record from which they may

estimate the statistical chance and magnitude of an extreme event. Often,

they use both these kinds of approaches.

According to a recent report from the U.S. National Academies titled

Attribution of Extreme Weather Events in the Context of Climate Change,

event attribution is more reliable when based on sound physical principles,

consistent evidence from observations, and numerical models that can

replicate the event. All these conditions are not satisfied for every type ofextreme weather event. Where long records exist, good models are

available and contribution from non climactic factors such as human activity

Did climate change cause those floods? - OPINION - The

HinduTuesday, March 29, 2016 11:31 AM

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over the other kinds of events described above. With regard to extratropical

or mid-latitude cyclones and convective storms, it appears that there is little

to no confidence in attributing them to climate change.

Another confounding issue is that there is a natural variability in the

occurrence of weather events in any case, so scientists would be looking for

a signal that is over and above the natural variability. For this reason, it is

difficult for a scientist to be absolutely sure that a particular singular event

has been caused by climate change.

As efforts to improve our understanding of extreme events improve, the

ability for attribution is expected to improve. As in any other kinds ofscientific studies, the accuracy improves with various advances including

validation across different approaches, advances in modelling methods, and

the accuracy of historical records of such events.

Fat tails and insurance

Global insurance companies were among the earliest groups in the world to

ring the alarm on climate change. They are on the frontlines since their

business is to estimate the risk of extreme events and then provide

protection from their potential impacts. The profits they make arise from the

fact that such events are rare. As their frequency, magnitude and impacts

increase, the companies losses escalate. Some insurers are, in fact, limiting

their coverage to those in areas with a moderate risk to climate change

impacts and are expanding their business and activities to include solutions

to climate change.

Scientists sometimes use the term fat tail to describe extreme events. A

normal distribution curve, what we know as a bell curve, shows a lot of

variation near the average, but produces very few points at the far end of the

curve. Biological parameters such as height of Indian women or men are

examples of normal curves. In a fat-tailed distribution, on the other hand,

portions of the curve that are distant from the average are thicker, and this

implies that there is a higher chance of large deviations from the average.

Climate models generally assume a normal distribution rather than a fat tail

distribution around the mean, thus ignoring the low probability high-impact

events. Economists and some scientists have been telling us that we need to

be prepared for extreme temperature and weather events. Gernot Wagner

and Martin Weitzman explain the implications of fat tails for climate policy in

their book, Climate Shocks: The Economic Consequences of a Hotter Planet.

Many of the points discussed here may appear nuanced, perhaps not

significant, and also difficult to address within the regular political cycles of

4-5 years. But it is the extreme weather events and their incidence that arebeginning to increase our everyday experience of climate change. We do not

have the capacity to appreciate a change in average temperatures over

50-100 years, but can see what havoc an unusually intense storm or severe

drought can cause in our own lifetime.

International agreements such as the recent Paris climate pact and the global

targets for sustainable development set goals for governments and political

parties to enable nations and communities to address the risks the world

faces in the medium and longer terms. We must address anticipated risks

even before all our models become accurate enough to estimate every detail

of climate extremes. Otherwise, we will reach thresholds beyond whichmaking corrective improvements to deal with climate change may not yield

the protection we need

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We must address anticipated risks even before all our models become

accurate enough to estimate every detail of climate extremes

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climate-change-cause-those-floods/article8403301.ece

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1) In India it is scientifically proven that groundwater is

overexploited and there is an urgent need to conserve it anduse it judiciously. Why do you think its exploitation continues?

What innovative measures would you suggest to use water

judiciously? Discuss. (200 Words)

The protest by farmers in Chikballapur recently, over the

scarcity of drinking water, received extensive news coverage as

it halted Bengaluru in its tracks after key highways were

blocked. Interestingly, very little of that coverage was devotedto the groundwater crisis that underpins the problem in such

regions.

Groundwater plays an important role in our lives and Indias

economy, but it is disappearing fast. There is mounting

evidence that we are extracting more than can be naturally

replenished. In the hard-rock aquifers of peninsular India,

drilling 800 ft or deeper is becoming the norm. Groundwater-dependent towns and villages spend an increasing fraction of

their budgets chasing the water table. Stories abound of

farmers spending their life savings or taking loans to drill a

borewell, but failing to find water. If we run out of

groundwater, millions of people will be left without any means

to sustain themselves.

Scientific evidence also points to over-exploitation. The CentralGround Water Board classifies all blocks in India based on the

fraction of recharge that is extracted and trends in long-term

groundwater levels. Since 2004, almost a third of blocks have

been classified over-exploited or semi-critical. If we

understand the problem and if the consequences are so severe,

Why we must have water budgets - OPINION - The HinduTuesday, March 29, 2016 11:42 AM

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why are we unable to address it? The answer lies partly in

politics, partly in the invisible nature of groundwater, and partly

in our reliance on simple techno-economic fixes.

Flawed regulatory structure

Electricity is supplied to farmers free of cost. This policy made

sense when groundwater was abundant in the 1980s. Indeed, it

helped millions of farmers escape poverty. But today, where

groundwater levels have fallen hundreds of feet below the

ground, the subsidy is actually only utilised by the richest

farmers who can afford to drill deep. And even so, not all are

lucky enough to strike water. Access to groundwater in hard-

rock regions has almost become a lottery. Yet in the absence of

alternative water sources, charging farmers for electricity is

seen as political suicide.

Groundwater is inherently difficult to monitor and control, in

part because of its invisibility, which also perpetuates the

illusion that each well is independent. The myth is enshrined in

Indian groundwater law that allows landowners to extract as

much as they want. In reality, not only is groundwater within anaquifer interconnected, but aquifers and rivers are also

interconnected. So depleting groundwater means drying rivers.

Despite this, groundwater and rivers are regulated by different

agencies that do not properly account for the linkages between

them, often double counting the quantum of the resource.

Much of the current action on the ground is through techno-

economic fixes. These have clear benefits in terms of reducingpumping costs and using local aquifers instead of building big,

expensive dams. But what they do not do is create new

water.

Boosting recharge through rainwater harvesting structures such

as small check dams is a popular measure. However, any water

that recharges is water that does not flow downstream. Often

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users located near check dams simply extract more water,

while users further downstream wonder why their rivers and

tanks are drying up. Another technological solution is to

improve efficiency through subsidised drip irrigation or energy-

saving pumps. Again, these have often resulted in farmers

increasing their irrigation area with no decrease in waterextracted. And farmers are not alone; conscientious urban

dwellers take pride in reusing wastewater for gardens and

parks. But this could result in more wasteful water use, with the

additional wastewater used in lawns or golf courses where

none previously existed.

Science and fairness

Techno-economic fixes do not address the underlying zero-

sum game nature of water resource use. Ultimately, the water

management problem is that of allocating the water available

each year among users both people and the ecosystem.

Without understanding how much water is available, how

much is being used and by whom, solving Indias water crisis is

going to be a non-starter.

The way forward is comprehensive water budgeting,

simultaneously in each watershed and the river basin as a

whole. Water budgets at the watershed level will inform

communities about how much water they have, so it can be

equitably shared within communities. Water budgets for the

river basin will inform communities how much must be left for

downstream users, ensuring that water resources are allocatedbetween communities fairly and transparently.

Given the zero-sum nature of the game and the impossibility of

creating new water, it is likely that we cannot restore the

water balance in severely depleted regions without painful cuts

in water use. However, there are some glimmers of hope.

Water users everywhere are worried about the disappearing

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resource and willing to engage. The trick lies in combining

technology (low-water-use crops, xeriscaping) and economic

incentives that reduce actual water use (cash-for-blue

schemes) without reducing productivity or quality of life. This

needs a strong water governance system based on awareness

building, science and a commitment to fairness andsustainability.

- Veena Srinivasan and Sharachchandra Lele are Fellows at the

Centre for Environment and Development, Ashoka Trust for

Research in Ecology and the Environment, Bengaluru.

If we run out of groundwater, millions of people will be left

without any means to sustain themselves

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