Flooding

I am Ilan Kelman.

I am professor of disasters and health at University College

London and also affiliated with the University of Agder in

Southern Norway.

At UCL, I am half at the Institute for Risk and Disaster Reduction and

half at the Institute for Global Health.

Here, I will be speaking about the impacts of climate change.

Does climate change create or worsen flood disasters?

Science answers not really.

The evidence shows how much we could do to avoid flood disasters

even as we change floods by changing the climate.

The reason is that floods by themselves

are not really disasters.

Disasters are when people, our infrastructure,

or our livelihoods are adversely affected.

Floods are not a problem unless we cannot deal with them.

People make choices or are forced to make choices

or do not have choices that stop them dealing with floods.

Perhaps we enjoy the recreation and views afforded by living

next to a river.

A fair enough choice?

But then we should not be surprised when the river floods.

If we've not prepared our dwelling and our lives to deal

with river water safely,

then our choices, not the river's behavior,

led to a disaster.

More commonly and more insidiously,

people live by a river because it is the only place they can afford,

or they might be forced to live there in order to work as an

agricultural laborer on the farm which has rich soil.

It has rich soil because it is in a floodplain.

People might not have the money to improve the flood resistance

of their abode, to buy insurance,

or to lose wages by evacuating as the waters rise.

Social norms might not permit women to leave their house on

their own, or social norms might accept harassment

and violence along evacuation routes and in public shelters

that would discourage women from evacuating.

These are societal choices to create a disaster from floods,

with people being vulnerable because of someone else's choices.

Human caused climate change is also our choice with the more

affluent minority choosing it for the less

affluent majority.

Irrespective, neither the climate nor the weather nor consequent floods

make vulnerability choices

for us.

Cultural systems, forcing inequity and discrimination,

are exactly that.

Cultural systems, not climate systems.

These vulnerabilities set the stage for disasters,

irrespective of what climate change does to the flood.

If we wish to avoid disasters,

then we need to tackle the societal processes

and values producing vulnerability,

not focus on the hazards such as floods or the changing

hazards, changing partly because of climate change.

As another potential example, storms, including hurricanes,

cyclones, typhoons,

and what are called polar lows in the Arctic,

they are likely declining in numbers but increasing in

intensity due to human caused climate change.

They might be slowing as they move along their tracks,

meaning that more rain can be dumped in one place.

We should be able to deal with wind, rain, freshwater

flooding, and ocean flooding called storm surge,

Even if some are becoming more intense due to human caused climate change,

we should be able to deal with them considering that these

tempests have been hitting us for millennia.

If we are flooded,

then any storm could have done the same irrespective of climate change.

Climate change alone cannot be said to cause, exacerbate,

make, or increase disasters involving flooding

with some exceptions.

And these exceptions could produce major problems for us.

Sea level rise from human caused climate change has three main processes.

First, melting land based snow,

ice, and permafrost

is raising sea level by several meter millimeters per year.

Second, oceans absorb most of the heat from the warming air and the water expands.

Is called thermal expansion.

This will raise sea level by several centimeters per year.

Currently, these two factors are each contributing

around fifty percent to sea level rise with thermal

expansion soon dominating.

These contributions to sea level rise are not extensive.

And before the year twenty one hundred,

do not seem likely to bring sea level above its maximum since

the last ice age ended.

The real challenge is a third factor.

Enormous ice sheets, most prominently in Kalaallit

Nuunad, which is a name for Greenland,

and Antarctica might melt,

potentially adding dozens of meters to sea level over centuries.

Numerous cities and island countries would probably become

entirely inundated, leading to drastic societal changes.

While we have a long time beforehand to plan for this

scenario, and it could be managed

effectively if we choose,

the loss of or major changes to so much inhabited land

could rightly be termed a flood disaster from human caused climate change.

Additionally,

oceans absorb carbon dioxide from the air,

which is rising in concentration due to our

actions and which combines with water

to form carbonic acid.

This increased acidity affects marine ecosystems

and might especially harm hard corals and some beaches.

Without a reef protecting the shore from the sea's wave

power, some islands and shorelines

could erode rapidly, leading to coastal flooding and disasters.

Apart from these exceptions,

which are big enough to be reasons themselves for tackling

human caused climate change, our known impacts on the climate

cannot be blamed for causing disasters involving floods

even when floods are substantially worsened.

The disaster comes from vulnerability,

and we can choose to tackle vulnerability for avoiding disasters,

or we can choose otherwise no matter how we are changing the climate.