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Climate, Climate change

Wading into the Fire, Episode 10: Risk and uncertainty

Happy belated solstice, dear readers. We’re officially in full-blown summer here in Columbus, with days that are sunny until after 9 pm and skies so moist that they’re hazy.

Work breaks spent running around outside with the puppy now end with puppy and me collapsed in a panting heap, one of us sweating profusely and the other with tongue lolling sideways. (I’d like to say that we alternate in these roles, but the puppy doesn’t sweat.) Humid heat is definitely not my favourite weather. Unfortunately, if temperatures rise into the future, I’ll probably have to put up with humid heat more often and for longer periods at a stretch. 

As I ponder ways to minimize my discomfort now and in a perpetually sweaty world – better insulation in the house, more shady trees, an industrial-sized fan? – I’m very aware that being sticky may be the least of my worries.

Escalator under water at the South Ferry, taken from images released by the MTA of New York's subway system after Hurricane Sandy, October 2012.

Escalator under water at the South Ferry, taken from images released by the MTA of New York’s subway system after Hurricane Sandy, October 2012.

It seems there is growing consensus among climate scientists that we’ll see increased variability in response to a changing climate. Increased variability is a technical term that just means less weather that is average and more weather that’s extreme, on both ends of the spectrum.

One example of this shift could be that the total amount of rain during the year stays the same, but instead of falling gradually over several months, it’ll come in short bursts of intense storms interspersed by long dry periods. That kind of increased rainfall variability was recently predicted for the Indian monsoon, described in this journal article.

Increased variability is generally bad news for us and the systems we depend on. Hurricanes, droughts, fires and floods – directly causing loss of life and injury, not to mention effects on drinking water supplies, crop yields, disease transmission, and so on – could all become more frequent and severe as the climate shifts.

But here’s the rub: we don’t really know for certain if these events will become more frequent, or how severe they might be if they do get more frequent.

That’s the nature of working with the climate system; as the adage goes, climate is what you expect, weather is what you get. When a climate scientist tries to predict what the world might look like 20 years from now, all she can do is tell you what she thinks is likely to happen. She can’t give you a precise forecast for a specific day. One source of uncertainty is the limitations in climate models, like parameterization schemes and things we’ve discussed in previous posts. But other sources of uncertainty are simply gaps in our knowledge due to imperfect observations and the chaotic nature of weather.

There will always be some degree of uncertainty associated with climate projections, no matter how good our science gets or how sophisticated our models become.

Bushfires ravaged Tasmania during the hot Australian summer in January, 2013. Photo by Karl Hofman, Source: Brisbane Times.

Bushfires ravaged Tasmania during the hot Australian summer in January, 2013. Photo by Karl Hofman, Source: Brisbane Times.

Which leads us to the subject of risk. Engineers know a lot about risk. So do farmers, surgeons and anyone else who has to work with a very low tolerance for failure. You want the person who designed the plane you’re flying in to have figured out how the structure might fail and then have added a safety factor (or five) to reduce the risk of crashing. We encounter risk management in some form in many parts of our daily lives, whether we know it or not.

Risk is inherently tied to uncertainty. If we knew for certain what the outcome would be, there would be no risk involved in deciding on a course of action. (And Las Vegas might cease to exist.) So when we talk about the uncertainty of future climate changes and increased variability, what we’re really talking about is climate risk.

Political rhetoric and standard business practice usually adopt the position that it is too expensive to take actions that mitigate against potential future climate change until we have more certainty about exactly how the climate will change. I interpret this argument as saying that the risk of future climate change currently seems too low to justify any investment that might safeguard against that change.

Now, I certainly don’t want to tell people how much risk they should be willing to accept in their lives. I’ve willingly jumped out of an airplane at 15,000 feet, but I won’t drive a motorcycle. Everyone accepts a different level of personal risk.

But, as we’ve talked about before, the climate system is not a personal issue. It’s a regional and a global one. The potential impacts of increased climate variability will be felt by entire communities and countries.

So, how should we be thinking about climate risk? How do we evaluate the risk of future climate changes? What sort of steps, if any, should we be taking to protect ourselves against an unreasonable level of risk? Is there a way to quantify climate risk and incorporate that into our decision-making?

I really don’t know the answers, but I think these are the questions that our politicians, engineers and other societal designers and decision-makers should be talking about. Recently, it seems that more scientists are also starting to think in risk language, to think about how climate uncertainty and the risk of climate variability might affect our societies.

For instance, a study published in 2011 examined the sensitivity of the US economy to weather variability. The idea behind that study was to get a quantitative feel for which parts of the US economy might be affected by future climate changes, i.e. to understand how vulnerable the US economy might be to climate risk.

Figure 5: State sensitivity to weather variability as a percentage of total GSP (gross domestic product by state). From Lazo et al. 2011, "U.S. economic sensitivity to weather variability".

Figure 5: State sensitivity to weather variability as a percentage of total GSP (gross domestic product by state). From Lazo et al. 2011, “U.S. economic sensitivity to weather variability”.

The authors noted right up front that being able to predict the weather (and, implicitly, being able to make accurate climate projections) has important economic implications (see page 1 of this link):

“Weather directly and indirectly affects production and consumption decision making in every economic sector of the United States at all temporal and spatial scales. From very local short-term decisions about whether or not to pour concrete on a construction project to broader decisions of when to plant or harvest a field, to the costs of rerouting an airplane around severe weather, to predicting peak demand electricity generation in response to extreme heat, or to forecasting early season snow for a bumper ski season in Colorado, drought in the Midwest, or wind-fueled wildfires in California, weather can have positive or negative effects on economic activity.”

Of course, one industry already thinking about the economic impacts of variable weather is insurance:

  • A quick internet search in preparing this article showed insurance companies talking about how they evaluate the risk of future climate changes.
  • An article in the New York Times last month quoted a couple of sources in reinsurance as saying that the insurance industry is less amenable to political persuasion than others and follows the consensus in scientific thought that climate change will bring an increase in extreme events.
  • A public forum is being held in California on June 28 on the topic, “Insurance in an era of climate change”, particularly as it pertains to wild fires, drought and vulnerable homeowners.

Clearly, the insurance industry has added climate change and climate variability to its risk analysis.

The 2011 study I mentioned just before suggests that insurance companies are wise to be thinking about climate risk: the results showed that “weather variability is significantly related to variability in economic activity in every state and sector”, with sensitivity for each state and sector ranging from 2% to 14%.

The figure above shows the average economic sensitivity to weather variability for each state. Aggregating across all states and sectors, the study concluded that the range in US annual GDP affected by weather variability is approximately 3.36%, or $485 billion in 2008 dollars.

One way to interpret that result might be that we should be willing to spend up to half a trillion dollars to make our systems more resilient to climate risk, given that’s the price tag of weather sensitivity.

Of course, the potential impacts of increased climate vulnerability will not be evenly spread across industrial sectors or geographic regions. One sector that has been the focus of more detailed study thus far is agriculture.

Figure 1: Impact and capacity approaches to adaptation planning. From Vermeulen et al. 2013, "Addressing uncertainty in adaptation planning for agriculture."

Figure 1: Impact and capacity approaches to adaptation planning. From Vermeulen et al. 2013, “Addressing uncertainty in adaptation planning for agriculture.”

An article published last month investigated ways that policy-makers could make decisions about necessary measures to buffer agriculture against future climate impacts for different levels of climate change over different time frames.

The article noted that scientific data should be helping policy-makers to make better decisions by providing information of two kinds: projections of climatic impacts and assessments of adaptive capacity. These two kinds of assessments are illustrated in the figure at left. These assessments are, in essence, different kinds of risk assessments.

This is but one of an increasing number of articles I’m starting to see being published about how we might take steps to plan for future climate risk.

Uncertainty in general is not a reason for inaction; we take action based on a lack of certainty all the time in other areas of our lives and in society in general. I don’t think the conversation should hinge on waiting until scientists have near perfect certainty about how the climate might unfold going forward, especially since we most likely will never have that kind of certainty.

Instead, I think the conversation about climate risk should proceed the same way we talk about other kinds of risk: quantify the type and level of risk as best we can with the knowledge at hand, decide how much we value the systems at risk of impact, and then invest in mitigation measures equal to the potential loss in value if we were to lose those systems.

I realize that climate risk is not just another type of risk in our lives, akin to the chance of a plane crashing. We’re talking about the risk of change within an entire system that is much bigger than us, with high levels of uncertainty in some components and more certainty in others, and it’s risk that will be felt across political boundaries. It’s a larger degree of risk in all regards than anything we’ve had to deal with before.

But to quote the recent article about agricultural impacts (see page 1 of this link):

“The magnitude of plausible impacts, and costs of inaction or delayed action, mean that individuals and societies must undertake adaptation actions despite uncertainty.”

We don’t have to wait for 100% certainty about climate variability in order to make our societies more robust to environmental variability, more resilient to future disasters, and maybe even more profitable in the present. Many efficiency and waste reduction measures actually make business sense now, regardless of any environmental outcome. Other actions may provide new jobs, diversify the economy, make infrastructure less vulnerable and prepare people for increased hazards.

A website I came across recently – Climate CoLab – is a neat idea for crowd-sourcing ideas about climate change mitigation and reducing our vulnerability to climate risk. Ideas are split into different topics, such ‘Urban adaptation: Climate resilient cities’ and ‘Enabling adaptation’. If you have a few minutes, it’s good food for thought. How would you go about reducing our vulnerability to climate risk?

We’ve spent the past couple of months in this article series talking about some of the nitty gritty details of climate science and climate modelling. Although it involves a lot of physics, calculus, coding and other difficult subjects, in some ways the science is the easy part. Taking all that information and figuring out what we should do with it is much harder.

I am certain that I don’t have the answers, and I’m pretty certain that there isn’t one answer to be found. But I also don’t think it’s in our best interests to ignore the risk and hope it goes away. Humans are smart, resourceful and adaptable. We should act that way.

Yours in the pursuit of spaceships,


Missed what happened last time? Catch up on Episode 9 here


2 thoughts on “Wading into the Fire, Episode 10: Risk and uncertainty

  1. Thanks hun! So glad you had time to read the article, and that you liked it. And very pleased you are sharing with the global change folks. :)

    Posted by Rebecca Gianotti | July 4, 2013, 10:46 am
  2. This is an the most lucid concise summary of climate uncertainty and climate risk I’ve read, thanks Dr. B! I’m sharing this link and the ClimateCoLab with the Global Change instructors at my uni, who involve web resources in their class a lot.

    Posted by Virginia | July 4, 2013, 10:24 am

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