Category Archives: Catastrophe Response

Operational Drought Monitoring

To reduce the risk to food security posed by drought, it’s crucial that we develop systems able to disseminate accurate information in a timely manner. Although doing this may seem straightforward in an era of near-ubiquitous satellite measurements and increasingly high-powered computational models, there are challenges relating both to the analysis and dissemination of information in an operational context. I’ll explore the challenges to producing operational drought forecasts and monitors in this post and write about the challenges of disseminating those forecasts in my next post.

Broadly, most operational drought systems may be subdivided into those that monitor current conditions (and perhaps make historical readings available) and those that provide projections for future conditions. Coincidentally, while doing some research for this post I started to compile a list of available hydrological monitors and data portals, which you can find here. I focused on drought, but included a few others as well.

Drought monitoring, despite the availability of near real-time satellite data, faces great challenges of data availability. In fact, methods using satellite measurements currently perform comparably to those using only a handful of gauge stations. Satellite measurements are additionally challenged with a short climatology, and inconsistencies between products. Never-the-less, these products provide unparalleled coverage for regions with sparse in-situ measurements (as is often the case in developing countries), where drought monitoring has a crucial role to play in maintaining adequate levels of food security.

Although it is often described as a “slow onset” phenomenon, the development and evolution of drought can be remarkably difficult to predict. Part of this stems from an incomplete understanding of the oceanic forcings of drought (ENSO), and part of it stems from the inherently chaotic nature of the atmosphere. A chaotic systems sensitive to initial conditions creates an environment in which errors propagate through models and forecasts quickly diverge from one another. Shukla et al., 2013 analyzed the skill of a forecast as it relates to either (1) the initial conditions of the model or (2) the forecast skill, and found that the skill was dependent on both region and time of the year.

One means of improving both the monitoring and the forecasting of drought is to further explore the limitations to current model skill under different climate regimes. While Smith et al., explored times of the year and regions, the underlying factors of substance are the moisture-temperature-atmosphere regimes. It shouldn’t be ignored that during a drought, the region of interest (which may normally be energy-limited) will be abnormally arid (and therefore potentially moisture-limited). This shift may in fact mean that where the initial condition of soil moisture was once not a limiting factor for forecast skill, it may become one during the forecast of drought recovery. In that sense, forecasting the onset as opposed to the recovery of a drought may be two problems with distinct characteristics.

A second aspect of the drought system that warrants further exploration is the dynamics of vegetation during the evolution of multi-seasonal droughts. Previous studies have pointed towards dynamic vegetation as one source of increased interannual variability in precipitation, however, the impact of this dynamic vegetation on evapotranspiration and therefore on the atmospheric boundary layer may also play a significant role in determining how a drought develops. This is particularly true during multi-year droughts when drying of the soil occurs more deeply than during one-season droughts.

How we talk about Hurricane Sandy

As perhaps I should have expected, Google provided an incredibly useful, accessible tool for visualizing information immediately leading up to and in the wake of Hurricane Sandy. The tool provided the projected the track, intensity, precipitation and storm surge associated with the event. Even more useful, it included Red Cross shelters, FEMA shelters and food distribution points. Although this is a particularly powerful example of how social media and the web may aggregate available information to anticipate and respond to extreme weather, as a country we need to shift from a mindset of disaster response to one of disaster prevention.

Calling events like Hurricane Sandy the “New Normal” is not only scientifically simplistic, – see Curtis Brainard’s and Andrew Revikin’s discussion of Hurricane Sandy in the context of climate change – psychologically it implies that we should simply accept the increasing cost of extreme weather events (a cost that has largely come from increasing our exposure to extreme weather as opposed to an increase in the incidence of that weather). There is little that could be more dangerous than implying that as the climate changes there is neither anything we can do to mitigate that change, nor anything we can do to reduce our vulnerability to that change. When communicating projections of changing intensity and distributions of extreme events, language should be chosen very carefully. The risk management community has already provided numerous studies on the effects that word choice has on public perception as they have sought to express the risks posed by low frequency, high intensity events.

The risk posed by extreme weather is often obtuse and difficult to explain. People rarely understand how dangerous an area may be unless they have lived through a disaster, but that does not mean that the scientific community has no responsibility to work on effective communication. There must be a concerted effort on the part of the scientific community to develop a lexicon appropriate for the public, and one appropriate for decision makers. Without this effort we risk falling further into a mindset of reaction. Into a mindset that decouples our actions from the losses that ensue. There are too many examples of this already.

Perhaps the most frustrating example of policy reflecting a complacent acceptance of increasingly frequent weather-related losses is flood zone development. In this case it is often not an issue of risk communication, anyone that cantilevers a restaurant out over the ocean can take a look out the window at high tide to get an idea of flood risk. Despite a clear understanding and communication of potential losses, zoning continues to encourage development in high risk areas. An Article in the Huff Post does a particularly good job of detailing the paradoxical calls to action made by Mayor Bloomberg in the midst of continuing coastal development in NYC. The article cites at least a half dozen ways in which the city and the state pioneered funding research to characterize the risks posed by sea level rise and storm surge, only to promptly dismiss the most substantive concerns raised by these reports.

As a country we need to firmly establish a starting point for bringing our policies on coastal development in line with our risk assessment research. Although altering already developed coasts is a more difficult conversation, wrought with both moral and political issues, preventing knowingly locating people in the path of a disaster should be less controversial. We can’t afford to continue sending the message through implemented policies that coastal development is a matter of economic interest only. There is a certain audacity to pausing the breakneck development of coastal areas only long enough to grieve for those lost in the storm before resuming work as before. I’m not implying a halt to development, only a balance of the economic benefits with the physical risks.