Tag Archives: James A. Rising

1 Million Years of Stream Flow Data

The 9,322 gauges in the GAGES II database are picked for having over 20 years of reliable streamflow data from the USGS archives. Combined, these gauges represent over 400,000 years of data.
They offer a detailed sketch of water availability over the past century. But they miss the opportunity to describe a even fuller portrait.

In the AWASH model, we focus on not only gauged points within the river network and other water infrastructure like reservoirs and canals, but also on the interconnections between these nodes. When we connect gauge nodes into a network, we can infer something about the streamflows between them. In total, our US river network contains 22,619 nodes, most of which are ungauged.

We can use the models and the structure of the network to infer missing years, and flows for ungauged junctions. To do so, we create empirical models of the streamflows for any guages for which we have a complete set of gauged of upstream parents. The details of that, and the alternative models that we use for reservoirs, can be details for another post. For the other nodes, we look for structures like these:

Structures for which we can infer missing month values, where hollow nodes are ungauged and solid nodes are gauged.

If all upstream values are known, we can impute the downstream; if the downstream value is known and all but one upstream values are known, we can impute the remaining one; if upstream or downstream values can be imputed according to these rules, they may allow other values to be imputed using that new knowledge. Using these methods, we can impute an average of 44 years for ungauged flows, and an average 20 additional years for gauged flows. The result is 1,064,000 years of gauged or inferred streamflow data.

We have made this data available as a Zenodo dataset for wider use.

Economic Damages from Climate Change

When I tell people I study climate change, sooner or later they usually ask me a simple question: “Is it too late?” That is, are we doomed, by our climate inaction? Or, less commonly, they ask, “But what do we really know?”

With our new paper, Estimating Economic Damage from Climate Change in the United States, I finally have an answer to both of these questions; one that is robust and nuanced and shines light on what we know and still need to understand.

The climate change that we have already committed is going to cost us trillions of dollars: at least 1% of GDP every year until we take it back out of the atmosphere. That is equivalent to three times Trump’s proposed cuts across all of the federal programs he cuts.

If we do not act quickly, that number will rise to 3 – 10% by the end of the century. That includes the cost of deaths from climate change, lost labor productivity, increased energy demands, costal property damage. The list of sectors it does not include– because the science still needs to be done– is much greater: migration, water availability, ecosystems, and the continued potential for catastrophic climate tipping points.

But many of you will be insulated from these effects, by having the financial resources to adapt or move, or just by living in cooler areas of the United States which will be impacted less. The worst impacts will fall on the poor, who in the Untied States are more likely to live in hotter regions in the South and are less able to respond.

Economic damages by income deciles

One of the most striking results from our paper is the extreme impact that climate change will have on inequality in the United States. The poorest 10% of the US live in areas that lose 7 – 17% of their income, on average by the end of the century, while the richest 10% live where in areas that will lose only 0 – 4%. Climate change is like a subsidy being paid by the poor to the rich.

That is not to say that more northern states will not feel the impacts of climate change. By the end of the century, all by 9 states will have summers that are more hot and humid than Louisiana. It just so happens that milder winters will save more lives in many states in the far north than heat waves will kill. If you want to dig in deeper, our data is all available, in a variety of forms, on the open-data portal Zenodo. I would particularly point people to the summary tables by state.

Economic damages by county

What excites me is what we can do with these results. First, with this paper we have produced the first empirically grounded damage functions that are driven by causation rather than correlation. Damage functions are the heart of an “Integrated Assessment Model”, the models that are used by the EPA to make cost-and-benefit decisions around climate change. No longer do these models need to use out-dated numbers to inform our decisions, and our numbers are 2-100 times as large as they are currently using.

Second, this is just the beginning of a new collaboration between scientists and policy-makers, as the scientific community continues to improve these estimates. We have built a system, the Distributed Meta-Analysis System, that can assimilate new results as they come out, and with each new result provide a clearer and more complete picture of our future costs.

Finally, there is a lot that we as a society can do to respond to these projected damages. Our analysis suggests that an ounce of protection is better than a pound of treatment: it is far more effective (and cheaper) to pay now to reduce emissions than to try to help people adapt. But we now know who will need that help in the United States: the poor communities, particularly in the South and Southeast.

We also know what needs to be done, because the biggest brunt of these impacts by far comes from pre-mature deaths. By the end of the century, there are likely to be about as many deaths from climate change as there are currently car crashes (about 9 deaths per 100,000 people per year). That can be stemmed by more air-conditioning, more real-time information and awareness, and ways to cool down the temperature like green spaces and white roofs.

Our results cover the United States, but some of the harshest impacts will fall on poorer countries. At the same time, we hope the economies of those countries will continue to grow and evolve, and the challenges of estimating their impacts need to take this into account. That is exactly what we are now doing, as a community of researchers at UC Berkeley, the University of Chicago, and Rutgers University called the Climate Impacts Lab. Look for more exciting news as our science evolves.

Probabilistic Coupling

Environmental Modelling & Software has just published my work on a new technique for coupling models: Probabilistic Coupling. My thoughts on coupled models had been percolating for a couple years, before a session at the International Conference on Conservation Biology in 2013 offered me a chance to try it out.

Probabilistic coupling has three main goals:

  • Allowing models to be coupled without distortionary feedback
  • Allowing multiple models to inform the same variable
  • Allowing models to be coupled with different scales

With these three features, the very nature and approach of coupling models can change. Current model coupling requires carefully connecting models together, plugging inputs into outputs, and then recalibrating to recover realistic behavior again. Instead, this allows for what I call “Agglomerated Modeling”, where models are thrown together into a bucket and almost magically sort themselves out.

The code for the model is available within the OpenWorld framework, as the coupling example.