Even after heavy snow and rainfall in January, western states still face an ongoing drought risk that is likely to grow worse thanks to climate change. A whopping snowpack is good news, but it doesn’t reduce the need for long-term planning.

Confronted with a shrinking supply of water for agriculture, industry and residential uses, water agencies have pursued different strategies to encourage water conservation. They have nudged customers to reduce water use, limited outdoor watering and offered incentives to rip out lawns. On the supply side, there are innovative ideas about using heavy rains to recharge groundwater.

Basic economics teaches us that a higher price for water would encourage conservation. Up until now, however, concerns about harming low-income households have limited discussions about raising water prices to reduce demand.

We know that it’s hard to pay more for essential goods such as food, energy and water, especially for lower-income households. Rather than raising everyone’s water prices, we propose a customized approach that lets individual consumers decide whether to pay higher prices.

Who is most able and willing to conserve?

One of the most common challenges involved in making markets work well is what economists call asymmetric information – when one party has more access to relevant information than the other party. Think about buying or selling a car before online tools like Carfax were available. Owners and dealers knew more about what each car was really worth, so they had greater bargaining power than buyers.

The West has millions of water users with a broad range of incomes who consume water at widely varying levels. These consumers, including urban households, businesses and farmers, know more than water agencies do about how readily they can conserve water.

For example, a person who owns a home with a large green lawn and who is conservation-minded may need only a small incentive to switch to native, low-water plants. Some farmers may need only a small incentive to replace water-intensive alfalfa production with a less water-intensive crop.

Water agencies could elicit this private information by making a “take it or leave it” offer to water consumers. Some of California’s electric utilities have already experimented with this opt-in approach to encourage energy conservation.

Target the big users

Every western water district has access to customer-level big data on monthly and even daily water consumption. Agencies could use this information to identify the top 10% of water consumers in their territories, based on volume used – like the household in the Bel Air neighborhood of Los Angeles that used 11.8 million gallons of water in 2014.

Water agencies could randomly select customers among the largest water users in their service areas to participate in a small pilot study. Each invitee would receive an opt-in contract offering to pay them an annual fee for enrolling for three years in a water conservation program. In return, the price the consumer paid for each gallon of water would triple. This approach would give the consumer a guaranteed payment for participating and a clear incentive to use less water.

Data scientists would collect information on who accepted the offer and could survey invitees to learn how they decided whether or not to participate. Combining these two data sets would make it possible to test hypotheses about which factors determined willingness to accept the opt-in offer.

Using customer-level water consumption data over time, water agencies could track usage and compare customers who participated in the price increase program with others who turned down the offer. This would make it possible to estimate the water conservation benefits of introducing customized water prices.

There are many different ways in which water users could cut back, including swapping out old appliances or watering their gardens less often. Farmers could install more efficient irrigation systems. Customers who chose the payment in return for higher prices would decide which conservation strategies worked best for them.

Big potential insights

Conducting a pilot study using a randomly chosen sample of high-usage customers is a low-stakes strategy. If it fails to promote water conservation at a low cost, then a valuable lesson has been learned. If it succeeds, the same opt-in offer could be made to more high-usage customers.

Water agencies would need funds to support the pilot study, possibly from state or federal sources. Since pumping, treating and heating water uses energy, and thus creates greenhouse gas emissions, funds from the Inflation Reduction Act might be an option. Successful water conservation would help to slow climate change.

Today, most water agencies don’t know how responsive individual customers would be to higher prices. By conducting the type of pilot study that we have described, agencies could answer that question without raising prices for vulnerable households. If such initiatives succeeded, they could be replicated in other drought-prone areas of the West. Since farms consume the largest share of water in western states, it is especially important to learn more about farmers’ willingness to conserve.

Water is essential for life, but westerners have different abilities and willingness to conserve it. We recommend a strategy that rewards those who are most able to reduce their usage without punishing those who are least able.

Matthew E. Kahn, Provost Professor of Economics and Spatial Sciences, USC Dornsife College of Letters, Arts and Sciences and Bhaskar Krishnamachari, Ming Hsieh Faculty Fellow and Professor of Electrical and Computer Engineering, University of Southern California

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Over the past century, the Earth’s average temperature has swiftly increased by about 1 degree Celsius (1.8 degrees Fahrenheit). The evidence is hard to dispute. It comes from thermometers and other sensors around the world.

But what about the thousands of years before the Industrial Revolution, before thermometers, and before humans warmed the climate by releasing heat-trapping carbon dioxide from fossil fuels?

Back then, was Earth’s temperature warming or cooling?

Even though scientists know more about the most recent 6,000 years than any other multimillennial interval, studies on this long-term global temperature trend have come to contrasting conclusions.

To try to resolve the difference, we conducted a comprehensive, global-scale assessment of the existing evidence, including both natural archives, like tree rings and seafloor sediments, and climate models. Our results, published Feb. 15, 2023, suggest ways to improve climate forecasting to avoid missing some important slow-moving, naturally occurring climate feedbacks.

Global warming in context

Scientists like us who study past climate, or paleoclimate, look for temperature data from far back in time, long before thermometers and satellites.

We have two options: We can find information about past climate stored in natural archives, or we can simulate the past using climate models.

There are several natural archives that record changes in the climate over time. The growth rings that form each year in trees, stalagmites and corals can be used to reconstruct past temperature. Similar data can be found in glacier ice and in tiny shells found in the sediment that builds up over time at the bottom of the ocean or lakes. These serve as substitutes, or proxies, for thermometer-based measurements.

For example, changes in the width of tree rings can record temperature fluctuations. If temperature during the growing season is too cold, the tree ring forming that year is thinner that one from a year with warmer temperatures.

Another temperature proxy is found in seafloor sediment, in the remains of tiny ocean-dwelling creatures called foraminifera. When a foraminifer is alive, the chemical composition of its shell changes depending on the temperature of the ocean. When it dies, the shell sinks and gets buried by other debris over time, forming layers of sediment at the ocean floor. Paleoclimatologists can then extract sediment cores and chemically analyze the shells in those layers to determine their composition and age, sometimes going back millennia.

Climate models, our other tool for exploring past environments, are mathematical representations of the Earth’s climate system. They model relationships among the atmosphere, biosphere and hydrosphere to create our best replica of reality.

Climate models are used to study current conditions, forecast changes in the future and reconstruct the past. For example, scientists can input the past concentrations of greenhouse gases, which we know from information stored in tiny bubbles in ancient ice, and the model can use that information to simulate past temperature. Modern climate data and details from natural archives are used to test their accuracy.

Proxy data and climate models have different strengths.

Proxies are tangible and measurable, and they often have a well-understood response to temperature. However, they are not evenly distributed around the world or through time. This makes it difficult to reconstruct global, continuous temperatures.

In contrast, climate models are continuous in space and time, but while they are often very skillful, they will never capture every detail of the climate system.

A paleo-temperature conundrum

In our new review paper, we assessed climate theory, proxy data and model simulations, focusing on indicators of global temperature. We carefully considered naturally occurring processes that affect the climate, including long-term variations in Earth’s orbit around the Sun, greenhouse gas concentrations, volcanic eruptions and the strength of the Sun’s heat energy.

We also examined important climate feedbacks, such as vegetation and sea ice changes, that can influence global temperature. For example, there is strong evidence that less Arctic sea ice and more vegetation cover existed during a period around 6,000 years ago than in the 19th century. That would have darkened the Earth’s surface, causing it to absorb more heat.

Our two types of evidence offer different answers regarding the Earth’s temperature trend over the 6,000 years before modern global warming. Natural archives generally show that Earth’s average temperature roughly 6,000 years ago was warmer by about 0.7 C (1.3 F) compared with the 19th century median, and then cooled gradually until the Industrial Revolution. We found that most evidence points to this result.

Meanwhile, climate models generally show a slight warming trend, corresponding to a gradual increase in carbon dioxide as agriculture-based societies developed during the millennia after ice sheets retreated in the Northern Hemisphere.

How to improve climate forecasts

Our assessment highlights some ways to improve climate forecasts.

For example, we found that models would be more powerful if they more fully represented certain climate feedbacks. One climate model experiment that included increased vegetation cover in some regions 6,000 years ago was able to simulate the global temperature peak we see in proxy records, unlike most other model simulations, which don’t include this expanded vegetation.

Understanding and better incorporating these and other feedbacks will be important as scientists continue to improve our ability to predict future changes.

Ellie Broadman, Postdoctoral Research Associate in Climate Science, University of Arizona and Darrell Kaufman, Professor of Earth and Environmental Sciences, Northern Arizona University

This article is republished from The Conversation under a Creative Commons license. Read the original article.