Dear EarthTalk: What is so-called attribution science and how does it relate to climate change? ~ William C., New York, NY
Attribution science is a rapidly evolving field that aims to understand the link between human activities and extreme weather. By discerning the extent to which climate change affects the frequency and intensity of these events, attribution science plays a crucial role in climate research. Understanding this relationship is essential for developing effective climate policies and enhancing global resilience to climate impacts.
Attribution science seeks to quantify the influence of climate change on specific weather events. It involves the use of sophisticated computer models and extensive data analysis to compare current climatic conditions with hypothetical scenarios devoid of human-induced changes. The primary objective is to determine how climate change alters the probability and severity of extreme weather events. Key terms in this field include: climate, which refers to long-term atmospheric conditions; climate change, indicating significant changes in these conditions over time; computer models, which simulate climate behavior under various scenarios; and data, which provide the empirical basis for these simulations.
There are two main types of attribution science: event attribution and source attribution. Event attribution focuses on how climate change affects specific extreme weather events. For instance, human-caused climate change significantly increased the likelihood of the 2019 European heatwave and made the 2018 South African drought three times more likely. Moreover, climate change increased the rainfall during Hurricane Harvey by at least 15 percent and nearly doubled the area burned by wildfires in Western US forests. Meanwhile, source attribution identifies the pollutants and activities contributing to climate change. It involves measuring atmospheric concentrations, analyzing emissions data, and conducting modeling studies to pinpoint specific sources of greenhouse gasses.
Attribution science has roots in the 1990s and has advanced considerably with the development of more sophisticated computer models and statistical methods. These advancements have enhanced its accuracy and reliability, allowing for more precise connections between human activity and climate-related events.
The methodology involves comparing real-world data with counterfactual models—simulations of the world without human-induced climate change. High-quality observational data is crucial for these comparisons, but there are challenges, particularly in data-scarce regions like developing countries. Future research aims to develop new methods suitable for such regions with limited data, examine regional impacts, and quantify slow-onset phenomena like sea level rise. These advancements will enhance our understanding of climate impacts and inform more effective adaptation strategies. Attribution science is crucial for shaping climate policies and strategies. Communicating the links between specific weather events and climate change raises public awareness and influences real-time decisions. Insights from attribution studies help communities build resilience against future climate risks.
MORE INFORMATION: https://blog.ucsusa.org/delta-merner/from-research-to-action-the-growing-impact-of-attribution-science/; https://yaleclimateconnections.org/2024/05/how-do-scientists-know-how-much-climate-change-affects-a-hurricane-a-heat-wave-a-drought-and-more/.
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Dear EarthTalk: I live in Massachusetts and often walk in the woods. It seems as if there are endless pests and diseases attacking our native trees. There are so many fallen or dead trees in the woods now. Is there hope for our forests? ~ Molly Goodwin, via e-mail
In colonial days, wood was a hot commodity in New England. It was so widely used for agriculture and other industries that, between the 17th and 20th centuries, several New England states saw a 60 percent reduction in woodlands. Today, roughly 80 percent of New England is wooded again, but over 99 percent of the trees were planted within the last 100 years. These new-growth forests are remarkably homogenous, being evenly spaced, similar in height and size, and primarily of the same species.
Though trees have significantly rallied, financial support for New England land conservation has dropped by half since 2008. The annually conserved land area declined sixfold in just a decade, from 333,000 acres in the early 2000s to just 50,000 acres since 2010. A Harvard study showed that New England is losing 65 acres of woods daily to development, half which is related to increasing residential demands. Beyond development threats, the lack of biodiversity in these homogenous new-growth forests makes them particularly vulnerable to environmental changes, invasive species and infectious diseases.
Rising temperatures put new-growth trees at risk of droughts, soil deterioration and extreme weather events. Invasive southern insects like the gypsy moth and Southern pine beetle are migrating northward as historically colder climates begin to warm. These bugs defoliate trees, bore bark to feed on tree sap, and cause needle loss. And invasive plants are now outcompeting native ones by releasing enzymes into the soil that limit the native plant growth and form dense thickets that shade out native species.
Citizens, scientists and ecologists must work together to prevent a ‘bare New England.’ State and local governments have the power to strengthen conservation efforts. For one, the Massachusetts Community Preservation Act permits towns to impose a surcharge of up to three percent on property taxes which is then diverted to preservation. Participation is voluntary, but 56 percent of towns have opted in.
Sustainable forestry is needed to prevent more tree loss. Selective cutting removes specific trees rather than clear-cutting. Building upwards instead of outwards reduces land clearance. Improving paper and wood recycling efforts reduces the demand for raw materials from forests. Removing invasive species would improve soil health and enhance ecosystem resilience. However, the process is labor-intensive and costly. Despite these challenges, finding the right balance between conservation, demand reduction, and invasive species removal may be the key to preserving the New England forests.
MORE INFORMATION: https://www.massaudubon.org/nature-wildlife/invasive-plants-in-massachusetts.
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Dear EarthTalk: What’s the story with so-called “deadbeat dams” causing ecosystem problems across the country? ~ George H., Seattle, WA
The invention of dams was certainly one of humanity’s most innovative feats of engineering. Able to harness power from the water currents, reserving water and effectively controlling floods, dams have been crucial to civilizations since 3,000 B.C. Modern dams are made of concrete and steel, built to withstand tons of water pressure. But over time, many dams have fallen into disrepair and no longer serve their intended purposes. These dams lost to time are called “deadbeat dams.”
Deadbeat dams disrupt surrounding ecosystems by altering water temperature and hindering fish migration patterns. When dams impede river the flows, water temperatures increase, decimating fish sensitive to temperature changes and prevent fish migrations, further damaging their chances of survival.
Loss of fish populations can devastate the entire surrounding ecosystem as they are the primary food source for many animals including birds and mammals, so they are integral to maintaining balance in the food web. Communities that rely on fish in their diet can also be largely affected. The Kwoneesum Dam was abandoned in the 1980s and has since then obstructed 6.5 miles of the Washougal River, preventing the Native nations’ access to the salmon and steelhead population that nourished them for generations.
Effective and safe dam removal is a large and costly challenge, often taking many years and millions of dollars. When removing dams, workers must be careful to ensure debris and sediment from the construction site are not released into the environment, and to test for possible contaminants within the sediment. In 1973, the Fort Edward Dam on New York’s Hudson River was removed without its sediments tested for contaminants. According to the Columbia Climate School, this resulted in “tons of sediment laden with toxic PCBs” washing downstream and “affecting human and wildlife health.”
Across the U.S., 20,000 of the 90,000 total dams are considered unsafe. But due to logistical and financial difficulties, dam removal has been slow: Since 1912, only 2,000 dams have been removed. In recent years, native communities have made headway in advocating for deadbeat dam removals. Through extensive efforts on their part and that of policymakers, millions of dollars have been raised to fund dam removal across the Pacific Northwest. The Seattle Times reports that, in 2024, $40 million from a $75 million Washington state act will go towards “nine [dam removal] projects led by tribal nations.” To ensure the longevity of our precious natural resources, deadbeat dams is an issue we can no longer overlook. Their presence is a constant disruption to nature and to those dependent on nature.
MORE INFORMATION: www.seattletimes.com/seattle-news/climate-lab/why-deadbeat-dam-removals-are-so-difficult-in-wa-pnw.
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