Climate Change Is Shrinking Winter Snowpack and Harming Northeast Forests Year-Round
By Andrew Reinmann and Pamela Templer
Climate change often conjures up images of heat, drought and hurricanes. But according to the latest U.S. National Climate Assessment, released on Nov. 23, 2018, winters have warmed three times faster than summers in the Northeast in recent years. These changes are also producing significant effects.
Historically, more than 50 percent of the northern hemisphere has had snow cover in winter. Now warmer temperatures are reducing the depth and duration of winter snow cover. Many people assume that winter is a dormant time for organisms in cold climates, but decades of research now shows that winter climate conditions—particularly snowpack—are important regulators of the health of forest ecosystems and organisms that live in them.
In particular, our work over the last decade shows that declining snow cover may impair tree health and reduce forests' ability to filter air and water. Our latest study finds that continued winter warming could greatly reduce snow cover across the northeastern U.S., causing large declines in tree growth and forest carbon storage.
Changes in snowmelt-related streamflow timing for rivers, 1960-2014, show that snow is melting earlier in the year in the Northeast. USGCRP / NCA4
Snow as a Blanket
We study northern hardwood forests, which are dominated by sugar maple, yellow birch and American beech trees and span 85,000 square miles, from Minnesota and south-central Canada east to the Canadian Maritime Provinces and the northeastern U.S. These forests are famed for their vibrant fall colors. They generate revenue by drawing tourists, hikers, hunters and campers, and support timber and maple syrup industries. They also provide important ecological services, such as storing carbon and maintaining water and air quality.
When winter encroaches on this region, with temperatures often dipping well below freezing, every species needs insulation to cope. Tree roots and soil organisms like insects rely on deep snowpack for protection from cold—a literal blanket of snow. Even in sub-zero temperatures, if snow is sufficiently deep, soils can remain unfrozen.
Six decades of research from the Hubbard Brook Experimental Forest in New Hampshire—one of the longest-running studies anywhere—shows that winter snowpack is declining. Research conducted by other scholars indicates that if this trend continues, it will increase the likelihood of soil freeze-thaw cycles, with harmful effects on forest health.
How Acid Rain Transformed A Forest Into A Laboratory youtu.be
Why Northern Forests Need Snow
For more than 10 years we have manipulated winter snowpack at Hubbard Brook to study the effects of projected climate change on northern hardwood forests. In early winter, we head outdoors after each snowfall to remove snow from our experimental plots. Then we analyze how losing this insulating layer affects trees and soil.
We have found that in plots where we remove snow, frost penetrates a foot or more down into the soil, while it rarely extends more than two inches deep in nearby reference plots with unaltered snowpack. And just as freeze-thaw cycles create potholes in city streets, soil freezing abrades and kills tree roots and damages those that survive.
This root damage triggers a cascade of ecological responses. Dead roots decompose and stimulate losses of carbon dioxide from the soil. Trees take up fewer nutrients from soil, accumulate the toxic element aluminum in their leaves and produce less branch growth. Nitrogen, a key nutrient, can wash out of soils. Soil insect communities become less abundant and diverse.
Research plot at Hubbard Brook Experimental Forest with snowpack experimentally reduced Pam Templer, CC BY-ND
Declining Snowpack Affects Tree Growth
In our most recent paper, our climate and hydrological models show that the area of forests across the northeastern U.S. that receives insulating midwinter snowpack could decline by 95 percent by the year 2100. Today, 33,000 square miles of forests across northern New York and New England typically have snowpack for several months in winter. By the year 2100, this area could shrink to a patch smaller than 2,000 square miles—about one-fifth the size of Vermont.
This decline will undoubtedly harm the skiing and snowmobiling industries and expose Northeast roads to more freeze-thaw cycles. It also will significantly affect tree growth.
Historical and projected changes in spatial extent of insulating winter snowpack in the northeastern U.S. (left panels) and the distribution of sugar maple trees and forest area influenced by insulating winter snowpack (right panels)Reinmann et al., 2018, CC BY-ND
To assess the relationship between snowpack and tree growth, we used a specialized hollow drill bit called an increment borer to remove straw-sized wood cores from multiple sugar maple stems. Each of these trees experienced either natural winter snowpack or five consecutive years in which we removed early winter snowpack. When we sanded the cores and viewed them under a microscope, they revealed annual growth rings that we could use to understand how each tree responded to its environment.
Within just the first two years, our analyses showed a 40 percent decline in sugar maple growth from plots without snowpack. Growth rates remained depressed by 40 to 55 percent over the next three years. By contrast, there was no growth decline in the sugar maple trees in our reference plots where snow covered trees' roots in midwinter. These results are comparable to root mortality that other researchers observed in an earlier snow removal experiment at Hubbard Brook.
At Hubbard Brook, sugar maples can account for more than half of annual forest biomass accumulation. Consequently, changes in climate that reduce winter snowpack and increase soil freezing could reduce forest growth rates in the northern hardwood forest region by 20 percent just through their impacts on these trees. But we know that yellow birch also suffers root damage in response to soil freezing, so our estimate for changes in whole forest growth is likely to be low.
Removing a tree core with an increment borer Andrew Reinmann, CC BY-ND
Could warmer growing season temperatures compensate at least partially for this damage by stimulating rates of tree growth, as some research suggests? Very little work has been done to understand how forests in seasonally snow-covered regions will respond to interactive effects of climate change across seasons. To help fill this gap, we established the Climate Change Across Seasons Experiment at Hubbard Brook in 2013.
In this project we use buried heating cables to warm forest soils by 9 degrees Fahrenheit (5 degrees Celsius) during the snow-free season from April through November. In winter we use a combination of warming with buried heating cables and snow shoveling to induce soil freeze-thaw cycles. Our results so far show that root damage and reduced tree growth caused by winter soil freeze-thaw cycles are not offset by soil warming during the growing season.
Our work shows how often-overlooked changes in winter climate can impact forest ecosystems. Losing snowpack can reduce forest growth, carbon sequestration and nutrient retention, which will have important implications for climate change and air and water quality all year-round.
40 Scientists: Protecting #Forests Is an Urgent Climate Issue #TuesdayThoughts #TuesdayMotivation https://t.co/lXppfDYQtW— EcoWatch (@EcoWatch)1539094222.0
Andrew Reinmann is an assistant professor at CUNY Graduate Center. Pamela Templer is a professor at Boston University.
Disclosure statement: Andrew Reinmann receives funding from the U.S. Environmental Protection Agency. Pamela Templer has received funding from the National Science Foundation, National Oceanic and Atmospheric Administration, United States Department of Agriculture, and U.S. Geological Survey. She is on the governing board of the Ecological Society of America.
Reposted with permission from our media associate The Conversation.
By Victoria Masterson
Using one of the world's problems to solve another is the philosophy behind a Norwegian start-up's mission to develop affordable housing from 100% recycled plastic.
Sustainable Homes<p>UN-Habitat says an <a href="https://unhabitat.org/un-habitat-aims-to-use-plastic-waste-to-support-housing-for-all" target="_blank">estimated 60% of people living in urban areas of Africa are in informal settlements</a>. At the same time, between 1990 and 2017, African countries imported around 230 metric tonnes of plastic, "which mostly ended up in dump sites creating a massive environmental challenge," the agency adds.</p><p>UN-Habitat deputy executive director, Victor Kisob, said the aim of the partnership with Othalo was to "promote adequate, sustainable and affordable housing for all."</p>
Artist's impression of an Othalo community, imagined by architect Julien De Smedt. Othalo<p>Othalo's process involves shredding plastic waste and mixing it with other elements, including non-flammable materials. Components are used to build up to four floors, with a home of 60 square metres using eight tons of recycled plastic. A factory with one production line can produce 2,800 housing units annually.</p><p>Following successful laboratory tests, Othalo's factory in Estonia has started producing components to build three demonstration homes for Kenya's capital, Nairobi; Yaoundé, the capital of Cameroon and Dakar, the capital of Senegal.</p><p>Othalo founder Frank Cato Lahti has been developing and testing the technology since 2016 in partnership with <a href="https://www.sintef.no/en/" target="_blank">SINTEF</a>, a 70-year-old independent research organization in Trondheim, Norway, and experts at Norway's <a href="https://en.uit.no/startsida" target="_blank" rel="noopener noreferrer">University of Tromsø</a>.</p>
Othalo founder Frank Cato Lahti. Othalo<p>Almost <a href="https://www.un.org/development/desa/publications/2018-revision-of-world-urbanization-prospects.html" target="_blank">seven out of every 10 people in the world are expected to live in urban areas by 2050</a>. More than 90% of this growth will take place in Africa, Asia, Latin America, and the Caribbean.</p><p>"In the absence of effective urban planning, the consequences of this rapid urbanization will be dramatic," UN-Habitat warns.</p><p>Lack of proper housing and growth of slums, inadequate and outdated infrastructure, escalating poverty and unemployment, and pollution and health issues, are just some of the effects.</p><p>Mindsets, policies, and approaches towards urbanization need to change for the growth of cities and urban areas to be turned into opportunities that will leave nobody behind, UN-Habitat says.</p>
Pioneers of Change<p>Reimagining cities and communities for greater resilience and sustainability was a key topic at the<a href="https://www.weforum.org/events/pioneers-of-change-summit-2020" target="_blank"> World Economic Forum's Pioneers of Change Summit 2020</a>.</p><p>The digital event brought together innovators and stakeholders from around the world to explore solutions to the challenges facing enterprises, governments and society.</p><p>Opening the summit, <a href="https://www.weforum.org/events/pioneers-of-change-summit-2020/sessions/opening-plenary-8f731cbc65" target="_blank">Stephan Mergenthaler, the Forum's Head of Strategic Intelligence and a member of the Executive Committee</a>, said: "We need to change the way we produce, the way we live and interact in our cities to make this transition to net-zero emissions a reality…</p><p>"And as this year has illustrated so dramatically, we need to make every effort that we keep populations healthy, if we want to avoid jeopardizing all this progress."</p><p><em>Reposted with permission from </em><em><a href="https://www.weforum.org/agenda/2020/11/un-africa-recycled-plastic-housing/" target="_blank">World Economic Forum</a>.</em><a href="https://www.ecowatch.com/r/entryeditor/2649069252#/" target="_self"></a></p>
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By Dolf Gielen and Morgan Bazilian
John Kerry helped bring the world into the Paris climate agreement and expanded America's reputation as a climate leader. That reputation is now in tatters, and President-elect Joe Biden is asking Kerry to rebuild it again – this time as U.S. climate envoy.
Energy Is at the Center of the Climate Challenge<p>The <a href="https://science2017.globalchange.gov/chapter/1/" target="_blank">effects of climate change</a> are already evident across the globe, from <a href="https://theconversation.com/100-degrees-in-siberia-5-ways-the-extreme-arctic-heat-wave-follows-a-disturbing-pattern-141442" target="_blank">extreme heat waves</a> to <a href="https://science2017.globalchange.gov/chapter/12/" target="_blank">sea level rise</a>. But while the challenge is daunting, there is hope. Solar and wind power have become the <a href="https://www.irena.org/publications/2020/Jun/Renewable-Power-Costs-in-2019" target="_blank">cheapest forms of power generation globally</a>, and technology progress and innovation continue apace to support a transition to clean energy.</p><p>In the U.S. under a Biden administration, long-term national climate legislation will depend on who controls the Senate, and that won't be clear until after two run-off elections in Georgia in January.</p><p>But there is no shortage of <a href="https://www.bloomberg.com/features/2020-biden-climate-change-advice/" target="_blank">ideas for ways Biden</a> could still take action even if his proposals are blocked in Congress. For example, he could use executive orders and direct government agencies to tighten regulations on greenhouse gas emissions; increase research and development in clean energy technologies; and empower states to exceed national standards, <a href="https://www.reuters.com/article/us-autos-emissions-california/defying-trump-california-locks-in-vehicle-emission-deals-with-major-automakers-idUSKCN25D2CH" target="_blank" rel="noopener noreferrer">as California did in the past with auto emission standards</a>. A focus on a just and equitable transition for communities and people affected by the decline of fossil fuels will also be key to creating a sustainable transition.</p><p>The U.S. position as the world's largest oil and gas producer and consumer creates political challenges for any administration. U.S. forays into European energy security are often treated with suspicion. Recently, France blocked <a href="https://www.wsj.com/articles/frances-engie-backs-out-of-u-s-lng-deal-11604435609" target="_blank">a multi-billion dollar contract</a> to buy U.S. liquefied natural gas because of concerns about limited emissions regulations in Texas.</p><p>Strengthening cooperation and partnerships with like-minded countries will be critical to bring about a transition to cleaner energy as well as sustainability in agriculture, forestry, water and other sectors of the global economy.</p>
Creating a Global Sustainable Transition<p>How the world recovers from COVID-19's economic damage could help drive a lasting shift in the global energy mix.</p><p>Nearly one-third of Europe's US$2 trillion economic relief package <a href="https://www.bloomberg.com/news/articles/2020-07-21/eu-approves-biggest-green-stimulus-in-history-with-572-billion-plan" target="_blank" rel="noopener noreferrer">involves investments that are also good for the climate</a>. The European Union is also strengthening its 2030 climate targets, though each country's energy and climate plans will be critical for successfully implementing them. The <a href="https://joebiden.com/clean-energy/" target="_blank" rel="noopener noreferrer">Biden plan</a> – including a $2 trillion commitment to developing sustainable energy and infrastructure – is aligned with a global energy transition, but its implementation is also uncertain.</p><p>Once Biden takes office, Kerry will be joining ongoing <a href="https://www.un.org/en/conferences/energy2021/about#:%7E:text=The%20overarching%20goal%20of%20the,2030%20Agenda%20for%20Sustainable%20Development.&text=Accelerate%20delivery%20of%20United%20Nations,related%20issues%20at%20all%20levels." target="_blank" rel="noopener noreferrer">high-level discussions on the energy transition</a> at the U.N. General Assembly and other gatherings of international leaders. With the U.S. no longer obstructing work on climate issues, the G-7 and G-20 have more potential for progress on energy and climate.</p><p>Lots of technical details still need to be worked out, including international trade frameworks and standards that can help countries lower greenhouse gas emissions enough to keep global warming in check. <a href="https://www.carbonpricingleadership.org/what" target="_blank" rel="noopener noreferrer">Carbon pricing</a> and <a href="https://www.csis.org/analysis/how-can-europe-get-carbon-border-adjustment-right" target="_blank" rel="noopener noreferrer">carbon border adjustment taxes</a>, which create incentive for companies to reduce emissions, may be part of it. A consistent and comprehensive set of national energy transition plans will also be needed.</p><p>The global shift to <a href="https://www.irena.org/publications/2019/Jan/A-New-World-The-Geopolitics-of-the-Energy-Transformation" target="_blank">clean energy will also have geopolitical implications for countries and regions</a>, and this will have a profound impact on wider international relations. Kerry, with his experience as secretary of state in the Obama administration, and Biden's plan to make the climate envoy position part of the National Security Council, may help mend these relations. In doing so, the U.S. may again join the wider community of countries willing to lead.</p>
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