Category: Environment

An effective climate change solution may lie in rocks beneath our feet

Weathering of rocks like these basalt formations in Idaho triggers chemical processes that remove carbon dioxide from the air. Matthew Dillon/Flickr, CC BY

By Benjamin Z. Houlton, University of California, Davis

Why has Earth’s climate remained so stable over geological time? The answer just might rock you.

Rocks, particularly the types created by volcanic activity, play a critical role in keeping Earth’s long-term climate stable and cycling carbon dioxide between land, oceans and the atmosphere.

Scientists have known for decades that rock weathering – the chemical breakdown of minerals in mountains and soils – removes carbon dioxide from the atmosphere and transforms it into stable minerals on the planet’s surface and in ocean sediments. But because this process operates over millions of years, it is too weak to offset modern global warming from human activities.

Acid rain damage to buildings and monuments, like this sandstone statue in Dresden, Germany, is a form of chemical weathering. Slick/Wikipedia

Now, however, emerging science – including at the California Collaborative for Climate Change Solutions’ (C4) Working Lands Innovation Center – shows that it is possible to accelerate rock weathering rates. Enhanced rock weathering could both slow global warming and improve soil health, making it possible to grow crops more efficiently and bolster food security.

Rock chemistry

Many processes weather rocks on Earth’s surface, influenced by chemistry, biology, climate and plate tectonics. The dominant form of chemical weathering occurs when carbon dioxide combines with water in the soil and the ocean to make carbonic acid.

About 95% of Earth’s crust and mantle – the thick layer between the planet’s crust and its core – is made of silicate minerals, which are compounds of silicon and oxygen. Silicates are the main ingredient in most igneous rocks, which form when volcanic material cools and hardens. Such rocks make up about 15% of Earth’s land surface.

When carbonic acid comes in contact with certain silicate minerals, it triggers a chemical process known as the Urey reaction. This reaction pulls gaseous carbon dioxide from the atmosphere and combines it with water and calcium or magnesium silicates, producing two bicarbonate ions. Once the carbon dioxide is trapped in these soil carbonates, or ultimately washed into the ocean, it no longer warms the climate.

When carbonic acid dissolves calcium and magnesium silicate minerals, they break down into dissolved compounds, some of which contain carbon. These materials can flow to the ocean, where marine organisms use them to build shells. Later the shells are buried in ocean sediments. Volcanic activity releases some carbon back to the atmosphere, but much of it stays buried in rock for millions of years. Gretashum/Wikipedia, CC BY-SA

The Urey reaction runs at a higher rate when silicate-rich mountains such as the Himalayas expose fresh material to the atmosphere – for example, after a landslide – or when the climate becomes hotter and moister. Recent research demonstrates that humans can speed up the process substantially to help fight modern global warming.

Accelerated weathering

The biggest limit on weathering is the amount of silicate minerals exposed at any given time. Grinding up volcanic silicate rocks into a fine powder increases the surface area available for reactions. Further, adding this rock dust to the soil exposes it to plant roots and soil microbes. Both roots and microbes produce carbon dioxide as they decompose organic matter in the soil. In turn, this increases carbonic acid concentrations that accelerate weathering.

One recent study by British and Americans scientists suggests that adding finely crushed silicate rock, such as basalt, to all cropland soil in China, India, the U.S. and Brazil could trigger weathering that would remove more than 2 billion tons of carbon dioxide from the atmosphere each year. For comparison, the U.S. emitted about 5.3 billion tons of carbon dioxide in 2018.

Farming with rocks

One compelling aspect of enhanced weathering is that, in controlled-environment studies involving basalt amendments of soil, cereal grain yields are improved by roughly 20%.

As basalt weathers, it increases vital plant nutrients that can boost production and increase crops yields. Mineral nutrients such as calcium, potassium and magnesium create healthier soils. Farmers have been amending soil with rock minerals for centuries, so the concept is nothing new.

Spreading lime on a field in Devon, England to improve soil quality. Mark Robinson/Wikipedia, CC BY

At the Working Lands Innovation Center, we are conducting perhaps the largest enhanced weathering demonstration experiment on real farms in the world. We are partnering with farmers, ranchers, government, the mining industry and Native American tribes in California on some 50 acres of cropland soil amendment trials. We are testing the effects of rock dust and compost amendments on greenhouse gas emissions from the soil, carbon capture, crop yields, and plant and microbial health.

Our initial results suggest that adding basalt and wollastonite, a calcium silicate mineral, increased corn yields by 12% in the first year. Working with California’s greenhouse gas emissions trading program and our state’s diverse agricultural interests, we hope to establish a pathway that would offer monetary incentives to farmers and ranchers who allow enhanced rock weathering on their lands. We aim to create a protocol for farmers and ranchers to make money from the carbon they farm into the soil and help businesses and industry achieve their carbon neutrality goals.

Why negative emissions matter

Under the 2015 Paris climate agreement, nations have pledged to limit global warming to less then 2 degrees Celsius above preindustrial levels. This will require massive cuts in greenhouse gas emissions.

Pulling carbon dioxide from the air – also known as negative emissions – is also necessary to avoid the worst climate change outcomes, because atmospheric carbon dioxide has an average lifespan of more than 100 years. Every molecule of carbon dioxide that is released to the atmosphere through fossil fuel combustion or land clearing will remain there for many decades trapping heat and warming Earth’s surface. In an even faster version of enhanced weathering, scientists pump supercritical carbon dioxide underground into basalt formations, where it reacts with minerals to form new solid rock.

Nations need a portfolio of solutions to create negative emissions. Enhanced weathering is poised for rapid scale-up, taking advantage of farm equipment that’s already in place, global mining operations and supply chains that currently deliver fertilizers and seeds worldwide. By addressing soil erosion and food security along with climate change, I believe rock weathering can help humans escape the hard place we find ourselves in today.

Benjamin Z. Houlton, Professor of Global Environmental Studies, Chancellor’s Fellow and Director, John Muir Institute of the Environment, University of California, Davis

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

The Conversation

Science Friday Remote Learning Kit

Read the full post from Science Friday.

Science Friday Educate resources are always free and openly available, but we’ve also created a set of GoogleDoc assignments that can be easily assigned via Google Classroom, shared with students in your remote online learning platforms, or emailed to students directly. Simply add Science Friday’s Remote Learning Kit to your Google Drive, make a copy of any assignment you want to use, and assign away!

In the kit you will find:

So choose your own adventure! Dive directly into the folder, go through the indexed assignments below (using either the slide show or the descriptions), or check out the Remote Learning Kit Guide.

ENB’s summer vacation

We're taking a summer break. Posts resume July 22

Listening to Silence: Why We Must Protect the World’s Quiet Places

Read the full story at e360.

As more people push into once-remote areas, truly quiet spots — devoid of the noise of traffic or crowds of tourists — have become increasingly scarce. Now, a coalition of activists, scientists, and park officials are trying to preserve the last quiet places on the planet.

NASA, ESA and JAXA’s new tool shows our climate changed by Covid-19

Read the full story at Silicon Republic.

NASA, ESA and the Japanese Aerospace Exploration Agency (JAXA) have unveiled a new tool designed to give researchers and policymakers access to planet-wide changes in the environment and human society following the coronavirus pandemic.

The Covid-19 Earth Observation Dashboard integrates multiple satellite data records with analytical tools to allow user-friendly tracking of changes in air and water quality, climate, economic activity, and agriculture.

The future of finance is sustainable — and profitable

Read the full story from Accenture.

The finance ecosystem—clients and employees, shareholders and stakeholders—is striving for purpose and sustainability. Environmental, social and governance (ESG) considerations are at the forefront of financial decisions, supported by the Sustainable Development Goals (SDGs) and increased awareness of the climate emergency.

Sustainable finance is sometimes referred to as green finance, but it’s not just about reducing emissions or preventing environmental damage.

  • Environmental concerns include air and water pollution, deforestation and biodiversity. More generally, they relate to how a company performs as a steward of nature.
  • Social factors reveal how well a company manages relationships with employees, suppliers, customers and the communities with which it engages. Social issues vary from diversity in the workplace to human rights and labor standards across the supply chain.

How Lebanese environmentalists helped spark a green revolution

Read the full story in Grist.

Like youth activists around the world, Lebanese environmentalists are objecting to the status quo, which in Lebanon means protesting against rampant government corruption, a faltering economy, and a long list of environmental problems that dominate daily life. Hoping to capitalize on the current unrest, they are also working to set the country on a greener path.

On spring break from March 9-13

We're taking a short break. Posts resume March 16.

The Librarian’s Guide to Citizen Science

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We hope this guide will help you:

  • Learn more about citizen science and connections with libraries.
  • Discover STEM-related issues of interest or concern to your
  • Connect existing programs and communities to projects on SciStarter.
  • Access resources to help people learn about and engage in citizen science
  • Access information, resources, projects, and even instruments needed to collect and analyze data.
  • Plan Citizen Science Day events.
  • Sustain ongoing engagement in citizen science.

Hundreds of Environmental Groups Urge Massive Rulemaking Changes to Control Air Emissions at Plastics Manufacturing Facilities

Read the full story at JD Supra.

Led by the Center for Biological Diversity, a group of 364 environmental and other non-governmental organizations have filed a petition with the U.S. Environmental Protection Agency (EPA) to revise standards applicable to petro-plastics production facilities under sections 111 and 112 of the Clean Air Act (CAA). The petition requests that EPA impose unprecedented controls on such facilities and take the following actions, in short:

  1. List ethylene, propylene, polyethylene, and polypropylene production facilities as a source category under CAA section 111 and promulgate New Source Performance Standards (NSPS) for nitrogen oxides (NOx) and other pollutants from these sources.
  2. Require all on-site energy needs at those facilities be met with zero-emission energy.
  3. Update the NSPS for facilities that produce plastic precursors and resins to effectively eliminate the emissions of criteria pollutants and volatile organic compounds (VOCs) from new sources.
  4. Update the Generic Maximum Achievable Control Technology Standards (MACT) for Ethylene Production to effectively eliminate emissions of hazardous air pollutants from new and existing facilities.
  5. Update the NSPS and National Emissions Standards for Hazardous Air Pollutants (NESHAPs) to reflect advances in detection and control technologies.

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