Greenhouse gas emissions (GHG)

Capturing carbon dioxide from the air or industries and recycling it can sound like a win-win climate solution. The greenhouse gas stays out of the atmosphere where it can warm the planet, and it avoids the use of more fossil fuels. But not all carbon-capture projects offer the same economic and environmental benefits. In fact, some can actually worsen climate change. I lead the Global CO₂ Initiative at the University of Michigan, where my colleagues and I study how to put captured carbon dioxide (CO₂) to use in ways that help protect the climate. To help figure out which projects will pay off and make these choices easier, we mapped out the pros and cons of the most common carbon sources and uses. Replacing fossil fuels with captured carbon Carbon plays a crucial role in many parts of our lives. Materials such as fertilizer, aviation fuel, textiles, detergents and much more depend on it. But years of research and the climate changes the world is already experienci...

Urban agriculture is expected to be an important feature of 21st century sustainability and can have many benefits for communities and cities, including providing fresh produce in neighborhoods with few other options. Among those benefits, growing food in backyards, community gardens or urban farms can shrink the distance fruits and vegetables have to travel between producers and consumers – what’s known as the “food mile” problem. With transportation’s greenhouse gas emissions eliminated, it’s a small leap to assume that urban agriculture is a simple climate solution. But is urban agriculture really as climate-friendly as many people think? Our team of researchers partnered with individual gardeners, community garden volunteers and urban farm managers at 73 sites across five countries in North America and Europe to test this assumption. We found that urban agriculture, while it has many community benefits, isn’t always better for t...

Reading down the lengthy final agreement of the COP28 United Nations climate conference held in December 2023, you’ll go a long way before finding a strong, active verb. The lengthy recitation of climate impacts “notes with concern” and occasionally with “significant concern” glaring gaps in countries’ current policies. But while countries volunteered pledges to act, they were less keen to have those pledges framed as binding agreements in the final text. Reactions to COP28’s conclusion have been understandably mixed. Going into the talks, the world was more on track to avert catastrophic warming than it would have been without the 2015 Paris Agreement, but a long way from where it needs to be. Even if all the pledges made at COP28 are implemented, the world will still exceed the Paris goal of keeping global warming under 1.5 degrees Celsius (2.7 Fahrenheit) compared to preindustrial temperatures....

Tropical forest landscapes are home to millions of Indigenous peoples and small-scale farmers. Just about every square meter of land is spoken for, even if claims are not formally recognized by governments. These local landholders hold the key to a valuable solution as the world tries to slow climate change – restoring deforested tropical landscapes for a healthier future. Tropical forests are vital to Earth’s climate and biodiversity, but a soccer field-size area of mature tropical forest is burned or cut down about every 5 seconds to clear space for crops and cattle today. While those trees may be lost, the land still has potential. Tropical forests’ combination of year-round sunshine and high rainfall can lead to high growth rates, suggesting that areas where tropical forests once grew could be valuable sites for reforestation. In fact, a host of international agreements and declarations envision just this. The Worl...

As government leaders and climate negotiators gather in Dubai for the COP28 United Nations climate conference, an enormous challenge looms over the proceedings: decarbonizing the global industrial sector. Industry has accounted for over 30% of total greenhouse gas emissions in recent years. It is the single largest emitting sector when accounting for its electricity use and heat generation. For countries to meet their goals to cut greenhouse gas emissions, stopping emissions from carbon-intensive industries like steel, cement and chemicals is imperative. There are promising technologies and innovations that can drive decarbonization in industry: green hydrogen fuel made from clean electricity and water, energy efficiency measures across supply chains, and carbon capture, use and storage to name a few. However, these solutions have yet to be deployed at the speed and scale required to slow global warming. Global industrial emissions will need to fall by 25% by 2030 for the...