As world leaders negotiate rules for cutting greenhouse gas emissions at the COP24 meeting in Poland, US, cities have a vested interest in the outcome. About 85 percent of Americans live in cities, and urban areas produce of our nation’s greenhouse gas emissions. Many cities are highly vulnerable to climate change impacts, such as flooding and heat waves.
Cities are central to shaping effective solutions, too. After US President Donald Trump announced in 2017 that he planned to from the , more than – representing 69 million people – . Some cities are going further and aiming for net carbon neutrality by 2050. Their efforts are sorely needed: According to a 5 December report from the Global Carbon Project, , the largest rise in seven years.
Mayors believe they can while making their communities greener and cleaner. To succeed, they will have to take bold policy actions and demonstrate that emissions are declining. However, tracking greenhouse gas emissions requires models, forecasting tools and lots of data. Today most of that information is organised at the or , not at city scales.
Now, though, this is changing. Over the last decade, our work on has shown that with the right combination of , it is possible to independently quantify and emissions from urban areas. Just as researchers measure local smog concentrations for public health, they now can measure local greenhouse gases for climate action.
Move Fast and Measure Carefully
As an example, by reducing urban and suburban vehicle travel, making electric vehicles more affordable, and expanding use of public transit, cities can cut carbon emissions and also reduce local air pollution. But such actions require very long lead times. The much-anticipated in Los Angeles has a construction timeline of 14 years, but was preceded by decades of planning and negotiation.
To track actual progress over time, urban agencies also need to generate and share local-scale information. Nongovernment organisations like the and have produced tools that make this kind of data more accessible and transparent, but it is still challenging to . Resource constraints, data gaps and shifting local priorities make it difficult for many cities to regularly report emissions in a consistent way.
We work with a where researchers are quantifying greenhouse gas emissions across urban regions. For example, in Boston we are analysing how influence greenhouse gas levels, and how local traffic congestion of carbon dioxide as well as air pollutants. And in Salt Lake City, researchers have with sensors to measure greenhouse gases and air quality in real time.
Remote sensing is another promising data source. are already , with . The Orbiting Carbon Observatory 3 , soon to be installed on the International Space Station, will focus on observing cities and urban areas across the globe. It will provide scientists and city governments regularly with vital data on local carbon dioxide concentrations.
Scientists can use models like this one from NASA’s Orbiting Carbon Observatory (OCO-2) satellite to better understand and predict where CO2 concentrations could be especially high or low, based on activity on the ground.
Regular air measurements aren’t just valuable for measuring progress. They also can help researchers identify unknown emissions sources through “atmospheric detective work,” spotting sources that aren’t well controlled or illicit “dumping” of pollutants into the atmosphere.
This happened in 2014, when scientists using satellite instruments to monitor atmospheric methane concentrations detected in northwestern New Mexico that did not appear in any existing emissions inventories. A targeted field campaign using aircraft and ground-based sensors narrowed down the source to .
More recently, atmospheric measurements published in May 2018 detected in concentrations of a chemical known as CFC-11 that had been targeted for phaseout under the 1987 . Using atmospheric models, researchers narrowed down the source region of these emissions to . Investigations subsequently identified over 18 companies in China .
The Problem with Offsets
Cities are unlikely to cheat on their own pledges in this way, but they may use strategies that are hard to measure or verify. A key example is buying energy and carbon credits instead of directly reducing emissions. In these transactions, buyers receive credit for investing in renewable energy or other green initiatives, such as planting trees, to “offset” their own carbon-intensive activities.
Buying offsets is a popular way to show support for the environment. For example, the ride sharing company Lyft has pledged to buy enough carbon offsets that “.” And cities may meet clean energy commitments by from power providers outside their limits.
Offset projects can be very cost-effective and important for reducing overall US emissions, but they may not do anything for improving local air quality in cities. Those Lyft drivers will still be generating air pollution. So will the urban power plants that keep running while local governments buy green power credits from sources elsewhere.
As these examples show, the more cities rely on offsets to meet their climate targets, the harder it will be to assess whether they are actually reducing their contributions to climate change.
If you can't measure it, you can't manage it. Tomorrow, @Bloomberg’s annual #D4GX will bring together leaders from the public and private sector to explore how data science methods can improve civic and social outcomes.— Mike Bloomberg (@MikeBloomberg) September 15, 2018
You Can’t Manage What You Can’t Measure
To sustain momentum and achieve their climate goals, we believe US cities should embrace the transparency and validation that direct measurements can provide to show that progress is real and not just on paper. In our view, it also is time for a major push to connect local climate action plans across cities with observations and data. Ambitious climate targets are a key first step, but now cities need to show their residents – and each other – that they are making verifiable progress.
(This is an opinion piece and the views expressed above are the authors’ own. The Quint neither endorses nor is responsible for the same. This article was originally published on The Conversation. Read the original article here.)
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