Computing Profession Editor's letter

What Do DDT and Computing Have in Common?

  1. Article
  2. References
CACM Editor-in-Chief Andrew A. Chien

Writing on the 50th Earth Day brings to mind the origins of U.S. environmental movement.

DDT is, of course, Bis(4-chlorophenyl)- 1,1,1-trichloroethane, perhaps the most effective insecticide ever invented. DDT was used widely with remarkable effectiveness in the 1940s and 1950s to combat malaria, typhus, and the other insect-borne human diseases. Its efficacy was unsurpassed in insect control for crop and livestock production, and even villages and homes. In short, it was a wonder chemical.7

Following Rachel Carson's Silent Spring2 highlighting DDT's persistent negative environmental effects, including precipitous declines in wildlife and multiple human health problems, Carson's advocacy led to the banning of DDT and the creation of the U.S. Environmental Protection Agency (1970).

DDT and computing both have amazing benefits, but now that I've got your attention, my point is they also both have significant negatives. And, their good doesn't offset their bad. So, in addition to reaping computing's bounty (education, information access, entertainment, commerce, efficiency, and more), we should "own" and work to reduce the negative impacts of computing.

What are computing's negative environmental impacts?

  • Carbon emissions of >500 million metric tons of CO2/year
  • E-waste of >50 million metric tons/year

Both are growing fast and need attention!3 Even AI is an exemplar of computing's dual nature—driving remarkable advances whilst driving increased computing carbon emissions.1,4

Is this critical? Is it urgent? Climate change is regularly called an existential crisis for humanity. Further, as Greta Thunberg, who led worldwide protests in 2019 that dwarfed all previous environmental rallies, points out—all must do their part to solve our climate challenge.

"I'm just a technologist, what can I do"? Here are some ideas.

Carbon emissions from computing are growing: the hyperscale cloud is the headline driver—with power consumption increasing 6.5-fold from 2010 to 2018, and even faster since 2018.5 But cloud computing can become truly carbon neutral, 7×24 hourly matching! The opportunity for this transformation is the rise of low-cost renewable generation in power grids that produces excess supply (Terawatt-hours) of carbon-free power worldwide. Despite the challenge of the volatility of these renewable excesses, research has proven models that "flex" computing in space and time, and thereby produce zerocarbon compute can be scientifically and economically feasible.8

For emissions, we should adopt a goal of zero carbon emission computing for operations. To achieve this, we must design applications and workloads and manage resources to time- and space-shift computing to align with the availability of renewables. This is possible for the cloud, due in no small part to efficient hyperscale datacenters, global scale, and spectacular management and optimization systems! Lest you still consider this idealistic, there is real movement in this direction.6

Computing e-waste is growing rapidly with the explosion of IoT, universal Internet access, and 5G networks. We must extend the lifetime of computing hardware—servers and clients—and increase the circularity of the computing economy far beyond the <20% of e-waste that avoids landfills today.

For e-waste, we should adopt a goal to double the lifetime of computing hardware, increasing server lifetime far beyond six years for cloud and enterprise computing, and for smartphones as high as eight years. In vertical, global ecosystems controlled by a few players, there are increasing opportunities. In a new NSF OAC project we are working with universities to create an extended ecosystem for servers that combines zero-carbon operation with extended lifetime.

What can software professionals do? Software can be designed and tuned for efficiency and memory size, enabling client devices to remain viable for over eight years. Software upgrades should have as a design goal to avoid driving client hardware obsolescence. For the cloud, software professionals should reengineer applications to be time flexible, adapting the availability of excess renewable energy.

What can hardware professionals do? Designs can be repairable and upgradeable, and complemented by network services for longer life. Products designed for de-manufacture can reduce environmental pollution and enable circular economy. Create and drive circular economy practice—for all computing hardware.

Changing how computing does business is important. If we undertake these goals, our technologies will be both more flexible and more broadly useful. And perhaps we will attract and inspire more young computing professionals!

Happy 50th Earth Day! I'm looking forward to zero-carbon and zero e-waste computing at the 60th in 2030!

Be safe and be well!

Andrew A. Chien, EDITOR-IN-CHIEF

    1. AI for Climate Change, 2020; https://www.climatechange.ai/

    2. Carson, R. Silent Spring. Houghton-Mifflin, 1962, ISBN-0618249060.

    3. Chien, A.A. Owning computing's environmental impact. Commun. ACM 62, 3 (Mar. 2019).

    4. Hao, K. Training a single AI model can emit as much carbon as five cars in their lifetimes: Deep learning has a terrible carbon footprint. Technology Review (June 6, 2019).

    5. Masanet, E., Shehabi, A., Lei, N., Smith, S. and Koomey, J. Recalibrating global data center energy-use estimates. Science 367, 6481 (2020) 984–986.

    6. Radovanovic, A. Our data centers now work harder when the sun shines and wind blows. Google Data Centers and Infrastructure blog (Apr. 22, 2020); https://bit.ly/2SeEKbE

    7. Rogan, W. J. and Chen, A. Health risks and benefits of bis (4-chlorophenyl)-1, 1, 1-trichloroethane (DDT). The Lancet 366, 9487 (2005), 763–773.

    8. Yang, F. and Chien, A. Large-scale and extreme-scale computing with stranded green power: Opportunities and costs. IEEE Trans. Parallel and Distributed Systems 29, 5 (May 1, 2018), 1103–1116.

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