Cornell professor Natalie Mahowald offered straightforward and hopeful testimony on Earth’s warming atmosphere Feb. 13 in a three-hour hearing on climate change before the House Science, Space and Technology Committee.

“Scientific evidence is clear that human activities have caused [atmospheric] warming of 1.0 degrees Celsius since the late 1800s. If we keep warming at the same rate, we will pass 1.5 degrees Celsius around 2040,” said Mahowald, the Irving Porter Church Professor of Engineering in the Department of Earth and Atmospheric Sciences.

“Past emissions alone, however, are unlikely to cause 1.5 degrees of warming,” she told the committee. “In other words, if we can cut [carbon dioxide] emissions quickly enough, we can arrest the Earth’s warming trends to keep temperature increases below 1.5 degrees.”

Mahowald was invited to testify before the committee at the hearings on “The State of Climate Science and Why It Matters,” organized by chair Rep. Eddie Bernice Johnson (D-Texas). Mahowald was scheduled to appear in person, but bad weather canceled her flight and forced her to testify via live video.

Last October, the United Nations’ Intergovernmental Panel on Climate Change (IPCC) released its “Special Report on Global Warming of 1.5 Degrees Celsius.” Mahowald, also the faculty director for Cornell’s Atkinson Center for a Sustainable Future, served as the report’s lead author for a global team of scientists.

The IPCC report presented scenarios beyond 2040 if Earth does not contain and reduce greenhouse gases from its atmosphere; it also offered feasible and practical solutions for governments and policymakers.

“[Keeping temperatures below 1.5C warming] require extremely ambitious emission cuts – a 45 percent reduction in global emissions by 2030 – which is much more ambitious than agreed to by the Paris agreement,” she told the congressional committee.

“In fact, the voluntary reductions agreed to by the Paris agreement [in 2015] are likely to result in warming of about 3 degrees Celsius by 2100,” she said, explaining that while a 3-degree Celsius average temperature rise falls short of Paris agreement goals, it is lower than business-as-usual scenarios. If countries do nothing about climate change, there will likely be as much as a 5-degree Celsius average increase by 2100.

The lively testimony spurred questions from House members. Rep. Paul Tonko (D-N.Y.) asked how scientific understanding of climate change has changed in the last decade.

“Our understanding of climate science over the last 10 years has really benefited from the leaps in technology,” said Mahowald. “Computer simulations [and] big data analysis methods … [have] allowed us to see the impact of small changes in temperatures on humans and ecosystems.”

Tonko wanted to get a sense of the scientific urgency for solutions. “There is more urgency – every day there are more people on this planet, asking for more energy,” Mahowald said.

Rep. Ami Bera (D-Calif.) sought to understand the viability of atmospheric carbon dioxide sequestration. Mahowald said that it is an important, innovative new area of research, but more investment in the development and deployment of these technologies is needed. She noted that Cornell’s Atkinson Center is coordinating with other universities to promote this research.

In the context of how the U.S. interacts globally, Mahowald told the committee that the world is different from a half-century ago.

“Keeping America in a business and technological leadership role requires thoughtful investment in research, development and deployment of innovative technologies and techniques that our international competitors are already investing in,” she said. “[This] will result in a more prosperous, healthier and safer America and world.”