In the first — and possibly only — debate of the US presidential candidates Kamala Harris and Donald Trump On September 10th, science issues were overshadowed by economics, immigration and national security. Still, Harris and Trump made some vague comments on issues such as climate change and scientific competitiveness.

Neither candidate revealed much about specific policies they would like to implement if they win the election in November. But researchers say that wasn't necessarily the goal.

“We rarely learn anything substantive in debates, but we do form impressions of who the candidates are as people,” says Matt Carlson, a media researcher at the University of Minnesota in Minneapolis. “This debate offered a particularly stark contrast between Trump’s angry gut reactions and Harris’ optimistic attitude.”

Analyzed hereNature, what the candidates have said — and what they haven't — about science, and what researchers think of the candidates' positions.

Abortion and women's health

This was one of the big topics of the debate. Harris expressed her support for restoring protections fromRoe v. calf— the U.S. Supreme Court ruling that once granted the right to abortion until a fetus can live outside the womb — typically around 23 weeks of pregnancy. It was repealed in 2022 from a majority conservative court, from which three were appointed during Trump's presidency. Trump said the decision on whether to ban abortions should be left to each U.S. state and did not directly answer a question about whether he would oppose a national abortion ban if it were on his desk.

Harris also spoke about how abortion bans exist in various states the health care by saying women who experience miscarriages are being denied vital help in emergency rooms. That statement is true, says Daniel Grossman, an obstetrician-gynecologist and director of Advancing New Standards in Reproductive Health, a research program at the University of California, San Francisco. His team released a report earlier this week, which details, among other things, how people with pregnancy complications have been put at risk because of delayed access to abortion services.

Trump stated that abortions should be allowed in cases of rape, incest and when the pregnant person's life is in danger. Grossman notes that implementing these exceptions in practice is very difficult. “Medicine is not black and white,” he says. “How threatened must the life of the pregnant person be before someone is eligible for a legal abortion?” Doctors worried about criminal prosecution have difficulty making such decisions, he adds.

China and scientific competitiveness

When asked about the economy, the candidates argued about tariffs. Trump praised the tariffs his administration has placed on goods from China, which he said have injected money into the economy. Harris countered that during his presidency, Trump "sold American chips to China to help them improve and modernize their military technology." The United States should focus on domestic innovation, she said, which means “investing in technology-focused companies in the U.S. to win the AI ​​and quantum computing race.”

While it's true that during the first phase of the Trump administration, U.S. companies like Santa Clara, California-based Nvidia exported advanced semiconductor chips and high-performance GPUs to China, those technology exports later became increasingly restricted, says Denis Simon, a non-resident fellow at the Quincy Institute for Responsible Statecraft, a foreign policy think tank in Washington DC. The government of Harris and the current US President Joe Biden followed with further restrictions and the Chips and Science Act, which authorized more funding for U.S. research agencies to promote innovation and strengthen domestic semiconductor production.

Simon says it's a missed opportunity that Harris didn't talk about it, even though he thinks she had the upper hand in the debate. As far as China is concerned, he would have liked either candidate to have a clear policy. “It’s the second largest economy in the world,” says Simon. “What China does or doesn’t do is an important part of the international landscape.”

The United States cannot isolate itself from China, says Caroline Wagner, a science, technology and international affairs specialist at Ohio State University in Columbus. "We have benefited a lot from having China in the knowledge system. You can't close the door without getting your fingers caught." The world also cannot make meaningful progress on global challenges like climate change and food security if the United States does not have a cooperative relationship with China, agrees Simon.

Climate change and energy

At the end of the debate, the two candidates were asked directly about climate. Harris pointed to climate-related disasters and praised the Biden administration's historic investments in clean energy and advanced manufacturing. “We know we can actually overcome this problem,” she said. However, as the debate progressed, Harris found herself on the defensive about oil and gas production, and particularly the controversial 'fracking' technologies that have allowed companies to expand oil and gas production in the US. Although she once said she was against it, she repeatedly emphasized her support for fracking while also pointing out that she supported the use of various energy sources.

Trump didn't answer the question and instead talked about imports from China, ending with personal attacks on Biden. Earlier in the debate, however, he stressed the need to increase fossil fuel production and warned that a Harris administration would lead the United States to rely on "windmills" and solar energy systems, which he said take up too much land and are "not good for the environment." (It is true that renewable energy systems can have significant environmental impacts 1, but researchers have argued that the damage from the production and burning of fossil fuels, which causes millions of premature deaths annually due to air pollution, is changing the climate 2, are far worse.)

Michael Mann, a climate scientist at the University of Pennsylvania in Philadelphia, says there is room for growth in Harris' approach to climate change. In line with the Biden administration, it is taking a “demand-side approach” to reducing emissions by promoting renewable energy, which is “not enough,” he says. But it at least accepts the scientific consensus and recognizes the “catastrophic impact on human health,” while a second term for Trump, who once called climate change a hoax, would represent “the final end of climate policy as we know it,” he says.

In terms of the energy and climate issues actually discussed during the debate, the biggest factor may be the issue of tariffs and "the real arms race between the two parties to show who's going to be tougher on China," says David Victor, a political scientist at the University of California, San Diego. This could increase the cost of technology imports to the United States and disrupt clean energy supply chains, he adds.

In the end, however, neither the candidates nor the debate moderators spent much time on the topic. “If this debate is a barometer of what will determine the election, it is not climate and energy,” says Victor.