The quick answer is “most probably”, but not “necessarily”. One thing is clear though, whoever becomes the next US president, the world cannot afford to have the second largest greenhouse gas (GHG) emitter in the world withdraw again from the GHG emission reduction targets that it committed to under the Paris Agreement.

Following the US presidential election debate on September 10 between vice-president Kamala Harris and former president Donald Trump, not a lot of coverage was given to the candidates’ responses when asked by moderator Linsey Davis what they would do to address climate change.

Perhaps, this is because their respective positions are already known; and, let’s face it, climate change is not really an exciting topic compared with other issues like “the audience leaving Trump’s rallies out of boredom” or “immigrants eating pets”.

But since climate change is a much longer-term issue that will outlast the term of the next president, it’s still worth mentioning how they responded and what the likely impact of their respective positions would be.

Harris emphasized that climate change is “very real” and pointed to the Biden administration's investments in clean energy. Trump, on the other hand, offered no clear plan to combat climate change and criticized solar farms for requiring large areas of land, claiming they were inefficient. He also reiterated his commitment to boosting oil, gas and coal production.

It’s worth recalling that Trump withdrew the US from its climate change commitments under the Paris agreement (the withdrawal was announced on June 1 2017, but the official exit took effect on November 4 2020, which was one day after the 2020 US presidential election, which was won by Joe Biden) for a variety of reasons, but principally to prioritize US domestic energy production. This meant promoting development of the oil industry, thus further raising the country’s greenhouse gas (GHG) emissions level.

The US is the second-largest GHG emitter in the world, accounting for 11.19% of total GHG emission as of 2022, according to data from the 2023 Report of the Emissions Database for Global Atmospheric Research, published by the European Commission.

Incoming president Biden, however, quickly reversed the withdrawal. The day of his inauguration, January 20 2021, he signed an executive order for the US to officially rejoin the Paris agreement on February 19 2021. Biden’s move signalled his administration’s commitment to addressing climate change and working with other nations to reduce GHG emissions.

If Trump is re-elected, he will likely, based on what he said during the debate, withdraw the US from the Paris agreement again and derail the progress that has already been made towards achieving the GHG reduction targets, not only for the US but on a global level. Since GHG emissions are a global phenomenon, a US failure to meet its commitments to reduce its GHG emission levels will adversely impact the rest of the world.

On the other hand, Harris, during the debate, committed to addressing climate change as a high priority for her administration if she becomes president. As vice-president Harris was already a strong advocate for climate action, helping to push policies that focus on reducing carbon emissions, promoting renewable energy and addressing environmental justice issues.

As a senator, she introduced the Climate Equity Act to ensure that climate policies consider how they affect disadvantaged groups, particularly focusing on the impact it has on low-income and marginalized communities.

Harris has also voiced support for the Green New Deal, an ambitious framework that calls for a transition to renewable energy, jobs in clean energy sectors and addressing the climate crisis with the urgency that scientists have recommended.

Also, Harris has been a part of the legislative discussions on climate change, both as a senator and vice-president, particularly those involving the Infrastructure Investment and Jobs Act and the Inflation Reduction Act, which include substantial investments in clean energy and climate resilience.

Harris is also expected to continue engagement with other signatories to the Paris agreement as she recognizes the importance of global cooperation in combating climate change and may push for more aggressive international commitments.

The big challenge for Harris in pushing her climate change agenda would be getting legislative support for any climate change initiative from the US Congress, something that may be more difficult if it continues to be polarized and divided during her administration. But, if the US Congress is dominated by the Democrats, chances of success for addressing climate change will be better, not only for the US, but for the world.